A proton imaging system using a volumetric liquid scintillator: a preliminary study

Abstract

With the expansion of proton radiotherapy for cancer treatments, it has become important to explore proton-based imaging technologies to increase the accuracy of proton treatment planning, alignment, and verification. The purpose of this study is to demonstrate the feasibility of using a volumetric liquid scintillator to generate proton radiographs at a clinically relevant energy (180 MeV) using an integrating detector approach. The volumetric scintillator detector is capable of capturing a wide distribution of residual proton beam energies from a single beam irradiation. It has the potential to reduce acquisition time and imaging dose compared to other proton radiography methods. The imaging system design is comprised of a volumetric (20 × 20 × 20 cm 3 ) organic liquid scintillator working as a residual-range detector and a charge-coupled device (CCD) placed along the beams'-eye-view for capturing radiographic projections. The scintillation light produced within the scintillator volume in response to a 3-dimensional distribution of residual proton beam energies is captured by the CCD as a 2-dimensional grayscale image. A light intensity-to-water equivalent thickness (WET) curve provided WET values based on measured light intensities. The imaging properties of the system, including its contrast, signal-to-noise ratio, and spatial resolution (0.19 line-pairs/mm) were determined. WET values for selected Gammex phantom inserts including solid water, acrylic, and cortical bone were calculated from the radiographs with a relative accuracy of −0.82%, 0.91%, and −2.43%, respectively. Image blurring introduced by system optics was accounted for, resulting in sharper image features. Finally, the system's ability to reconstruct proton CT images from radiographic projections was demonstrated

Combined proton radiography and irradiation for high-precision preclinical studies in small animals

“…This represents an improvement over other reported implementations (e.g., Darne et al. ( 38 ): 47.2 mGy, Harms et al. ( 41 ): 50mGy).…”

Image quality evaluation of projection- and depth dose-based approaches to integrating proton radiography using a monolithic scintillator detector

“…Previous work has shown that proton radiography is feasible using a single-camera scintillator imaging system. 20 Potential experimental setups utilizing multiple cameras for imaging of proton beams has also been described. 21 Light emission from a monolithic scintillator placed in the path of the beam is captured in the lateral and beam's-eyeview using 2 digital cameras.…”

“…The distal camera directly captures light emitted from the scintillator, which acts as a surrogate for the total energy deposited in and LET of the medium. 10,11,20 Light captured by the distal camera is converted to WET by using a series of calibration curves generated by irradiating phantoms of various thicknesses, see supplementary material for further explanation. 10,11 This method is expected to provide higher spatial resolution when compared to the below-mentioned lateral reconstruction technique due to the finer gridding of the camera sensor.…”

Research on proton beam spot imaging based on pixelated gamma detector

“…One kind of stripline-type beam position monitor (BPM) was designed and used for measuring the position and phase of the proton beam in air in a non-destructive way [5]. A proton imaging system has been also developed to measure the proton range, which is composed of a scintillator and a charge-coupled device [6]. China Spallation Neutron Source (CSNS) has been built and commissioned successfully since August 2018, whose purpose is dedicated to the multidisciplinary research on material science [7].…”