Feasibility Study of Using XRV-124 Scintillation Detector for Collinearity Measurement in Uniform Scanning Proton Therapy

Abstract

Purpose The purpose of this work is to study the feasibility of using an XRV-124 scintillation detector in measuring the collinearity of the x-ray system and uniform scanning proton beam. Methods A brass aperture for Snout 10 was manufactured. The center of the aperture had an opening of 1 cm in diameter (4 cm for the film measurements). The 2D kV x-ray images of the XRV-124 were acquired such that the marker inside the detector is aligned to the imaging isocenter. After obtaining the optimal camera settings, a uniform scanning proton beam was delivered for various ranges (12 g/cm2 to 28 g/cm2 in step size of 2 g/cm2). For each range, 10 monitor units (MU) of the first layer were delivered to the XRV-124 detector. Collinearity tests were repeated by using EDR2 and EBT3 films following our current quality assurance protocol in practice. The results from the XRV-124 measurements were compared against the collinearity results from EDR2 and EBT3 films. Results and Discussion The collinearity results were evaluated in the horizontal (x) and vertical (y) directions. The average deviation in collinearity in the x-direction was −0.24 ± 0.30 mm, 0.57 ± 0.39 mm, and −0.27 ± 0.14 mm for EDR2, EBT3, and XRV-124, respectively. In the y-direction, the average deviation was 0.39 ± 0.07 mm, 0.29 ± 0.14 mm, and 0.39 ± 0.03 mm for EDR2, EBT3, and XRV-124, respectively. Conclusion The measurement results from the XRV-124 and films are in good agreement. Compared to film, the use of the XRV-124 detector for collinearity measurements in uniform scanning protons is more efficient and provides results in real time.

Development of a digital star‐shot analysis system for comparing radiation and imaging isocenters of proton treatment machine

“…Most of these studies are designed to use patient‐specific QA 13 or spot size measurement for particle therapy 14,15 . Commercial products are also available, Lynx (IBA Dosimetry, Schwarzenbruck, Germany) 27 and XRV‐124 (Logos Vision System, CA, USA) 28 . Especially, XRV‐124 computes the offset value of the radiation isocenter from the imaging isocenter in real time 29,30 .…”

“… 14 , 15 Commercial products are also available, Lynx (IBA Dosimetry, Schwarzenbruck, Germany) 27 and XRV‐124 (Logos Vision System, CA, USA). 28 Especially, XRV‐124 computes the offset value of the radiation isocenter from the imaging isocenter in real time. 29 , 30 But the purchasing price is much higher than our system.…”