Home
|
Search
|
Ahead of print
|
Current Issue
|
Archives
|
Instructions
|
Subscription
|
Reader Login
The official journal of AMPI, IOMP and AFOMP
Users online: 457
Export selected to
Endnote
Reference Manager
Procite
Medlars Format
RefWorks Format
BibTex Format
Most cited articles *
Archives
Most popular articles
Most cited articles
Show all abstracts
Show selected abstracts
Export selected to
Cited
Viewed
PDF
REVIEW ARTICLE
Automated medical image segmentation techniques
Neeraj Sharma, Lalit M Aggarwal
January-March 2010, 35(1):3-14
DOI
:10.4103/0971-6203.58777
PMID
:20177565
Accurate segmentation of medical images is a key step in contouring during radiotherapy planning. Computed topography (CT) and Magnetic resonance (MR) imaging are the most widely used radiographic techniques in diagnosis, clinical studies and treatment planning. This review provides details of automated segmentation methods, specifically discussed in the context of CT and MR images. The motive is to discuss the problems encountered in segmentation of CT and MR images, and the relative merits and limitations of methods currently available for segmentation of medical images.
[ABSTRACT]
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
140
29,406
2,630
Tumor delineation: The weakest link in the search for accuracy in radiotherapy
CF Njeh
October-December 2008, 33(4):136-140
DOI
:10.4103/0971-6203.44472
PMID
:19893706
Radiotherapy is one of the most effective modalities for the treatment of cancer. However, there is a high degree of uncertainty associated with the target volume of most cancer sites. The sources of these uncertainties include, but are not limited to, the motion of the target, patient setup errors, patient movements, and the delineation of the target volume. Recently, many imaging techniques have been introduced to track the motion of tumors. The treatment delivery using these techniques is collectively called image-guided radiation therapy (IGRT). Ultimately, IGRT is only as good as the accuracy with which the target is known. There are reports of interobserver variability in tumor delineation across anatomical sites, but the widest ranges of variations have been reported for the delineation of head and neck tumors as well as esophageal and lung carcinomas. Significant interobserver variability in target delineation can be attributed to many factors including the impact of imaging and the influence of the observer (specialty, training, and personal bias). The visibility of the target can be greatly improved with the use of multimodality imaging by co-registration of CT with a second modality such as magnetic resonance imaging (MRI) and/or positron emission tomography. Also, continuous education, training, and cross-collaboration of the radiation oncologist with other specialties can reduce the degree of variability in tumor delineation.
[ABSTRACT]
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
79
8,466
1,021
ORIGINAL ARTICLES
Homogeneity Index: An objective tool for assessment of conformal radiation treatments
Tejinder Kataria, Kuldeep Sharma, Vikraman Subramani, KP Karrthick, Shyam S Bisht
October-December 2012, 37(4):207-213
DOI
:10.4103/0971-6203.103606
PMID
:23293452
Homogeneity Index (HI) is an objective tool to analyz the uniformity of dose distribution in the target volume. Various formulae have been described in literature for its calculation but there is paucity of data regarding the ideal formula and the factors affecting this index. This study was undertaken to analyze HI in our patients using various formulae and to find out the co-relation between HI and prescribed dose, target volume and target location. A retrospective review of 99 patients was performed. HI was calculated using five different formulae (A-E). The patients were divided in five groups each, based on prescribed dose, target volume and target location and mean HI of each group was analysed to find the co-relation between these factors and HI. When there were multiple target volumes the primary target volume was studied. The statistical calculation was done using SPSS version 16.0. Ninety nine patients were found evaluable with 75 males and 24 females. Ninety five patients were treated with radical intent and four with palliative intent. The sites treated were head and neck (46.4%), Pelvis (17.1%), brain (15.1%), abdomen (12.1%), and thorax (6.1%). The mean prescribed dose was 4304 cGy (centiGray) and the mean target volume was 476.2 cc. The mean value of HI was 1.21, 2.08, 30.13, 21.51 and 1.27 with different formulae. There was considerable agreement between HI calculated using various formulae specially the formulae considering prescribed dose (C, D). On statistical analysis, there was no significant co-relation between the location and volume of target but there was a trend toward better HI with increasing prescribed dose. Future studies with more number of patients can confirm our results.
