Comparison of radiation dose calculation differences between uRT-TPS and Monaco-TPS for the same linear accelerator in multiple cancers / 中国癌症杂志

Background and purpose:In recent years,domestic radiotherapy equipment and related software have made great progress,and testing the functionality and stability of the equipment and software is an essential step.This paper focused on comparing the differences in intensity-modulated radiation therapy(IMRT)plans dosimetry and organ at risk(OAR)volume calculations for common cancers between uRT-treatment planning system(TPS)and Monaco-TPS,and to evaluate the feasibility of dose calculation for Infinity linac(linear accelerator,Elekta,Sweden)using uRT-TPS.Methods:Twenty cases of rectal cancer,lung cancer,breast cancer and nasopharyngeal carcinoma were selected.The IMRT plans were completed in uRT-TPS and Monaco-TPS.The dose uniformity and conformity,mean dose,maximum dose of planning target volume(PTV)and OAR between two plans under the same prescribed dose of PTV were compared.And the pass rates of two TPS plans validated at the same linear accelerator were compared.Meanwhile,monitor units(MU),source skin distance(SSD)and the volume of OAR in uRT-TPS and Monaco-TPS were compared.Results:Wonderful plans that met the clinical requirements were obtained in uRT-TPS and Monaco-TPS.Comparable uniformity and conformability was received in PTV,and the maximum dose of PTV was reduced by 1.1 Gy for uRT-TPS(P = 0.006).For breast cancer and lung cancer,the dose in lung was lower for Monaco-TPS(P＜0.05).For nasopharyngeal carcinoma,the dose indicators that oral cavity and throat in the uRT-TPS was reduced by 9.2%and 5.1%,respectively.The verification results of absolute point dose(＜3%)and three-dimensional surface dose(＞95%)for both plans met the clinical requirements.The region of interest in uRT-TPS was smaller compared with Monaco-TPS(P＜0.05).Conclusion:A comparable IMRT plan was obtained for common tumors in uRT-TPS and Monaco-TPS.It is feasible to calculate the dose of Infinity linac using uRT-TPS.

Impact of BRCA1/2 germline mutation on the incidence of second primary cancer following postoperative radiotherapy in patients with triple-negative breast cancer / 中国癌症杂志

Background and purpose:BRCA1/2 plays an important role in maintaining the genome stability.Whether BRCA1/2 germline mutation could increase the tumor sensitivity to radiotherapy,thereby inducing secondary primary cancer after radiotherapy is unclear.This study aimed to investigate whether postoperative radiotherapy is a risk factor for the development of second primary cancer in triple-negative breast cancer(TNBC)patients with BRCA1/2 germline mutation.Methods:This research was based on a previously reported retrospective cohort,i.e.,the Fudan University Shanghai Cancer Center TNBC cohort.Between January 1,2007 and December 31,2014,a total of 292 female TNBC patients with BRCA1/2 mutation were enrolled.We performed logistic regression analysis in patients without BRCA1/2 germline mutation(n=261)and BRCA1/2 germline mutation patients(n=31),respectively,to assess the risk factors affecting the incidence of second primary cancer.We then performed interactive analysis on the above two analyses to evaluate the interactive effect between BRCA1/2 germline mutation and postoperative radiotherapy.P<0.05 indicates a statistically significant difference.The research was approved by Fudan University Shanghai Cancer Center TNBC Ethics Committee(050432-4-2108),and each patient provided written informed consent.Results:Logistic regression analysis in patients with BRCA1/2 germline mutations showed that postoperative radiotherapy significantly increased the risk of secondary primary disease compared to non-radiotherapy[odds ratio(OR)=2.475,95%confidence interval(CI):1.933-3.167,P<0.001].In patients without BRCA1/2 germline mutation,the effect of radiotherapy on the incidence of second primary tumor was not significant.There was a significant interaction between BRCA1/2 germline mutation and postoperative radiotherapy for the incidence of secondary primary cancer(OR=9.710,95%CI:0.320-295.250,P=0.193).Conclusion:Although statistical analysis results show that patients with BRCA1/2 germline mutations have an increased risk of developing a second primary tumor after postoperative radiotherapy compared to patients who have not received radiotherapy,there is no significant correlation between BRCA1/2 germline mutations and radiotherapy for the development of a second primary tumor.Therefore,patients with BRCA1/2 germline mutations who receive radiotherapy after surgery may not increase the risk of developing a second primary tumor.

