Year : 2017 | Volume
: 42 | Issue : 5 | Page : 1--17
|How to cite this article:|
. Invited Talks.J Med Phys 2017;42:1-17
|How to cite this URL:|
. Invited Talks. J Med Phys [serial online] 2017 [cited 2023 Mar 28 ];42:1-17
Available from: https://www.jmp.org.in/text.asp?2017/42/5/1/217110
I-1: Production of Carbon Ions for Heavy-Ion Radiotherapy
National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan. E-mail: [email protected]
Introduction: In order to treat a deep-seated tumor with the good localized dose distributions, carbon ion was predicted as a good candidate for heavy-ion radiotherapy by Rovert R. Willson in 1946. Based on physics, lighter ion species cause larger multiple scattering in the deep side, and heavier ion species give unexpected dose over the end-point due to the projectile fragmentation. In addition, the biological dose distribution depends on the depth and thickness of a tumor. In the case of ten and several cm depth and several cm thickness, the linear energy transfer of neon ions is too high than that of carbon ions shown by Lawrence Berkeley Laboratory, University of California in 1980's. Although heavier ions shows other biological advantages like oxygen enhancement ratio, the National Institute of Radiological Sciences (NIRS) chose carbon ions for the clinical trial at the Heavy-Ion Medical Accelerator in Chiba (HIMAC) in 1994. By HIMAC's success, the existing and almost all the planned heavy-ion radiotherapy facilities require a carbon beam.
Objectives: The requirement of carbon-beam intensity strongly depends on the facility design, i.e. the volume and shape of the target, the efficiency of the irradiation method, the transmission of the accelerator complex and so on. In order to obtain the biological dose rate of 5 GyE/min. (roughly equal to a physical dose of 2 Gy/min.), a few 108 particles per second are required at a typical present facility. The long-term stability and reproducibility are important for daily treatment. On the other hand, the short-term stability of the ion sources is not so sensitive. Because the existing facilities consist of a synchrotron and any injector and the fine structure of the beam pulse will almost disappear during the acceleration in the synchrotron. Moreover easy operation and maintenance are also important to reduce the operation cost. An ion source should satisfy these requirements.
Materials and Methods: An electron cyclotron resonance ion source (ECR) has been developed at HIMAC. An ECR ion source is a type of electron bombardment ion sources. The minimum B structure of magnetic field for the plasma confinement consists of a pair of mirror magnets and radial multipole magnet. The microwave is fed to maintain the plasma by ECR heating. The carbon ions are produced from a gaseous compound like CH4 or CO2. Since the ECR ion source has no consumptive or deteriorate parts, it is expected from view points of long lifetime, easy operation and maintenance. At present, ECR ion sources have been adopted at all existing facilities.
Results and Discussion: The existed ECR ion sources have been successfully operated in heavy-ion radiotherapy facilities. On the other hand, it seems that a present typical facility is still too large for a hospital. The size of facility is roughly 3000 m2 and its initial construction cost will be a hundred and several million US dollars. At present the ECR ion source mainly supplies C4+ ions. If it's able to increase the charge state, it can help to reduce the cost of injector. The research and development for the higher charge-state production have been continued. The drastic innovation to change a present typical accelerator structure has been considered too. QST has started a new development project for the combination of a laser acceleration and superconducting magnets. A future ion source will face new requirements and technical problems.
I-2: Introduction to Proton Therapy
Radiation Quality Control Section, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan. E-mail: [email protected]
The aim of this lecture is to provide some introductory knowledge and the most recent status of proton therapy including leading-edge medical physics technology and facilities to medical physicists who are familiar with the radiation therapy using X-rays, electrons, but unfamiliar with proton therapy.
After tracing the history of the charged particle therapy including proton and other ions beam therapy briefly, we will concentrate on the way to make irradiation fields to realize the rationale of the radiotherapy, that is, the delivery of high dose of energy to the tumors while sparing normal tissue around it. High energy proton beams have good property, which is termed, Bragg curve and Bragg peak, to realize the rationale easily compared to X-rays. What makes the Bragg peak will be explained. In addition, we discuss issues related to interactions between charged particle beams and tissues such as linear energy transfer (LET), relative biological effectiveness (RBE) and oxygen enhancement ratio (OER).
We also review some proton beam facilities and their components including ion sources, accelerators, irradiation system, planning system and positioning system and so on. Furthermore, we delineate a picture of the future of proton beam therapy.
Proton therapy is expected to be a promising method for offering the superior quality of life to patients. The number of proton therapy facilities has been increasing over the world. However, there are some issues to be solved such as clinical performance compared to other methods such as IMRT and IGRT, reduction of building and maintenance costs and human resources. There are coming some new technologies and ideas to solve these problems.
I-3: The Present Status of Boron Neutron Capture Therapy in Japan
Division of Radiation Medical Physics, Research Reactor Institute, Kyoto University, Kyoto, Japan. E-mail: [email protected]
The world's first clinical irradiation for boron neutron capture therapy (BNCT) was carried out using a neutron irradiation field for BNCT, installed at Brookhaven Graphite Research Reactor (BGRR) in USA in 1951. The first BNCT clinical irradiation in Japan was carried out at Hitachi Training Reactor (HTR) in 1968. Thereafter, BNCT clinical irradiation had been continuously performed at Musashi Institute of Technology research Reactor (MuITR), Kyoto University Reactor (KUR) and JAERI Research Reactor 2 (JRR-2) in Japan. In Kyoto University Research Reactor Institute (KURRI), BNCT clinical study using the Heavy Water Facility installed in KUR came to be regularly performed from February 1990. At first, BNCT in this institute was performed just for malignant brain tumor and melanoma. The application was extended for head and neck tumors in 2001, and for body tumors such as liver tumor, lung tumor, malignant pleural mesothelioma, etc. in 2005. It may be said that the development of current BNCT is supported by this wider application. There were the several interruption periods, but 510 clinical irradiations were carried out using KUR Heavy Water Facility as of August 2017. For the reactor-based BNCT, it is performed using only a few BNCT facilities at KURRI, National Tsing Hua University in Taiwan and so on, as of August 2017.
For accelerator-based neutron source for BNCT, the combination of Li-7 (p, n) Be-7 reaction and protons of nearly 2.5 MeV was the most reliable and the studies had been performed by some research groups in USA, UK, Russia, and so on, from the early 1980s. Spallation due to high-energy neutrons was expected for the larger neutron yield, and it had been studied by some research groups in Switzerland, and so on. In early 2009, the world's first accelerator-based system for BNCT clinical irradiation, “Cyclotron-Based Epi-thermal Neutron Source (C-BENS)” was completed at KURRI. For C-BENS, the combination of Be-9 (p, n) B-9 reaction and 30-MeV protons was selected. The clinical trial using C-BENS was started in 2012. At present, the development of the accelerator-based irradiation system for BNCT is energetically performed by various groups in the world. Especially in Japan, BNCT using various accelerator-based irradiation systems including C-BENS may be carried out at plural facilities in the near future.
Thus, it is the time when BNCT is shifting from a special particle therapy to a general therapy, now. In order to promote this shift, not only the development and improvement for the irradiation system but also the preparation and improvement in the physical engineering and medical physics, such as dosimetry system, etc., is important. The historical background for BNCT is introduced, and the present status of BNCT, especially in Japan, are reported focusing on the topics for physical engineering and medical physics.
I-4: Beginning of Computer-Aided Diagnosis in Medical Imaging
1Department of Radiology, The University of Chicago, Chicago, Illinois, USA, 2Gunma Prefectural College of Health Sciences, Maebashi, Japan. E-mail: [email protected]
Computer-aided diagnosis (CAD) has become one of the major research subjects in medical physics and diagnostic radiology. Many different types of CAD schemes are being developed for detection and/or characterization of various lesions in medical imaging, including conventional projection radiography, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound imaging. Organs that are currently being subjected to research for CAD include the breast, chest, colon, brain, liver, kidney, and the vascular and skeletal systems. Commercial systems for detection of breast lesions on mammograms have been developed and have received FDA approval for clinical use. It has been reported that more than 10,000 commercial CAD systems have been used at many hospitals, clinics, and screening centers in the United States and in Europe for assisting radiologists in their task of detecting breast cancers. It has been reported also from prospective studies that CAD has provided a gain of approximately 10-20% in the early detection of breast cancers on mammograms.
CAD may be defined as a diagnosis made by a physician who takes into account the computer output as a “second opinion”. The purpose of CAD is to improve the quality and productivity of physicians in their interpretation of radiologic images. The quality of their work can be improved in terms of the accuracy and consistency of their radiologic diagnoses. In addition, the productivity of radiologists is expected to be improved by a reduction in the time required for their image readings. The computer output is derived from quantitative analysis of radiologic images by use of various methods and techniques in computer vision, artificial intelligence, and artificial neural networks (ANNs), including machine learning and deep-learning convolution neural network. The computer output may indicate a number of important parameters, for example, the locations of potential lesions such as lung cancer and breast cancer, the likelihood of malignancy of detected lesions, and the likelihood of various diseases based on differential diagnosis in a given image and clinical parameters. Because the basic concept of CAD is broad and general, CAD is applicable to all imaging modalities, and to all kinds of examinations and images. In this lecture, the basic concept of CAD is first defined, and the current status of CAD research is then briefly described. In addition, the potential impact of CAD in the future is discussed and predicted.
I-5: Journey of Radiology in Last Over 120 Years what a Difference 120 Years Can Make!
Department of Radio-Diagnosis, Santokba Durlabhji Memorial Hospital, Jaipur, Rajasthan, India. E-mail: [email protected]
In November 1895, Wilhelm Conrad Rontgen first produced and detected X-rays.
