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I'mRT MatriXX is one of the common offline dosimetry tools used for the pre-treatment verification quality assurance (QA) of intensity modulated radiation therapy (IMRT) treatment plans in radiotherapy. It has 1020 pixel ionisation chambers (PIC) arranged in 32×32 grid in a plain. In this study the angular response of the I'mRT MatriXX was measured using treatment planning system (TPS) calculated dose and I'mRT MatriXX measured dose. The angular response correction factor (CF) of the I'mRT MatriXX was found by measuring the ratio of MatriXX measured dose to the treatment planning system (TPS) calculated dose in 5°step size of MatriXX angle from 0°to 355°u nder the similar set up condition for MatriXX with MULTICube Phantom and TPS plan. This CF can be applied directly in OmniPro software and used if the user have gantry angle sensor. The aim of this work is to apply this CF without gantry angle sensor to each of the 1020 PIC with the help of a simple program on MATLAB and verify with the TPS treatment plan field by field. For the 10 Ca cervix patients which were planned with standard 7 fields IMRT, there is improvement in the pass percentage of gamma index 3% dose difference and 3 mm distance to dose agreement. At 0°IMRT field, there is insignificant improvement but at other fields like 50°, 100°, 150°, 200°, 250°and 300°there are significant improvement in the gamma index pass percentage.

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Introduction In this study we compared radiation dose received by organs at risk (OARs) after breast conservation surgery(BCS) and mastectomy in patients with left breast cancer. Materials and methods Total 30 patients, 15 each of BCS and mastectomy were included in this study. Planning Computerised Tomography (CT) was done for each patient. Chest wall, whole breast, heart, lungs, LAD, proximal and distal LAD, and contra lateral breast was contoured for each patient. Radiotherapy plans were made by standard tangent field. Dose prescribed was 40Gy/16#/3 weeks. Mean heart dose, LAD, proximal and distal LAD, mean and V5 of right lung, and mean, V5, V10 and V20 of left lung, mean dose and V2 of contra lateral breast were calculated for each patient and compared between BCS and mastectomy patients using student’s T test. Results Mean doses to the heart, LAD, proximal LAD and distal LAD were 3.364Gy, 16.06Gy, 2.7Gy, 27.5Gy; and 4.219Gy, 14.653Gy, 4.306Gy, 24.6Gy, respectively for mastectomy and BCS patients. Left lung mean dose, V5, V10 and V20 were 5.96Gy, 16%, 14%, 12.4%; and 7.69Gy, 21%, 18% and 16% in mastectomy and BCS patients, respectively. There was no statistical significant difference in the doses to the heart and left lung between mastectomy and BCS. Mean dose to the right lung was significantly less in mastectomy as compared to BCS, 0.29Gy vs. 0.51Gy, respectively (p = 0.007). Mean dose to the opposite breast was significantly lower in patients with mastectomy than BCS (0.54Gy Vs 0.37Gy, p = 0.007). The dose to the distal LAD was significantly higher than proximal LAD both in BCS (24.6Gy Vs 4.3Gy, p = <0.0001) and mastectomy (27.5Gy Vs 2.7Gy, p = <0.0001) patients. Conclusion There was no difference in doses received by heart and left lung between BCS and mastectomy patients. Mean doses to the right lung and breast were significantly less in mastectomy patients.

RÉSUMÉLe technétium 99 est un produit de fission à vie longue, dont la production au cours de la combustion de l'uranium enrichi n'est pas à négliger. Des études concernant la gestion de ce déchet ont été mises en place au CEA. Celies-ci vont entraîner une exposition potentielle du personnel de recherche. Il était donc nécessaire de disposer d'une surveillance radiotoxicologique adaptée. La méthode proposée permet une détection précoce de 99Tc dans les urines par scintillation liquide, en sachant que 10 % de la contamination par inhalation se retrouve dans les urines dès les 48 premières heures après l'incorporation.Cette méthode est rapide (1 heure) et relativement sensible (limite de détection a 0,06 Bq ml-', ce qui correspond à une incorporation par inhalation égale à 8,4 x 10-5 LAI soit 1,7 x 103 Bq de V c ) . ABSTRACTMethod of Technecium 99 determination in urine through liquid scintillation. Technetiuh 99 is a long-life fission product; when enriched uranium is burnt, its amount is rather small but cannot be overlooked. Studies about reprocessing of this waste are being carried out by the CEA. They will lead to possible exposure to 99Tc of research workers. So it seems necessary to develop a close radiotoxicological watch suited to the situation. The proposed method enables an early detection of 99Tc in urine through liquid scintillation, owing to the fact that 10% of the contamination by inhalation is found in the 48 first hours urine after intake. This method is quick (60 min) and rather sensitive (detection is possible from 0.06 Bq ml-', that corresponds to an incorporation of 8.4 x 10-5 LAI or 1.7 x 103 Bq of q c ) .