Uncertainty of active breathing coordinator technology for liver and lung cancer therapy using proton and heavy ion / 中华放射肿瘤学杂志

Objective:To study and analyze the uncertainty of active breathing coordinator (ABC) technology for liver and lung cancer therapy using proton and heavy ion.Methods:Before each treatment, each patient received a verification radiograph through the supporting imaging frame in treatment room. 200 verification radiographs were taken for 20 lung cancer patients and 200 for 20 liver cancer patients. Ipiodol markers, which were fixed relative to the location of the tumor, were injected into the liver cancer patients. The position changes of ipiodol markers could reflect the position changes of liver tumors. Verification radiographs were registered with the vertebral body as the main target, and the change value of tumor location was recorded.Results:For liver cancer cases, the values of position change in the left and right, head and foot, and dorsal abdomendirection were (-0.05± 0.28) cm, (0.15±0.33) cm, (-0.12±0.27) cm, and (-0.03±0.13) cm, (-0.05±0.14) cm and (0.02±0.16) cmfor lung cancer cases, respectively ( P=0.280, <0.001, <0.001). For liver cancer cases, the dispersionin the left and right, head and foot, and dorsal abdomendirectionwas (0.20±0.09) cm, (0.25±0.06) cm, (0.19±0.09) cm, and (0.09±0.03) cm, (0.10±0.03) cm and (0.13±0.03) cm for lung cancer cases, respectively ( P<0.001, <0.001, 0.008). The proportion of tumor location changes of≤5 mm in three directions in liver and lung cancer patientswas (92%, 83%, 93%) vs. (99%, 99%, 100%)( P=0.030, 0.002, 0.007). Conclusion:The application of ABC technology in the proton heavy ion therapy of lung and liver cancer has good reproducibility, and the stability of ABC technology in the treatment of lung cancer is better than that of liver cancer.

Effects of proton and heavy ion radiotherapy on nutritional status and adverse events in patients with malignant tumor / 中华临床营养杂志

Objective:To understand the effects of proton and heavy ion radiotherapy on nutritional status in patients with malignant tumors and to analyze the influencing factors of adverse events.Methods:Patients with malignant tumors who received proton and heavy ion therapy between October 2016 and September 2021were retrospectively included. The demographic characteristics, clinical diagnosis, radiotherapy regimen, nutritional indicators and adverse events were collected. Paired t test was used to analyze the changes in nutritional status before and after treatment and logistic regression was used to analyze the influencing factors of adverse events. Results:A total of 2,390 patients were enrolled and were stratified into 4 groups according to different radiotherapy regimen, namely proton, heavy ion, proton + heavy ion and photon + heavy ion radiotherapies. The prevalence of nutritional risk were 17.5% and 27.8% at admission and discharge, respectively. The prevalence of nutritional risk at discharge were 73.9% ( χ2 = 237.149, P < 0.01) in patients who received photon + heavy ion radiotherapy and 30.8% ( χ2 = 36.925, P < 0.01) in those who received proton + heavy ion radiotherapy. The prevalence of critical weight loss at discharge was 14.1%, with the absolute weight loss of 4.84 kg ( t = 11.716, P < 0.01) and 1.52 kg ( t = 29.530, P < 0.01) in photon + heavy ion radiotherapy and proton + heavy ion radiotherapy groups, respectively. All groups showed significant changes in serum albumin (ALB) and total lymphocyte count (TLC). Specifically, photon + heavy ion and proton + heavy ion therapy had a greater effect on serum ALB and TLC, with a decrease of 2.88 g/L and 2.18 g/L for ALB as well as a decrease of (1.06×10 9) /L and (0.80×10 9) /L for TLC ( P < 0.01). Multivariate logistic regression analysis showed that nutritional risk at admission and concurrent chemotherapy were independent factors for adverse events of proton and heavy ion radiotherapy ( OR = 1.404, 95% CI: 1.039 to 1.898; OR = 2.370, 95% CI: 1.781 to 3.154). Compared with heavy ion radiotherapy, the other 3 groups had more adverse events (proton, OR = 3.982, 95% CI: 2.533 to 6.259; proton + heavy ion, OR = 4.995, 95% CI: 3.688 to 6.766; photon + heavy ion, OR = 7.716, 95% CI: 5.079 to 11.720). Conclusions:Patients receiving proton and heavy ion therapy showed poorer nutritional status. Photon + heavy ion therapy had the greatest impact on nutritional status. Nutritional risk at admission and concurrent chemotherapy were independent factors for adverse events in patients receiving proton and heavy ion therapy.

Evaluation on the design and application effect of pure water analysis system of medical proton and heavy ion accelerator / 中国医学装备

Objective: To design an online pure water analysis system based on the proton and heavy ion accelerator (IONTRIS system) in Shanghai proton and heavy ion center (SPHIC), and to evaluate its application effect by operating data statistics. Methods: The system used the control system of Siemens S7-300 PLC to collect online data from sensors of pure water system. Analyzing the operation rules and setting the limiting value of alarm, and using WINCC software to develop monitoring and analysis system of central computer so as to real-time operate online data. The application effect of the system was evaluated by comparing the cost of one month consumables between before and after the system was applied. Results: After the system was applied, the real-time monitoring of pure water system was realized, and the efficiency of the consumables was enhanced. Conclusion: The application of the pure water analysis system has a good effect on the operation efficiency of the pure water system.