[ABSTRACT]
[FULL TEXT]
[PDF]
[Mobile Full text]
[EPub]
[CITATIONS]
[PubMed]
64
13,725
1,002
TECHNICAL NOTE
Infrared thermal imaging for detection of peripheral vascular disorders
S Bagavathiappan, T Saravanan, John Philip, T Jayakumar, Baldev Raj, R Karunanithi, T.M.R Panicker, M Paul Korath, K Jagadeesan
January-March 2009, 34(1):43-47
DOI
:10.4103/0971-6203.48720
PMID
:20126565
Body temperature is a very useful parameter for diagnosing diseases. There is a definite correlation between body temperature and diseases. We have used Infrared Thermography to study noninvasive diagnosis of peripheral vascular diseases. Temperature gradients are observed in the affected regions of patients with vascular disorders, which indicate abnormal blood flow in the affected region. Thermal imaging results are well correlated with the clinical findings. Certain areas on the affected limbs show increased temperature profiles, probably due to inflammation and underlying venous flow changes. In general the temperature contrast in the affected regions is about 0.7 to 1
°
C above the normal regions, due to sluggish blood circulation. The results suggest that the thermal imaging technique is an effective technique for detecting small temperature changes in the human body due to vascular disorders.
[ABSTRACT]
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
51
9,917
653
REVIEW ARTICLE
Recent developments of optically stimulated luminescence materials and techniques for radiation dosimetry and clinical applications
AS Pradhan, JI Lee, JL Kim
July-September 2008, 33(3):85-99
DOI
:10.4103/0971-6203.42748
PMID
:19893698
During the last 10 years, optically stimulated luminescence (OSL) has emerged as a formidable competitor not only to thermoluminescence dosimetry (TLD) but also to several other dosimetry systems. Though a large number of materials have been synthesized and studied for OSL, Al
2
O
3
:C continues to dominate the dosimetric applications. Re-investigations of OSL in BeOindicate that this material might provide an alternative to Al
2
O
3
:C. Study of OSL of electronic components of mobile phones and ID cards appears to have opened up a feasibility of dosimetry and dose reconstruction using the electronic components of gadgets of everyday use in the events of unforeseen situations of radiological accidents, including the event of a dirty bomb by terrorist groups. Among the newly reported materials, a very recent development of NaMgF
3
:Eu
2+
appears fascinating because of its high OSL sensitivity and tolerable tissue equivalence. In clinical dosimetry, an OSL as a passive dosimeter could do all that TLD can do, much faster with a better or at least the same efficiency; and in addition, it provides a possibility of repeated readout unlike TLD, in which all the dose information is lost in a single readout. Of late, OSL has also emerged as a practical real-time dosimeter for in vivo measurements in radiation therapy (for both external beams and brachytherapy) and in various diagnostic radiological examinations including mammography and CT dosimetry. For in vivo measurements, a probe of Al
2
O
3
:C of size of a fraction of a millimeter provides the information on both the dose rate and the total dose from the readout of radioluminescence and OSL signals respectively, from the same probe. The availability of OSL dosimeters in various sizes and shapes and their performance characteristics as compared to established dosimeters such as plastic scintillation dosimeters, diode detectors, MOSFET detectors, radiochromic films, etc., shows that OSL may soon become the first choice for point dose measurements in clinical applications. A brief review of the recent developments is presented.
[ABSTRACT]
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
46
11,192
1,126
ORIGINAL ARTICLES
Segmentation and classification of medical images using texture-primitive features: Application of BAM-type artificial neural network
Neeraj Sharma, Amit K Ray, Shiru Sharma, KK Shukla, Satyajit Pradhan, Lalit M Aggarwal
July-September 2008, 33(3):119-126
DOI
:10.4103/0971-6203.42763
PMID
:19893702
The objective of developing this software is to achieve auto-segmentation and tissue characterization. Therefore, the present algorithm has been designed and developed for analysis of medical images based on hybridization of syntactic and statistical approaches, using artificial neural network (ANN). This algorithm performs segmentation and classification as is done in human vision system, which recognizes objects; perceives depth; identifies different textures, curved surfaces, or a surface inclination by texture information and brightness. The analysis of medical image is directly based on four steps: 1) image filtering, 2) segmentation, 3) feature extraction, and 4) analysis of extracted features by pattern recognition system or classifier. In this paper, an attempt has been made to present an approach for soft tissue characterization utilizing texture-primitive features with ANN as segmentation and classifier tool. The present approach directly combines second, third, and fourth steps into one algorithm. This is a semisupervised approach in which supervision is involved only at the level of defining texture-primitive cell; afterwards, algorithm itself scans the whole image and performs the segmentation and classification in unsupervised mode. The algorithm was first tested on Markov textures, and the success rate achieved in classification was 100%; further, the algorithm was able to give results on the test images impregnated with distorted Markov texture cell. In addition to this, the output also indicated the level of distortion in distorted Markov texture cell as compared to standard Markov texture cell. Finally, algorithm was applied to selected medical images for segmentation and classification. Results were in agreement with those with manual segmentation and were clinically correlated.
