This article briefly describes the imaging performance standards of the kilovolt X-ray image guidance system used in radiotherapy, analyzes the main aspects that should be considered in the image quality of X-IGRT system, and focuses on parameters that should be considered in the imaging performance evaluation criteria of the CBCT X-IGRT. The purpose is to sort out the imaging performance evaluation standards of kilovolt X-IGRT system, clarify the image quality requirements of X-IGRT equipment, and reach a consensus when evaluating the imaging performance of X-IGRT system.
Radiotherapy Planning, Computer-Assisted/methods* ; Cone-Beam Computed Tomography/methods* ; Spiral Cone-Beam Computed Tomography ; Radiotherapy, Intensity-Modulated/methods* ; Radiotherapy, Image-Guided/methods*

Biology-guided radiotherapy (BgRT) is a novel technique of external beam radiotherapy, combining positron emission tomography-computed tomography (PET-CT) with a linear accelerator (LINAC). The key innovation is to utilize PET signals from tracers in tumor tissues for real-time tracking and guiding beamlets. Compared with a traditional LINAC system, a BgRT system is more complex in hardware design, software algorithm, system integration and clinical workflow. RefleXion Medical has developed the world's first BgRT system. Nevertheless, its actively advertised function, PET-guided radiotherapy, is still in the research and development phase. In this review study, we presented a number of issues related to BgRT, including its technical advantages and potential challenges.
Positron Emission Tomography Computed Tomography ; Radiotherapy Planning, Computer-Assisted/methods* ; Algorithms ; Particle Accelerators ; Biology ; Radiotherapy, Image-Guided/methods* ; Radiotherapy Dosage

Advanced radiotherapy technology enables the dose to more accurately conform to the tumor target area of the patient, providing accurate treatment for the patient, but the gradient of the patient's radiation dose at the tumor edge is getting larger, which putting forward higher requirements for radiotherapy dose verification. The dose verification system software KylinRay-Dose4D can verify the patient's pre-treatment plan and the in vivo/on-line dose during the patient's treatment, providing important reference for the physicist to modify the radiotherapy plan and ensuring that the patient receives accurate treatment. This study introduces the overall design and key technologies of KylinRay-Dose4D, and tests the pre-treatment plan dose checking calculation and 2D/3D dose verification through clinical cases. The test results showed that the 2D/3D gamma pass rate (3 mm/3%) of KylinRay-Dose4D reconstructed dose compared with TPS plan dose and measured dose is larger than 95%, which indicating that the reconstructed dose of KylinRay-Dose4D meets the requirement of clinical application.
Humans ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted/methods* ; Radiotherapy, Intensity-Modulated/methods* ; Software ; Neoplasms ; Phantoms, Imaging ; Radiometry/methods*

OBJECTIVE: To study the feasibility and potential benefits of beam angle optimization (BAO) to automated planning in liver cancer. METHODS: An approach of beam angle sampling is proposed to implement BAO along with the module Auto-planning in treatment planning system (TPS) Pinnacle. An in-house developed plan quality metric (PQM) is taken as the preferred evaluating method during the sampling. The process is driven automatically by in-house made Pinnacle scripts both in sampling and scoring. In addition, dosimetry analysis and physician's opinion are also performed as the supplementary and compared with the result of PQM. RESULTS: It is revealed by the numerical analysis of PQM scores that only 15% patients whose superior trials evaluated by PQM are also the initial trials. Gantry optimization can bring benefit to plan quality along with auto-planning in liver cancer. Similar results are provided by both dose comparison and physician's opinion. CONCLUSIONS It is possible to introduce a full automated approach of beam angle optimization to automated planning process. The advantages of this procedure can be observed both in numerical analysis and physician's opinion.
Humans ; Radiotherapy Planning, Computer-Assisted/methods* ; Feasibility Studies ; Radiometry/methods* ; Liver Neoplasms/radiotherapy* ; Radiotherapy, Intensity-Modulated/methods* ; Radiotherapy Dosage

Dynamic multi-leaf collimator, which has the function of radiation beam shaping, is a key executive component of tumor precise radiotherapy, and plays a core role in improving the accuracy, efficiency and quality of radiotherapy. A new type of collimator leaf end structure with circular arc and plane combination was studied, and collimator penumbra performance analysis model combining analytical expression and graphic analysis was developed. The influence of leaf end structure on penumbra was analyzed quantitatively, and a set of three-dimensional structure design of dynamic multi-leaf collimator was completed. The feasibility of the structural design and analysis model was verified through experimental measurements.
Humans ; Radiotherapy Planning, Computer-Assisted/methods* ; Particle Accelerators ; Neoplasms ; Radiotherapy Dosage

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.
Radiotherapy, Intensity-Modulated/methods* ; Titanium ; Radiotherapy Dosage ; Alloys ; Radiometry/methods* ; Radiotherapy Planning, Computer-Assisted/methods*

