UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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2024-11-23 18:10
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Conference: Bucharest University Faculty of Physics 2016 Meeting


Section: Biophysics; Medical Physics


Title:
Consideration on the Clinical Component of Patient Specific Quality Assurance in IMRT Using Gamma Retrospective Analysis


Authors:
Mihai DUMITRACHE (1), Rodica ANGHEL (2,3), Florentina MOGOS (3), Alina TANASE (1)


Affiliation:
1) Emergency Central Military Hospital ”Dr. Carol Davila”, Bucharest, Romania

2) University of Medicine and Farmacy „Dr. Carol Davila”, Bucharest, Romania

3) ONCOFORT - Radiotherapy Center - GRAL MEDICAL, Bucharest, Romania


E-mail
mihai149@yahoo.com


Keywords:
Gamma analysis, IMRT, dose distribution, action level, clinical data


Abstract:
The aim of this study is to assess the intensity modulated radiotherapy (IMRT) accuracy of delivered dose distribution versus treatment planning system (TPS), through the variability of the success rate of the gamma index (GI), based on analysis of retrospective clinical data. Although numerous studies and guides provide recommendations for specific gamma analysis criteria for IMRT, the values are still under the validation process. According to the literature, 3 %/3 mm or 2 %/2 mm are the most used levels of acceptability. For this reason, we have evaluated both tolerance levels. The study includes 85 treatment plans for 74 patients, with fractionation between 1.67Gy - 2.3 Gy. The equipment used consists in: Elekta Synergy Platform accelerator, Xio V.4.6 TPS, 2D array 729 and VeriSoft ver.4.2. Patients were grouped as follows: 20 cases head&neck with simultaneously integrated boost (SIB); 11 cases of prostate cancer; 14 cerebral tumour cases; 8 lung tumour cases; 21 cervical cancer cases. Simulations of the cases mentioned in TG119, using 3 %/3 mm, respectively 2 %/2 mm criteria, have provided a GI average success rate of (97.2 ± 2.4) %, respectively (94.5 ± 3 9) %, while the results of the clinical cases, using the same criteria. have provided a GI average success rate of (98.5 ± 1.7) %, respectively (93.3 ± 4.6) %. The normality analysis of the distribution of GI values was assessed both graphically and analytically using the Shapiro-Wilk test. For the criterion, 3 %/3 mm, the analysis also highlighted a statistical relationship between commissioning tests and clinical cases with p = 0.092, confirming the null hypothesis. Regarding criterion 2%/2 mm, the probability was p = 0.0025, considering the null hypothesis as being false. In order to ensure the accuracy of dose distribution based on the retrospective statistical clinical data, this study proposes the action levels, based on clinical practice in a highly specialized department.