Rontgen's discovery opened a window on the previously invisible interior of the human body and spawned the existence of an entirely new medical specialty, RADIOLOGY. Roentgen's discovery and its subsequent revolutionary impact represent one of sciences greatest stories. Since these early x-rays, there have been many milestones in the field of radiology including ultrasound, CT scan, MRI, mammography, nuclear imaging including position emission tomography [PET] which are used to diagnose and/or treat disease. In today's era, medical procedures are performed with the guidance of imaging technologies by Interventional Radiologists. While medical imaging technology has greatly advanced in last 120 years, the ways in which radiologists interact with these images has remained largely unchanged. Medical images can now be stored digitally in the picture archiving and communication system [PACS]. Patient can now easily store and share their medical images online. Patients and doctors all over the world can access these digital images any time. Direct access and control to digital medical images is the next evaluation in Radiology.
Despite the ever changing health care landscape, the future of Radiology on the 2017 horizon is bright. Radiologist will continue to play an important role in the journey to value based care from improving patient outcomes to cost efficient techniques. Through the adoption of innovative technologies and solutions, radiology will not only continue to make an impact, but will drastically improve overall quality of care.
I-6: What if Radiology was an Art? When Relationships Define Image Quality and Not the Physics
Hogeschool, Medical Imaging IMAGO, Universiteit Brussel Health Sciences, Brussels, Belgium. E-mail: [email protected]
Loved by some, hated by others, the appreciation for art has always been a discussion in cultures and societies. What if a radiology department was just a small society? A society of different professions, collaborating to produce an acceptable radiography, with their background and ideas on the quality of a radiograph? Based on current research, the interaction between radiologists and radiographers will be analysed within the sociology framework. After outlining the cornerstones of this inter-professional culture, the influence of relationships on learning strategies and assessment of image quality will lead the reasoning to the conclusion of a common “gestalt” or the presence of a shared mental image of the ideal radiograph. In a “high tech” department, such as medical imaging, the role of technology and the interaction with the users cannot be neglected. After outlining the interpretative framework of current post-phenomenology, key points of human-machine interactions will be combined with the gestalt. The combination of sociology and phenomenology leads into a more philosophical approach to image quality, maybe unconventional, but therefore not less exciting.
I-7: Codes of Conduct and Codes of Ethics in Medical Physics
W. Howell Round
School of Engineering, University of Waikato, Hamilton, New Zealand. E-mail: [email protected]
Purpose: Many organizations and societies that represent professional groups have a “Codes of Conduct” or “Codes of Ethics” document that their members commit to abide by. The Asia-Oceania Federation of Organizations for Medical Physics (AFOMP) has decided to produce a Code of Ethics to act as a model for its national member organizations to adopt.
Methods: A survey was made of a number of medical physics professional societies and organizations to obtain their codes of conduct or ethics. This was initially done by searching on-line for such statements, and later most of the IOMP member organizations were approached individually for copies of their codes of conduct or ethics.
Results: It was clear that very few such statements have been developed by medical physics professional societies or organizations. Those that had been developed ranged from short outlines that covered a couple of pages to in-depth statements running to a dozen pages that set out complaint and disciplinary procedures. In some countries, medical physicists are subject to codes of conduct or codes of ethics that have been developed by government agencies to apply to all medical disciplines and employees.
Medical physicists' codes tend to follow the same principles. These principles are commonly found in the codes of many professional bodies both within and outside of the medical based professions such as engineering and teaching. These are Professional Ethics, (1) Commitment to patients/society, (2) Accept responsibility for their work, (3) Work within limits of knowledge/experience, (4) Integrity, fairness and confidentiality, (5) Avoid conflicts of interest, (6) Stay up to date, (7) Report unethical behavior.
Research Ethics, (1) Fulfill legal/regulatory relations, (2) Get approval from relevant ethics committee, (3) Welfare of patients and animals, (4) Fully inform patients, (5) Don't misrepresent results, (6) Appropriate acknowledgement in publication.
Education Ethics, (1) Respect students/safe environment, (2) Equal opportunity/no discrimination, (3) Commit to students' completion, (4) Fair evaluation, (5) Confidentiality, (6) Students' right to review records/evaluation, (7) Avoid consensual relationships.
It must be noted, though, that many codes of ethics focus only on the professional ethics listed above. However, as medical physicists are often involved in research and development and in education and training, then ethical behaviour in research and education are also important.
Conclusions: As AFOMP is an umbrella organization for approximately 20 medical physics national member organizations from different countries, it needs to develop a code of ethics that is acceptable to all of its members taking into consideration the different cultures involved. This does not mean that it should set low expectations for the ethical conduct of the medical physicists in those countries, but it must still specify standards that are internationally acceptable.
I-8: Resources to Run an RT Department - Staffing and Materials
Chair, International Educational Activities Committee (AAPM), Chair, Professional Relations Committee (IOMP), New York, USA. E-mail: [email protected]
I-9: From IOMP To IMPCB: How a Decades Old Wish Became Reality
Raymond K. Wu
Chief Executive Officer, International Medical Physics Certification Board, Phoenix, Arizona, Professor in Radiation Oncology (Retired), Eastern Virginia Medical School, Norfolk, Virginia, USA. E-mail: [email protected]
The International Labour Office in 2008 published the International Standard Classification of Occupations ISCO-08. In which the occupation of Medical Physicist is recognized with other professions under Group 2111 Physicists and Astronomers. A note was included on page 111 “medical physicists are considered to be an integral part of the health workforce alongside those occupations classified in Group 22: Health Professionals”. IOMP subsequently published the Policy Statements 1 and 2, which outlined the role and responsibilities of Medical Physicists, the academic qualifications, and training requirements. In May 23rd 2010, the International Medical Physics Certification Board (IMPCB) was officially formed with help from IOMP and the IOMP Professional Relations Committee. At present there are fifteen Supporting Organizations of which IOMP is the Principal Supporting Organization. With the support of IOMP and other organizations, IMPCB can focus on standardization and accreditation of certification programs in accordance with IOMP guidelines. IOMP also provides supports through the scientific and educational programs for the benefit of certified individuals for continuing professional development purposes. In 2014 IMPCB began its accreditation program for local certification programs. Two programs had been fully accredited and the third one is being evaluated. In 2017, the first direct certification examinations session was offered in Trieste Italy in May for Part I and Part II, followed by other examination sessions in December (please refer to www.IMPCB.org). Only the specialty of Radiation Oncology Physics is offered for 2017 examinations. It is expected that in 2018 the specialty of Diagnostic Imaging and Interventional Radiological Physics will be included in examination sessions in Prague during the World Congress and elsewhere. In this special symposium the author will present the background and missions of IMPCB. He will make a report of the progress of IMPCB in the past twelve months. He will then announce the IMPCB near term plans, and explore the potential long term evolution as driven by the changes in the field and in the society. Requirements for accreditation of local certification boards will be described in the perspectives of US, Asian Oceania, and European medical physicists. Finally the author will explain how IMPCB upholds the policy statements of IOMP to achieve the goal of identifying those meeting the minimum requirements and confers the Board Certificates. Time will be reserved for open discussions with a panel of IMPCB officeholders.
I-10: Education Trends After the Official Recognition of Medical Physics Occupation in ISCO08
President, International Organisation for Medical Physics (IOMP), Department of Medical Engineering and Physics, King's College London, UK. E-mail: [email protected]
One of the main achievements of the International Organisation for Medical Physics (IOMP) during 2011 was the inclusion of Medical Physics in the International Standard Classification of Occupations (ISCO). This was a result of many years hard work of the IUPESM, IOMP and IFMBE. This recognition of the profession by the International Labour Organisation opens new horizons and presents new challenges in front of us.
A specific horizon is the growing need of medical physicists in hospitals, as our profession is already an important part of the infrastructure of healthcare provision. This reflects in the need of opening new university courses in medical physics. To help with this IOMP published in 2011 a Guide for establishing such courses– the Model Curriculum and recently started Accreditation activities. This is related to the double growth of our profession in the past 20 years and the expected triple growth of the profession in the future 20 years.
One of the challenges in front of our Education is how to accommodate the constantly increasing volume of the professional knowledge in the limited space available in a post-graduate (MSc) teaching programme. A number of medical physics courses already cut parts of the teaching programme in order to include newer methods. This is expected to be topped-up during the practical training, following the university education, but such training is not offered in all places. At the same time some universities are offering introductory medical physics modules at BSc level, which are very attractive for students. This has led to the beginning of formation of new under-graduate (BSc) programmes in Medical Physics. The lecture will present several successful examples of such BSc-level programme.
I-11: Processing of Medical Image Using Lattice Boltzmann Method Case Study: Cerebral Aneurysm Segmentation
Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Homi Bhabha National Institute, Mumbai, Maharashtra, India. E-mail: [email protected]
Recent advancement of multiscale multiphysics solution in the field of medical imaging invites mesoscopic mathematical tool for solving macroscopic fluid dynamics problems generally described by partial differential equations (e.g., Navier-Stokes equations in case of fluid mechanics problems). The Lattice Boltzmann Method (LBM) is an appropriate technique to achieve this target. The idea of the LBM is to construct or simulate a simplified discrete dynamics of macroscopic behaviours at mesoscopic scales by implementing distributions of particles on a lattice. Literature study on several research papers suggest that LBM is a promising tool to image processing. The LBM to image processing, especially to nonlinear anisotropic diffusion of images is first time applied by Jawerth et al ., Zhao proposed the GPU-accelerated LBM to solve the diffusion lattice problems including volume smoothing, surface fairing and image editing. LBM for image denoising was mentioned in. It can be proved that LBM based anisotropic diffusion model makes medical images smooth. Also Wang et al . proposed a LBM-based anisotropic diffusion model to segment the lumen and the thrombus of aneurysm. An aneurysm is an abnormal bulging outward of an artery. Because of certain histopathologic and hemodynamic factors, aneurysms most commonly occur in arteries that supply blood to the brain. Cerebral aneurysm is a fragile area on the wall of a blood vessel in the brain, which can rupture and cause major bleeding and cerebrovascular accidents. The segmentation of cerebral aneurysm is a primordial step for diagnosis assistance, treatment and surgery planning. Unfortunately, manual segmentation is still an important part in clinical angiography but has become a burden given the huge amount of data generated by medical imaging systems. Automatic image segmentation techniques such as partial differential equation based segmentation provides an essential way to simplify and speed up clinical examinations, reduce the amount of manual interaction and lower inter operator variability. The central idea of partial differential equation based methods is to evolve an initial curve towards to the lowest potential of a cost function, where its definition reflects the task to be addressed. Mostly, the minimization of the cost functional can be expressed as geometrical constraints on the evolving curve. One of the partial differential equation based aneurysm image segmentation technique known as lattice Boltzmann based geodesic active contour method (LBGACM) has been applied for segmentation of cerebral aneurysm image. Mathematical and computational details of LBGACM are beyond scope in the abstract, however, in this method, LBM applies to solve the GAC evolution equation. Cerebral aneurysm is one of the most serious diseases forming part of the stroke, and it is estimated to occur in 1 to 6 percent of the population. Also, up to 85 percent of subarachnoid haemorrhages, which are potentially lethal events with mortality rate as high as 50 percent are caused by the rupture of cerebral aneurysms. Computed tomography angiography (CTA) plays an essential role in the diagnosis, treatment evaluation, and monitoring of cerebral aneurysms. It allows us to detect narrowing or obstruction of blood vessels in time so that corrective therapy can be done, and it can also detect the minute changes in the vessel structure and anatomy. In addition, CTA images may give more precise anatomical details than either ultrasound or magnetic resonance images (MRI), particularly for small blood vessels. Now, CTA is becoming the radiological examination of choice for blood vessels diseases.
