In this work, the standard CsI(Tl) scintillator was used to determine the characteristics of a proton beam. By irradiating the scintillator with a proton beam, it was able to subsequently measure the emitted light using a spectrometer. This work presents the dose response of a scintillator and its use to measure the depth-dose profile of a proton beam. The measurement of the dose response showed that the emission light of the scintillator depended on the total dose of the proton beam. For the design of the depth-dose measurement, the setup of the water phantom included a scintillator and a water tank. The depth-dose profile was determined through varying the water depth at various positions along the path of the proton beam until the end of the Bragg peak region. To compare the measured depth-dose profile, the deposited energy was simulated and fitted Birks constant for collecting quenching. Furthermore, the recommended measurement design suggested using a thin scintillator, as it resulted in a narrower shape of the depth-dose profile. Based on experiment and simulation data, a standard CsI(Tl) scintillator was promising for determining the characteristic proton beam.
Purpose: This study aims to optimize and characterize the response of a mPSD for in vivo dosimetry in HDR brachytherapy. Methods: An exhaustive analysis was carried out in order to obtain an optimized mPSD design that maximize the scintillation light collection produced by the interaction of ionizing photons. Several mPSD prototypes were built and tested in order to determine the appropriate order of scintillators relative to the photodetector, as well as their length as a function of the scintillation light emitted. Scintillators BCF-60, BCF-12 and BCF-10 constituted the mPSD sensitive volume…
Ultra-high dose rate electron sources require dose rate independent dosimeters and a calibrated dose control system for accurate delivery. In this study, we developed a single-pulse dose monitoring and a real-time dose-based control system for a converted clinical linear accelerator (LINAC). A point scintillator detector was coupled to a gated amplifier and a real-time controller for dose monitoring and feedback control loop. The controller was programmed to integrate dose and measure pulse width of each radiation pulse and gate the LINAC beam when the prescribed dose was delivered. The scinti…
Purpose: To present the performance of a multi-point plastic scintillation detector (mPSD) as a tool in vivo dosimetry in brachytherapy. Methods: A previously optimized three-point sensor system was used for in vivo HDR brachytherapy measurements (using the scintillators BCF-60, BCF-12, and BCF-10). The light detection system of the mPSD consisted of compactly assembled photomultiplier tubes (PMTs) and dichroic mirrors and filters to achieve a highly sensitive scintillation light collection. The PMT signals were recorded using a NI-DAQ board at a rate of 100 kHz. Dose measurements covering a r…
The high dose gradients near the source characteristics of brachytherapy are equivalent to nefarious effects if unnoticed errors take place during the patient treatment. In vivo dosimetry is the only method to quantify the delivered dose. Previous studies to this one, have characterized potential detectors that can be used as in vivo dosimeter. Some of them have focused on the source tracking topic in HDR brachytherapy. The aim of this study is to perform 3D source position reconstruction by combining in vivo dosimetry measurements from two independent detector systems. The first was based on …
Purpose: We sought to evaluate the feasibility of using machine learning algorithms for multipoint plastic scintillator detector calibration in high-dose-rate brachytherapy. Methods: The dosimetry system consisted of an optimized 1-mm-core mPSD and a compact assembly of photomultiplier tubes coupled with dichroic mirrors and filters. An $^{192}$Ir source was remotely controlled and sent to various positions in a homemade PMMA holder. Dose measurements covering a range of 0.5 to 12 cm of source displacement were carried out according to TG-43 recommendations. Individual scintillator doses were …
Since large dose are administrated to the patient in brachytherapy treatment, ensuring the right dose is delivered is highly critical. This study presents a first step in solving the standing issue of accurately knowing the dosimeter position at all time during in vivo dosimetry. In this work, an energy independent dosimeter, namely plastic scintillation detector, is coupled to an electromagnetic (EM) sensor having sub-mm positional accuracy for real-time tracking of the dosimeter position. However, adding an EM sensor adds materials in the path to the scintillator and thus could potentially p…
Nanophotonic control of spatial information in scintillation detectors
Research Laboratory of Electronics, MIT（麻省理工学院电子研究实验室）；Department of Mechanical Engineering, MIT（麻省理工学院机械工程系）；Department of Physics, MIT（麻省理工学院物理系）；Department of Materials Science and Engineering, MIT（麻省理工学院材料科学与工程系）；Harvard John A. Paulson SEAS, Harvard University（哈佛大学约翰·A·保尔森工程与应用科学学院）；Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology（麻省理工学院士兵纳米技术研究所）；Neuroradiology Division, Department of Radiology, Massachusetts General Hospital, Harvard Medical School（哈佛医学院马萨诸塞州总医院放射科神经放射学分部）；Institute of Science and Technology Austria (ISTA)（奥地利科学与技术研究所）
Anatomical motion and deformation pose challenges to the understanding of the delivered dose distribution during radiotherapy treatments. Hence, deformable image registration (DIR) algorithms are increasingly used to map contours and dose distributions from one image set to another. However, the lack of validation tools slows their clinical adoption, despite their commercial availability. This work presents a novel water-equivalent deformable dosimeter that simultaneously measures the dose distribution and tracks deformation vector fields (DVF). The dosimeter in made of an array of 19 scintill…
Proton therapy is a cancer treatment technique currently in growth worldwide. It offers advantages with respect to conventional X-ray and $γ$-ray radiotherapy, in particular, a better control of the dose deposition allowing to reach a higher conformity in the treatments. Therefore, it causes less damage to the surrounding healthy tissue and less secondary effects. However, in order to take full advantage of its potential, improvements in treatment planning and dose verification are required. A new prototype of proton Computed Tomography scanner is proposed to design more accurate and precise t…
An innovative dose rate independent 2D Ce-doped YAG scintillating dosimetry system for time resolved beam monitoring in ultra-high dose rate electron FLASH radiation therapy
Background : Proton flash therapy is an emergency research topic in radiation therapy since the Varian announced the promising results from the first in human clinical trial of Flash therapy recently. However, it still needs a lot of researches on this topic, not only to understand the mechanism of the radiobiological effects but also to develop an appropriate dose monitoring system. Purpose : In this study we setup an experimental station for small animal proton Flash irradiation in a clinical machine. The dose monitoring system is able to provide real-time irradiation dose and irradiation ti…
Purpose: To experimentally validate the Fastcat cone beam CT (CBCT) simulator against kV and MV CBCT images acquired with a Varian Truebeam linac. Methods: kV and MV CBCT images of a Catphan 504 phantom were acquired using a 100 kVp beam with the on-board imager (OBI) and a 6 MV treatment beam with the electronic portal imaging device (EPID), respectively. The kV Fastcat simulation was performed using detailed models of the x-ray source, bowtie filter, a high resolution voxelized virtual Catphan phantom, anti-scatter grid, and the CsI scintillating detector. Likewise, an MV Fastcat CBCT was si…
Secondary radiation measurements for particle therapy applications: prompt photons produced by $^{4}$He, $^{12}$C and $^{16}$O ion beams in a PMMA target
