ESTRO 2024 - Abstract Book

S3234

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

[4] S. Kim et al., “Characteristics of photopolymerized tissue equivalent plastic scintillator in high dose rate radiotherapy”,” Radiat. Phys. Chem., vol. 203, p. 110600, 2023, doi: https://doi.org/10.1016/j.radphyschem.2022.110600.

[5] H. Leutz, “Scintillating fibres,” Nucl. Instruments Methods Phys. Res. Sect. A Accel. Spectrometers, Detect. Assoc. Equip., vol. 364, no. 3, pp. 422–448, 1995, doi: https://doi.org/10.1016/0168-9002(95)00383-5.

1135

Digital Poster

Dosimetric Results of Four Different SunNuclear Edge Diode Dosimeters for Small Field Measurements

BURAK BAŞLANGIÇ 1 , Burcu GERÇEK KALYONCU 1 , Volkan YONETMEN 1 , Sezen Emek 2

1 Acıbadem Eskişehir Hospital, Radiation Oncology, ESKISEHIR, Turkey. 2 Acıbadem Atakent Hospital, Radiation Oncology, ISTANBUL, Turkey

Purpose/Objective:

With the development of treatment techniques such as VMAT, IMRT and small fields due to mlc movement and the treatment of much smaller volumes in plans such as SBRT and SRS, dosimetric uncertainties in small fields have become important and detectors have been developed to eliminate these uncertainties. In this study, it is aimed to compare the dosimetric results of the small field measurements of four different Sunnuclear diode detectors with 6MV energy and to investigate the responses of the detectors depending on the fabrication processes.

Material/Methods:

In the study, 6MV was used in Varian Vitalbeam device. In SunNuclear 3D scanner water phantom, 4 different edge diode detectors were used; 200,300,400,500,600,1000MU/min by giving 200MU and dose rate dependence with the ratio to 400MU/min, dose linearity with the readings taken for 50,100,200,400,400,600 MU at 300MU/min, output factors by giving 200MU in 1x1,2x2,3x3,4x4,5x5 and 10x10cm2 areas, PDD examides for dmax,D5cm%, D10cm% values in 1x1,2x2,3x3,4x4,5x5 and 10x10cm2 areas. Flatness and symmetry, right and left penumbra values were compared by taking profile measurements at 1.5,5,5,10 and 20 cm depths in 1x1,2x2,3x3,4x4,5x5 and 10x10cm2 areas. Dose and field calibrations were performed before the measurements. 3D scanner water phantom operates with a single voltage value, the voltage was set to 0 and measurements were taken without a reference dosimeter.

Results:

Among the parameters examined, dosimeters gave linear results for dose linearity and showed small differences among themselves depending on the dose readings. Diode readings were similar at dose rates and relative values were found to be less than 1% different at low dose rates when compared to 400MU/min. Output factors were similar for all areas when compared to the 10x10cm2 area readings of the detectors. PDD values were similar for all areas