The lumen appearing as a focal object of giant aneurysms and thrombus part of the same having a low contrast compared to neighbouring tissues makes it difficult to obtain the manual or automatic segmentation reasoning the segmentation of giant aneurysms of the brain from CTA imaging remains a challenge. In this talk, an innovative segmentation methodology based on the combined use of the LBM and the level set method is proposed. The first methodology consists in extracting the group consisting of lumen and thrombus using a procedure in two steps, then refining the shape of the thrombus using the level set method. A typical experiments are performed on 258 slices of 8 patients CTAs with different types of giant aneurysms. The results on real images showed that the proposed method is comparable to manual segmentation, and quantitatively, the matching factors obtained using the proposed method are high, demonstrating good accuracy of the segmentation. The computational scheme of LBGACM based segmentation technique will be presented in detail.
Jawerth B, Lin P, Sinzinger E. Lattice Boltzmann models for anisotropic diffusion of images. J Math Imaging Vis1999;11:231-7.Zhao Y. Lattice Boltzmann based PDE solver on the GPU. Vis Comput 2008;24:323-33.Wolf-Gladrow D. A lattice Boltzmann equation for diffusion. J Stat Phys1995;79:1023-32.Chang Q, Yang T. A lattice Boltzmann method for image denoising. IEEE Trans Image Process 2009;18:2797-802.Wang Y, Courbebaisse G, Zhu YM. Segmentation of Giant Cerebral Aneurysms using a Multilevel Object Detection Scheme Based on Lattice Boltzmann Method. In Signal Processing, Communications and Computing (ICSPCC), 2011 IEEE International Conference on, IEEE. 2011. p. 1-4.Seibert B, Tummala RP, Chow R, Faridar A, Mousavi SA, Divani AA, et al. Intracranial aneurysms: Review of current treatment options and outcomes. Front Neurol 2011;2:45.
I-12: Recent Developments on Magnetic Nanoparticles and their Applications in Magnetic Hyperthermia and Drug Delivery
Ambesh Dixit1,2, Suvra Laha1,2, Humeshkar2
1Department of Physics and Center for Solar Energy, Indian Institute of Technology, Jodhpur, Rajasthan, India, 2Department of Physics and Astronomy, Wayne State University, Detroit, Michigan, USA. E-mail: [email protected]
Magnetic nanoparticles (MNP) are attracting attention due to their potential for numerous applications including spin electronics, magnetic storage, ferrofluids, and microfluidics in conjunction with biomedical applications. MNPs provide a multifunctional platform for magnetic hyperthermia treatments acting as a localized source of heat, magnetically guided targeted drug delivery, magnetic resonance imaging (MRI) contrast agents and magnetic separation. MNPs are beneficial due to their (i) small crystallite size (few nanometer), which provides easy intravenous injection and externally controlled delivery via bloodstream to the malignant tumor that is not possible with other means; (ii) high surface to volume ratio for MNPs allows for surface engineering with few or multiple recognition molecules, which can assure targeting toward specific tumor tissues; and (iii) the remote heating of MNPs by the externally applied magnetic field allows the heat action only to the zone of accumulation of nanoparticles.
The magnetic hyperthermia is used in treating cancer using magnetically mediated localized heating with the aid of external oscillating magnetic field as malignant cancers cells start dying at or above 41°C. The onset of heating is either from the hysteresis losses or from Neel or Brown relaxation process and depends on geometry, composition, and magnetic moment of the MNPs in conjunction with the applied frequency and magnetic field strength. In addition, MNPs can be integrated/functionalized for loading and releasing drug, magnetically targeted to a specific site and activated for drug release. The discussion will cover the impact of magnetic nanoparticle anisotropy on magnetic properties leading to efficient magnetic hyperthermia and drug delivery. The associated physics and challenges will be covered in realizing the in vivo clinical trials for both magnetic hyperthermia and drug delivery.
I-13: Implementing Egsnrc Monte Carlo in a Clinical Setup and its Potential Applications
B. Paul Ravindran
Professor of Radiation Physics, Department of Radiation Oncology, Christian Medical College, Vellore, India. E-mail: [email protected]
Introduction: Radiation dose calculation plays a very important role in radiotherapy treatment planning and quality assurance. Though there are several algorithms that have been developed to get accurate dose calculation, Monte Carlo (MC) simulation is known to be the most accurate method for radiotherapy. In MC simulation, one computes how a particle propagates step by step according to fundamental physics principles. A number of MC algorithms have been developed, viz., as EGS4/5, EGSnrc, MCNP, PENELOPE, and GEANT4. In this work we describe the implementation of EGSnrc in our clinic.
Materials and Methods: EGSnrc Monte Carlo: The history of the EGSnrc system and underlying codes date back to the 1970s, called the Electron Gamma Shower (EGS), but we have now implemented the one of recent versions of EGSnrc (2016). The system is owned and maintained by the National Research Council (NRC) of Canada. The EGSnrc has two main modules; the BEAMnrc a general purpose user code for simulating radiation sources and DOSXYZnrc a general purpose EGSnrc user code to score an absorbed dose in a rectilinear voxelised phantom geometry. For the use of CT dataset, another user code, ctcreate , has been provided, that allows the user to build a DOSXYZnrc phantom from a CT dataset. Modelling linac for EGSnrc: BEAMnrc is a general purpose EGSnrc user code for simulating radiation sources and modelling radiation transport through various structures, such as alinac treatment head. In the case of linac, the simulation is based on the geometry model of the treatment head. The user specifies the various parts of the treatment head using the component modules (CMs) where each structure of the linac head is entered as a CM and the accelerator model thus built with various input parameters and cross-section data is compiled prior to simulation. The output data of the EGSnrc is collected on a user-specified plane, to a phase space file, in which the energy, position, direction, weight and charge of each particle are recorded which serves as an input for the DOSXYZnrc for generating the dose distribution in the phantom. For IX models linacs, the treatment head geometry and material information are provided by Varian, but for TrueBeam, the IAEA phase space files at the level of the collimator is provided which could be used as input to obtain the phase space file at the phantom surface. DOSXYZnrc: This is a user code provided to generate the phantom and the dose deposition in the phantom. The output phase space file from the EGSnrc is used as the input file and the phantom geometry is defined in DOSXYZnrc to obtain the dose distribution. The calculated dose deposition is written in an output file with '3ddose' extension by the DOSXYZnrc. An in-house Matlab routine was developed to read the 3Ddose file, the output file of the DOSXYZnrc. The depth dose, beam profile and the output factor data could be derived using the Matlab code.
Conclusion: Implementation of Monte Carlo: One of the issues in MC simulation is the long computational time and porting MC packages onto parallel computing architectures is a direct way for increasing their efficiency. To address this a multi core (16 core) processor is used in our clinic and a bash script that splits an EGSnrc command over “n” independent processes was used where “n” is the number of cores in the CPU. The other method to further increase the processing speed is to distribute jobs over a number of computers in a cluster and we hope to implement this in future.
I-14: Clinical Electron Bram Dosimetry: Transition from AAPM TG-25 TO AAPM TG-70
Radiation Physics Division, Department of Radiation Oncology, Perelman Center for Advanced Medicine, University of Pennsylvania, Philadelphia, PA, USA. E-mail: [email protected]
The absolute calibration of clinical electron beams is increasingly based on TG-51 protocol. In addition, recently published dosimetry data on electrons beams bring up the question of how would one need to modify the widely used TG-25 that originally was based on TG-21 calibration protocol?
The answer to the question is given by the recently published TG-70. This new protocol operates as supplement and update to TG-25 on issues that need to be modified because of TG-51 approach to electron dosimetry and because of newer data on clinical electron beams. It describes in detail the procedure of converting measured depth-ionization curves with ion chambers into depth-dose curves, making use of recently published stopping-power ratios and other conversion factors. It also describes the use of water equivalent phantoms to perform relative electron dosimetry based on recently published conversions factors. The report discusses small and irregularly shaped electron field dosimetry using the concept of lateral buildup ratio (LBR) as an avenue to evaluate electronic equilibrium and compute dose per MU for those fields. Finally, it gives some common clinical examples where electron beam dosimetry are applied.
This presentation will try to provide assistance to better understanding the methods and recommendations in TG-70. In addition, how to link the absolute dose calibration recommendations of TG-51 to the relative dose measurements of TG-71.
Educational Objectives: (1) Understand how TG-70 is a modification of TG-25. (2) Understand the methodologies presented in TG-70 for relative electron beam dosimetry. (3) Understand the practical use of clinical electron beams via clinical examples. (4) Outline the major recommendations of TG-70.
