Objective:To assess performance advantages of voxel-less optimization(VoLO)algorithm of CyberKnife-based S7 treatment plan system for the optimization of stereotactic body radiation therapy(SBRT)for liver cancer.Methods:The case data of 20 patients with hepatocellular carcinoma from Chinese PLA General Hospital during June 2022 and April 2023 were retrospectively selected,which included 10 patients with large hepatocellular carcinoma and 10 patients with small hepatocellular carcinoma.All patients adopted respectively sequential optimization(SO)and VoLO to conduct optimization for plan.The optimized quality of plan and execution efficiency of two kinds of algorithms were assessed,and the influences of different tumor volumes also were considered.The planed quality assessment included dosimetric parameters of the target region and organ at risk(OAR).The assessment parameters of execution efficiency included the numbers of monitor units(MUs),nodes and beams,and estimated treatment time.Paired t-test method was adopted to analyze quality of plan and treatment efficiency.Results:On the aspect of the dose of target region,for small hepatocellular carcinoma,the conformity index(CI)value(1.08±0.05)of target region of VoLO algorithm was significantly better than(1.17±0.06)of SO algorithm(t=4.631,P<0.05).The gradient index(GI),coverage rate and dose by 95%(D95%)of VoLO algorithm were better than those of SO algorithm,while the differences were not significant(P>0.05).According to the defined standards of liver surgery,for large hepatocellular carcinoma,the differences in CI,GI,coverage rate and D95%of target region between two kinds of algorithms were significant(t=3.337,4.238,-3.359,-3.311,P<0.05),respectively.On the aspect of dosimetry for OAR,for the target region of large hepatocellular carcinoma,the differences of liver Dmean and D700 cm3 between two kinds of algorithms were significant(t=4.114,3.415,P<0.05).However,for small hepatocellular carcinoma,there was no significant statistical difference in dosimetry parameters of OAR between two kinds of algorithms(P>0.05).The execution efficiency of the plan of VoLO group was obviously higher than that of SO group,and the differences of MU number,node number,beam number and estimated treatment time between two groups were significant(t=12.661,4.423,5.024,9.487,P<0.05).Conclusion:The quality of VoLO plan is significantly better than that of SO,which has a significant improvement in execution efficiency of treatment.For the cases of large hepatocellular carcinoma with more complexity,the VoLO optimization shows better advantages on the aspect of dose on target region,and protection for normal liver.

Objective:To assess performance advantages of voxel-less optimization(VoLO)algorithm of CyberKnife-based S7 treatment plan system for the optimization of stereotactic body radiation therapy(SBRT)for liver cancer.Methods:The case data of 20 patients with hepatocellular carcinoma from Chinese PLA General Hospital during June 2022 and April 2023 were retrospectively selected,which included 10 patients with large hepatocellular carcinoma and 10 patients with small hepatocellular carcinoma.All patients adopted respectively sequential optimization(SO)and VoLO to conduct optimization for plan.The optimized quality of plan and execution efficiency of two kinds of algorithms were assessed,and the influences of different tumor volumes also were considered.The planed quality assessment included dosimetric parameters of the target region and organ at risk(OAR).The assessment parameters of execution efficiency included the numbers of monitor units(MUs),nodes and beams,and estimated treatment time.Paired t-test method was adopted to analyze quality of plan and treatment efficiency.Results:On the aspect of the dose of target region,for small hepatocellular carcinoma,the conformity index(CI)value(1.08±0.05)of target region of VoLO algorithm was significantly better than(1.17±0.06)of SO algorithm(t=4.631,P<0.05).The gradient index(GI),coverage rate and dose by 95%(D95%)of VoLO algorithm were better than those of SO algorithm,while the differences were not significant(P>0.05).According to the defined standards of liver surgery,for large hepatocellular carcinoma,the differences in CI,GI,coverage rate and D95%of target region between two kinds of algorithms were significant(t=3.337,4.238,-3.359,-3.311,P<0.05),respectively.On the aspect of dosimetry for OAR,for the target region of large hepatocellular carcinoma,the differences of liver Dmean and D700 cm3 between two kinds of algorithms were significant(t=4.114,3.415,P<0.05).However,for small hepatocellular carcinoma,there was no significant statistical difference in dosimetry parameters of OAR between two kinds of algorithms(P>0.05).The execution efficiency of the plan of VoLO group was obviously higher than that of SO group,and the differences of MU number,node number,beam number and estimated treatment time between two groups were significant(t=12.661,4.423,5.024,9.487,P<0.05).Conclusion:The quality of VoLO plan is significantly better than that of SO,which has a significant improvement in execution efficiency of treatment.For the cases of large hepatocellular carcinoma with more complexity,the VoLO optimization shows better advantages on the aspect of dose on target region,and protection for normal liver.