OBJECTIVES: The automatic delineation of organs at risk (OARs) can help doctors make radiotherapy plans efficiently and accurately, and effectively improve the accuracy of radiotherapy and the therapeutic effect. Therefore, this study aims to propose an automatic delineation method for OARs in cervical cancer scenarios of both after-loading and external irradiation. At the same time, the similarity of OARs structure between different scenes is used to improve the segmentation accuracy of OARs in difficult segmentations. METHODS: Our ensemble model adopted the strategy of ensemble learning. The model obtained from the pre-training based on the after-loading and external irradiation was introduced into the integrated model as a feature extraction module. The data in different scenes were trained alternately, and the personalized features of the OARs within the model and the common features of the OARs between scenes were introduced. Computer tomography (CT) images for 84 cases of after-loading and 46 cases of external irradiation were collected as the train data set. Five-fold cross-validation was adopted to split training sets and test sets. The five-fold average dice similarity coefficient (DSC) served as the figure-of-merit in evaluating the segmentation model. RESULTS: The DSCs of the OARs (the rectum and bladder in the after-loading images and the bladder in the external irradiation images) were higher than 0.7. Compared with using an independent residual U-net (convolutional networks for biomedical image segmentation) model [residual U-net (Res-Unet)] delineate OARs, the proposed model can effectively improve the segmentation performance of difficult OARs (the sigmoid in the after-loading CT images and the rectum in the external irradiation images), and the DSCs were increased by more than 3%. CONCLUSIONS Comparing to the dedicated models, our ensemble model achieves the comparable result in segmentation of OARs for different treatment options in cervical cancer radiotherapy, which may be shorten time for doctors to sketch OARs and improve doctor's work efficiency.
Female ; Humans ; Image Processing, Computer-Assisted/methods* ; Machine Learning ; Organs at Risk/radiation effects* ; Radiotherapy Planning, Computer-Assisted/methods* ; Uterine Cervical Neoplasms/radiotherapy*

OBJECTIVE: To investigate the influence of positioning accuracy of the multi-leaf collimators (MLC) on the passing rate of the plan dose verification for volumetric modulation arc therapy (VMAT) of cervical cancer using an Elekta linear accelerator. METHODS: The dose distributions were measured using Sun Nuclear's Mapcheck and Arccheck semiconductors matrix before and after MLC calibration in30 cervical cancer patients undergoing VMAT. Dosimetric comparisons were performed with 2D and 3D gamma passing rates of 3%, 3 mm and 2%, and 2 mm. The 3D gamma distribution was reconstructed with respect to the patient's anatomy using 3DVH software to evaluate the possible influence of MLC positioning accuracy. RESULTS: Before and after MLC calibration, the gamma passing rates of Mapcheck were (88.80±1.81)% and (99.25 ± 0.53)% under 3% and 3 mm standard, respectively, with an average increase of 10.45%. The corresponding gamma passing rates of Arccheck were (87.61±1.98)% and (98.13±0.99)%, respectively, with an average increase of 10.52%. The gamma passing rates of 3DVH were (89.87±2.28)% and (98.3±1.15)%, respectively, with an average increase of 8.43%. CONCLUSION The MLC positioning accuracy is one of the main factors influencing dosimetric accuracy of VMAT for cervical cancer. The application of Autocal software facilitates MLC calibration and improves the accuracy and safety of VMAT delivery for cervical cancer.
Female ; Humans ; Particle Accelerators ; Quality Control ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted/methods* ; Radiotherapy, Intensity-Modulated/methods* ; Uterine Cervical Neoplasms/radiotherapy*