I-15: New Approach to Managing Radiotherapy Patients with Cardiac Implanted Devices: Modern Technology RT and CIEDS
Dimitris Mihailidis, Bipin Agarwal1, Moyed Miften2
Radiation Physics Division, Department of Radiation Oncology, Perelman Center for Advanced Medicine, University of Pennsylvania, Philadelphia, PA, USA, 1Chief Physicist, Department of Radiation Oncology, Phoebe Putney Memorial Hospital, Albany, GA, 2School of Medicine, University of Colorado, Denver, CO, USA. E-mail: [email protected]
It has been twenty years since the AAPM published TG-34 on cardiac pacemakers of older technology, which has been the standard document for clinical use, even today, for managing patients with pacemakers (ICPs). Management of radiotherapy patients with modern technology cardiac implantable electronic devices (CIEDs) has been widely published in literature without the provision of a new comprehensive and concise set of recommendations. This need is clearly supported by the numerous publications in literature on effects of different irradiation modalities on pacemakers and defibrillators, the last 10 years. As treatment delivery technologies (IMRT, SBRT, dose escalations, proton beams, etc.,) and CIED technology advance, the need to address the management of patients with such devices receiving radiation treatment becomes increasingly important. As such, this session will provide updated guidance for caring for radiotherapy patients with CIEDs.
Learning Objectives: (1) Review the purpose and function of CIEDs. (2) Provide a review on sources of potential malfunctions of modern CIEDs, including malfunction mechanisms from high-LET radiation and transient effects attributed to medical imaging for radiotherapy. (3) Review the management of radiotherapy patients with cardiac devices. (4) Utilize recently available data and computation methods of out-of-field/peripheral dose by scattered photons and secondary neutrons estimate cumulative doses to CIEDs during treatment. Risk of failure associated with these doses will be discussed. (5) Provide comprehensive recommendations for management of radiotherapy patients with implanted cardiac devices from initial patient consultation to treatment delivery.
I-16: Motion Management in Radiation Therapy
School of Medicine, Washington University in St. Louis, St. Louis, Missouri, USA. E-mail: [email protected]
Motion management in Radiation Therapy (MMRT) is important for tumors that move. Intra fraction motion is an issue that needs to be addressed during simulation, planning and treatment delivery. During simulation, a surrogate device is used that correlates the position of the tumor to the respiratory cycle to generate a 4DCT. Various methodologies in 4DCT, namely phase and amplitude based binning and generation of Maximum intensity projections (MIP), Minimum intensity projections (minIP), or Average Intensity projections (AI) will be reviewed. Depending on the method chosen for treatment delivery, the target delineation can be restricted to individual phases like exhale, inhale or part or entire tumor motion envelope (Internal Tumor Volume (ITV). Average or Helical CT can be used for treatment planning. Treatment Delivery during tumor motion causes blurring of the dose distribution. Using respiratory synchronized techniques can reduce this blurring by turning the beam ON/OFF during the selected period of the breathing cycle or by moving the Multileaf collimators (MLCs) to track the tumor motion. Various motion management techniques like breath hold, active breathing control (ABC), self-controlled breathing, forced shallow breathing or automated respiratory synchronized techniques like gating or tracking and the quality assurance recommendations from TG76 and TG142 will be discussed.
Learning Objectives: (1) Understand the methods to acquire a 4D CT scan and its use in treatment planning and treatment delivery. (2) Discuss commissioning and QA Methods. (3) Discuss which clinical tumor sites would benefit from Motion Management.
I-17: Challenges of High Tech Radiotherapy: A Radiation Oncologist'S Perspective
Department of Radiation Oncology, Bhagwan Mahaveer Cancer Hospital & Research Centre, Jaipur, Rajasthan, India. E-mail: [email protected]
Ongoing innovations in radiation oncology pose a challenge to the radiation oncologist to develop the beneficial and safe treatments for patients as well as to integrate them effectively in to the multimodality treatment. The revolution in radiation therapy has made the results comparable to standard surgical techniques in some cases. With the newer technologies like Intensity Modulated Radiation therapy (IMRT), Image Guided radiation Therapy (IGRT), Volumetric Modulated Arc Therapy (VMAT), Stereotactic Body RT (SBRT) therapeutic window is widening. But every leap and progress in science has to pay some price and so have the technological advances in RT. These challenges could be technical, psychological, economical and ethical.
Technical challenges include lack of experience and training in using the high precision radiation techniques. One has to constantly keep abreast not only about the sophisticated RT techniques but has to keep pace with the evolving sister modalities-chemotherapy and surgery. With the advent of volumetric RT planning the knowledge of anatomy has become very pertinent.
Contouring, verification of plans and QA checks consume lot of time but they have become an integral part of life of a modern radiation oncologist. In high tech RT, the margins around targets have tightened and there is a gradual shift from conventional fractionation to hypo fractionation. Dose escalation is being experimented because of sub millimeter precision. Radiation oncologists have to be more vigilant than ever before about geographic miss of target and dose to OARS because with high doses per fraction and tight margins these lapses could be hazardous.
With the easy access to technology we are now dealing with more educated and aware patients and their families. Their expectations have gone up. One has to customize treatment for every patient. Counseling has become even more important as one has to explain the patient and family why a particular modality (which may not necessarily be the most expensive one) will be optimum.
Availability and access to high tech facility, trained personnel and funds for above remain an unmet need in ever growing cancer population in a developing country like ours. The cancer treatment is becoming expensive day by day as there is a cost for high tech RT, newer chemotherapeutic and targeted drugs and advanced surgical procedures. Often we face dilemma of choosing a better modality which is more apt or the modality the one which the patient can afford. Though health insurance is coming up but still it has a long way to go.
With the existing market forces, pressure from the employees who have invested huge sum in high tech RT equipments, colleagues who may advertise that a particular technique is the only way to cure, the pressure to overuse the high tech RT is tremendous. To follow evidence based treatment and maintain ethnical practice is a tough task for a radiation oncologist in high tech RT era.
In a world of constant progress the driving force for changing our perspective must arise from within if we wish to be a part of the mainstream.
I-18: High Tech Radiotherapy: Challenges in the Perspective of Medical Physicists
K. Krishna Murthy, P. B. L. D. Prasad, K. Kaviarasu, T. Pratap Reddy
Department of Radiation Oncology, Krishna Institute of Medical Sciences, Secunderabad, Telangana, India. E-mail: [email protected]
The aim of high tech radiotherapy is to reduce radiation damage in healthy tissue while delivering desired optimal dose to the cancerous tissues (target volume). This principle has evolved many technical advances in the field and is achieved by integrating image modalities for contouring, numerical algorithms for planning, IGRT systems for delivery verification and software and networking systems to manage quality assurance of the treatments.
Exploiting the integration of these advances has led to the current high tech therapeutic approaches such as IMRT, VMAT, SRS, SBRT, IGRT, Heavy ion and proton therapy etc. Technological innovations continue to progress and improve the accuracy and precision both in the delivery and quality assurance of RT. The increasing complexity of radiation therapy planning and delivery posing many challenges to Medical Physicists in quality management of high tech radiation therapy. To meet the challenges a Medical Physicist must understand the complexity of using new and emerging technologies and implement thorough QA protocols, possibly driven by increased regulations. The challenges in the perspective of Medical Physicists are;
Perspective-I: Imaging Related Challenges: (a) Image registration, fusion of various types of images for planning, (b) Verification and IGRT related images.
Perspective-II: Planning Related Challenges: (a) Thorough knowledge about beam data configuration and various softwares, (b) IMRT, VMAT, SRS, SBRT related planning techniques.
Perspective-III: Machine Specific QA Challenges: (a) QA related to Linacs with MLCs, OBI, Exactrac system, RPM- gating, FFF etc., (b) QA related to cyber knife, Tomotherapy, Gamma knife, Linacs with MRI, Heavy ion and Proton therapy units.
Perspective-IV: Patient Specific QA Challenges; (a) Various dosimetric systems and (b) Small field dosimetry.
Action Plans Needed to Meet the Challenges: The AMPI and CMPI should look for the: (a) Preparation of need based protocols such as TG100 and Auditing like NABH, (b) Planning of need based training programmes such as providing more in-depth training (for example, establishing a website and give QM recommendations regarding various radiation therapy procedures and technologies. Provide web based training and focused workshops on quality and safety in radiation). In this talk, the challenges posed to a Medical Physicist in high tech radiotherapy planning, delivery, implementation of QA and need for the changes required to meet them are discussed.
I-19: The Emerging Technological Development Challenges and Ways to Address Them: RTT Perspective
Rakesh Kaul, R. K. Munjal
Department of Radiation Oncology, Max Super Speciality Hospital, New Delhi, India. E-mail: [email protected]
The Radiation Delivery method plays a critical role in achieving primary goal that is improving cure and control of malignant tumors through the use of emerging technologies in Radiation Oncology. Technological development in Radiation Therapy such as 3D-CRT, Intensity Modulated Radiation Therapy, SRS, SBRT and Gating all are non-invasive treatments that precisely deliver high doses of focused Radiation beams to tumors.
In addition to technological developments there has been a parallel advances in imaging technology and computer software that has led to significant improvement in the Radiation Therapy treatment accuracy. These technological development have provided improved outcomes and better quality of life for cancer patients. However there are chances which may result in unintended harm if not used properly. It is, therefore essential that adoption of these new Technologies be evidence based and should be implemented in clinical practice cautiously.
The main Health professionals involved in the delivery and execution of Radiation treatment are Radiation Oncologist, Medical Physicist and Radiotherapy Technologist. Each of the disciplines work through an integral process to plan, execute and deliver quality radiotherapy treatment to patients.
The potential or actual use of new technologies raises questions about cost, efficacy and ethics. The increased capital and operating costs and economic burden of increased QA is a challenging. Advanced technologies have many advantages but it requires well qualified professional and excellent QA/QC programs, as there is a little chance of adjustment once the treatment has been initiated.
