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OBJECTIVE To investigate the prognostic value of pre-treatment serum lactate dehydrogenase(LDH)levels in patients with locally recurrent nasopharyngeal carcinoma(NPC)treated with salvage intensity-modulated radiotherapy(IMRT)and to determine its association with rT staging.METHODS The records of 97 patients with locally relapsed and non-metastatic NPC who received salvage IMRT treatment in our center from January 2018 to April 2022 were collected,including 51 patients who died,18 patients with distant metastases,30 patients with local failure,and 67 patients with prognostic adverse events(death,distant tumors/local metastases).Clinical data,local failure-free survival(LFFS),distant metastasis-free survival(DMFS)and overall survival(OS)were obtained from all patients,and the relationship between LDH and the prognosis of salvage IMRT therapy in NPC patients was analyzed.RESULTS The serum LDH level before salvage IMRT was significantly higher in the death[221.25(178.24,339.13)U/L vs.124.82(79.0,159.50)U/L,Z=-5.122],local failure[230.75(170.89,394.50)U/L vs.157.85(91.78,216.95)U/L,Z=-3.442],distant metastasis[261.62(153.55,465.50)U/L vs.168.98(101.75,237.75)U/L,Z=-2.478]and poor prognosis group[220.05(167.20,506.16)U/L vs.93.45(69.95,154.35)U/L,Z=-6.018],and all P<0.05.Serum LDH levels were divided into dichotomous variables according to median values(≥177.50 U/L vs.<177.50 U/L),the Cox univariate model found that the hazard ratios of LDH affecting LFFS,DMFS,OS and toxic-related death(TRD)were 3.759(1.660-8.558),4.217(1.383-12.861),3.226(1.715-6.069),3.363(1.750-6.463),P<0.05.LDH remained an independent prognostic factor for LFFS,DMFS,OS,and TRD in multivariate regression analysis(P<0.05).Compared with patients with LDH<177.50 U/L,more patients in the LDH≥177.50 U/L group had local progression-related death,and the no LFFS stage,no DMFS stage and OS were shorter in the LDH≥177.50 U/L group(log rank=11.624,7.559,14.758),P<0.05.In predicting overall survival,adding LDH to the rT stage is preferable to the rT stage alone.CONCLUSION LDH is an important factor in predicting LFFS,DMFS,OS,and TRD after saving IMRT in patients with locally relapsed,non-metastatic NPC,and the value of LDH combined with rT staging in predicting overall survival is high.
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High-precision radiotherapy represented by stereotactic body radiation therapy(SBRT)plays an important role in every stage of lung cancer treatment.The development of medical imaging technology,more accurate dose calculation methods,and the application of advanced imaging and dose verification algorithms provide guarantee for the realization of high-precision radiotherapy.Four-dimensional computed tomography(4D CT)can better display the individualized motion of tumors affected by respiration.Four-dimensional cone beam computed tomography(4D-CBCT)is an image-guided technology to delineate and obtain the internal target volume(ITV),which Can provide guarantee for precise treatment.The combination of the two technologies can correct the displacement error,monitor the range of tumor motion,and ensure that the moving target is within the irradiation range,which is the guarantee of stereotactic radiotherapy.From the perspective of image-guided radiation technology in the application of precise radiotherapy for lung cancer,the clinical application value of 4D CT combined with 4D-CBCT in SBRT of tumors was reviewed,aiming to provide reference for clinical radiotherapy of lung cancer.
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Objective:To investigate the necessity of adaptive re-planning during radiotherapy for nasopharyngeal carcinoma (NPC) and its impact on dose improvement.Methods:Clinical data of 89 NPC patients admitted to Sun Yat-sen University Cancer Center from July 2014 to December 2017 were retrospectively analyzed. All patients received 25+7 rounds of adaptive re-planning during radiotherapy. Plan-A was defined as the initial CT scan-based 25-fraction radiotherapy plan, while plan-B was defined as the re-planned 7-fraction radiotherapy plan based on a subsequent CT scan. The changes in the target and parotid gland volumes were compared between plan-A and plan-B. Plan-I was a one-time simulation of plan-A extended to 32 fraction radiotherapy plan, and plan-II was generated through registration and fusion of the plan-A and plan-B for adaptive re-planning. The differences in dose metrics, homogeneity index (HI), conformity index (CI), and dose to organs at risk (OAR) were compared between plan-I and plan-II. Statistical analysis was performed by using paired t-test. Results:Compared with plan-A, the gross tumor volume of massive bleeding lesions (GTV nx) and parotid gland volume of plan-B were decreased by 13.14% and 11.12%, respectively (both P<0.001). While planning clinical target volume of metastatic lymph nodes (PCTV nd) of plan-B was increased by 7.75%( P<0.001). There were significant changes in the lymph nodes of plan-A and plan-B. The D mean, D 5%, D 95% of massive bleeding lesions planning target volume (PTV nx) and D 5% of high risk planning target volume (PTV1) in plan-II were all significantly higher than those in plan-I (all P<0.05). The CI of PTV nx and PTV1 in plan-II was closer to 1 than that in plan-I. In all assessed OAR, the D mean, D 50%, and D max of plan-II were significantly lower than those of plan-I (all P<0.05). Conclusions:During radiotherapy, NPC patients may experience varying degrees of primary tumor shrinkage, parotid gland atrophy, and lymph node changes. It is necessary to deliver re-planning and significantly improve the dose of target areas and OAR.
