The goal of conformal radiation therapy treatment planning is to three dimensionally shape the high dose region to the target anatomy and to minimize the dose to surrounding normal tissue. Conformal treatment design can result in treatments which either 1) significantly reduce complications to normal tissue or 2) increase the probability of tumour control by allowing delivery of higher levels of dose to the tumor without significant increase in normal tissue complications. Conformal treatment planning requires accurate volumetric tumor and normal tissue localization, flexible computerized treatment planning tools for design and evaluation, and ultimately, verifiable setup and treatment delivery. Based on conformal treatment designs, clinical dose escalation studies have been undertaken in the brain, the prostate and the liver. Many other sites have also been treated with conformal treatment design using conventional dose regimes. Treatment to each of these sites currently involves 1) tumor localization through complete CT volume studies and, in the brain, MRI studies, 2) the design and use of multiple fixed (often non-coplanar) fields with focused blocks, 3) the use of Beam's Eye View for block design, and 4) dose volume histograms and three- dimensional displays to assist in treatment plan selection. This paper demonstrates the type of conformal treatment planning which has been achieved clinically for these sites. In addition, new treatment planning tools are described which have been developed explicitly for design of multi-segmental static and dynamic beam delivery using the new generation of computer controlled treatment machines. The author had submitted colour pictures. However, due to the high cost of colour printing, the colour codes have been converted to letter codes. It is hoped that this has not lead to any unacceptable loss in clarity - Editor.

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Intracavitary therapy by afterloading techniques is the choice of treatment for carcinoma of uterine, cervix. To compare the dosimetry and clinical results it was considered advantageous, if all hospitals in India used identical type of applicators. With this in view a national committee was appointed by the Director, BARC and on the basis of its recommendations a new manual afterloading applicator was designed in collaboration with Isotope Group, BARC (Present BRIT) and Tata Memorial Hospital, Bombay. The design features of the applicator which incorporates I3'cs sources and the dosimetric aspects are discussed in this paper

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Diagnostic x-ray units stand first among all. the man made sources of irradiation of the public to ionising radiations. This study brings in first hand information about the status of diagnostic uses of x-rays in Calicut District. The data presented below highlight the fact that majority 0f X-ray units are having improper housing, they are operated by unqualified persons, work practices are substandard and radiation safety aspects are given insufficient importance

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Computed Tomography plays an important role in treatment planning of tumours through its ability in localization of tumour and normal tissue most accurately. It presents the true cross-sectional picture of anatomy in terms of varying CT numbers. It helps through the treatment planning system in applying inhomogeniety corrections to dosage calculations. CT also helps to obtain a three dimensional representation of the tumour volume which helps in reducing geometrical miss of the tumour during radiation therapy. Various technical and procedural requirements and clinical considerations of the role of CT in treatment planning are discussed.

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Current technology and perspective of future technology related to PACS are discussed in terms of hardware as well as software. Items covered are: computers, communication, Al, software, standardization, and technology assessment.

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The development of a thin stainless steel ophthalmic applicator is described. The features of this device are that it can be assembled with the radioactive sources (1-125) precisely positioned without the use of adhesives or mechanical devices such as clamps or screws in a matter of a few minutes under sterile conditions. Dismantling occurs in seconds after which the applicator is ready for cleaning and re-sterilisation. The radioactive sources are contained in an acrylic button which fits neatly into a stainless steel shell 1 mm thick. Different distributions of sources may be accommodated in the same stainless steel shell by inserting a different acrylic button. The overall thickness of the plaque is 2.6 mm but potentially can be reduced to 2.1 mm. Suture holes are provided on a flange subtending 120" around the circumference of the shell and are exactly matched on a stainless steel template. An analysis of the dosimetry suggests that the treatment of the radioactive 1-125 seeds as point sources may lead to only small errors in the determination of dose at the scleral surface and tumour apex. The differences in the dosimetry resulting from the treatment of the seeds as line sources appear to be of little consequence. As a result, point source dosimetry with anisotropy factor removed is quite satisfactory.

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