With the development of emerging technology the professional role of Radiotherapy Technologists (RTT's) has changed tremendously over the last two decades. Presently RTT's task include, Mould room procedures, simulator planning, patient positioning and image verification to treatment delivery. But with the emerging technological development the RTT's role should be wider and should open more advance scope for practice. From the RTT's perspective there are various challenges while adopting and implementing new techniques and technology which needs to address in a professional way (1) Active participation in professional growth through training and continuing education, research and development and improving and delivering high quality patient cancer care. (2) Involvement in developing protocols, work instructions and training and reviewing current practice. (3) Extensive training and how to use the diagnostic image modalities effectively such as CT, MRI, PET and ultrasound based images in Radiotherapy planning. (4) To have an important role during on (On line / Off Line) image verification on Medical linear accelerator and involvement in decision making for re-planning. (5) Machine QA - Patient specific QA for all patients and dosimetric procedures. (6) Use knowledge, skills and compassion to attend to normal and emergency patient needs. (7) Demonstrate effective communication skills with patient and their relatives.
I-20: Real-Time MR Guided Advancements in RT
Bhudatt Paliwal, K. Mittauer, P. Yadav, D. Tewatia, J. Bayouth, M. L. Bassetti
Departments of Human Oncology and Medical Physics, School of Medicine & Public Health, University of Wisconsin, Madison, WI, USA. E-mail: [email protected]
With the advent of MR integrated radiation therapy systems there has been a significant advancement in the delivery of radiation therapy. Real-time MR imaging provides high quality MRI images, with superior soft-tissue contrast. This ability has contributed to innovative approach to manage respiratory and cardiac motionas well as the impact of gastrointestinal processes. New MR acquisition techniques reduce imaging times to about 12 seconds, providing 3D MRI sequence for motion artifact-free images with a large field of view (FOV) for short breath hold. Image based breathold management for gating is relatively superior to operator guidance.
Real-time MR guidance, on-table adaptive therapy, allows to incorporate anatomical changes that can take place within a short period of time. Treatment plan can be re-optimized to escalate or de-escalate dose based upon the proximity of nearby critical structures while the patient is on the treatment table. A seamless workflow permits re-planning to reduce dose to organs at risk while giving a greater dose to the target.
Clinical examples of lung, liver, pancreas and duodenum cases will be used to illustrate the above advances and the adaptive capability of an MR integrated radiation therapy system. The benefits of real-time adaptive therapy applied to previously untreatable targets will be highlighted.
Further transition from a Cobalt to Linac systems will be described.
I-21: Mitigation of Consequential Effects of Misadministration in Nuclear Medicine
A. K. Shukla
Department of Nuclear Medicine, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India. E-mail: [email protected]
Misadministration as such includes the practices in nuclear medicine where wrong radiopharmaceutical or excess/inadequate radioactivity is administered to a patient causing undesirable radiation doses or repeat procedure in a patient. Misadministration is also said to have been caused if unjustified procedure involving use of radioactivity/radiopharmaceuticals is conducted either in pregnant or lactating female patients. Incorrect route of activity administration can also cause misadministration and may lead to repeat of the procedure apart fro undesirable radiation doses to patients. As a matter of fact each centre should establish its own guidance levels and protocols for diagnostic and therapeutic procedures in Nuclear Medicine. In general any deviation of administered activity of more than twenty five per cent from the prescribed activity in the guidance level would be regarded as misadministration. The absence of local rules to deal with abnormal situations can also lead to misadministration.
Causative Factors: The causative factors for misadministration include (1) Miscommunications, invisible labeling of vials/syringes containing activity, (2) Distraction due to increased patient load or ahy other stressful conditions, (30 Unawareness about the emergency procedures/absence of safety protocols, (4) Inefficient quality assurance and audit to detect inadequacies.
In addition to above listed factors it is also important to record the initiating events and contributing factors identified in cases of emergencies so as to ensure prevention of the similar incidents and potential radiation exposures in future.
Mitigational Initiatives: (1) Minimize and contain adverse effects by using all safety related protocols/devices, (2) Inform patient, referring physician and the nuclear physician, (3) Calculate radiation dose and institute corrective measures with prompt implementation, (4) A comprehensive event report to be prepared for submission to regulatory authority, (5) Concerned staff to be notified about the accident/misadministration, (6) Removal of orally administered radiopharmaceutical by use of laxatives, enemas, emesis and gastric lavage, (7) Induced and rapid excretion of administered radiopharmaceuticals by hydration or dieresis, (8) In case of serious patients removal of urine by catheterization, (9) Appropriate use of blocking agents to reduce radiation dose to thyroid, salivary gland and stomach etc.
Illustrative Example: A middle aged female patient scheduled for thyroid scan reported the department and informed the concerned technologist that she has no evidence of pregnancy but she was trying to get pregnant. The patient, however, was curious to know about the associated radiation risks if any and justification of the diagnostic examination. Technologist due to distracting factors misunderstood the patient and got an impression that patient is not interested in getting the examination done. The patient was persuaded to get the examination done and later it was found that the patient was in her early stages of pregnancy.
In a usual course the local rules of the department would have stated that a female patient to be considered as pregnant unless proven otherwise. However the absence of any local rules this could not be ascertained.
It can therefore be contemplated that precise guidelines in concordance with regulatory requirements need to be evolved specifically including the common factors that might lead to adverse effects from patient safety viewpoint and are attributable to therapeutic and diagnostic procedures involving use of radiopharmaceuticals/radioisotopes.
I-22: Preparedness for Response to Radiological Emergencies
K S Pradeep Kumar
Outstanding Scientist(OS), Associate Director, HS&E Group, Head, Radiation Safety Systems Division, Bbhabha Atomic Research Centre, Trombay, Mumbai, Maharashtra, India. E-mail: [email protected]
I-23: Recent Advances in Brachytherapy
D. D. Deshpande
Department of Medical Physics, Tata Memorial Hospital, Parel, Mumbai, Maharashtra, India. E-mail: [email protected]
Introduction: The advantage of brachytherapy is the ability to deliver very high dose to the tumour while sparing the surrounding critical organs. The brachytherapy has evolved tremendously over past few decades. High Dose Rate (HDR) remote after-loading coupled with advances in treatment planning systems has ensured well defined protocols and methods for brachytherapy dose analysis. Recently use of imaging techniques for 3-D data acquisition for brachytherapy application, contouring and treatment planning hasmade significant contribution for better brachytherapy dose delivery.
Imaging in Brachytherapy: Orthogonal radiographs generally are used widely to feed the source positions and applicator geometry to obtain the brachytherapy plan. The CT and MRI are also being used for contouring various volumes like target and clinical organs which coupled with 3-D planning algorithms gives direct doses to critical organs with volume analysis. In case of intracavitary application MRI gives better visualization of soft tissue so that we can more clearly see the critical organs like bladder and rectum
Axial, sagittal and coronal images of MRI are being used for ICA planning. Delineation of GTV, HRCTV and OARs were performed. Reconstruction of applicators can be done with special dummy markers (water/gadolinium) inserted in the applicators.
Target and Other Volume Definitions: Treatment planning aims that the tumor receives the maximum dose and Organs At Risk (OAR's) receive the minimum.
International Commission on Radiation units and measurements (ICRU) through its various reports has standardized the brachytherapy treatments to a great extent. The most important was ICRU 38 (1985) which has given guidelines for reporting intracavitary therapy in Gynecology. American Brachytherapy Society (ABS) Image guided Brachytherapy working group (IGBWG) have provided guidelines in reporting the image based brachytherapy, which recommends the prescription of dose to a volume rather than a point. Later GEC ESTRO published guidelines for the practice and reporting of image based ICA, which has been widely accepted so that a unified approach is formed among the users of image based brachytherapy.
3D Planning in Interstitial Brachyterapy: The interstitial brachytherapy is carried out extensively in H and N, soft tissue, prostate etc. The CT images taken with dummies in the catheters and are directly transferred to planning system. The catheters are input by tracking algorithm and dose distribution is analyzed in 3D view. The target volume and surrounding critical organs are also marked, which helps in evaluation of dose to these volumes by DVH analysis and dose volume indices.
With stepping source dosimetry system (SSDS) with HDR brachytherapy use of wide variations of source positions inside the catheters and different dwell times for each position is possible. Also various optimization techniques like Geometric optimization, Dose point optimization, polynomial optimization etc. can be adopted after visualizing 3-D images of the target volume, implanted needles and dose distribution.
Imaging in Brachytherapy Application: The imaging also plays important role in actual application of brachytherapy in operation theatre. Ultrasound guided prostate I-125 seed implants are commonly performed. Also needle (template) prostate implant under the guidance of Transrectal Ultrasound probe (TRUS) is widely used. US guided intracavitary application is also performed so as to avoid perforation of uterine wall.
I-24: Image Guided Application in Medical Physics
Tae Suk Suh
Department of Biomedical Engineering, Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul, South Korea. E-mail: [email protected]
Recently, advances in medical imaging technology have accelerated the development of medical physics: the utilization of images in diagnosis and radiation therapy such as intensity modulated radiation therapy (IMRT), image guided radiation therapy (IGRT), Tomotherapy and Robot-guided RT. Single or multi-modality imaging for static or dynamic target has been applied in the field of medical physics to determine the local tumor volume and location of the tumor. While all radiation therapy are more or less image guided traditionally, imaging technology has primarily been used in producing 3D information of patient anatomy to identify the location of the tumor to treatment. New radiation treatment technique derived from the image guided technique has been developed to optimize the accuracy of radiotherapy. Especially, image guided applications are classified into two major aspects: (1) multi-modality imaging for better definition of tumor volume, (2) time-resolved imaging for modeling the intrafraction organ motion. In this presentation, two available imaging techniques will be highlighted, with emphasis on the principle and quality control of multi-modality imaging and moving organ.
Multi-modality imaging involves the incorporation of two or more the following imaging modalities: single photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI), computed tomography (CT) and optical imaging. The incorporation of multi-modality imaging provides functional and anatomic information. Multi-modality imaging is essential for a primary diagnosis and determining the most suitable treatment plan, and can help us to reduce errors. In addition, it has attracted interest in the fields of molecular and functional imaging for primary-to-metastatic cancer screening and functional neuroimaging. Therefore, the application of multi-modality imaging should lead to a better and more reliable diagnosis and treatment.
