The advent of Intensity Modulated Radiation Therapy (IMRT) is rapidly changing the field of Radiation Oncology. IMRT has the potential to improve clinical implementation of highly conformal non-convex dose distributions. Nonetheless, a number of IMRT approaches including coplanar and noncoplanar beam techniques with 5 to 9 beams at different angles have been used in an effort to get the best dose distribution. The purpose of this study is to compare the dose to normal tissue and dose-limiting structures, conformity index, homogeneity index, number of monitor units required for the treatment of prostate cancer in 3 sets of five and seven beam IMRT plans and thus to select the best IMRT approach for patients with prostate cancer.

Pilocytic astrocytoma (PA) is a low grade benign tumor, commonly occurs in Cerebellum (42-60%), Optic & hypothalamic region (9-30%), Brain Stem (9%). They rarely spread. It rarely occurs within the ventricle. In this report, we described our experience with cranial pilocytic astrocytoma in a 14-year-old child, who initially treated with near total decompression of tumor. Four and half years later, recurrence of primary tumor with obstructive hydrocephalus occurred for which he underwent ventriculo-peritoneal shunt followed by re-excision. As further treatment was being evaluated for radiotherapy in view of recurrence at the primary site, he got detected to have significant spinal drop metastasis seen on MRI Spine. Finally, he underwent craniospinal irradiation (CSI).

Purpose: This study was aimed to compare the suitable treatment plan for left-sided chest wall, regional node irradiation by the intensity-modulated radiotherapy (IMRT), and volumetric-modulated arc therapy (VMAT). Materials and Methods: Fifteen patients' computed tomography data set was import into the treatment planning system (Oncentra). Two plans were generated for each patient, the first one using the VMAT technique with two partial arcs and the second one using the IMRT technique with seven coplaner radiation portals using 3D Oncentra TPS with 6 MV photons, step and shoot treatment delivery technique with 80 leaf multileaf collimator, and 1 cm leaf width at the isocenter. The VMAT plans optimized using the collapsed cone (GPU) algorithm and IMRT plans optimized using a collapsed cone algorithm. A hypofractionated prescription dose of 40 Gy/15# was used. The VMAT and IMRT plans compared for Planning Target Volume (PTV) target coverage, homogeneity index (HI), conformity index (CI), and monitor units (MUs) were evaluated. The Organ At Risk (OAR) doses also compared. Results: A comparable PTV coverage (V95%) and mean PTV doses were observed between VMAT and IMRT plans. The PTV maximum dose was higher within IMRT than the VMAT. We observed a better HI for VMAT plans. For conformity index (CI) both plan showed no significant difference. MU values of VMAT are higher than the IMRT treatment in this study. However, VMAT plans show significantly better right lung, heart, and larynx sparing when compared to the IMRT plans. No significant difference was observed in both groups of plan for the right breast and spinal cord. The maximum dose for the left humerus head was compared for both groups of plans. Conclusions: VMAT is dosimetrically superior to the IMRT for irradiation of left-sided chest wall and regional nodes patients in terms of target coverage and OAR sparing.

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