[ABSTRACT]
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
42
15,157
1,029
REVIEW ARTICLES
Positron emission tomography: An overview
AK Shukla, Utham Kumar
January-March 2006, 31(1):13-21
DOI
:10.4103/0971-6203.25665
PMID
:21206635
The rate of glucose utilization in tumor cells is significantly enhanced as compared to normal cells and this biochemical characteristic is utilized in PET imaging using FDG as a major workhorse. The PET systems as well as cyclotrons producing positron emitting radiopharmaceuticals have undergone continuous technological refinements. While PET (CT) systems enable fusion images as well as precise attenuation correction, the self-shielded cyclotrons developed provide dedicated systems for in-house production of a large number of PET radiopharmaceuticals. The application of PET images in oncology includes those of pulmonary, colorectal, breast, lymphoma, head & neck, bone, ovarian and GI cancers. The PET has been recognized as promising diagnostic tool to predict biological and physiological changes at the molecular level and hence offer a potential area for future applications including Stem Cell research.
[ABSTRACT]
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
32
13,240
1,835
Whole body radiotherapy: A TBI-guideline
Ulrich Quast
January-March 2006, 31(1):5-12
DOI
:10.4103/0971-6203.25664
PMID
:21206634
Total Body Irradiation (TBI) is one main component in the interdisciplinary treatment of widely disseminated malignancies predominantly of haematopoietic diseases. Combined with intensive chemotherapy, TBI enables myeloablative high dose therapy and immunoablative conditioning treatment prior to subsequent transplantation of haematopoietic stem cells: bone marrow stem cells or peripheral blood progenitor stem cells. Jointly prepared by DEGRO and DGMP, the German Society of Radio-Oncology, and the German Association of Medical Physicists, this DEGRO/DGMP-Leitlinie Ganzkoerper-Strahlenbehandlung - DEGRO/DGMP Guideline Whole Body Radiotherapy, summarises the concepts, principles, facts and common methods of Total Body Irradiation and poses a set of recommendations for reliable and successful application of high dose large-field radiotherapy as essential part of this interdisciplinary, multimodality treatment concept. The guideline is geared towards radio-oncologists, medical physicists, haematooncologists, and all contributing to Whole Body Radiotherapy. To guide centres intending to start or actualise TBI criteria are included. The relevant treatment parameters are defined and a sample of a form is given for reporting TBI to international registries.
[ABSTRACT]
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
30
14,278
1,383
INVITED PAPERS
Advances in multimodality molecular imaging
Habib Zaidi, Rameshwar Prasad
July-September 2009, 34(3):122-128
DOI
:10.4103/0971-6203.54844
PMID
:20098557
Multimodality molecular imaging using high resolution positron emission tomography (PET) combined with other modalities is now playing a pivotal role in basic and clinical research. The introduction of combined PET/CT systems in clinical setting has revolutionized the practice of diagnostic imaging. The complementarity between the intrinsically aligned anatomic (CT) and functional or metabolic (PET) information provided in a "one-stop shop" and the possibility to use CT images for attenuation correction of the PET data has been the driving force behind the success of this technology. On the other hand, combining PET with Magnetic Resonance Imaging (MRI) in a single gantry is technically more challenging owing to the strong magnetic fields. Nevertheless, significant progress has been made resulting in the design of few preclinical PET systems and one human prototype dedicated for simultaneous PET/MR brain imaging. This paper discusses recent advances in PET instrumentation and the advantages and challenges of multimodality imaging systems. Future opportunities and the challenges facing the adoption of multimodality imaging instrumentation will also be addressed.
[ABSTRACT]
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
25
5,625
400
REVIEW ARTICLE
Consideration of the radiation dose delivered away from the treatment field to patients in radiotherapy
Michael L Taylor, Tomas Kron
April-June 2011, 36(2):59-71
DOI
:10.4103/0971-6203.79686
PMID
:21731221
Radiation delivery to cancer patients for radiotherapy is invariably accompanied by unwanted radiation to other parts of the patient's body. Traditionally, considerable effort has been made to calculate and measure the radiation dose to the target as well as to nearby critical structures. Only recently has attention been focused also on the relatively low doses that exist far from the primary radiation beams. In several clinical scenarios, such doses have been associated with cardiac toxicity as well as an increased risk of secondary cancer induction. Out-of-field dose is a result of leakage and scatter and generally difficult to predict accurately. The present review aims to present existing data, from measurements and calculations,and discuss its implications for radiotherapy.
