The aim of this study is to report the treatment outcomes, toxicities, and dosimetric feasibility of simultaneous integrated boost by RapidArc (RA-SIB) compared with 3dimentional-conformal radiation therapy (3D-CRT) for patients with glioblastoma. Methods: Eleven patients with unifocal glioblastoma (grade IV astrocytoma, WHO classification) were treated during the period from April 2011 until February 2013 with postoperative irradiation and concomitant temozolomide 75 mg/m 2 followed by 6-12 months of adjuvant temozolomide 200 mg/m 2 for 5 days/4weeks. One patient received temozolomide for 12 months, 5patients for 6 months, and 5patients did not receive adjuvant temozolomide. RA-SIB technique was used and patients received 46 Gy per fraction of 2 Gy in 23 sessions on the planning target volume (PTV1) (contrast enhancement + per-focal edema as seen in T2 MR + 2.3 cm) with concomitant daily superimposed boost (SIB) on PTV2 corresponding to the contrast enhancement + 2.3 cm. The treatment outcomes and toxicity were assessed. Dose Volume Histogram DVH analysis was performed between SIB-RA and 3D-CRT plans of each patient. For the PTV, the comparison parameters included, the mean dose, the standard deviation, maximum dose, conformity index (CI), and homogeneity index (HI). Results: The median progression free survival (PFS) and overall survival (OS) were 13 months (95% CI, 8.2-17.8), and 16 months (95% CI, 2.1-29.9) respectively. Four of six patients (67%) showed local progression (recurrence) after initial response, all recurrences occurred at the site of PTV2. Seven patients experienced acute grade 1-2 toxicities during the treatment. Late post radiation brain edema was reported in 3 patients. Conclusion: The SIB-RA did not prove the superiority in survival outcomes compared with the historical data using 3D-CRT. From the dosimetric standpoint, SIB-RA is a superior technique with respect to 3D-CRT when there are overlaps between organs at risk (OARs) and PTV.

IP-IMRT selectively spared critical organs to greater degree with better target coverage and should be considered the standard of treatment in head and neck tumors.

Purpose: To study the accuracy of Brainlab pencil beam and Clarkson algorithms in homogeneous phantoms and heterogeneous geometries. Materials and method: In this study PMMA was used as the homogenous phantom. Different heterogeneous geometries were designed by introducing different materials between the PMMA slabs. In each situation one material is used with different thicknesses: (a) thickness of 2.7 cm and 8.1cm low‐density material and (b) thickness of 3.8 cm and 7.6 cm of high‐density material. The low‐ and high‐density material is placed beneath 6 cm of PMMA. All the phantoms were CT scanned. Six different irregularly shaped beams were designed using a Brainlab multileaf collimator. Calculations were performed for these beams in the homogenous phantom using the Brainlab pencil beam, Clarkson, Modified Clarkson and equivalent square dose calculation algorithms. The percentage depth doses based on different models were compared to measurements. A dose of 150 cGy was specified to a point beneath the inhomogeneous material for the heterogeneous cases. Modified Clarkson, pencil beam and equivalent square algorithms were used to calculate the dose and then compared to measurements. Results: All the models agreed well with measurements; the equivalent square method showed the highest average deviations of 0.55% from measured dose values. In heterogeneous geometries the equivalent square method gave very large deviations (up to 17 %). Clarkson and pencil beam algorithms disagreed with measurements by 4.8 % and 3.8 % for the low‐density material of 2.7 cm thickness, and by 8 % and 6.9 % for the low‐density material of 8.7 cm thickness, respectively. Conclusion: All Brainlab dose calculation models are reliable for homogeneous phantom but some may differ significantly from measurements in heterogeneous geometries, especially in low‐density issues.

In this Review of current clinical practice of set-up error verification by means of portal imaging, we firstly define the various types of setup errors using a consistent nomenclature. The different causes of set-up errors are then summarized. Next, the efforts done to minimize patient set-up errors are presented in different body sites. Also we focus on the more recent studies in order to assess the criteria for good clinical practice in patient positioning. We then present the result of our preliminary experience in the use of electronic portal image device (EPID) for the first time in our department. This a retrospective analysis for the images taken to patients treated with three dimensional conformal radiation therapy (3D-CRT) in our department between October 2005 and July 2006. Our results in shift of set-up errors reported in different tumor sites in the X, Y, Z directions in addition to errors in rotation. The number of images in our studies was still low compared to the literatures, but still there were images from different body sites. Finally we are giving some recommendations, collected from many publications in the use of portal imaging devices in the correction of systematic and random set-up errors during routine clinical practice.