Abstract
The first proton therapy system in Thailand has been installed at King Chulalongkorn Memorial Hospital (KCMH) since 2019. Apart from its clinical usage, Suranaree University of Technology ...(SUT) has initiated the collaborative research work with KCMH to explore a possibility of developing a proton computed tomography (pCT) prototype. Due to the proton’s depth-dose properties, this technique is more effective than photon treatment. Prior to proton therapy, pCT could help with the treatment planning. This technique simplifies proton treatment calculations since both processes involve the same particle interaction with matter. We simulated the experiment setup using G4beamline with the proton beam using a monolithic active pixel sensor (MAPS) as a proton tracker. The sensor’s output revealed that the ratio of data from protons interacting on the sensor was low, so we pre-processed the data with MATLAB by applying a mean filter to replace any empty pixels with the average of their nearby pixels. A 3D reconstruction was performed by stacking all the axial images reconstructed by the back projection method. The result shows that the material densities of reconstructed samples can be identified, however, it is still in the preliminary stage and not yet suitable for clinical trials. It is, however, possible to improve the quality of images and obtain a better 3D reconstruction for the pCT prototype by using a back-projection method.
Abstract
The proton calorimeter is a key component of proton computed tomography (pCT). It aims to measure the residual energy and momentum of protons after passing through a patient’s body. In this ...study, we designed the prototype of the pCT calorimeter by including six layers of the ALICE pixel detector (ALPIDE) and six layers of the absorber. The absorber materials are carbon fiber (C), copper (Cu), and aluminum (Al) with 1 mm and 2 mm thicknesses. The prototype was tested by the proton source at King Chulalongkorn Memorial Hospital (KCMH), Bangkok. The number of activated pixels and the cluster sizes in each ALPIDE sensor obtained from the pCT calorimeter is measured at different proton beam energies. Moreover, this conceptual design of the pCT calorimeter was simulated by the G4Beamline Monte Carlo programming. At a proton beam energy of 70 MeV in the pCT calorimeter, simulations indicated Cu as the most effective absorber. Experimental results largely corroborated this, with Cu followed by Al, and then C in effectiveness. Both Cu and Al were found suitable for the pCT calorimeter prototype.
Abstract
Cholangiocarcinoma (CCA) is an aggressive cancer that is prevalent in the northeastern part of Thailand. Surgical treatment is the gold standard for CCA treatment, but some CCA patients are ...inoperable. Chemotherapy and radiotherapy are alternative treatments to improve the quality of life of patients. However, the effect of radiotherapy on CCA treatment is still unclear. In this study, we aimed to investigate the effect of X-rays and neutron beams on the human CCA cell line (KKU-055). First, KKU-055 cells were irradiated using 6 MV X-rays with a dose range of 0–5 Gy at King Chulalongkorn Memorial Hospital (KCMH) to obtain reference data. Next, cells were exposed to thermal neutron beams with doses ranging from 0 to 5 Gy using the Thai Research Reactor-1/Modification 1 (TRR-1/M1) at the Thailand Institute of Nuclear Technology (TINT). After neutron irradiation, survival curves were studied, and the relative biological effectiveness (RBE) was investigated. The findings revealed that the survival rate of the KKU-055 cells under X-ray irradiation is lower than that of neutron beams. To increase neutron interaction with the DNA of CCA cell lines, we plan to introduce boron compounds to CCA cell lines prior to neutron irradiation. This technique is referred to as boron neutron capture therapy (BNCT).
A Large Ion Collider Experiment (ALICE) is an experiment station at CERN that detects quark-gluon plasma, a state of matter thought to have formed immediately after the big bang. A plan was proposed ...to upgrade the particle detector in the Inner Tracking System (ITS) of ALICE by 2020. In the upgrade, new silicon sensor technology, the Monolithic Active Pixel Sensor (MAPS), will be used to replace the ITS. The new sensor is called ALICE PIxel DEtector (ALPIDE). This project focused on the characterization of ALPIDE sensors with a new version of a pixel sensor telescope using the 1.2 GeV electron beam at the Synchrotron Light Research Institute Beam Test Facility (SLRI-BTF). Seven ALPIDE sensors were lined up as a stacked sensor to perform a test using the electron beam at SLRI-BTF. The previous version of the telescope could only characterize the middle area of the sensor; however, the new sensor telescope can be used to characterize edges and corners of the sensor. This advantage provides us with a complete view of the detection efficiency in all sections of the ALPIDE sensor. The detection efficiency of the sensor will be investigated and analyzed by EUTelescope software.