[ABSTRACT]
[FULL TEXT]
[PDF]
[Mobile Full text]
[EPub]
[CITATIONS]
[PubMed]
24
7,736
412
ORIGINAL ARTICLES
Impact of 6MV photon beam attenuation by carbon fiber couch and immobilization devices in IMRT planning and dose delivery
RK Munjal, PS Negi, AG Babu, SN Sinha, AK Anand, T Kataria
April-June 2006, 31(2):67-71
DOI
:10.4103/0971-6203.26690
PMID
:21206667
Multiple fields in IMRT and optimization allow conformal dose to the target and reduced dose to the surroundings and the regions of interest. Thus we can escalate the dose to the target to achieve better tumor control with low morbidity. Orientation of multiple beams can be achieved by i) different gantry angles, ii) rotating patient's couch isocentrically. In doing so, one or more beam may pass through different materials like the treatment couch, immobilization cast fixation plate, head and neck rest or any other supportive device. Our observations for 6MV photon beam on PRIMUS-KXE2 with MED-TEC carbon fiber tabletop and 10 x 10 cm2 field size reveals that the maximum dose attenuation by the couch was of the order of 2.96% from gantry angle 120-160°. Attenuation due to cast fixation base plate of PMMA alone was of the order of 5.8-10.55% at gantry angle between 0 and 90°. Attenuation due to carbon fiber base plate alone was 3.8-7.98%. Attenuation coefficient of carbon fiber and PMMA was evaluated and was of the order of 0.082 cm-1 and 0.064 cm-1 respectively. Most of the TPS are configured for direct beam incidence attenuation correction factors only. Whereas when the beam is obliquely incident on the couch, base plate, headrest and any other immobilization device get attenuated more than the direct beam incidence. The correction factors for oblique incidence beam attenuation are not configured in most of the commercially available treatment planning systems. Therefore, such high variations in dose delivery could lead to under-dosage to the target volume for treatments requiring multiple fields in IMRT and 3D-CRT and need to be corrected for monitor unit calculations.
[ABSTRACT]
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
23
10,680
778
Measurement of gamma radiation levels in soil samples from Thanjavur using γ-ray spectrometry and estimation of population exposure
B Senthilkumar, V Dhavamani, S Ramkumar, P Philominathan
January-March 2010, 35(1):48-53
DOI
:10.4103/0971-6203.55966
PMID
:20177570
This study assesses the level of terrestrial gamma radiation and associated dose rates from the naturally occurring radionuclides
232
Th,
238
U and
40
K in 10 soil samples collected from Thanjavur (Tamil Nadu, India) using g-ray spectrometry. The activity profile of radionuclides has clearly showed the existence of low level activity in Thanjavur. The geometric mean activity concentrations of
232
Th,
238
U and
40
K is 42.9±9.4 Bq.kg
-1
, 14.7±1.7 Bq.kg
-1
and 149.5±3.1 Bq.kg
-1
respectively are derived from all the soil samples studied. The activity concentration of
232
Th,
238
U and
40
K in soil is due to the presence of metamorphic rocks like shale, hornblende-biotite gneiss and quartzofeldspathic gneiss in these areas. Gamma absorbed dose rates in air outdoors were calculated to be in the range between 32 nGy.h
-1
and 59.1 nGy.h
-1
with an arithmetic mean of 43.3 ±9 nGy.h
-1
. This value is lesser than the population weighted world-averaged of 60 nGy.h
-1
. Inhabitants of Thanjavur are subjected to external gamma radiation exposure (effective dose) ranging between 39.2 and 72.6 μSv.y
-1
with an arithmetic mean of 53.1±11 μSv.y
-1
. The values of the external hazard index determined from the soil radioactivity of the study area are less than the recommended safe levels.
[ABSTRACT]
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
21
8,691
390
Quantitation of normal metabolite concentrations in six brain regions by
in-vivo
1
H-MR spectroscopy
Ludovico Minati, Domenico Aquino, Maria Grazia Bruzzone, Alessandra Erbetta
July-September 2010, 35(3):154-163
DOI
:10.4103/0971-6203.62128
PMID
:20927223
This study examined the concentrations of brain metabolites visible to
in-vivo
1
H-Magnetic Resonance Spectroscopy (
1
H-MRS) at 1.5 T in a sample of 28 normal subjects. Quantitation was attempted for inositol compounds, choline units, total creatine and N-acetyl moieties, using open-source software. Six brain regions were considered: frontal and parietal white matter, medial temporal lobe, thalamus, pons and cerebellum. Absolute concentrations were derived using tissue water as an internal reference and using an external reference; metabolite signal intensity ratios with respect to creatine were also calculated. The inter-individual variability was smaller for absolute concentrations (internal reference) as compared to that for signal intensity ratios. Significant regional variability in concentration was found for all metabolites, indicating that separate normative values are needed for different brain regions. The values obtained in this study can be used as reference in future studies, provided the same methodology is followed; it is confirmed that despite unsuccessful attempts in the past, smaller coefficients of variation can indeed be obtained through absolute quantification.