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With the development of radiotherapy technology, the role of radiotherapy in the treatment of primary liver cancer has been gradually recognized. In recent years, precision radiotherapy for hepatocellular carcinoma has become a research hotspot. A number of clinical trials have shown that precision radiotherapy can significantly improve clinical prognosis of patients with hepatocellular carcinoma. In this article, the research progress and existing problems of radiotherapy in the treatment of hepatocellular carcinoma were reviewed, aiming to provide literature support for the application of radiotherapy in the treatment of hepatocellular carcinoma.
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Objective To evaluate the quality of treatment planning(TP)and re-optimization planning(RP)of radiotherapy for rectal cancer using PlanIQ software,thereby providing methods and tools for the screening and optimization of radiotherapy plans.Methods Twenty patients with rectal cancer who received radiotherapy were selected retrospectively,with 10 cases of intensity-modulated radiotherapy(IMRT)and 10 of volumetric modulated arc therapy(VMAT).(1)TP:IMRT plan involved 5-field irradiation,and VMAT plan involved two 360°arcs.The prescription doses were 50 Gy/25 f for PTV1 and 45 Gy/25 f for PTV2.All plans underwent direct machine parameter optimization and required 95%isodose lines to cover 100%of the target volume.Organs-at-risk(OAR)were limited by reference to tolerated dose standards.After the planning was completed,the plans were reviewed and confirmed by a physician,and the treatment was implemented after dose verification.(2)RP:a physicist with 10 years of experience re-optimized the 20 TP plans,with the irradiation technique and field setting unchanged.The re-optimization involved adjusting planning conditions and parameters based on individual experience until the dose to OAR was minimized while without affecting PTV coverage.The quality of TP plans and RP plans were quantitatively evaluated using PlanIQ software.Non-parametric Wilcoxon signed rank test was performed for dose-volume histogram parameters and plan quality index between two groups.Results The dose-volume histogram parameters in RP plans were superior to those in TP plans,and the differences in the Dmax of PTV1,the V45 Gy and Dmax of small intestine,and the V45 Gy of colon were statistically significant(P<0.05).The quality scores of RP plans for IMRT group,VMAT group and all patients were significantly higher than those of TP plans(P<0.05),with plan quality index of 88.55±3.35 vs 86.61±4.63(P=0.005),89.72±3.15 vs 87.21±3.04(P=0.028),and 89.14±3.22 vs 86.91±3.22(P=0.001),respectively.Conclusion RP can further improve the quality of radiotherapy plan for rectal cancer.PlanIQ software serves as an effective tool for quality control and screening of radiotherapy planning.
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Objective To analyze the effects of target volume optimization on oral mucosal reaction and salivary gland function in oropharyngeal cancer patients receiving intensity-modulated radiotherapy(IMRT).Methods A total of 120 patients with oropharyngeal cancer admitted to Affiliated Hospital of Jiangsu University from April 2020 to August 2022 were selected and randomly grouped into control group(n=60,conventional IMRT)and treatment group(n=60,cervical region Ⅱ and the oral target region were optimized during IMRT).The therapeutic efficacy,parotid gland dose,incidence of acute oral mucosal reaction,dry mouth and oral pain at 3 months after IMRT were compared between two groups.The resting-state apparent diffusion coefficient(ADC)values of parotid and submandibular glands at different time points(before radiotherapy,the 4th week of radiotherapy,the end of radiotherapy and 3 months after radiotherapy)were recorded.Results The difference in the objective reaction rate between two groups was trivial[80.00％(48/60)vs 75.00％(45/60),P>0.05].The mean dose(Dmean)and V34 of the unaffected parotid gland and the Dmean and V30 of the oral cavity in treatment group were lower than those in control group(P<0.05).The incidences of acute oral mucosal reaction,dry mouth and oral pain at 3 months after radiotherapy in treatment group were 41.67％,50.00％,and 58.33％,lower than those in control group(75.00％,78.33％,and 85.00％)(P<0.05).The resting-state ADC values of parotid and submandibular glands at the 4th week of radiotherapy,the end of radiotherapy,and 3 months after radiotherapy in both two groups were higher than those before radiotherapy(P<0.05).At the 4th week of radiotherapy,the end of radiotherapy,and 3 months after radiotherapy,the resting-state ADC values of parotid and submandibular glands in treatment group were lower than those in control group(P<0.05).Conclusion Optimizing target volume during oropharyngeal IMRT can effectively prevent the occurrence of radiation-induced mucositis,alleviate oral mucosal reaction,oral pain and dry mouth,reduce parotid gland dose,and diminish the effects of IMRT on salivary gland function in patients.