The aim of the ALICE Collaboration is to study the physics of strongly interacting matter by using the experimental results from a dedicated heavy-ion detector. The Inner Tracking System (ITS) is ...located at the heart of the ALICE detector surrounding the interaction point. Currently, ALICE is planning to upgrade the ITS for rare probes at low transverse momenta. The new ITS comprises seven layers of silicon pixel sensors on the supporting structure. One goal of the new design is to reduce the material budget (X/X0) per layer to 0.3% for the inner layers and 0.8% for the middle and outer layers. In this work, we perform simulations based on detailed geometrical descriptions of different supporting structures for the inner and outer barrels by using ALIROOT. Our results indicate that it is possible to reduce the material budget of the inner and outer barrels to the expected value. Manufacturing of such prototypes is also possible.
Performing realistic and reliable in vitro biological dose verification with good resolution for a complex treatment plan remains a challenge in particle beam therapy. Here, a new 3D bio-phantom ...consisting of 96-well plates containing cells embedded into Matrigel matrix was investigated as an alternative tool for biological dose verification. Feasibility tests include cell growth in the Matrigel as well as film dosimetric experiments that rule out the appearance of field inhomogeneities due to the presence of the well plate irregular structure. The response of CHO-K1 cells in Matrigel to radiation was studied by obtaining survival curves following x-ray and monoenergetic 12C ion irradiation, which showed increased radioresistance of 3D cell cultures in Matrigel as compared to a monolayer. Finally, as a proof of concept, a 12C treatment plan was optimized using in-house treatment planning system TRiP98 for uniform cell survival in a rectangular volume and employed to irradiate the 3D phantom. Cell survival distribution in the Matrigel-based phantom was analyzed and compared to cell survival in a reference setup using cell monolayers. Results of both methods were in good agreement and followed the TRiP98 calculation. Therefore, we conclude that this 3D bio-phantom can be a suitable, accurate alternative tool for verifying the biological effect calculated by treatment planning systems, which could be applied to test novel treatment planning approaches involving multiple fields, multiple ion modalities, complex geometries, or unconventional optimization strategies.
Synchrotron Light Research Institute (SLRI) has successfully constructed a new experimental station, a Beam Test Facility (BTF), to the current SLRI accelerator complex. SLRI-BTF is capable of ...producing electron test beams with the number of electrons ranging from a few to millions of electrons per spill and with tunable energy from 40 MeV up to 1.2 GeV. The required intensity and energy of the test beam are obtained using a combination of a metal target to reduce high-intensity primary beam and a synchrotron booster to accelerate secondary beam to desired energy. The repetition rate of the test beam is up to 0.5 Hz depending on the selected energy and the pulse width is 90 ns. SLRI-BTF targets to service electron test beams with defined intensity and energy for testing and calibration of high-energy particle detectors as well as other beam diagnostic instrumentations. In commissioning, a pixel sensor telescope was employed as a detector to measure the number of electrons and as a preparation to investigate efficiency of mono active pixel sensors. The results confirm production of the low multiplicity of high-energy electrons at SLRI-BTF and the efficiency of a test pixel sensor is successfully calculated.
Abstract
The design of detectors used for experiments in high-energy
physics requires a light, stiff, and efficient cooling system with a
low material budget. The use of silicon microchannel cooling ...plates
has gained considerable interest in the last decade. In this study,
we propose the development of silicon microchannel cooling frames
studied within the framework of the major upgrade of the Inner
Tracking System (ITS) of the ALICE experiment at CERN. The
preliminary results obtained with these frames demonstrate that they
can withstand the internal pressure arising from the flow of the
coolant with a limited mass penalty.
Wafers with different epitaxial layer thicknesses of 12, 18, 20, 25, 30 and 40 μm and high resistivities ranging from 0.03 to 8.0 kΩċcm have been investigated in this study. To verify their ...properties, surface resistivity measurement, scanning electron microscopy inspection and spreading resistance profiling have been performed. The results indicate that wafers with a 25-μm epitaxial thickness are well-suited to our requirements for use as a starting material for ALPIDE chip production in the ALICE ITS upgrade project.
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