ESTRO 2024 - Abstract Book

S3235

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

with dmax, D5cm%, D10cm% values gave similar results. The use of edge detectors for the measurements taken at the field center is satisfactory with their results. All diode detectors analyses showed similar right / left penumbra and flattness values in crossline and inline profiles in all field sizes and at different depths. Especially for areas smaller than 4x4cm2, the fact that 6MV energy acts like FFF and increases the flatness values is a situation that should be taken into consideration in small areas. ) Symmetry values, although showing different results in areas of 1x1,2x2,3x3,cm2 between detectors in areas and different depths, exceeded 2% values. Accordingly, all values dropped below 1% after centered by applying beam center in the software. In the areas of 5x5 and 10x10cm2 , the values were below 1% and showed similar results.

Conclusion:

Previous studies have shown the edge diode detectors are consistent with Monte Carlo simulations and in this study for all dedectors PDD, output factor, dose linearity, penumbra and flattness measurements are consistent among themselves. Especially the measurements at the center of the field are very consistent within themselves. Symmetry results, on the other hand, give very large values for beam center errors smaller than millimeters in very small areas such as 1x1,2x2cm2, and when corrected with software, the detectors still give similar results. The water phantom setup was checked after each set of data and no visible errors were found in the center and across the scan fields. These differences in small fields suggest that detector selection in small areas should be accurate and water phantom set-up errors should be minimized, and these results show that the edge detector manufacturing process is standardized.

Keywords: Edge detector , Small field dosimetry

References:

IPEM Report Number 103 Small Field MV-Photon Dosimetry

Dosimetric Characteristics of Edge Detector(TM) in Small Beam Dosimetry Kyung-Hwan CHANG; Bo-Ram LEE; You Hyun KIM; Kyoung-Sik CHOI; Jung-Seok LEE; Byung-Moon PARK; Yong-Ki BAE; Semie HONG; Jeong-Woo LEE. Korean Journal of Medical Physics ; : 191-198, 2009.

The clinical impact of detector choice for beam scanning Jacob A Gersh 1, Ryan C M Best, Ronald J Watts J Appl Clin Med Phys. 2014 Jul 8;15(4):4801. doi: 10.1120/jacmp.v15i4.4801.

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