Dose rate response of Digital Megavolt Imager detector for flattening filter-free beams

Journal of Applied Clinical Medical Physics
Zhigang XuSamuel Ryu

Abstract

In this study we investigated the dose rate response characteristics of the Digital Megavolt Imager (DMI) detector, including panel saturation, linearity, and imager ghosting effects for flattening filter-free (FFF) beams. The DMI detector dose rate response characteristics were measured as a function of dose rate on a Varian TrueBeam machine. Images were acquired at dose rates ranging from 400 to 1400 MU/min for 6XFFF and 400 to 2400 MU/min for 10XFFF. Line profiles and central portal doses derived from the images were analyzed and compared. The linearity was verified by acquiring images with incremental Monitor Unit (MU) ranging from 5 to 500 MU. Ghosting effects were studied at different dose rates. Finally, for validation, test plans with optimal fluence were created and measured with different dose rates. All test plans were analyzed with a Gamma criteria of 3%-3 mm and 10% dose threshold. Our study showed that there was no panel saturation observed from the profile comparison even at the maximum dose rate of 2400 MU/min. The central portal doses showed a slight decrease (1.013-1.008 cGy/MU for 6XFFF, and 1.020-1.009 cGy/MU for 10XFFF) when dose rate increased (400-1400 MU/min for 6XFFF, and 400-2400 MU/min for 10XFFF). Th...Continue Reading

References

Apr 28, 2004·Radiotherapy and Oncology : Journal of the European Society for Therapeutic Radiology and Oncology·Ann Van EschDominique Pierre Huyskens
Mar 23, 2006·Physics in Medicine and Biology·Oleg N VassilievMichael T Gillin
Aug 19, 2008·Radiotherapy and Oncology : Journal of the European Society for Therapeutic Radiology and Oncology·Wouter van ElmptBen Mijnheer
Feb 20, 2016·Journal of Applied Clinical Medical Physics·Robert W ChuterVivian P Cosgrove
Jul 28, 2016·Journal of Applied Clinical Medical Physics·Eduardo PardoSheila Ruiz Maqueda
Dec 9, 2016·Journal of Applied Clinical Medical Physics·Narges MiriPeter Greer

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Citations

Apr 2, 2019·Journal of Applied Clinical Medical Physics·Elizabeth L CovingtonRichard A Popple
Sep 28, 2020·Physica Medica : PM : an International Journal Devoted to the Applications of Physics to Medicine and Biology : Official Journal of the Italian Association of Biomedical Physics (AIFB)·Ana Rita BarbeiroXavier Franceries

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Software Mentioned

Portal Dosimetry
Eclipse Smart Leaf Motion Calculation ( LMC
Eclipse
Varian
Aria
Eclipse AAA

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