Intrafraction motion has been an issue that is becoming increasingly important in the era of IGRT. Estimation of surrogated respiration motion through breathing cycle and 4D images is the biggest focus to correlate with actual organ motion. If target is moving, we need to use larger beam field, which delivers extra radiation dose to normal tissue. The solutions to avoid this extra dose to normal tissue by moving organ are to utilize respiratory motion control techniques. Therefore, we are studying common methods used in the management of respiration motion in radiation therapy: breath-hold, gating, and tumor tracking techniques. These techniques are generally implemented through four steps: (1) localization consisted of respiratory signal control and image guidance, (2) planning (3) verification, and (4) delivery.
The analysis of the multi-modality images and image registration provide useful information in delineating the target volume for radiation treatment planning (RTP). In addition, we need more accurate time-resolved 4D localization technique for modeling the intrafraction organ motion.
I-25: Do we need audit of Radiation Oncology facilities - internal or external or both?
R K Munjal
Head, Department of Medical Physics, Max Healthcare, New Delhi, India. E-mail: [email protected]
I-26: Management of CT Image for Obese Patients in Radiotherapy Treatment Planning Procedure
S. N. Sinha
Chief Medical Physicist, Department of Radiation Oncology, Nayati Medicity, Mathura, Uttar Pradesh, India. E-mail: [email protected]
In radiotherapy treatment planning accurate CT data is essential. Computer tomography imaging has become mandatory for treatment planning in Radiotherapy. For obese patients when imaged with Diagnostic CT or even sometimes with large bore CT in the range 80 to 85 cm, corresponding image reconstruction FOV ranges between 50 cm to 65 cm. This implies that even if an obese patient is accommodated in the scanner, the CT data may have truncated image due to limitation in FOV size. The complete CT data is not available creating missing tissues laterally/obliquely where radiation beam path cannot be accurately derived due to lack of CT data and thereby giving error in monitor unit dose calculation.
Such incomplete data also brings in beam angulation constraints during IMRT, VMAT type planning. Some vendors have options for extended Field of View (eFOV) of 82 cm but is reported in literature to have degradation of Hounsfield units (HU) observed beyond nominal FOV. We have developed different modules in Matlab to tackle imaging obese patients and take appropriate measures for use in treatment planning system. The main module was developed using a line profile template match method to produce a composite CT image series for obese patients from two partial CT – one taken with patient left sided and the other with patient right sided on the CT couch. The software was implemented and tested on images with bony structures in phantom and also in actual patients with good results. Further practical pitfalls were observed during CT imaging with some heavy weight patients. Since patient treatment couch in Linear Accelerator are flat, it is mandatory to have flat couch top externally fitted on CT couch for imaging. Obese patients when scanned in CT shifted on one side many a times, a tilt of the image is observed. Such tilts due to patient weight were overcome by utilizing in-house built modules in Matlab. Module “Dicom image rotation” was developed where the user can specify the known rotational angle of the image in pitch (coronal plane) and roll (transverse plane) direction for any dicom image. Further modules like “point by point Orthogonal Planar image registration” was developed to be used with fiducial markers which helped in aligning the images before obtaining composite CT data. The different tools used for obese patients to acquire complete CT data sets gave good results to be used for radiotherapy treatment planning.
I-27: In-Vivo Dosimetry in Radiotherapy
Department of Radiation Physics, Kidwai Cancer Institute, Bengaluru, Karnataka, India. E-mail: [email protected]
The modern radiation treatment delivery techniques minimizes dose to the normal tissue and thereby increasing the prescribed dose to the tumor volume. Though there is an increase in the tumor control probability (TCP), the real advantage may be restricted by the probable raise in the normal tissue complication probability (NTCP). This necessitates the need for an accurate treatment delivery and measurement of dose delivered. The in-vivo dosimetry has become an integral part of verifying the treatment delivery to the patient. In-vivo dosimetry (IVD) is a vital component used to identify major deviations in treatment delivery as a part of quality assurance process thereby improving the quality of patient care in radiation therapy and is highly recommended by many international guidelines. The IVD does not imply that the dosimeter should necessarily be placed inside the living object. In EBRT, a dosimeter is normally placed on or near the surface of the patient, inside or in the neighborhood of the external beam.
There are different commercially available in-vivo dosimeters in practice. The current use of ionization chamber is mostly limited to phantom measurements though a few sealed chambers are used for in vivo measurements. Radiographic x-ray film performs several important functions in radiation therapy and can serve as relative radiation dosimeter and archival medium. Film provides excellent 2D spatial resolution and it gives information about the spatial distribution in the area of interest in a single exposure. Radiochromic film has a special dye and instantaneous colour change would occur after irradiation due to polymerization reaction. These films are used in the dosimetric verification of patient specific IMRT QA, stereotactic radiation and brachytherapy.
Thermoluminescence dosimeters (TLDs) are used in radiation therapy frequently as they can be placed on the skin or inside the patient body without the inconvenience of measuring cables. Also, they have wide applicable dose range, small dependence on energy, temperature and dose rate in the therapeutic range, very high sensitivity and no requirement to apply bias voltage and easy to transport. Plastic scintillator system offers excellent tissue equivalence, but their design makes it difficult to eliminate the noise signal produced from the actual plastic scintillator chip in the light-guide of the dosimetry system.
Diodes have been widely accepted in radiation dosimetry due to its robustness. Several correction factors have to be applied due to their energy dependence (Z =14), dose rate dependence, temperature dependence and angular dependence. The characteristics such as instantaneous read-out, small size, good linearity of the response and permanent storage of the dose demonstrated the efficacy of MOSFET as an in-vivo dosimeter in radiotherapeutic treatments for photon, electron and proton beams.
Diamond detectors have been considered suitable for clinical purposes due to their small size, good tissue equivalency and resistant to radiation damage. Diamond detectors exhibit high resolution and high sensitivity, however their advantage over semiconductor diodes is debated except for very small fields. It was reported in literatures that diamond detectors have less angular dependency than diodes in electron beams. Presently, EPIDs have largely replaced radioagraphic film as a tool for patient position verification during external beam radiation therapy. Since EPID images give dose information, their use in radiotherapy dose measurements was investigated by many groups. With the recent introduction of amorphous-silicon (a-Si) detectors, the interest in EPID dosimetry has been increased because of the favorable characteristics such as fast high resolution, image acquisition, digital format, and potential for IVD measurements.
The use of optically stimulated luminescence (OSL) as a dosimetry tool was recognized in the year 1950. The carbon–doped aluminium oxide Al2O3:C has become the dominant OSL material for dosimetric measurements due to its high sensitivity and other desirable properties. At present, OSLDs are available in various physical forms intended for different applications.
The presentation will focus on the need for IVD in radiotherapy practice, the advantages and limitations of various in-vivo dosimeters. Special attention will be given in highlighting the characteristics and practical advantages of OSL system which was implemented at our Institute recently.
I-28: Advances in Medical Physics and Phantom Development: A Pararallel Path. A Review from Historical to Computational Phantoms
Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy. E-mail: [email protected]
There are many origins of Medical Physics, deriving from the many scientific intersections between physics and medicine but probably modern Medical Physics (MP) initiates with the discover of X-rays by W. C. Röntgen W. C. awarded in 1901 by the Nobel Prize in Physics. Now a day MP encompass Medical Radiation Physics and embraces all medical specialities in diagnosis and therapy. Over the last few years MP has experienced tremendous technical and scientific advances in any application. Also methods of imaging and treatment procedures have become very sophisticated and complex. At any time Medical Physicists developed phantoms to mimic patient or human body characteristics in a given medical procedure either therapeutic or diagnostic. The complexity of a phantom is linked with the complexity of the medical procedure including the use of highly sophisticated equipment. The goal of the presentation is to review all types of phantom used in MP, from simple to complex, following the parallel development of advanced medical applications and phantoms. A short analysis and impact of the use of phantoms in Quality Control in modern equipment is also performed together with the necessity to give an adequate education to Medical Physicists in the aware use of complex phantoms.
I-29: Nanotechnology and its Applications in Health Care
S. H. Pawar1,2
1Centre for Research and Technology Developments, Sinhgad Institutes, Solapur, 2Centre for Interdisciplinary Research, D.Y. Patil University, Kolhapur, Maharashtra, India. E-mail: [email protected]
The use of magnetic nanoparticles for biological and clinical applications is undoubtedly one of the most challenging research areas in the field of nano-biotechnology. The use of magnetic nanoparticles (MNPs) has witnessed noteworthy advances and holds great potential for biological applications. Magnetic nanoparticle-based biological research has rapidly advanced to a point where the research focus is shifting away from synthesis and characterization to the development and investigation of multifunctional MNPs. MNPs, specifically super paramagnetic nanoparticles, based upon their unique physical, chemical and thermal properties, offer high potential and have been proposed extensively for nano-bio applications. MNPs are eligible for various biomedical applications, such as magnetic hyperthermia, magnetic resonance imaging, target drug delivery, bacteria detection, cell labeling, magnetic separation, and enrichment of DNA. In recent years, major attention has been focused on the development of MNPs due to their fundamental properties. Firstly, their size, which generally ranges from a few nanometers to tens of nanometers, places them at dimensions that are smaller than or comparable to those of a cell (10–100 mm), a virus (20–450 nm), a protein (5–50 nm) or a gene (2 nm wide and 10–100 nm long). This means that they can 'get closer 'to a biological entity of interest. Certainly, they can be coated with biomolecules to make them interact with or bind to a biological entity, thereby providing a controllable means of 'tagging' or addressing it. Secondly, MNPs exhibit interesting size-dependent superparamagnetism. Such MNPs are highly preferred due to their ability to be magnetized upon exposure to a magnetic field, but they have no permanent magnetization (remanence) once the field is turned off. Thirdly, MNPs can be manipulated by using an external magnetic field, which provides a huge advantage and opens up many nano-bio applications in vivo. This can be achieved by functionalization of MNPs, which can be defined as, “The addition of a chemical functional group on the surface of MNPs in order to achieve surface modification that enables their self-organization, renders them compatible and make them potential for various kinds of applications” Specific group of applications discussed here for this audience is in the area of health care.
