No abstract

angle which provides optimal dose distribution for the treatment of prostate cancer patients was consistent both statistically and as a result of measurements.

The aim of this study was to investigate the effect of the use of intermediate dose calculation module on dose volume histogram (DVH) during dose optimization in the treatment plans of radiotherapy patients diagnosed with lung cancer. This study was carried out by using Eclipse (Version 15.3) treatment planning system with Trilogy model Linear Accelerator device in Radiation Oncology Department of Şişli Hamidiye Etfal Training and Research Hospital. Ten patients with lung cancer were included in the study. In this study, critical organ doses, conformity index (CI) and homogenity index (HI) were compared by making optimization in cases where intermediate dose calculation module was active and inactive. The plans using the Intermediate dose calculation model are more homogeneous and uniform. Differences between critical organ doses, conformity index (CI) and homogenity index (HI) were statistically significant when using the intermediate dose calculation module. It has been demonstrated that the intermediate dose calculation method in heterogeneous lung cancer patients is superior in terms of dose homogeneity and tumor volume enveloping, which improves the quality of treatment plans.

In this study, it was aimed to investigate the effect of different dose rate and different computational resolutions on stereotactic vertebrae irradiation with the results of the verification schemes on Gamma analysis and the effect on dose for critical organ and target volume. Ten patients with vertebrae participated in the study. Patients participating in the study were investigated for their effect on doses for critical organ and target volume by recalculating treatment plans at different dose rates and different computational resolutions without changing the optimization parameters using Intensity Modulated Radiation Therapy (IMRT) technique and Anisotropic Analytical Algorithm (AAA) in the Eclipse (V15.3) treatment planning system with Varian Trilogy Linear Accelerator located in Şişli Hamidiye Etfal Training and Research Hospital, Radiation Oncology Department. Verification schedules of all the treatment plans The results were compared by using the Electronic Portal Imaging Device (EPID). Using different dose rates did not affect our treatment planning accuracy. However, it was seen that the high resolution calculated plans represented the target and critical organ doses better.

Twenty five patients diagnosed with head and neck cancer in the Radiation Oncology Clinic of Sisli Etfal Training and Research Hospital were included in the study. Major anatomic changes due to weight loss and tumor shrinkage are observed during radiotherapy treatment in most of the patients diagnosed with head and neck cancer. The aim of the study is to examine the changes in the dose distribution of the changes in the patient anatomy due to the weight loss observed during the treatment process and to compare the adaptive radiotherapy technique with the non-adaptive radiotherapy technique. When the treatment plans of the patients were made using the adaptive plan technique, the ipsilateral parotid volume ranged from 15.00±8.57 cc to 10.10±5.85 cc (p=0.046), and the contralateral parotid volume ranged from 12.21±7.34 cc to 7.50±3.55 cc (p=0.002), Ptv 54 volume from 759.8±285.9 cc to 432.4±126 cc (p=0.035), Ptv 60 volume from 338.7±18.9 cc to 185.5±58.5 cc (p=0.003) and total body volume also decreased from 6380±1600 cc to 5230±1570 cc (p=0.001), and a statistically significant decrease was observed using the T-test and Wilcoxan test. While ipsilateral parotid volume decreased at least 15% and maximum 46.3%, contralateral parotid volume decreased at least 16.6% and maximum 46.9%. The dose distribution results obtained from the dose volume histogram (DVH) using the adaptive radiotherapy technique are superior to the dose distribution results obtained without using the adaptive radiotherapy technique. Adaptive radiotherapy technique gives a more effective dose to the target volume and is more effective in protecting healthy tissues at the maximum rate.