Dosimetric Impact of Titanium Alloy Implant in Spinal IMRT Plan / 中国医疗器械杂志

The purpose of this study is to establish and apply a correction method for titanium alloy implant in spinal IMRT plan, a corrected CT-density table was revised from normal CT-density table to include the density of titanium alloy implant. Dose distribution after and before correction were calculated and compared to evaluate the dose deviation. Plans were also copied to a spinal cancer simulation phantom. A titanium alloy fixation system for spine was implanted in this phantom. Plans were recalculated and compared with the measurement result. The result of this study shows that the max dose of spinal cord showed significant difference after correction, and the deviation between calculation results and measurement results was reduced after correction. The method for expanding the range CT-density table, which means that the density of titanium alloy was included, can reduce the error in calculation.

Effects of different bolus strategies on doses in postmastectomy radiotherapy / 中华放射医学与防护杂志

Objective:To comprehensively evaluate the effects of different bolus usages in postmastectomy intensity-modulated radiotherapy (PM-IMRT) on doses.Methods:Fifty patients receiving PM-IMRT at Fudan University Shanghai Cancer Center from April to October 2021 were retrospectively studied. The planning target volume (PTV) was divided into four parts, namely chest wall (CW), internal mammary node, retained axillary lymph node, and supraclavicular node. The prescription dose was 50 Gy/25 fractions. Three PM-IMRT plans applying boluses with different thicknesses (3, 5 and 10 mm) were designed for each patient. The effects of different thicknesses and usage frequencies of boluses on PTV coverage, high dose volume of the CW skin, and dose to surrounding normal tissues were comprehensively evaluated.Results:When boluses were applied throughout the PM-IMRT, the PTV V95% of plans applying 10 mm-thick boluses was lower than that of plans applying 3 and 5 mm-thick boluses ( F=3.340, P < 0.05), the CI of plans applying 3 mm-thick boluses was higher than that of plans applying 5 and 10 mm-thick boluses ( F = 50.05, P < 0.05), and there was no statistically significant differences in the skin V105% and V110% of three plans( P > 0.05). Both PTV V95% and skin V105% were reduced with a decrease in the usage frequency of boluses. At a frequency of 20, PTV V95% decreased slightly (< 1%), while skin V105% decreased sharply to nearly half of the original values. At a frequency of 15, the PTV V95%, CI, and HI in the three plans showed no statistically significant dosimetric differences ( P > 0.05). The PTV Dmax of plans applying 3 mm-thick boluses was lower than that of plans applying 5 and 10 mm-thick boluses ( F = 9.21, P < 0.05). As for the dose to surrounding normal tissues, different bolus thicknesses and frequencies had negligible effects on doses to heart and lung, causing little different biological effects. Conclusions:For PM-IMRT, different bolus thicknesses have similar effects on doses to the PTV, skin, heart, and lung. Bolus usage frequency, rather than thickness, was the major factor determining the PTV coverage and the dose to CW skin.