OBJECTIVE: To compare the application among intensity-modulated radiotherapy (IMRT), three-dimensional conformal radiotherapy(3D-CRT) and conventional radiotherapy (CRT) for locally advanced middle-low rectal cancer. METHODS: From January 2015 to December 2016, 93 locally advanced middle-low rectal cancer patients with clinical stage cT3N+M0 or cT4N0/+M0 who underwent preoperative concurrent chemoradiotherapy at Department of Colorectal Surgery, the Third Affiliated Hospital of Kunming Medical University and had complete data were enrolled in this retrospective cohort study. Patients were divided into IMRT group (17 cases), 3D-CRT group (28 cases) and CRT group (48 cases) according to different radiotherapy methods. The frequency and dose of CRT were 1 time/day, 5 times/week, for a total of 5 weeks, with a single dose of 2.0 Gy, the total dose was 50 Gy. Frequency and dose of 3D-CRT and IMRT were 1 time/day, 5 times/week, for a total of 23 to 28 times, with a single dose of 1.8 to 2.0 Gy, and a total dose of 45.0 to 50.4 Gy. The chemotherapy regimen was performed with capecitabine tablets at a dose of 825 mg/m twice a day for 5 days every week, at the same time during radiotherapy. The efficacy, chemotherapy adverse reactions and immune function of the three groups were compared. RESULTS: There was no significant difference in the baseline data among the three groups (all P>0.05). The proportion of patients receiving permanent ostomy in the IMRT group and the 3D-CRT group was 29.4%(5/17) and 32.1%(9/28) respectively, which was lower than 58.3%(28/48) in CRT group, and the difference was statistically significant (χ²=7.982, P=0.030), while this proportion was not significantly different between IMRT and 3D-CRT group(χ²=0.037, P=0.848). The pathologic complete response(pCR) rate was 23.7%(22/93) in the whole study, and the pCR rate was 39.3%(11/28) in the 3D-CRT group, which was higher than that of CRT group and IMRT group [12.5%(6/48) and 29.4%(5/17)], and the difference was statistically significant (χ²=7.407, P=0.025), while there was no significant difference in pCR rate between CRT group and IMRT group (χ²=2.554, P=0.110). There was no adverse reaction of grade 3 or above in all three groups. No significant difference in the incidence of bone marrow suppression, abnormal liver and kidney function markers, digestive tract reaction or radiation dermatitis was found(all P>0.05). After receiving concurrent chemoradiotherapy, the proportion of CD3/CD4 cells in the IMRT group and the CRT group decreased compared with that before treatment(23.1±9.3 vs. 31.1±10.9, 27.4±10.7 vs. 33.6±7.2, respectively); the proportion of CD3/CD8 cells was up-regulated (36.1±15.2 vs. 24.8±10.9, 30.9±14.4 vs. 24.0±8.3,respectively), and the differences were statistically significant (both P<0.05), while the above indexes before and after treatment were not significantly different in the 3D-CRT group(all P>0.05). After treatment, the proportion of CD4/CD8 cells in IMRT group decreased (0.8±0.6 vs. 1.6±1.0, t=3.838, P=0.003), while this proportion was not significantly different in CRT group and 3D-CRT group(all P>0.05). CONCLUSIONS IMRT and 3D-CRT can reduce the rate of permanent stoma. 3D-CRT can increase pCR rate. No obvious advantage is shown in IMRT as compared with 3D-CRT in the short-term efficacy. On the contrary, an immunosuppressive status may occur. Therefore, 3D-CRT is recommended as the best preoperative treatment strategy for patients with locally advanced middle-low rectal cancer, especially for those with immunosuppression status.
Humans ; Radiotherapy ; methods ; standards ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; Radiotherapy, Conformal ; standards ; Radiotherapy, Intensity-Modulated ; standards ; Rectal Neoplasms ; radiotherapy ; Retrospective Studies

OBJECTIVE: To compare the accuracy of different methods for image registration in image-guided adaptive brachytherapy (IGABT) for cervical cancer. METHODS: The last treatment planning CT images (CT1) and the first treatment planning CT images (CT2) were acquired from 15 patients with cervical cancer and registered with different match image qualities (retained/removed catheter source in images) and different match regions [target only (S Group)/ interested organ structure (M Group)/body (L Group)] in Velocity3.2 software. The dice similarity coefficient (DSC) between the clinical target volumes (CTV) of the CT1 and CT2 images (CTVCT1 and CTVCT2, respectively) and between the organs-at-risk (OAR) of the two imaging datasets (OARCT1 and OARCT2, respectively) were used to evaluate the image registration accuracy. RESULTS: The auto-segmentation volume of the catheter source using Velocity software based on the CT threshold was the closest to the actual volume within the CT value range of 1700-1800 HU. In the retained group, the DSC for the OARs of was better than or equal to that of the removed group, and the DSC value of the rectum was significantly improved ( < 0.05). For comparison of different match regions, the high-risk target volume (HRCTV) and the low-risk target volume (IRCTV) had the best precision for registration of the target area, which was significantly greater than that of M group and L group ( < 0.05). The M group had better registration accuracy of the target area and the best accuracy for the OARs. The DSC values of the bladder and rectum were significantly better than those of the other two groups ( < 0.05). CONCLUSIONS The CT value range of 1700-1800 HU is optimal for automatic image segmentation using Velocity software. Automatic segmentation and shielding the volume of the catheter source can improve the image quality. We recommend the use of interested organ structures regions for image registration in image-guided adaptive brachytherapy for cervical cancer.
Brachytherapy ; methods ; standards ; Female ; Humans ; Organs at Risk ; diagnostic imaging ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; methods ; standards ; Radiotherapy, Image-Guided ; methods ; standards ; Software ; Tomography, X-Ray Computed ; methods ; standards ; Uterine Cervical Neoplasms ; diagnostic imaging ; radiotherapy