In India, remote afterloading units are increasingly being used for brachytherapy applications. To achieve the desired level of accuracy and consistency in the delivery of prescribed dose and to ensure optimum performance of the equipment, it is necessary to adhere to strict quality assurance procedures, not only for the remote afterloading unit, but also for the treatment planning system. This necessitates implementation of a well-formulated quality assurance protocol. This paper attempts to provide necessary guidelines to the user institutions on various parameters to be checked and suggests method for carrying out the tests prior to accepting the unit for patient treatment. The parameters to be checked include tests on general functioning of the machine, and functions related to clinical, dosimetric and radiation safety aspects. As per Indian regulations, it is mandatory for the users to submit the results of various tests to Radiological Physics and Advisory Division. Bhabha Atomic Research Centre, in the prescribed pre-commissioning perform, for evaluation. Approval of the equipment for patient treatment is granted by the Competent Authority, upon the recommendations of RP & AD, based on satisfactory performance in acceptance testing.

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This paper presents results of skin entrance and organ dose measurements from routine medical x-ray examinations. The doses were measured in 1,452 patients undergoing 20 common X-ray investigations on 9 X-ray machines. CaSO4:Dy thermo luminescent dosimeters were used for dose measurements. The organ doses were estimated using tissue air ratios obtained using Monte Carlo methods by another worker. The highest mean dose of 16.69 mSv was measured for LS spine lateral projection and lowest of 0.15 mSv was for extremities. In the most commonly used chest\PA investigation, the mean skin entrance dose was 0.21 mSv. The ovary doses were significant for abdomen and LS spine investigations.

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Computed tomography contributes a significant fraction to population exposures. In the present study, organ doses and effective doses, normalised to the air kerma along the axis of the phantom are estimated using Monte Carlo method. A computer code MCNP (Version 3.1) and a mathematical phantom developed for this purpose are used in this study. A source sub-routine is prepared to treat the rotation of the x-ray source and restrict the beam to slice thickness. This paper presents normalised organ doses and effective doses, in head and spine CT examinations for an average Indian adult.

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38 applications of MDR intracavitary radiotherapy using I3'cs were performed for the treatment of 18 cervical carcinoma patients at stages I, II and Ill. Prior to the intracavitary therapy, each patient had been treated with 60 Co external therapy using two opposing fields to deliver dose of 46 - 50 Gy at the pelvic area. The applicators used in the intracavitary therapy was the Fletcher Suit Delcos with 3 or 4 sources in the tandem and one source in each ovoid. Reference points were determined using AP and lateral radiographs according to ICRU Report 38. The bladder reference point was defined by the radiographs of empty bladder with Foley baloon field with radio opaque fluid, whereas the rectal reference points Ri, Rq, R3 and R4 were determined from the inserted rectal marker. The reference dose was defined as the dose at point A or at the bulk tumour, and prescribed at about 850 cGy per application. The analysis of the bladder and rectal doses showed the doses at these two organs were (63 + 17%) and (92 + 25%) of point A dose, respectively. The rectal area dose determined as the average dose at points R1, R2, R3, and R4, had the value of (74 + 14%) of point A dose. The conclusion is that the bladder and rectum receive relatively high doses in the intracavitary therapy; therefore the dose at these two organs should be considered in the dose optimization.

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Radiation doses to staff involved in intracoronary technique from a solution of 188Re and 186Re (60:40) in water of unit density following P.T.C.A. have been theoretically determined. The method employees EGS-4 Code system based on Monte Carlo technique of random sampling. Two dimensional dose distributions in tissue in a tabular form around a typical cylindrical syringe used to impart desired dose to an effected lesion is presented. No comparison is possible for want of similar data in literature. The maximum inaccuracy in this calculation is unlikely to exceed + 2%.

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