Health care is prime importance to every human being. It is well known that healthy mind lies in healthy body. Hence, every nation provides great importance for the provision of sufficient funds in its annual budget. The world health organization (WHO) keeps an eye on health care globally. It conducts the survey of diseases. Recent survey reveals that out of every 10 deaths in India, 8 are caused by non communicable diseases (NCDs) which include cardio vascular diseases, cancers, chronic respiratory diseases and diabetes. In light of these facts, our research group has focused the major thrust on the applications of nanotechnology in health care, specifically on atherosclerosis and nanotechnology, cancer nanotechnology, stem cells and regenerative medicine, wound healing and nanotechnology, and invitro fertilization. Our group has published considerable amount of research papers in highly reputed international research journals and reality available on website www.shpawar.com. In the present talk, attempts have been focused on right form synthesis and characterization of variety of nano materials, as per the requirements of diseases. Specifically, magnetic nanoparticles (MNPs) are of great interest for use in medicine for example, for targeted drug delivery, for enhancing the contrast of magnetic resonance images and in magnetic hyperthermia treatment. The role of magnetic NPs will be discussed at length in cancer nanotechnology, as it is a painless curing of cancer.
I-30: Grid Radiotherapy and its Abscopal Effect: Radiation Induced Immunogenic Response with Immunotherapy
T. S. Kehwar
Eastern Virginia Medical School, Sentara Obici Hospital, Suffolk, Virginia, USA. E-mail: [email protected]
Purpose: This study investigates immunogenic antitumor response of GRID radiotherapy and effect of immunotherapy in combination.
Introduction: GRID radiotherapy, also known as Spatially Fractionated Radiation Therapy (SFRT), is a radiation treatment modality in which radiation is delivered through a matrix of equally spaced beamlets. At present GRID radiotherapy is given as a precursor to standard fractionation schemes with single or parallel opposed fields. In GRID radiotherapy, GTV is covered by single or parallel opposed fields without any margin and dose to the critical organs is kept minimum by avoiding direct entry or exit of the beamlet. Dose distribution in GRID radiotherapy has peaks and valleys, i.e. high and low dose beamlets. Many mechanisms of action of GRID radiotherapy has been proposed by various researchers. In this paper, a bystander effect of GRID therapy on immunogenic cells is highlighted with possibility to boost with immunotherapy.
Materials and Methods: In the GRID radiotherapy, the high dose in peak region damages DNA molecules within the tumor cells, normal tissue cells and immune cells results in producing a number of small fragments of different organelles, including genetic material (DNA molecules) within the nucleus, of tumor, normal and immune cells, and are released into the extracellular matrix that diffuse to low dose region (valley), where naïve cells of innate and adoptive immunity system, such as dendritic (DC), T and natural killer (NK) cells, are activated. The fragments from tumor cells released from the dying tumor cells are TAA and potentially can provide antigenic stimulation that induces antitumor- specific immune responses. DC cell uptake TAA from extracellular matrix and cross-presented on MHC-I molecules. The cross-presentation permit DC cells to elicit CD8+ T as well as CD4+ T cell responses to exogenous antigens. GRID radiotherapy induced DC, T and NK cells can migrate to the distally located metastatic site and be able to cause deleterious effect to the tumor cells results in regression of metastatic cancers, which are away from the irradiation field. This phenomenon is called abscopal effect. Abscopal effect appears to be a result of enhanced immune response directed to tumor cells. This response is sometimes not effective, hence need to combine immunotherapy to enhance DCs, T and NK cells.
Results and Discussion : The GRID radiotherapy can be performed either by custom made tungsten or Cerrobend equally spaced grids or MLCs can be used to create beamlets. In the GRID radiotherapy, dose is prescribed either at the dmax or at a depth in the peak of the beamlet. To enhance immunogenic effect of GRID radiotherapy, any one or combination of (1) monoclonal antibodies, (2) immune checkpoint inhibitors, (3) cancer vaccines, or (4) other non-specific immunotherapies, can be used. Many clinical trials reports increased survival rate compared to other cancer therapies.
Conclusions: Manipulation of the immune response may enhance the effects of radiation therapy both local or systemic levels through abscopal effect and immunotherapy combination may shape the future of radiotherapy.
I-31: Implementation of International Basic Safety Standards for the use of Radiological Medical Imaging Devices
Magdalena Stoeva, Jitendra Sharma1, Maria Del Rosario Perez2, Emilie Van Deventer2, Pablo Jimemez3, Miriam Mikhail4, Ola Holmberg5, Stewart Whitley6, Jacques Abramowicz7
Medical Imaging Department Medical University, Plovdiv, Bulgaria, 1Andhra Pradesh MedTech Zone, Visakhapatnam, Andhra Pradesh, India, 3Pan American Health Organization (PAHO), Washington, 4RAD-AID International, Maryland, 7WFUMB, USA, 2WHO, Switzerland, 5IAEA, Wien, Austria, 6ISRRT, UK. E-mail: [email protected]
Introduction: The International Basic Safety Standards (BSS) for Protection against Ionizing Radiation and for the Safety of Radiation Sources represent a global benchmark for setting national regulations in the field of radiation protection. Co-sponsored by eight international organizations (IAEA, WHO, PAHO, FAO, ILO, EC, FAO and UNEP), the BSS include a robust set of safety requirements for medical use of ionizing radiation. BSS implementation in the health sector targets an improvementin radiation protection in medicine.
Results and Discussion: A Continuous collaboration between UN organizations, professional societies, patient advocates, manufacturers' associations, regulators and other relevant stakeholders is essential in ensuring that all patients at the global level are safe from undue excess amounts of ionizing radiation, and have access to safe medical imaging for diagnostic purposes.
Advanced technologies have opened new horizons for the use of radiation medical devices in diagnostic imaging and image-guided interventions, including the use of ionizing and non-ionizing radiation. Although safety and efficacy of procedures have improved, incorrect or inappropriate handling of these technologies can introduce potential hazards for patients and staff.
Among the major challenges are the justification of medical radiation exposure for new technologies, procedures or devices and of screening programs; the lack of radiation safety officers in medical facilities to ensure procurement of appropriate and safe devices; the need for increased number of medical physicists, for integration of radiation protection into HTA and for promotion of clinical audit programmes to ensure that clinical benefit outweighs radiation detriment.
This article presents the outcomes of a workshop on BSS implementation held as part of the 3rd WHO Global Forum on Medical Devices (Geneva, Switzerland, 10-12 May 2017). Presenters from the WHO, IOMP, ISRRT, RAD-AID International and WFUMB discussed their respective roles as medical physicists, radiologists and radiographers, and the actions conducted to promote the BSS as part of their missions and global outreach programs. Presenters from Norway and India shared their experiences indicating that implementation of the BSS requires an administrative framework involving dialogue and cooperation between relevant authorities and professional societies, beyond revising national laws and regulations. It was noted that similar BSS for non-ionizing radiation are lacking and some international organizations are joining efforts to bridge this gap. The upcoming ICRPM in Vienna in December 2017 will be influential in setting the stage for future handlings of radiation safety issues and improving implementation of BSS around the world.
Conclusion: The BSS Workshop at the WHO 3rd Global Forum on Medical Devices brought together comments from various national and international organizations, on how radiation safety in medical imaging is promoted globally. Continued collaboration leadership by each of these organizations will be essential to furthering the optimization of radiation safety alongside medical imaging for patients around the world.
I-32: Data Mining for Radiomics
Division of Quantum Science, Kyushu University, Fukuoka, JAPAN. E-mail: [email protected]
I-33: FDG PET/CT Simulation for Radiation Therapy Planning
1Division of Positron Emission Tomography, Institute of Advanced Clinical Medicine, Kindai University, 2Department of Medical Physics Graduate, School of Medical Science, Kindai University, Osaka, Japan. E-mail: [email protected]
18F-FDG PET/CT has an important role in radiation therapy planning. FDG PET/CT parameters such as standard uptake value and metabolic tumor volume provide important prognostic and predictive information. Importantly, FDG PET/CT for radiation planning has added biological information in defining the gross tumor volume (GTV) as well as involved nodal disease. Several studies have shown that PET has an impact on radiation therapy planning in an important proportion of patients.
On the other hands, FDG PET/CT for radiation therapy planning has several limitations. First of all, the method to determine the optimal threshold of FDG PET/CT images that generates the best volumetric match to GTV is not established. The size of the GTV derived from FDG accumulation changes significantly depending on the threshold value, the threshold value can affect the clinical target delineation. Secondly, FDG is not a cancer-specific agent, and false positive findings in benign diseases have been reported.
Successful radiation therapy planning requires cooperation of other professions and sufficient physical assessment.
The contents of this presentation are as follows. (1) QA and QC of the PET/CT system for radiation therapy planning. (2) Potential impact of metal artifact caused by patient immobilizers on PET/CT image. (3) 4-dimentional PET/CT system for radiation therapy planning. (4) Other PET tracers for radiation therapy planning. (a) Fluoromisonidazole (18F-FMISO) as a tracer for detecting hypoxic tumor cells. (b) Carbon-11-methionine (11C-MET) as a tracer for imaging brain tumor cells. (c) 4-borono-2-(18)F-fluoro-phenylalanine (18F-FBPA) on the boron neutron capture therapy.
I-34: Development of 4D In-Silico Stochastic Spatio Temporalmodel of Tumor Growth with Angiogenesis
Eva Bezak1,2, Jake Forster2,3, Michael Douglass2,3, Wendy Phillips2,3
1Sansom Institute for Health Research, School of Health Sciences, University of South Australia, 2Department of Physics, University of Adelaide, 3Department of Medical Physics, Royal Adelaide Hospital, Adelaide, Australia. E-mail: [email protected]
Introduction: Mathematical and computational models, describing the complex biophysical processes associated with radiation induced cell death, have been used since the early 1960s. In 1973, Chadwick first presented a mathematical formula which accurately fit experimental data of cell survival as a function of absorbed dose. It was the first model that attempted to consolidate theories of macroscopic dose deposition and micro/nanoscopic damages caused by ionising radiation. In macroscopic radiobiological models (such as Chadwick's) small scale behaviour is consolidated into a set of analytical equations representing the large scale behaviour of the system. While these models are fast in terms of computation time, they are not robust enough in order to predict outcomes for a wide range of input parameters. As physical, chemical and biological interactions of radiation within an organic medium are stochastic processes, a stochastic type model is required for their accurate description. As a result, with improvements to the speed and general availability of computer hardware, a transition is occurring from simple analytical models to more physically realistic stochastic (Monte Carlo) models. At our institution, we developed a 4D integrated radiobiological model by combining “in-house” generated models with an existing Monte Carlo particle tracking toolkit (GEANT4). The result is a 4D simulation that can: grow a tumour composed of individual cells (with realistic chemical composition/geometry/cell cycle time) and blood vessels, irradiate the tumour, record the microdosimetric track structure in each cell, cluster spatially correlated ionisation events into DNA double strand breaks and then predict the likelihood that any given cell will survive.