Objective:A dose verification system of two-dimensional semiconductor matrix(SRS MapCHECK)was used to verify the dose of the clinical treatment plan of patients who underwent CyberKnife(CK),which realized rapid verification for individualization of radiotherapy plans of patients through analyzed the γ-passing rates of them.Methods:A total of 253 patients with tumor who received CK clinical treatment in the First Medical Center of Chinese PLA General Hospital from March 2021 to May 2023 were selected.Among of them,121 cases received CK treatment on head,and 30 cases received that on lung,and 102 cases received CK treatment on abdomen and other metastatic tumor.In the MultiPlan treatment plan system,the plan of patient was mapped to the integrated model composed of StereoPHAN model and SRS MapCHECK matrix dose verification system by the means of the plan image center overlap.The dose verification was conducted on the plan of each patient on the basis of ensuring the consistency of the number of beam,direction of beam and the monitor unit.The different γ analysis standards(1%/1 mm,2%/1 mm,3%/1 mm,1%/2 mm,2%/2 mm,3%/2 mm,1%/3 mm,2%/3 mm and 3%/3 mm)were adopted to conduct global analysis of absolute dose for each verification plan,and the threshold(TH)of low dose was set as 10%.Results:The γ passing rates of phantom verification plans of 253 patients were respectively(88.64±5.91)%,(95.43±3.40)%,(97.90±2.06)%,(96.51±2.35)%,(98.15±1.68)%,(99.06±1.12)%,(98.30±1.39)%,(99.09±0.97)%and(99.52±0.63)%under different analysis standards.The γ passing rates of other standards of patients with tumor on different parts were larger than 95%except the analysis result of 1%1 mm standard.The overall analysis result of the deviation of central point dose was(-1.30±2.17)%,among of which the tumor of head,abdominal tumors and other metastatic tumor were about approximately-2%,while that of lung tumors were approximately-3%.The deviation of abdominal and other metastatic tumor was the minimum.The correlation analysis showed that the target volume and the size of the minimum collimator were respectively correlated to the dose deviation of the center.Conclusion:SRS MapCHECK dose verification system can conveniently and quickly realize the individualized verification for the plan of patients who receive CK treatment.

To study an automatic plan(AP) method for radiotherapy after breast-conserving surgery based on TiGRT system and and compare with manual plan (MP). The dosimetry parameters of 10 patients and the evaluation of scoring table were analyzed, it was found that the targets dose of AP were better than that of MP, but there was no statistical difference except for CI, The V5, V20 and V30 of affected lungs and whole lungs in AP were lower than all that in MP, the Dmean of hearts was slightly higher than that of MP, but the difference was not statistically significant, the MU of AP was increase by 16.1% compared with MP, the score of AP evaluation was increase by 6.1% compared with MP. So the AP could be programmed and automated while ensuring the quality of the plan, and can be used to design the plans for radiotherapy after breast-conserving surgery.
Breast Neoplasms/surgery* ; Female ; Humans ; Mastectomy, Segmental ; Organs at Risk ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; Radiotherapy, Intensity-Modulated