General situation of Association of Southeast Asian Nations radiotherapy resources and enlightenment for China's science and technology international assistance work / 中华放射肿瘤学杂志

Objective:To investigate and understand current status of radiotherapy resources in the Association of Southeast Asian Nations (ASEAN) and analyze the radiotherapy needs of ASEAN countries, aiming to provide suggestions for China's radiotherapy technology international assistance work.Methods:We created a database of 10 ASEAN countries using open-source data, including data on population size, per capita gross national income, new cancer cases, and radiotherapy equipment (megavolt units). We also estimated the number of cases requiring radiotherapy and the demand for radiotherapy equipment. Descriptive statistics were used to present aggregate data and national data.Results:In 2020, the number of new cancer cases in ASEAN countries was 1.0992 million, and the estimated total number of cancer patients requiring radiotherapy was 700 300. The number of radiotherapy equipment required was 1 406. At present, the actual number of radiotherapy equipment in ASEAN countries is 564, and there is a certain gap between the existing radiotherapy resources in some ASEAN countries and the actual needs of cancer patients in their own countries. In 2040, the estimated number of new cancer cases in ASEAN countries will be 1.803 million, and the estimated total number of cancer patients who need radiotherapy in ASEAN countries will be 1.141 2 million. The number of required radiotherapy equipment will be 2 287. By 2040, the growth rate of radiation therapy equipment demand in ASEAN countries will be 305%, and all ASEAN countries need to allocate more radiotherapy resources to cope with the increase in the number of cancer patients and radiotherapy demand.Conclusions:ASEAN countries have a huge demand for radiotherapy in the next two decades, while there are significant differences among different countries. China's precision radiotherapy science and technology have huge potential for ASEAN countries. Radiotherapy science and technology international assistance work based on the needs of ASEAN countries will help China's radiotherapy continue to exert influence and promote the health and well-being of people in ASEAN countries.

Consensus on taxonomy of planning automation for radiotherapy / 中华放射肿瘤学杂志

Powered by big data and artificial intelligence, the research and clinical application of treatment planning automation for radiation therapy are rapidly growing. The application and supervision of planning automation systems necessitate careful consideration of different levels of automation, as well as the context for use. For autonomous vehicles, the levels of automation have been defined at home and abroad. Nevertheless, no such definitions exist for radiotherapy planning automation. To promote and standardize the development of radiotherapy planning automation and initiate discussion within the community, we developed this recommendation with reference to the taxonomy of driving automation for vehicles and divided the radiotherapy planning automation into six levels (level 1 to 6).

The effect of environmental radiation of radiotherapy workplace on stereotactic radiation therapy plan dose verification using an Exradin W1 scintillator detector / 中华放射医学与防护杂志

Objective:To study the influence of environmental radiation of radiotherapy workplace on the stereotactic radiation therapy(SRT) plan absolute dose verification with plastic scintillator detector Exradin W1.Methods:The computed tomography (CT) image of the stereotactic dose verification phantom (SDVP) was scanned and imported into the treatment planning system. Three schemes, including 3 cm × 3 cm to 20 cm × 20 cm square gradient field irradiation, virtual planning target volume(PTV) non-coplanar arcs irradiation and 10 cases of volumetric modulated arc radiotherapy SRT (VMAT SRT) clinical plan verification, were measured with or without a home-made shield over the photodiode. Measurements were recorded to analyze the impact of environmental radiation on dose measurement under different conditions.Results:The noise effect of the photodiode increased with the the lager open field size, and decreased with the reduced distance between the photodiode and isocenter. The contribution of photodiode noise effect increase with the lager non-coplanar arc field size, with the largest up to 4.16%. As for the clinical SRT plan verification measurement, the relative difference between the SRT plan measurements and treatment planning system(TPS) before and after shielding were (1.39±1.05)% and (0.59±1.03)%, respectively ( t=-5.343, P < 0.05). and for W1 vs. A16 microchamber was (1.22±1.56)% and (0.42±1.42)%, respectively ( t=-5.414, P < 0.05). Conclusions:The measurements of Exradin W1 are in good agreement with the TPS result and the ionization chamber measurements, but its accuracy is easily affected by the environmental radiation of radiotherapy workplace. To measure non-coplanar radiation, the photodiode should be placed as far away as possible from the isocenter and be properly shielded, which can effectively improve the accuracy and stability of the measurement and provide a strong guarantee for clinical precision radiotherapy.

