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.

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.

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.

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.

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 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Application of radiomics approach for decoding normal liver features and predicting chemotherapy-associated liver injury:A preliminary study / 中国癌症杂志

Background and purpose:Radiomics refers to the comprehensive quantification of human tissues through assessing a large number of quantitative image features. Radiomics approach is used to decode tumor phenotypes and predict treatment outcomes. Here we present a study investigating radiomic analysis to assess normal liver features and predict chemotherapy-associated liver injury.Methods:Gastric cancer patients treated with surgery and adjuvant chemotherapy were enrolled in this study retrospectively. CT images were obtained before chemotherapy. The whole liver organ was delineated by radiation oncologists. Images were extracted and filtered by radiomic approach to extract radiomic features. Clustering was performed to reveal clusters of patients with similar radiomic expression patterns. Chi-squared tests were used to assess the association of radiomic data with clinical data and chemotherapy-related liver injury.Results:Radiomic features of 73 patients were clustered into two clusters. A significant association with gender (P=0.004, chi-squared test) was observed, where in male showed a higher presence in cluster Ⅰ. Incidence of abnormal liver function after chemotherapy was 48.7% in cluster I and 67.6% in cluster Ⅱ, respectively (Δ=18.9%). Clinical data including age, gender, chemotherapy modality, number of chemotherapy cycles, HBV infection history, HBs-antigen presence were not associated with liver function abnormalities after chemotherapy. Accuracy of radiomic analysis to predict liver injury is 0.59.Conclusion:Radiomic approach revealed different imaging features of liver between men and women. It could help to predict chemotherapy-associated liver injury. It is feasible to use radiomics approach to decode normal liver features and predict treatment-associated liver injury.

Application of the standard equation of a circle to prevention of collision between the gantry and the couch / 中国癌症杂志

Background and purpose:The radiation should move at the same direction in accordance with the position of the couch during radiotherapy due to the different location of gross target volume. However, under the condition of the long distance movement of the couch, collisions between the gantry and the couch (or the patients) may happen. To avoid the collisions between the gantry and the couch, the motion area conlfiction between the gantry and the couch was analyzed.Methods:The distance from isocenter to the surface center of linear accelerator head, and the width and the thickness of treatment bed were measured when the treatment bed was empty, and gantry and collimator were at zero position. Forty sets of bed movement data were collected. The sum of squares ofX-andY-coordinates of reference point was calculated and compared with squares of rotation radius. Then, it was anticipated whether the linear accelerator head will collide with treatment bed. Finally, practical veriifcation was made.Results:Whether linear accelerator head collides with treatment bed depends on the difference between the sum of squares ofX-andY-coordinates and the squares of rotation radius. No collisions will happen when the sum of squares ofX-andY-coordinates is less than that of the squares of rotation radius.Conclusion:It is feasible to avoid collisions of linear accelerator head with treatment bed by comparing the sum of squares ofX-andY-coordinates of reference point with squares of rotation radius.

Dosimetric study of simpliifed intensity-modulated radiation therapy for nasopharyngeal carcinoma / 中国癌症杂志

Background and purpose:Radiotherapy has been the preferred method for the treatment of naso-pharyngeal carcinoma (NPC). The aim of this paper was to compare the dosimetric differences in target volume and organ at risk between simpliifed intensity-modulated radiation therapy (sIMRT) and intensity-modulated radiation therapy (IMRT) in nasopharyngeal carcinoma.Methods:Treatment plans for ten NPC cases were designed with the same dose prescription and objective by means of IMRT and sIMRT respectively. Compare:(1) Plan dosimetric dis-tribution, conformity index (CI) and homogeneity index (HI) of the targets, the dosimetric parameters of organ at risk (OAR); (2)The total monitor units (MU) and the total segments.Results:The CI and HI of the planning gross tumor volume(PGTV) were 0.647 and 0.057 (IMRT), 0.633 and 0.071 (sIMRT), respectively (t=2.14,P=0.062;t=-6.21, P=0.000). Compared to IMRT, sIMRT had less inferior target homogeneity. However both treatment plans could achieve the clinical dosimetric demands. There was no signiifcant difference between IMRT and sIMRT in protecting OAR (t=-0.51-2.22,P=0.053-0.621). The sIMRT plan was better than IMRT plan in total MU and total segments. Conclusion:sIMRT is slightly inferior to IMRT in terms of target homogeneity, with similar target conformity and OAR dosimetric parameters. The sIMRT plan can reduce total monitor units and total segments. Thus it provides a clinical solution with high effciency for radiotherapy center with a large number of patients.