Intensity Modulated Radiation Therapy (IMRT) involves the modulation of radiation beam intensities in order to conform the target volumes and spare surrounding critical structures and normal tissues, IMRT can improve the dose distribution to a large extent compared to conventional 3DCRT. The purpose of this article is to discuss the methodology adopted in the Quality Assurance (QA) program for the implementation of IMRT on 2100 CID linear accelerator at our center. QA of Multi-Leaf Collimator (MLC) including mechanical tests, radiation tests, dynamic MLC tests and patient specific QA of the final IMRT plan has been described here in detail. The average transmission values were found to be 1.31% and 1.40% for A bank and B bank, respectively, for 6 MV photon beam measured with the parallel plate chamber. From film measurements, we got the maximum interleaf transmission value of 1.88%. The speed of the MLC leaves was found to be within the specification of the manufacturer. The MLC positional accuracy with the methods mentioned gave a precision of 1 mm, irrespective of the gantry positions. The absolute dose for 6 and 15 MV photons was estimated for the Dynamic MLC (DMLC) field periodically and was found to be consistent. The inverse-planning algorithm produced satisfactory dose distribution and adequate Planning Target Volume (PN) coverage with critical organ dose-volume parameters, within the respective tolerances. The percentage deviation between the measured and the calculated absolute dose for the intensity Modulated (IM) fields is found to be less than 3%. The clinical implementation of inverse planning and treatment delivery with DMLC is extremely complex and involves a substantial developmental effort. The dose delivery in a comprehensive QA is mandatory to ensure the safe and accurate dose delivery. DMLC mode needs a confirmation using established QA program that is both stringent and efficient. However, a comprehensive QA is mandatory to ensure the safe and accurate dose delivery.

High dose rate remote after loaders become a viable alternative to the traditional low dose rate brachytherapy system in the treatment of carcinoma of cervix. Treatment optimization is an important breakthrough in the modern remote after loading brachytherapy system. The term optimization refers to achieving clinically intended dose distribution by modifying some parameters of the treatment, such as dwell weight and source step size. The aim of this study is to evaluate optimization possibility in the treatment of carcinoma of cervix in Micro Selectron high dose rate remote after loading brachytherapy system. 15 patients who have undergone intracavitary application for the treatment of carcinoma of cervix have been considered in this study. Orthogonal pelvic simulation films were taken for dose computation at Point A, Point B and rectum and bladder. Step size and dwell weights of the source in intrauterine tandem and vaginal ovoid were modified using PLAT0 Treatment Planning System and Microselectron unit. All evaluated parameters are found to decrease with decreasing dwell weights to vaginal ovoid. The variation in bladder dose for different dwell weights and step size is not considerable as compared with the rectal dose variation. The pear shape volume is mainly affected by the dwell weights and step size of vaginal ovoid. The percentage variation in evaluated parameters is found to vary from patient to patient. Optimization helps to produce desirable isodose distribution, which assures that dose to reference points are maintained, whilst reducing the dose to the critical organs. Interactive optimization is a useful tool to produce clinically intended dose distribution in the intracavitary irradiation of carcinoma of cervix.

It has been observed that despite technical improvements, wide ranges of image quality and dose still exist in the current practice of mammography. In the current investigation, Mammography quality assurance (QA) procedures have been conducted using American College of Radiology (ACR) accredited phantom (RMI 156; Middleton, WI, USA) on a Siemens Mammography unit (Model 3000), in the light of ACR criteria. In addition, other quality assurance tests (kVp accuracy, collirnation test, focal spot size and HVL evaluation) were also performed for the assessment of unit performance and also to assure that the half value layer (HVL) of the x-ray beam is adequate to minimize patient breast dose, with good image contrast. With the evaluation of accreditation phantom (RMI-156), maximum of 9 visibility details were displayed bas per acceptability limits of ACR scoring criteria. The result of kVp accuracy, HVL and the calculated effective focal spot size for the mammographic unit were also found to be well within the specified values. Entrance exposure rate (EER) was found to be ranging from 0.8 - 1.9 R (7-16.5 mGy in air). The calculated maximum average glandular dose was found to be 3.4 mGy at 32 kVp. It is recommended that similar specific quality control standards must be adopted and applied at every centre engaged in the practice of mammography. The ACR mammography accreditation criteria can provide baseline information about the quality of mammography.

Purpose of the study is to do the radiological check of the dose reduction on application of automatic shield to the critical structure in gamma knife radio surgery. The comparative study- was. Continued between measured and Leksell Gamma Plan® calculated value of point dose at the centre of the phantom assuming that the risk zone lines at centre. Measurements were performed in two different sets, i.e. with and without 20 mm automatic shield simulating the treatment conditions. Leksell's stereotactic frame was affixed to the spherical phantom. In this study, prescription dose of 90 Gy at 50% prescription isodose was delivered in the vicinity of the centre of the phantom using one 18 mm collimator shot. Point dose calculations using Laksell Gamma Plan® and dose measurements using conventional 0.125 cc PTW inonization chamber were performed at the centre. 90.9% dose reeducation at measurement point was calculated by Leksell Gamma Plan® and 89.9% dose reeducation at the same point was found measurement. The difference lies within the acceptable limit of +1%. The dose reduction indicates the effectiveness of the automatic shielding feature in Leksell Gamma Plan R.