Methods: In this work, a head neck squamous cell carcinoma (i.e. cells and blood vessels) is modelled using Matlab. Tumour cell oxygenation is a function of distance to the nearest blood vessel and hypoxic cells have an increased cell cycle time. Cell quiescence is simulated at low oxygen tensions. Cells may also become necrotic and be resorbed. To simulate head and neck cancers, a cell hierarchy of stem cells, transit cells and differentiated cells is considered and differentiated cell loss is included. Simulations were performed on the Phoenix supercomputer, University of Adelaide, using as many as 32 cores to observe the effects of hypoxia and necrosis on the rate of tumour growth.
Results: A semi-realistic 4D tumour model with angiogenesis for head and neck cancer has been developed. In accordance with clinical data reported in literature for head and neck cancers, values of relative vascular volume between 0.7-14%, blood oxygenation between 20-100 mmHg and vessel-to-necrosis distance between 80-300 μm were considered. This resulted in values of HF10 (fraction of cells with oxygenation <10 mmHg) ranging from 0-0.91, values of HF2 (fraction with oxygenation <2 mmHg) from 0-0.54, mean oxygenation from 2.0-67 mmHg and relative necrotic volume from 0-38%. With a probability for stem cell symmetric division of 0.02 and 80% loss of differentiated cells, the doubling time increased from 47 ± 4 days to 209±10 days with increasing amounts of hypoxia and necrosis.
Conclusion: On going work includes growing tumours which are then finely voxelised and imported into Geant4 for irradiation using track structure methods, calculating both direct and indirect radiation damage. By taking into account cellular oxygenation and the formation of hydroxyl radicals, tumour response to photon radiotherapy is explored using this 4D tumour model for hypoxic tumours versus well oxygenated tumours. The novelty of this model is in its ability to predict both the microscopic and macroscopic outcome of radiobiology experiments while varying input parameters; e.g. cell type and its biological properties (including repopulation), radiation type, tumour geometry, dose, degree of hypoxia, oxygenation, effects of direct and indirect (i.e. free radical production) damageand others.
I-35: Development of Video Based Mechanical Quality Assurance System for Medical Linear Accelerator
Youngyih Han, Eun Hyuk Shin, Jung Suk Shin, Hee Chul Park, Doo Ho Choi, Jun Sang Cho
Department of Radiation Oncology, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea. E-mail: [email protected]
In state-of-the art radiation therapy, one of the most important factors is to focus radiation to a tumor while minimizing radiation to peripheral normal tissues. In particular, SBRT, SRS, IMRT, IMPT require much higher precision and accuracy than the conventional treatment techniques, due to highly conformal dose distribution to a tumor.
Accordingly, quality assurance (QA) of the medical linear accelerator and subordinated equipment should be able to measure the degree of required accuracy which are less than 1 mm and 1 degree for angle for mechanical function of the treatment system. In addition the quality assurance measures need to be objective, precise and analyzed automatically to be efficient QA procedure. Therefore, we have developed video based mechanical quality assurance system which can meet the aforementioned requirements.
The developed system composed of three components, which are an indicator for marker, image capturing camera and image analysis software. The indicator provides the reference position for measuring an isocentor of gantry rotation, collimator rotation, couch rotation as well as light field sizes. The camera is designed to be positioned at block slot of the linear accelerator and captures images which are transferred to a computer for analysis. The analysis software was coded using Labviewand it measured the track of the marker for rotation of the linac, couch and fidld sizes analyzed using the pixel calibration data. The performance of the developed system was verified against the false positive tests for light field sizes, isocenter offsets and couch movements.
The developed system meets the all the required level of accuracy and precision which were less than 0.2 mm of accuracy for isoceter offset and couch movement and 0.23 mm for light field size measurement, thereby providing objective and efficient quality assurance of the high performance linacs.
I-36: Medical Applications of 3D Printing
R. Ramaseshan1,2,3,4, A. Chiang1, J. Awotwi-Pratt1,2, L Mathew1, B. Vangenderen1, C. Appeldoorn1
1Department of Medical Physics, BC Cancer Agency-Abbotsford, 2Department of Medical Physics, University of the Fraser Valley, Abbotsford, 3Department of Medical Physics, Simon Fraser University, Surrey, 4Department of Medical Physics, University of British Columbia, Vancouver, British Columbia, Canada. E-mail: [email protected]
Purpose: Utilization of 3D printing methodology in radiotherapy and other medical applications.
Background: There are a number of medical applications that use 3D printing technology solutions, for e.g. dentistry and plastic surgery reconstruction modelling. Applications of 3D printing in radiation therapy have not been widely reported in the literature. The selection of 3D printing technology is critical and can heavily impact its efficiency and functionality in the radiotherapy clinic. We are evaluating 3D printing technology in our Radiation Therapy Department for conformal patient bolus with application in external beam treatment, brachytherapy surface molds, patient weight loss management, patient cervix model obtained from CT data for interstitial HDR treatment validation, eye shields, and custom special locking collets for interstitial implants, MRI accessories, lung breathing phantom, room laser self-alignment, 3D surgical print evaluation, and MLC guide blocks.
Materials and Methods: The particular technology we are currently using is called Multi Jet Printing (MJP) which delivers professional print quality, with high precision (0.003”) and is simple to use. All 3D printed parts removed from the print platform will contain support material to fill up spaces within the printed material. The supporting material has to be removed and cleaned completely for a perfect print. With a typical 3D printer removing supporting material is a complex process. Our post process for cleaning the parts is easy and hand free. Our printer's easy clean system uses steam to melt away the wax support material from even the most challenging print without compromising the part quality and functionality and is 4 times faster than the other similar methods used in the industry.
Applications and Results: For clinical applications, such as 3D printing of conformal bolus or brachytherapy surface molds the choice of material for tissue equivalency is an important consideration. Our printer is able to print 2 types of material; the first one is a UV Curable hard plastic and can be printed in Opaque White, Opaque Black and Translucent Clear. The second one is UV curable elastomeric material which is a rubber-like material similar to commonly used radiotherapy bolus and has 2 different colors, translucent Natural and Opaque Black. The wax support material is in white color, but gets removed completely by post processing. Dosimetrically, for 6 and 15 MV photon beams UV curable elastomeric bolus equivalent material has water equivalency within 1.5% on an average and the UV curable hard plastic has water equivalency of within 2% on average. The 3D printing of patient surface conformed bolus for external beam, Brachy surface mold, and patient weight loss management, patient cervix model obtained from CT data for interstitial HDR treatment validation and custom special locking collets for interstitial implants, MRI accessories, MLC guide block have been printed for validation and/or clinical use to date. Finally, workflow between the clinical treatment planning system (Eclipse) and 3D Printing software is straightforward. 3D custom bolus structure files exported from Eclipse and printed show excellent conformity with an anthropomorphic phantom.
Conclusion: 3D printing is a useful technology in a busy radiotherapy clinic and has a wider application in radiotherapy.
I-37: LA Technology Improves Patients Care on 6 High Theory
Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. E-mail: [email protected]
The big and fast development of the medical linear accelerator (LA) technology in the last 10 years, that brings a great clinical achievements by using SBRT (SRS), especially for NSCLC treatment. The modern medical LA has offered us very advanced technologies such as 5 highs:high output dose rate, high speed delivery, high resolution MLC leaves, high dose gradience on the edge of target, and high precision isocenter. Comparison on the modern single beam LA (such as C-arm and Ring based LA) with the ϒ-knife, the key difference between them is the dose rate in the target during the treatment delivery: for the former as the single beam is delivered at the sequential bases that results in the dose rate in target (tumor) is always lower than that in the tissue passing by, but for the later as it uses multi-converging beams which are delivered simultaneously that results in the dose rate in target is always higher than in the tissue passing by. Therefore a next generation LA will logically be using multi-beams instead of one beam that will add an extra sixth high dose rate in target to the present modern single beam C-arm based LA, namely that will integrate the functions of both modern single beam LA and modern ϒ-knife with 6 high beam characteristics. A next generation LA called TCFB (three 120° angled crossing firing beam) unit being developed in China now which will not only integrate all functions of the current single beam LA and ˠ-knife, but also offer us to do real-time IGRT and DGRT without bringing any extradoses to the patients.
RNMO-2017 DR. Ramaiah Naidu Memorial Oration-2017
P Gopalakrishna Kurup
Ex-President, Association of Medical Physicists of India (AMPI). E-mail: [email protected]
PD1: Multi-Room Proton Therapy Facility
Rajesh A. Kinhikar
Medical Physicist, Dept. of Medical Physics, Tata Memorial Hospital, Mumbai, Maharashtra, India. E-mail: [email protected]
PD2: Clinical Needs and Efficacy
Associate Professor, Department of Radiation Oncology, AIIMS, Delhi, India. E-mail: [email protected]
Medical Physics Department, Institute Curie Proton Therapy Centre, Orsay, Paris, France. E-mail: [email protected]
PD3: Compact Single Room Proton Therapy Facility
Senior Medical Physics & Head of Medical Physics Unit, Department of Radiotherapy, Dr. B. R. A. IRCH, AIIMS, New Delhi-29. India. E-mail: [email protected]
PD4: Carbon Ion Therapy Facility
National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology (NIRS-QST), Chiba, Japan. E-mail: [email protected]