Automatic delineation of rectal cancer target volume and organs at risk based on convolutional neural network / 中华放射肿瘤学杂志

Objective:To realize automatic delineation of rectal cancer target volume and normal tissues and improve clinical work efficiency.Methods:The deep learning method based on convolutional neural network was adopted to construct neural network, learn and realize automatic delineation, and compare the differences between automatic delineation and manual delineation.Results:Two hundred and ten cases with rectal cancer were randomly assigned to a training set of 190 and a validation set of 20. The complete delineation of a single case took about 10s; the average Dice of CTV was 0.87±0.04; the average Dice of other normal tissues was bigger than 0.8; the Hausdorff distance (HD) index of CTV was 25.33±16.05; the mean distance to agreement (MDA) index was 3.07±1.49, and the Jaccard similarity coefficient (JSC) index was 0.77±0.07.Conclusion:The deep learning method based on full convolutional neural network can realize the automatic delineation of rectal cancer target volume and improve work efficiency.

Study of automatic treatment planning of intensity-modulated radiotherapy based on deep learning technique for breast cancer patients / 中华放射肿瘤学杂志

Objective:To develop a deep learning-based approach for predicting the dose distribution of intensity-modulated radiotherapy (IMRT) for breast cancer patients, and evaluate the feasibility of applying the predicted dose distribution in the automatic treatment planning.Methods:A total of 240 patients with left breast cancer admitted to Fudan University Shanghai Cancer Center were enrolled in this study: 200 cases in the training dataset, 20 cases in the validation dataset and 20 cases in the testing dataset. A modified deep residual neural network was trained to establish the relationship between CT image, the contouring images of target area and organs at risk (OARs) and the dose distribution, aiming to predict the dose distribution. The predicted dose distribution was utilized as the optimization objective function to optimize and generate a high-quality plan.Results:Compared with the dose distribution of clinical treatment plan, the predicted dose distribution for target areas and OARs showed no statistical significance except for a simultaneous boost target PTV 48Gy. And the treatment plan generated based on the predicted dose distribution was basically consistent with the predicted outcomes. Conclusion:Our results demonstrate that the deep learning-based approach for predicting the dose distribution of IMRT for breast cancer contributes to further achieving the goal of automatic treatment planning.

Study on the Quick Daily Check for Medical Electron LINAC / 中国医疗器械杂志

This study presents an electronic portal imaging devices (EPIDs) based on daily check tool for Linac that is usable for different cancer centers.Several images of open rectangle fields were acquired with EPID and the key items of daily Linac check were derived from the obtained images using an in-house developed automatic analysis software.The experiment results showed that each parameter calculated by this tool is as reliable as the corresponding result measured by the commercial quality assurance devices and its measuring efficiency is much higher.

Introduction of image-guided stereotactic radiotherapy systems for small animals / 中华放射肿瘤学杂志

The theory and application of small animal radiotherapy models is critical for the research and development of radiobiology and clinical radiotherapy.Considering universality and cost effects,mouse models are widely used to explore the radiobiological mechanisms of cancerous and normal tissues.In recent years,there has been tremendous progress in image-guided stereotactic radiotherapy equipment for small animals,which could simulate the human radiotherapy process.This article introduces stereotactic radiotherapy systems for small animals guided by different imaging modalities,such as cone-beam computed tomography and magnetic resonance imaging,and then reviews small animal fluorescence imaging technology and summarizes the application of different bioluminescence and fluorescence imaging equipment in small animal imaging systems.Finally,we put forward the prospect of optimization direction of radiotherapy equipment for small animals in future.

