We studied a Monte Carlo simulation of the proton beam delivery system at the National Cancer Center (NCC) using the Geant4 Monte Carlo toolkit and tested its feasibility as a dose verification framework. The Monte Carlo technique for dose calculation methodology has been recognized as the most accurate way for understanding the dose distribution in given materials. In order to take advantage of this methodology for application to externalbeam radiotherapy, a precise modeling of the nozzle elements along with the beam delivery path and correct initial beam characteristics are mandatory. Among three different treatment modes, double/single.scattering, uniform scanning and pencil beam scanning, we have modeled and simulated the double.scattering mode for the nozzle elements, including all components and varying the time and space with the Geant4.8.2 Monte Carlo code. We have obtained simulation data that showed an excellent correlation to the measured dose distributions at a specific treatment depth. We successfully set up the Monte Carlo simulation platform for the NCC proton therapy facility. It can be adapted to the precise dosimetry for therapeutic proton beam use at the NCC. Additional Monte Carlo work for the full proton beam energy range can be performed.
Proton Therapy ; Protons* ; Radiotherapy

The main benefit of proton therapy over photon beam radiotherapy is the absence of exit dose, which offers the opportunity for highly conformal dose distributions to target volume while simultaneously irradiating less normal tissue. For proton beam therapy two patient specific beam modifying devices are used. The aperture is used to shape the transverse extension of the proton beam to the shape of the tumor target and a patient-specific compensator attached to the block aperture when required and used to modify the beam range as required by the treatment plan for the patient. A block of range shifting material, shaped on one face in such a way that the distal end of the proton field in the patient takes the shape of the distal end of the target volume. The mechanical quality assurance of range compensator is an essential procedure to confirm the 3 dimensional patient-specific dose distributions. We proposed a new quality assurance method for range compensator based on image processing using X-ray tube of proton therapy treatment room. The depth information, boundaries of each depth of plan compensatorfile and x-ray image of compensator were analyzed and presented over 80% matching results with proposed QA program.
Humans ; Proton Therapy ; Protons

er to detect the beam quality of the SC200 superconducting cyclotron,measure the beam at the extraction reference and the acceptance of the accelerator is realized.This article mainly introduces the design that use the scintillation screen at the extraction reference to measure the beam profile,position and use the Faraday cup to measure the current intensity with 2.5 level accuracy.The remoted controlling of probes and the acquisition and processing of signal based on LabVIEW and PLC.
Proton Therapy ; instrumentation

Electromagnetic compatibility testing of proton therapy system is different from that of traditional products in an anechoic chamber. It has high requirements on the division of sample composition, the understanding of applicable standards, the formulation of operation mode, the selection of test location, and the test of ambient noise. According to the requirements of GB 4824-2019 standard, the test method of radiation emission of proton therapy equipment was developed to provide reference advice for the industry, and the problems encountered in the actual test were studied.
Electromagnetic Phenomena ; Proton Therapy

Proton is quite different from x-ray in terms of energy emission. As it enters a cancer patient's body through skin and tissue, it releases a relatively low dose of energy before it reaches the target. It, however, hits the targeted tumor by depositing the biggest dose of energy on it, then suddenly stopping its activity afterwards. The point where the highest energy is released is called as the Bragg peak. The proton beam has many advantages over the conventional x-ray beam because the proton beam radiates primarily the tumor site, leaving the surrounding healthy tissue and organs totally unharmed or relatively less damaged. Thus, the patients can enjoy much more enhanced quality-of-life during and after the treatment as well as have a high probability to be cured from their diseases.
Humans ; Proton Therapy ; Protons ; Skin

Geant4 (GEometry ANd Tracking) provides various packages specialized in modeling electromagnetic interactions. The validation of Geant4 physics models is a significant issue for the applications of Geant4 based simulation in medical physics. The purpose of this study is to evaluate accuracy of Geant4 electromagnetic physics for proton therapy. The validation was performed both the Continuous slowing down approximation (CSDA) range and the stopping power. In each test, the reliability of the electromagnetic models in a selected group of materials was evaluated such as water, bone, adipose tissue and various atomic elements. Results of Geant4 simulation were compared with the National Institute of Standards and Technology (NIST) reference data. As results of comparison about water, bone and adipose tissue, average percent difference of CSDA range were presented 1.0%, 1.4% and 1.4%, respectively. Average percent difference of stopping power were presented 0.7%, 1.0% and 1.3%, respectively. The data were analyzed through the kolmogorov-smirnov Goodness-of-Fit statistical analysis test. All the results from electromagnetic models showed a good agreement with the reference data, where all the corresponding p-values are higher than the confidence level alpha=0.05 set.
Adipose Tissue ; Magnets ; Proton Therapy ; Protons ; Water