[ABSTRACT]
[FULL TEXT]
[PDF]
[Mobile Full text]
[EPub]
[CITATIONS]
[PubMed]
21
6,835
267
Magnetic resonance imaging for adaptive cobalt tomotherapy: A proposal
Tomas Kron, David Eyles, Schreiner L John, Jerry Battista
October-December 2006, 31(4):242-254
DOI
:10.4103/0971-6203.29194
PMID
:21206640
Magnetic resonance imaging (MRI) provides excellent soft tissue contrast for oncology applications. We propose to combine a MRI scanner with a helical tomotherapy (HT) system to enable daily target imaging for improved conformal radiation dose delivery to a patient. HT uses an intensity-modulated fan-beam that revolves around a patient, while the patient slowly advances through the plane of rotation, yielding a helical beam trajectory. Since the use of a linear accelerator to produce radiation may be incompatible with the pulsed radiofrequency and the high and pulsed magnetic fields required for MRI, it is proposed that a radioactive Cobalt-60 (60Co) source be used instead to provide the radiation. An open low field (0.25 T) MRI system is proposed where the tomotherapy ring gantry is located between two sets of Helmholtz coils that can generate a sufficiently homogenous main magnetic field. It is shown that the two major challenges with the design, namely acceptable radiation dose rate (and therefore treatment duration) and moving parts in strong magnetic field, can be addressed. The high dose rate desired for helical tomotherapy delivery can be achieved using two radiation sources of 220TBq (6000Ci) each on a ring gantry with a source to axis-of-rotation distance of 75 cm. In addition to this, a dual row multi-leaf collimator (MLC) system with 15 mm leaf width at isocentre and relatively large fan beam widths between 15 and 30 mm per row shall be employed. In this configuration, the unit would be well-suited for most pelvic radiotherapy applications where the soft tissue contrast of MRI will be particularly beneficial. Non-magnetic MRI compatible materials must be used for the rotating gantry. Tungsten, which is non-magnetic, can be used for primary collimation of the fan-beam as well as for the MLC, which allows intensity modulated radiation delivery. We propose to employ a low magnetic Cobalt compound, sycoporite (CoS) for the Cobalt source material itself. Rotational delivery is less susceptible to problems related to the use of a low energy megavoltage photon source while the helical delivery reduces the negative impact of the relatively large penumbra inherent in the use of Cobalt sources for radiotherapy. On the other hand, the use of a 60Co source ensures constant dose rate with gantry rotation and makes dose calculation in a magnetic field as easy as the range of secondary electrons is limited. The MR-integrated Cobalt tomotherapy unit, dubbed 'MiCoTo,' uses two independent physical principles for image acquisition and treatment delivery. It would offer excellent target definition and will allow following target motion during treatment using fast imaging techniques thus providing the best possible input for adaptive radiotherapy. As an additional bonus, quality assurance of the radiation delivery can be performed
in situ
using radiation sensitive gels imaged by MRI.
[ABSTRACT]
[FULL TEXT]
[PDF]
[Mobile Full text]
[EPub]
[CITATIONS]
[PubMed]
20
12,379
850
Dosimetric evaluation of Acuros XB dose calculation algorithm with measurements in predicting doses beyond different air gap thickness for smaller and larger field sizes
Suresh Rana, Kevin Rogers
January-March 2013, 38(1):9-14
DOI
:10.4103/0971-6203.106600
PMID
:23532180
In this study, dose prediction accuracy of Acuros XB (AXB) dose calculation algorithm beyond air gap thickness (range 2, 4, and 6 cm) in simple inhomogeneous phantoms was investigated. The evaluation of AXB was performed by comparing the doses calculated by AXB with the doses calculated by Anisotropic Analytical Algorithm (AAA) and the measured data for different field sizes (3 × 3, 5 × 5, and 10 × 10 cm
2
) of a 6 MV photon beam. The dose computation was performed within Eclipse treatment planning system, and measurements were acquired with a cylindrical ionization chamber. Central axis depth dose comparisons were done in solid-water material region up to 5 cm distance from air/solid-water interface. The results of AXB had better agreement with measurements at all measured points than that of AAA. The discrepancies between AXB and measured data were seen from − 3.81% to + 0.9%, whereas the AAA differences with measurement from − 3.1% to − 10.9%. The combination of the smallest test field size and the largest air gap produced the highest range (1-5 cm distance from air/solid-water interface) in dose difference (AAA: −4.0% to − 10.6% and AXB: −3.8% to + 0.6%). The AAA computational time was about 8 times faster than that of AXB. In conclusion, AXB is more appropriate to use for dose predictions, especially when low-density heterogeneities are involved.