Application of Xenapp-based virtualized system in radiotherapy / 中华放射肿瘤学杂志

Objective Multiple software applications and systems and complex hardware are utilized in the process of radiotherapy. In this paper,Xenapp-based visualized system was adopted to integrate each system during the radiotherapy procedures. Methods Windows2008r2 operating system,Citrix Xenapp 6. 5 sp1 enterprise edition,sqlserverr2008 express database were utilized. The Xenapp server was installed and the commonly used software applications were installed and published on this server. CitrixReceiver was installed on the computers in the local network in Department of Radiotherapy. A web browser was utilized to log in the Xenapp server to access all the applications published on the server. Results The application of Citrix Xenapp-based virtualized system significantly reduced the cost of computer hardware by more than 50％,decreased the maintenance cost of technical personnel. Besides,it made the process of Department of Radiation Oncology seamless and improved the efficiency of the staff in the Department of Radiation Oncology. Conclusions The Xenapp-based virtualized system can save cost and improve efficiency in the process of radiotherapy,which is worthy of widespread application in clinical practice.

Progress in charged particle therapy / 中华放射肿瘤学杂志

Charged particle therapy offers a better effect and obvious dosimetric and biological advantages over conventional radiotherapy in tumor control.Charged particles form Bragg peak in the dose distribution in tissue, enable most of energy to be deposited in the target region, and thus enhance tumor control and reduce the damage to normal tissues surrounding the tumor.With the increasing demand for charged particle therapy and the advances in particle accelerator, particle therapy technology is developing rapidly.The core apparatus of particle therapy facility is particle accelerator, and the accelerator type, particle type, and implementation technique determine the performance and therapeutic effect of the facility.This article provides a detailed comparative analysis of various particle therapies.Statistical data show that proton therapy is dominant in particle therapy, and high construction difficulty, large facility size, and extremely high cost have limited the development of heavy ion therapy.Nowadays, there are still some technical problems regarding charged particle therapy, and more clinical trials are required.

A study of automatic treatment planning based on kernel density estimation / 中华放射肿瘤学杂志

Objective To develop an automatic algorithm to predict the dose-volume histogram (DVH) and implement it in clinical practice.Methods Based on the prior information in the existing plan,such as dosimetric results of organs at risk (OARs) and OAR-target spatial relationship,a two-dimensional kernel density estimation was implemented to predict the DVH of OARs.The predicted DVH curves were converted into objective functions that would be implemented in the Pinnacle treatment planning system.Comparisons between predicted and actual values and between Auto-plan and manual planning were made by paired t test.Results We applied this algorithm to 10 rectal cancer patients,10 breast cancer patients,and 10 nasopharyngeal carcinoma patients.The predicted DVH of OARs showed that the deviation between the actual and predicted values at important clinical dose points were within 5%(P>0.05).The re-planning for the 10 breast cancer patients using Auto-plan showed that the heart dose was significantly reduced and the target coverage was increased,which was consistent with the predicted results.Conclusions The method proposed in this study allows for accurat DVH prediction,and,combined with Auto-plan,can be used to generate clinically accepted treatment plans.

Correlation between weight loss and setup errors in intensity-modulated radiotherapy for rectal cancer / 中华放射肿瘤学杂志

Objective To investigate the change in body weight over time in rectal cancer patients receiving radiotherapy and the correlation between setup errors and weight loss,and to establish the image-guided radiotherapy regimens in different periods of treatment.Methods A total of 24 postoperative patients with rectal cancer admitted to our hospital in 2016 were selected.Before each fraction of radiotherapy,the body weight was recorded,and the patients underwent cone-beam computed tomography (CBCT) with different frequencies in every week.The planning CT was matched with CBCT to obtain setup errors.The paired t test was used for difference analysis;the Pearson method was used to analyze the correlation between setup errors and weight loss.Results Body weight was measured 456 times in the 24 patients,and these patients underwent CBCT scans and image registration 456 times.Two patients were excluded because of treatment discontinuance.In the first and second weeks,there was no significant change in body weight.In the third week,the mean weight loss was 1.53 kg.In the fourth week,the mean weight loss was 2.48 kg.In the fifth week,the mean weight loss was 3.24 kg.The setup errors obtained by CBCT image registration in the superior-inferior (SI),anterior-posterior (AP),and left-right (LR) directions were 0.19 cm,0.20 cm,and 0.18 cm,respectively,in the first week,0.18 cm,0.17 cm,and 0.15 cm,respectively,in the second week,0.20 cm,0.22 cm,and 0.21 cm,respectively,in the third week,0.19 cm,0.25 cm,0.24 cm,respectively,in the fourth week,and 0.34 cm,0.33 cm,and 0.31 cm,respectively,in the fifth week.The Pearson correlation analysis showed that weight loss increased the setup errors,with P values of 0.140,0.046,and 0.044 in the SI,AP,and LR directions,respectively.Conclusions For rectal cancer patients receiving radiotherapy,the body weight decreases significantly in the late period (especially in the fifth week),which influences the setup errors.Therefore,in the fourth and fifth weeks of radiotherapy for rectal cancer,the weight loss should be closely monitored,and the number of CBCT scans can be increased before the treatment fraction to ensure the accuracy and optimization of treatment.