Proton beams have been used for cancer treatment for more than 28 years, and several technological advancements have been made to achieve improved clinical outcomes by delivering more accurate and conformal doses to the target cancer cells while minimizing the dose to normal tissues. The state-of-the-art intensity modulated proton therapy is now prevailing as a major treatment technique in proton facilities worldwide, but still faces many challenges in being applied to the lung. Thus, in this article, the current status of proton therapy technique is reviewed and issues regarding the relevant uncertainty in proton therapy in the lung are summarized.
Lung Neoplasms ; Lung ; Proton Therapy ; Protons ; Uncertainty

Radiotherapy has an important role in the management of prostate cancer patients. It can be used as definitive treatment in place of surgery, postoperative adjuvant radiotherapy, or salvage treatment when recurrences develop after surgery. During definitive radiotherapy treatment, dose escalation can improve biochemical control but has not led to improved survival to date. Hypofractionated radiotherapy is applied for prostate cancer treatment, since prostate cancer has a low alpha/beta ratio. Contrary to theoretical expectations, hypofractionated treatment does not show improved therapeutic results and decreased toxicity, but it can reduce overall treatment time. Ongoing non-inferiority trials may assist in determining optimal hypofractionated treatment regimens. Adjuvant radiotherapy in patients with pathological T3 or positive resection margins can improve biochemical control and might increase overall survival. However, there is debate regarding the superiority of adjuvant radiotherapy over early salvage radiotherapy in high-risk patients after surgery. To address this issue, it will be necessary to wait for the results of current randomized trials.
Humans ; Prostatic Neoplasms* ; Proton Therapy ; Radiotherapy* ; Radiotherapy, Adjuvant ; Recurrence

Depth of prostate volume from the skin can vary due to intra-fractional and inter-fractional movements, which may result in dose reduction to the target volume. Therefore we evaluated the feasibility of automated depth determination-based adaptive proton therapy to minimize the effect of inter-fractional movements of the prostate. Based on the center of mass method, using three fiducial gold markers in the prostate target volume, we determined the differences between the planning and treatment stages in prostate target location. Thirty-eight images from 10 patients were used to assess the automated depth determination method, which was also compared with manually determined depth values. The mean differences in prostate target location for the left to right (LR) and superior to inferior (SI) directions were 0.9 mm and 2.3 mm, respectively, while the maximum discrepancies in location in individual patients were 3.3 mm and 7.2 mm, respectively. In the bilateral beam configuration, the difference in the LR direction represents the target depth changes from 0.7 mm to 3.3 mm in this study. We found that 42.1%, 26.3% and 2.6% of thirty-eight inspections showed greater than 1 mm, 2 mm and 3 mm depth differences, respectively, between the planning and treatment stages. Adaptive planning based on automated depth determination may be a solution for inter-fractional movements of the prostate in proton therapy since small depth changes of the target can significantly reduce target dose during proton treatment of prostate cancer patients.
Humans ; Prostate ; Prostatic Neoplasms ; Proton Therapy ; Protons ; Skin

Depth of prostate volume from the skin can vary due to intra-fractional and inter-fractional movements, which may result in dose reduction to the target volume. Therefore we evaluated the feasibility of automated depth determination-based adaptive proton therapy to minimize the effect of inter-fractional movements of the prostate. Based on the center of mass method, using three fiducial gold markers in the prostate target volume, we determined the differences between the planning and treatment stages in prostate target location. Thirty-eight images from 10 patients were used to assess the automated depth determination method, which was also compared with manually determined depth values. The mean differences in prostate target location for the left to right (LR) and superior to inferior (SI) directions were 0.9 mm and 2.3 mm, respectively, while the maximum discrepancies in location in individual patients were 3.3 mm and 7.2 mm, respectively. In the bilateral beam configuration, the difference in the LR direction represents the target depth changes from 0.7 mm to 3.3 mm in this study. We found that 42.1%, 26.3% and 2.6% of thirty-eight inspections showed greater than 1 mm, 2 mm and 3 mm depth differences, respectively, between the planning and treatment stages. Adaptive planning based on automated depth determination may be a solution for inter-fractional movements of the prostate in proton therapy since small depth changes of the target can significantly reduce target dose during proton treatment of prostate cancer patients.
Humans ; Prostate ; Prostatic Neoplasms ; Proton Therapy ; Protons ; Skin