Image-guided radiation therapy using magnetic resonance imaging (MRI) is a new technology that has been widely studied and developed in recent years. The technology combines the advantages of MRI imaging, and can offer online real-time tracking of tumor and adjacent organs at risk, as well as real-time optimization of radiotherapy plan. In order to provide a comprehensive understanding of this technology, and to grasp the international development and trends in this field, this paper reviews and summarizes related researches, so as to make the researchers and clinical personnel in this field to understand recent status of this technology, and carry out corresponding researches. This paper summarizes the advantages of MRI and the research progress of MRI linear accelerator (MR-Linac), online guidance, adaptive optimization, and dosimetry-related research. Possible development direction of these technologies in the future is also discussed. It is expected that this review can provide a certain reference value for clinician and related researchers to understand the research progress in the field.
Magnetic Resonance Imaging ; Particle Accelerators ; Radiometry ; Radiotherapy Planning, Computer-Assisted ; Radiotherapy, Image-Guided

MRI simulator(MRI-Sim) images have unique clinical advantages with higher resolution of soft tissue and clearer visualization of tissue boundaries. Thus, the precise positioning of the tumor target area can be achieved and it is widely used in the field of radiotherapy. This article focuses on the acceptance test project and image quality assurance work of MRI-Sim equipment. The obtained ACR phantom images were used to analyze various image quality assurance indicators, and the results all reached the set standards, thereby ensuring that the obtained images meet the requirements of clinical applications.
Magnetic Resonance Imaging ; Phantoms, Imaging ; Quality Assurance, Health Care

The treatment plans were designed based on planning CT of Catphan phantom's homogenic and heterogenetical module, respectively. With the OBI system, Catphan phantom was scanned under different scanning conditions. The dose was recalculated by applying treatment plans based on planning CT to the CBCT images with its individual hounsfield unit-electron density calibration curve. The dose distributions were compared with those of the original plan, the results ofHI showed a good agreement.CIs in the homogenic module were superior to those in the heterogenetical one. There is a good dose distribution for CBCT images under different scanning conditions. It is helpful for CBCT images directly used for dose re-calculation in adaptive radiation therapy (ART).

Objective To evaluate the cone beam CT (CBCT) image quality and its long-term stability for HUs under different scanning conditions.Methods With the OBI system, Catphan 504 phantom using the different modes was scanned through one year. Analysis of variance (ANOVA) was used to evaluate the CBCT images.Results The results of contrast resolution under different scanning conditions met the requirements of acceptance test procedure. Spatial contrast resolution(≥5 lp/cm) of half-fan scanning conditions were inferior to those (≥7 lp/cm) of ful-fan mode. The accuracies of spatial linear distance and angle were within±1%. HUs in air density plug were constant, but HUs of other plugs with different conditions had the signifi cant difference (F=660.84,P=0). Under different conditions in a year, the mean HUs showed a good agreement.Conclusions HUs of CBCT image under different scanning conditions exist a little difference, but there is a good consistency for the long term stability analysis. It is helpful for CBCT images directly used for dose re-calculation in adaptive radiation therapy (ART).

Objective Evaluation of intensity-modulated radiation therapy(IMRT) delivery quality assurance(DQA) using EDOSE software based on accelerator electronic portal imaging device (EPID).Methods Analysed the dose response uniformity correction of EPID imaging plate in different fields and the gamma pass rates about the fields; And compared the calculated parameters of the EDOSE and the Pinnacle planning station.Results The uniformities on the homogeneous region of thefi elds are good after who corrected by EDOSE. The gamma(γ, 3mm/3%) pass rates are in the ideal range. The volume of the organs at risk(OAR) have no statistical signifi cance except the right lung; A part of the parameters have statistical signifi cance.Conclusions The results of the calculation and analysis of EDOSE has a high agreement with the planning system.

Helical tomotherapy (HT), as a new IMRT technology, utilizes a fan beam of radiation for treatment. It combines the main characteristics of a modern CT scanner and a linear accelerator to achieve the function of helical tomotherapy. Due to the complexity of the system with a highly integrated and automated features, monitoring its operation, continuing to improve the stability and reliability, and simplifying its quality control procedures has become an important part of quality assurance (QA) for HT. Based on the results of afi ve-year quality control (QC) program, and the initial application of new QA equipment, this study wil summarize the standardization mode of its QA and explore the changes of QA mode.