Radiomics in Precision Radiotherapy / 中华放射肿瘤学杂志

Radiomics is a new area of research, which converts imaging data into high?resolution quantitative imaging features by applying the automatic high?throughput imaging?feature?extraction algorithm. With the development of data science, more and more attention has been paid to the non?invasive and quantitative method in precision radiotherapy all over the world. This paper will briefly introduce the concept of radiomics and its application in precision radiotherapy.

Investigation of image guidance strategy for intermittent breath-hold cone beam CT / 中华放射肿瘤学杂志

Objective To develop a practical image acquisition strategy using intermittent breath?hold cone beam computed tomography (CBCT). Methods A breathing phantom was used to simulate the movement of tumor near the diaphragm during free breathing and breath hold and scanned by conventional breath?hold CBCT and type Ⅰ/Ⅱ intermittent breath?hold CBCT. In the conventional breath?hold CBCT, scan paused and free breathing occurred at the break of breath hold and free breathing was not included in the scan. In the intermittent breath?hold CBCT, one scan covered several breath holds separated by free breathing in a ratio of 3 vs1. Image quality and three?dimensional registration accuracy were quantitatively compared between conventional breath?hold CBCT and type Ⅰ/Ⅱ intermittent breath?hold CBCT. Comparison of image quality parameters between conventional breath?hold CBCT and intermittent breath?hold CBCT was made by paired t test. Results Motion artifacts arose in type I and Ⅱ intermittent breath?hold CBCT scans. There were no significant differences in the reconstructed pixel value or uniformity between intermittent breath?hold CBCT and conventional breath?hold CBCT ( P>0. 05, and P= 0. 02, 0. 53 ) . Compared with conventional breath?hold CBCT images, the signal?to?noise ratios of type I andⅡintermittent breath?hold CBCT images were reduced by 30% and 60%, respectively ( P<0. 05 ) . The registration error was up to 0 . 4 cm in the anterior?posterior direction and less than 0 . 1 cm in other directions . Conclusions The phantom study shows that intermittent breath?hold CBCT does not significantly reduce image quality or registration accuracy compared with conventional breath?hold CBCT. The feasibility of intermittent breath?hold CBCT in clinical application needs to be further validated among a large number of patients.

The primary experience of an entire QA workflow management in radiotherapy / 中华放射肿瘤学杂志

Objective To retrospectively review the history and development of radiotherapy quality assurance ( QA) in the Affiliated Cancer Hospital of Fudan University, and to report the primary experience and evolvement of an entire QA workflow management. Methods The multidisciplinary QA team has implemented an entire QA workflow management process in the Radiotherapy Center using the failure modes and effects analysis ( FMEA) and plan?do?check?act ( PDCA) tool since April 2015. Treatment data of approximately 6000 patients before and after implementation were compared. Results The error rate was reduced from 17% to 09% after using the entire QA workflow management. Conclusions Entire QA workflow management effectively improves the accuracy and safety of radiotherapy.

