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Accuracy of Beamscan Software in Determining the Inflection Point from the FFF Beam Profile Using Several Array
Kanakavel Kandasamy1, E James Jebaseelan Samuel1
1Department of Physics ,School of Advanced Sciences, VIT University, Vellore, India.
Asian Pacific Journal of Cancer Prevention : APJCP
|June 25, 2024
Summary
The Beamscan software accurately determines inflection points in Flattening Filter Free (FFF) beam profiles. Higher resolution measurements improve accuracy, with Beamscan providing FWHM values close to nominal field sizes.
Area of Science:
- Medical Physics
- Radiation Oncology
- Radiotherapy Physics
Background:
- Accurate characterization of radiation beam profiles is crucial for precise radiotherapy delivery.
- Flattening Filter Free (FFF) beams offer dosimetric advantages but require robust analysis methods.
- The PTW Beamscan program is a tool for analyzing beam profiles, but its accuracy needs validation.
Purpose of the Study:
- To assess the accuracy of the PTW Beamscan program in identifying the inflection point of Flattening Filter Free (FFF) beam profiles.
- To compare the performance of Beamscan against manual calculations using multiple detectors.
- To evaluate the impact of detector resolution on the accuracy of inflection point and Full Width at Half Maximum (FWHM) determination.
Main Methods:
- Profile measurements were acquired using a True Beam Linear Accelerator with 6FFF and 10FFF photon energies.
- Various detectors were employed, including PTW 729, 1500, 1600 SRS arrays, Starcheck, Pinpoint 3D with Beamscan, and Linac's EPID.
- The first-order derivative method was used in both Excel and Beamscan software to locate inflection points and calculate FWHM.
Main Results:
- Differences in FWHM varied by detector and field size, with the largest discrepancies observed for the 729 Array (up to 5.16 mm).
- The difference in FWHM between manual and software analysis generally decreased with detector resolution.
- For a 15x15 cm2 field size, the peak of the first-order derivative coincided with the chamber position for most detectors.
Conclusions:
- Higher measurement resolution leads to more accurate determination of inflection points and FWHM.
- Beamscan software consistently provided FWHM values closer to the nominal field size, irrespective of measurement resolution.
- The Beamscan software demonstrates high accuracy for routine analysis of FFF beam profiles, with good agreement from Excel, Starcheck, and EPID data.
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