[ABSTRACT]
[FULL TEXT]
[PDF]
[Mobile Full text]
[EPub]
[CITATIONS]
[PubMed]
20
12,981
616
SIMIND Monte Carlo simulation of a single photon emission CT
MT Bahreyni Toossi, J Pirayesh Islamian, M Momennezhad, M Ljungberg, SH Naseri
January-March 2010, 35(1):42-47
DOI
:10.4103/0971-6203.55967
PMID
:20177569
In this study, we simulated a Siemens E.CAM SPECT system using SIMIND Monte Carlo program to acquire its experimental characterization in terms of energy resolution, sensitivity, spatial resolution and imaging of phantoms using
99m
Tc. The experimental and simulation data for SPECT imaging was acquired from a point source and Jaszczak phantom
.
Verification of the simulation was done by comparing two sets of images and related data obtained from the actual and simulated systems. Image quality was assessed by comparing image contrast and resolution.
Simulated and measured energy spectra (with or without a collimator) and spatial resolution from point sources in air were compared. The resulted energy spectra present similar peaks for the gamma energy of
99m
Tc at 140 KeV. FWHM for the simulation calculated to14.01 KeV and 13.80 KeV for experimental data, corresponding to energy resolution of 10.01and 9.86% compared to defined 9.9% for both systems, respectively. Sensitivities of the real and virtual gamma cameras were calculated to 85.11 and 85.39 cps/MBq, respectively. The energy spectra of both simulated and real gamma cameras were matched. Images obtained from Jaszczak phantom, experimentally and by simulation, showed similarity in contrast and resolution. SIMIND Monte Carlo could successfully simulate the Siemens E.CAM gamma camera. The results validate the use of the simulated system for further investigation, including modification, planning, and developing a SPECT system to improve the quality of images.
[ABSTRACT]
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
19
6,613
281
EDITORIAL
CyberKnife: A new paradigm in radiotherapy
Gopalakrishna Kurup
April-June 2010, 35(2):63-64
DOI
:10.4103/0971-6203.62194
PMID
:20589114
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
18
4,840
670
INVITED PAPERS
Technique alternatives for breast radiation oncology: Conventional radiation therapy to tomotherapy
N Fournier-Bidoz, Y Kirova, F Campana, J El Barouky, S Zefkili, R Dendale, MA Bollet, A Mazal, A Fourquet
July-September 2009, 34(3):149-152
DOI
:10.4103/0971-6203.54849
PMID
:20098562
Breast conserving radiotherapy uses tangential fields and compensating wedges. This conventional approach can be improved by a field-in-field technique using the linac multi-leaf collimator (MLC). A simplified field-in-field technique that planners can easily achieve and which improves dose uniformity in the breast volume is presented here. Field junction problems are more easily solved by the use of a virtual simulation. A unique isocenter can be set at the junction between the supra-clavicular field and the breast tangential fields. However, careful quality assurance of the treatment planning system must be performed. Tomotherapy has promising clinical advantages: the ability of a tomographic image to correct for random set-up errors, a continuous cranio-caudal delivery which suppresses junction problems, the conformality of the dose distribution throughout the complex volumes formed by the lymph nodes and the breasts. Tomotherapy is a valuable recourse for complex irradiations like bilateral breast or mammary plus axillary irradiation while a field-in-field associated with a unique isocenter technique can be used for majority of the patients.
[ABSTRACT]
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
18
6,611
443
ORIGINAL ARTICLES
Small field dose delivery evaluations using cone beam optical computed tomography-based polymer gel dosimetry
Timothy Olding, Oliver Holmes, Paul DeJean, Kim B McAuley, Ken Nkongchu, Giles Santyr, L John Schreiner
January-March 2011, 36(1):3-14
DOI
:10.4103/0971-6203.75466
PMID
:21430853
This paper explores the combination of cone beam optical computed tomography with an
N
-isopropylacrylamide (NIPAM)-based polymer gel dosimeter for three-dimensional dose imaging of small field deliveries. Initial investigations indicate that cone beam optical imaging of polymer gels is complicated by scattered stray light perturbation. This can lead to significant dosimetry failures in comparison to dose readout by magnetic resonance imaging (MRI). For example, only 60% of the voxels from an optical CT dose readout of a 1 l dosimeter passed a two-dimensional Low's gamma test (at a 3%, 3 mm criteria, relative to a treatment plan for a well-characterized pencil beam delivery). When the same dosimeter was probed by MRI, a 93% pass rate was observed. The optical dose measurement was improved after modifications to the dosimeter preparation, matching its performance with the imaging capabilities of the scanner. With the new dosimeter preparation, 99.7% of the optical CT voxels passed a Low's gamma test at the 3%, 3 mm criteria and 92.7% at a 2%, 2 mm criteria. The fitted interjar dose responses of a small sample set of modified dosimeters prepared (a) from the same gel batch and (b) from different gel batches prepared on the same day were found to be in agreement to within 3.6% and 3.8%, respectively, over the full dose range. Without drawing any statistical conclusions, this experiment gives a preliminary indication that intrabatch or interbatch NIPAM dosimeters prepared on the same day should be suitable for dose sensitivity calibration.