A study of PET-CT SUV range for dose verification in carbon ion radiation therapy / 中华放射肿瘤学杂志

Objective The positron generated at the dose deposition site by using high-energy carbon ions to hit the material annihilate with the negative electron in the material to release the gamma photon.The positron-emitting isotope (PEI) distributions in the target volume are activated significantly by carbon ions.Therefore, the mean values of positron emission tomography (PET) activity could be related to the delivered doses to the clinical target volume from carbon ion.This specialty can be used for the image registration fusion of the carbon ion treatment planning computed tomography (CT) and treatment verification PET-CT.After radiation in the almost same decay period, the relationship between the different target volume and the PET-CT SUV of different every single fraction dose can be found, then the range of SUV for the radiation target could be decided.So this PET-CT standardized uptake value (SUV) range can also provide a reference for the correlation and consistency in planning target dose verification and evaluation for the clinical trial.Methods The head phantom was used as a simulation of the real human body, the 1 cc, 4 cc, and 10 cc cube volume target contouring were done in the TPS, the 90 degree fixed carbon ion beams were delivered in different single fraction effective dose of 2.5 GyE, 5 GyE, and 8 GyE.After the beam delivery, later the PET-CT scanning was performed and parameters of scanning followed the trial regulation.The MIM Maestro software was used for the image processing and fusion to determine the maximum, minimum, average, and total values of SUV in the virtual clinical target volumes for the different single fraction dose.Results The results showed that for the same target volume, the SUV range of target had an approximate linear correlation with effective dose of target (P=0.000).The same effective dose for the different target volumes got the same SUV range (P>0.05).Conclusions For the carbon ion treatment plan, the SUV range from image registration and fusion of planning CT and PET-CT after treatment can be used to make an evaluation for accuracy of the dose distribution.And this method also could be used in the hyper-fraction treatment plan.In the SUV range research of different decay periods, the similar method can be performed for the exploration.

Evaluation of volumetric modulated arc therapy planning for rectal cancer based on Auto-Planning / 中华放射肿瘤学杂志

Objective To determine whether Auto-Planning-based volumetric modulated radiotherapy(Auto-VMAT)planning can improve planning efficiency without compromising plan quality compared with current manual trial-and-error-based volumetric modulated arc therapy(Manual-VMAT) planning for patients with rectal cancer. Methods Ten patients with stage Ⅱ-Ⅲ rectal cancer who underwent Dixon surgery were enrolled as subjects. The Pinnacle 9.10 planning system was used to design Manual-VMAT and Auto-VMAT plans. Dose distribution,homogeneity index(HI),conformity index(CI), D meanvalues of different organs at risk or dose-volume histogram of regions of interest,total planning time, and manual planning time were compared between the two plans. The differences were analyzed by paired t test. Results Dosimetric prescriptions were achieved in both plans. There were no significant differences in HI or CI between the Auto-VMAT plans and the Manual-VMAT plans(0.058 vs. 0.058, P=0.972;0.921 vs. 0.940,P=0.115). Compared with the Manual-VMAT plans,the V 40,D mean,and D 50%of the bladder were significantly reduced by 25.6%, 11.5%, and 8.9%, respectively, in the Auto-VMAT plans(P=0.004,0.016,0.001);the V 40,D mean,and D 50%of the small intestine were also significantly reduced by 12.1%,5.4%,and 6.8%,respectively,in the Auto-VMAT plans(P=0.023,0.001,0.001);the V 30, D mean,and D 50%of the left and right femoral heads were slightly reduced in the Auto-VMAT plans. The Auto-VMAT plans had significantly longer total planning time but significantly shorter manual planning time than the Manual-VMAT plans(50.38 vs. 36.81 min, P= 0.000;4.47 vs. 16.94 min, P= 0.000). Conclusions Compared with the Manual-VMAT plans, the Auto-VMAT plans have substantially shorter manual planning time and improved planning efficiency.