Assessment of occupational exposure doses to physicians in clinical practice at Shanghai Proton and Heavy Ion Center / 中华放射医学与防护杂志

Objective To assess the occupational exposure doses received by the physicians in clinical practice at Shanghai Proton and Heavy Ion Center ( SPHIC ) . Methods A total of 40 patients treated from September to November in 2016, including 20 proton cases and 20 carbon cases at SPHIC, were selected using simple random sampling method. Particle type, total particle number and prescribed doses were recorded for all the cases. The dose rates in the control room were measured by using a photon and neutron personal radiation detector during patient treatment. The dose rates around the surface of the patient's tumor 1 min after completion of beam delivery and the dose rates about 30 cm to the tumor surface (where a physician stands) were also measured during unfixing and assisting the patients. Finally, the dose rates surrounding the fixtures, couch, robotic arm and window of BAMS were measured. The factors affecting the occupational exposure of physician were analyzed and the annual dose equivalent was assessed for physicians in SPHIC. Results Proton and heavy ion released nearly all energy in the tumor for Bragg peak advantage, so there was no induced radioactivity in the treatment room. However, the tumor became the main induced radioactivity source to the occupational exposure dose to physicians in clinical practices. The dose rate around the surface of the patient's tumor 1 min after completion of beam delivery was (20. 68 ± 21. 91) μSv/h, which was the highest in the working places of physicians, thus regarded as the main source. A significant positive correlation (r=0. 828, P<0. 05) was shown between dose rates and total number of particles delivered for the treatment. The dose rate measured in the control room was (0. 08 ± 0. 01 )μSv/h, and the dose rate measured surrounding the fixtures, couch, robotic arm and BAMS window was ( 0. 09 ± 0. 01 )μSv/h. No neutron was detected. The dose rate about 30 cm to the tumor surface ( where physicians stand) was ( 2. 03 ± 2. 84 ) μSv/h during unfixing and assisting the patients. The average annual dose to physicians was about 0. 508 mSv. Conclusions The average annual dose to physicians was at a low level in SPHIC

Research on quality testing for active spot scanning proton and heavy ion accelerator / 中华放射医学与防护杂志

Objective To study the quality testing of dose delivery system of the active spot scanning proton and heavy ion accelerator,in order to provide the reference for the quality control of related equipment.Methods In the four therapy rooms,both 0.6 cc chambers and Gafchromic EBT3 films were used,respectively,to test the accelerator for dose reproducibility,dose linearity,dose stability,depth dose distribution,beam scanning position deviation and radiation field uniformity in each therapy room.Results Dose reproducibility variation coefficients are all less than 1.5％,dose linearity's maximum deviations less than 2％,dose stability's deviations less than 2％,depth dose distribution stability within 2％,beam scanning position deviation less than 1 mm,consistency of irradiation field's deviation less than 2 mm,and flatness within ± 5％.Conclusions The indicators about quality testing for the active spot scanning proton and heavy ion accelerator are all in line with the requirements of IEC standards draft.

Quality control research of active spot scanning proton and heavy ion accelerator's radiation field uniformity / 中华放射医学与防护杂志

Objective To develop the method for testing the consistency of irradiation field produced by the active spot scanning proton and heavy ion accelerator.Methods Calibration of the EBT3 films were carried out with the calibrated ion beam to establish the dose calibration curve.According to the different proton and carbon ion energies (proton:94.29,150.68,212.62 McV;carbon ion:175.99,283.43,412.54 MeV/u),EBT3 films were located in the solid water phantoms in each therapy room,respectively.Finally,the irradiated EBT3 films were scanned and the radiation field size's deviation and flatness were analyzed.Results In different conditions,radiation field size's deviations were all less than 2 mm and the flatness parameters were all controlled below the 5％.Conclusions EBT3 films can be used to test the active spot scanning proton and heavy ion accelerator's radiation field uniformity.

Monte Carlo method for proton and heavy ion treatment room shielding calculation / 中华放射医学与防护杂志

Objective To use Monte Carlo method to build a shielding calculation model for the proton and heavy ion treatment room,and to provide a reliable calculation method for shielding design.Methods A Monte Carlo-based FLUKA code was adopted to build the shielding calculation model for the proton and heavy ion treatment room,and to simulate the radiation field distribution in the proton and heavy ion treatment room.The calculation model was verified through the radiation detection around the proton and heavy ions treatment room.Results The FLUKA code-based simulation results were consistent with the radiation detection.Conclusions The shielding calculation model based on FLUKA code can simulate the radiation field from proton and heavy ions.Among the secondary particles,secondary neutrons are the dominant component and the main concern of accelerator shielding design.In shielding calculation,the emphasis should be put on both beam intensity and energy.