[ABSTRACT]
[FULL TEXT]
[PDF]
[Mobile Full text]
[EPub]
[CITATIONS]
[PubMed]
18
6,274
212
REVIEW ARTICLE
Image-guided radiation therapy: Physician's perspectives
T Gupta, C Anand Narayan
October-December 2012, 37(4):174-182
DOI
:10.4103/0971-6203.103602
PMID
:23293448
The evolution of radiotherapy has been ontogenetically linked to medical imaging. Over the years, major technological innovations have resulted in substantial improvements in radiotherapy planning, delivery, and verification. The increasing use of computed tomography imaging for target volume delineation coupled with availability of computer-controlled treatment planning and delivery systems have progressively led to conformation of radiation dose to the target tissues while sparing surrounding normal tissues. Recent advances in imaging technology coupled with improved treatment delivery allow near-simultaneous soft-tissue localization of tumor and repositioning of patient. The integration of various imaging modalities within the treatment room for guiding radiation delivery has vastly improved the management of geometric uncertainties in contemporary radiotherapy practice ushering in the paradigm of image-guided radiation therapy (IGRT). Image-guidance should be considered a necessary and natural corollary to high-precision radiotherapy that was long overdue. Image-guided radiation therapy not only provides accurate information on patient and tumor position on a quantitative scale, it also gives an opportunity to verify consistency of planned and actual treatment geometry including adaptation to daily variations resulting in improved dose delivery. The two main concerns with IGRT are resource-intensive nature of delivery and increasing dose from additional imaging. However, increasing the precision and accuracy of radiation delivery through IGRT is likely to reduce toxicity with potential for dose escalation and improved tumor control resulting in favourable therapeutic index. The radiation oncology community needs to leverage this technology to generate high-quality evidence to support widespread adoption of IGRT in contemporary radiotherapy practice.
[ABSTRACT]
[FULL TEXT]
[PDF]
[Mobile Full text]
[EPub]
[CITATIONS]
[PubMed]
18
10,263
829
ORIGINAL ARTICLES
Dose volume histogram analysis and comparison of different radiobiological models using in-house developed software
Arun S Oinam, Lakhwant Singh, Arvind Shukla, Sushmita Ghoshal, Rakesh Kapoor, Suresh C Sharma
October-December 2011, 36(4):220-229
DOI
:10.4103/0971-6203.89971
PMID
:22228931
The purpose of this study is to compare Lyman-Kutcher-Burman (LKB) model versus Niemierko model for normal tissue complication probability (NTCP) calculation and Niemierko model versus Poisson-based model for tumor control probability (TCP) calculation in the ranking of different treatment plans for a patient undergoing radiotherapy. The standard normal tissue tolerance data were used to test the NTCP models. LKB model can reproduce the same complication probability data of normal tissue response on radiation, whereas Niemierko model cannot reproduce the same complication probability. Both Poisson-based and Niemierko models equally reproduce the same standard TCP data in testing of TCP. In case of clinical data generated from treatment planning system, NTCP calculated using LKB model was found to be different from that calculated using Niemierko model. When the fractionation effect was considered in LKB model, the calculated values of NTCPs were different but comparable with those of Niemierko model. In case of TCP calculation using these models, Poisson-based model calculated marginally higher control probability as compared to Niemierko model.
[ABSTRACT]
[FULL TEXT]
[PDF]
[Mobile Full text]
[EPub]
[CITATIONS]
[PubMed]
17
10,172
399
INVITED PAPERS
Optimization of beam angles for intensity modulated radiation therapy treatment planning using genetic algorithm on a distributed computing platform
Daryl P Nazareth, Stephen Brunner, Matthew D Jones, Harish K Malhotra, Mohammad Bakhtiari
July-September 2009, 34(3):129-132
DOI
:10.4103/0971-6203.54845
PMID
:20098558
Planning intensity modulated radiation therapy (IMRT) treatment involves selection of several angle parameters as well as specification of structures and constraints employed in the optimization process. Including these parameters in the combinatorial search space vastly increases the computational burden, and therefore the parameter selection is normally performed manually by a clinician, based on clinical experience. We have investigated the use of a genetic algorithm (GA) and distributed-computing platform to optimize the gantry angle parameters and provide insight into additional structures, which may be necessary, in the dose optimization process to produce optimal IMRT treatment plans.
