Synopses of Oral Papers

IMRT plans by using 6 MV photon beam. For the first and second plans A comparative study of three coplanar IMRT plans for fatty we used 5 fields. The gantry angles were 35°, 100°, 180°, 270° and prostate patients by using pinnacle 3-D treatment planning 325° and 0°, 75°, 135°, 225° and 285° respectively; with couch angle 0°. The third plan had 7 fields for which the gantry angles were 0°, Suvendu Sahoo, AK Rath, NK Painuly, BK Mohanta, H Mod*, 51°, 102°, 153°, 204°, 255° and 306° with couch angle 0°. ICRU 50 S Pattnaik*. Dept. of Medical Physics and *Radiation Oncology, recommendation was followed for the contouring of CTV and other Hemalata Hospitals and Research Center, Bhubaneswar, Orissa, India critical structures. The PTV was generated from CTV having 5 mm 3D­ marigin. The critical structures taken were rectum, bladder and the Introduction: For localized prostate cancer; radiation therapy is an femoral heads. Our study has compared three plans on the basis of effective modality. Prostate is one of the sites that is well suited for dose volume histograms (DVH) of all parameters like PTV and other all IMRT. IMRT planning and treatment delivery show significant potential critical structures. for further improving the therapeutic ratio and reducing toxicity and Results and Discussion: The effect of number of beams in IMRT thereby improving the quality of life. It is the responsibility of the planning for fatty cases is an important decision for a planner. The medical physicist (planner) to obtain an optimal IMRT plan. The purpose mean data of DVH of 5 patients for 3 IMRT plans are given in the of this study is to highlight some important points that need to be Tables. It was seen that, out of the three plans; the third plan was taken care of before embarking upon the IMRT plan. These are: (A) most suitable for patient treatment because the out side PTV maximum the treatment site (B) the facilities available with machine i.e., number dose was much higher in first two plans and comparatively less in the of photon beams, MLC or mMLC and (C) the patient separation third plan. It was seen that in the case of fatty patients the beam path (thickness) from all sides. Of the above three points; first two points length is more in patient body thereby leading to more deposition of are well known to a planner. We want to highlight the third point i.e., dose in the patient body comparative to Planning Target Volume in 5 the patient thickness, which is an important parameter when planning field plans. But in case of 7 fields plan, due to more number of beams IMRT for prostate cancer. Our objective is to show by comparing three the deposition of dose out side PTV was less thereby delivering the co-planner particular IMRT plans; the effect of numbers of beams maximum dose to planning target volume. from various directions on the final dose distribution. Conclusion: This study states that, for fatty prostate patients the 7 Materials and Methods: Our centre is equipped with PINNACLE 3fields IMRT plan is a better optimum plan as compared to a 5 fields D treatment planning system and digital linear accelerator (ELEKTA) IMRT plan. This conclusion will thus be helpful to a planner during a having 40 pairs MLC facility, each MLC width is 1 cm at isocenter. For prostate IMRT planning. our study we took 5 patients of localized prostate cancer, whose AP­ PA separations were 26 to 30 cm and lateral separations were 36 to 40 O-02 cm. For the above comparative study we generated three coplanar Study of dose modeling for IMRT beamlets Sudesh Deshpande, Suresh Chaudhari, V Anand, Sandeep De, Table 1: PTV dose comparison V Kannan. Department of Radiation Oncology, P. D. Hinduja National Hospital and Medical Research Center, Mahim, Mumbai, India PTV PTV min PTV max PTV mean coverage dose dose dose Introduction: Intensity modulated radiation therapy (IMRT) beams (Gy.) (Gy.) (Gy.) are created by using a segmentation algorithm that converts the PLAN-1 (5 FIELDS) 95% 58.16 80.42 74.92 ideal fluence map into deliverable beam segments. This fluence can system