For an IMRT prostate patient, we produced the first generation of 40 samples, each of five gantry angles, by selecting from a uniform random distribution, subject to certain adjacency and opposition constraints. Dose optimization was performed by distributing the 40-plan workload over several machines running a commercial treatment planning system. A score was assigned to each resulting plan, based on how well it satisfied clinically-relevant constraints. The second generation of 40 samples was produced by combining the highest-scoring samples using techniques of crossover and mutation. The process was repeated until the sixth generation, and the results compared with a clinical (equally-spaced) gantry angle configuration. In the sixth generation, 34 of the 40 GA samples achieved better scores than the clinical plan, with the best plan showing an improvement of 84%. Moreover, the resulting configuration of beam angles tended to cluster toward the patient's sides, indicating where the inclusion of additional structures in the dose optimization process may avoid dose hot spots.
Additional parameter selection in IMRT leads to a large-scale computational problem. We have demonstrated that the GA combined with a distributed-computing platform can be applied to optimize gantry angle selection within a reasonable amount of time.
[ABSTRACT]
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
16
4,685
355
REVIEW ARTICLE
Magnitude, impact, and management of respiration-induced target motion in radiotherapy treatment: A comprehensive review
SA Yoganathan, KJ Maria Das, Arpita Agarwal, Shaleen Kumar
July-September 2017, 42(3):101-115
DOI
:10.4103/jmp.JMP_22_17
PMID
:28974854
Tumors in thoracic and upper abdomen regions such as lungs, liver, pancreas, esophagus, and breast move due to respiration. Respiration-induced motion introduces uncertainties in radiotherapy treatments of these sites and is regarded as a significant bottleneck in achieving highly conformal dose distributions. Recent developments in radiation therapy have resulted in (i) motion-encompassing, (ii) respiratory gating, and (iii) tracking methods for adapting the radiation beam aperture to account for the respiration-induced target motion. The purpose of this review is to discuss the magnitude, impact, and management of respiration-induced tumor motion.
[ABSTRACT]
[FULL TEXT]
[PDF]
[Mobile Full text]
[EPub]
[CITATIONS]
[PubMed]
15
4,497
428
EDITORIAL
Has the time come for doing away with Cobalt-60 teletherapy for cancer treatments
R Ravichandran
April-June 2009, 34(2):63-65
DOI
:10.4103/0971-6203.51931
PMID
:20098538
[FULL TEXT]
[PDF]
[CITATIONS]
[PubMed]
14
5,522
588
TECHNICAL NOTES
Evaluation of radiation shielding properties of the polyvinyl alcohol/iron oxide polymer composite
K Srinivasan, E James Jabaseelan Samuel
October-December 2017, 42(4):273-278
DOI
:10.4103/jmp.JMP_54_17
PMID
:29296043
Context:
Lead is the conventional shielding material against gamma/X-rays. It has some limitations such as toxic, high density, nonflexibility, and also bremsstrahlung production during electron interaction. It may affect the accuracy of radiotherapy outcome.
Aims:
To theoretically analyze the radiation shielding properties of flexible polyvinyl alcohol/iron oxide polymer composite with five different concentrations of magnetite over the energy range of 15 KeV–20 MeV.
Subjects and Methods:
Radiological properties were calculated based on the published literature. Attenuation coefficients of pure elements are generated with the help of WinXCOM database.
Results:
Effective atomic numbers and electron density are increased with the concentration of magnetite. On the other hand, the number of electrons per gram decreased. Mass attenuation coefficient (μ/ϼ) and linear attenuation coefficients (μ) are higher in the lower energy <100 KeV, and their values decreased when the energy increased. Computed tomography numbers (CT) show the significant variation between the concentrations in <60 KeV. Half-value layer and tenth-value layers are directly proportional to the energy and indirectly proportional to the concentration of magnetite. Transmission curve, relaxation length (ƛ), kinetic energy released in the matter, and elemental weight fraction are also calculated and the results are discussed.
Conclusions:
0.5% of the magnetite gives superior shielding properties compared with other concentrations. It may be due to the presence of 0.3617% of Fe. Elemental weight fraction, atomic number, photon energy, and mass densities are the important parameters to understand the shielding behavior of any material.
[ABSTRACT]
[FULL TEXT]
[PDF]
[Mobile Full text]
[EPub]
[CITATIONS]
[PubMed]
14
2,877
239
* Source: CrossRef
Search this journal
Advance Search
Editorial Board
The Journal
The Association
Alerting
Feedback
Contact Us
Contact us
|
Sitemap
|
Advertise
|
What's New
|
Copyright and Disclaimer
|
Privacy Notice
© 2006 - Journal of Medical Physics | Published by Wolters Kluwer -
Medknow
Online since 10
th
April, 2006