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Objective To assess inter-observer variations(IOV)in the delineation of target volumes and organs-at-risk(OAR)for intensity-modulated radiotherapy(IMRT)of nasopharyngeal carcinoma(NPC)among physicians from different levels of cancer centers,thereby providing a reference for quality control in multi-center clinical trials.Methods Twelve patients with NPC of different TMN stages were randomly selected.Three physicians from the same municipal cancer center manually delineated the target volume(GTVnx)and OAR for each patient.The manually modified and confirmed target volume(GTVnx)and OAR delineation structures by radiotherapy experts from the regional cancer center were used as the standard delineation.The absolute volume difference ratio(△V_diff),maximum/minimum volume ratio(MMR),coefficient of variation(CV),and Dice similarity coefficient(DSC)were used to compare the differences in organ delineation among physicians from different levels of cancer centers and among the 3 physicians from the same municipal cancer center.Furthermore,the IOV of GTVnx and OAR among physicians from different levels cancer centers were compared across different TMN stages.Results Significant differences in the delineation of GTVnx were observed among physicians from different levels of cancer centers.Among the 3 physicians,the maximum values of △V_diff,MMR,and CV were 97.23%±83.45%,2.19±0.75,and 0.31±0.14,respectively,with an average DSC of less than 0.7.Additionally,there were considerable differences in the delineation of small-volume OAR such as the left and right optic nerves,chiasm,and pituitary,with average MMR>2.8,CV>0.37,and DSC<0.51.However,relatively smaller differences were observed in the delineation of large-volume OAR such as the brainstem,spinal cord,left and right eyeballs,and left and right mandible,with average△V_diff<42%,MMR<1.55,and DSC>0.7.Compared with the differences among physicians from different levels cancer centers,the differences among the 3 physicians from the municipal cancer center were slightly reduced.Furthermore,there were also differences in the delineation of target volumes for NPC among physicians from different levels cancer centers,depending on the staging of the disease.Compared with the delineation of target volumes for earlier stage patients(stages I or II),the differences among physicians in the delineation of target volumes for advanced stage patients(stages III or IV)were smaller,with average △V_diff and DSC of 98.31%±67.36%vs 69.38%±72.61%(P<0.05)and 0.55±0.08 vs 0.72±0.12(P<0.05),respectively.Conclusion There are differences in the delineation of GTVnx and OAR in radiation therapy for NPC among physicians from different levels of cancer centers,especially in the delineation of target volume(GTVnx)and small-volume OAR for early-stage patients.To ensure the accuracy of multicenter clinical trials,it is recommended to provide unified training to physicians from different levels of cancer centers and review their delineation results to reduce the effect of differences on treatment outcomes.
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Objective To explore the distributions of dose differences and their correlations with tumor types in independent three-dimensional dose verification for intensity-modulated radiotherapy(IMRT)plan,and to establish prediction models.Methods The fixed field IMRT plans of 180 patients with head and neck,chest,and abdominal tumors were collected.Independent sample t-test was used to analyze the consistency between the initial dose calculated in treatment planning system and the verified dose for evaluating the feasibility of independent validation.The distributions of planning target volume(PTV)dose differences among different tumor types were analyzed.The correlations of PTV dose differences with conformity index(CI)and homogeneity index were analyzed using correlation analysis and multiple linear regression method.Results The PTV dose differences for head and neck,chest,and abdominal tumors were within±1.2%,and the average 3%/3 mm gamma passing rate between the initial dose and the verified dose was higher than 99.5%,indicating good consistency in dose distribution between independent validation and treatment planning system.The distributions of PTV dose differences were different in head and neck,chest,and abdominal plans,and were significantly correlated with CI which could be used to preliminarily determine the PTV dose differences in independent validation.The multiple regression equation based on CI and homogeneity index could be used to estimate the dose verification differences of IMRT plan.Conclusion Independent verification can quickly achieve pre-treatment validation for radiotherapy plans,improving the efficiency of quality control of radiotherapy plans.The estimation based on dose differences provides guidance for optimizing radiotherapy plans.
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Introducción: El cáncer de cabeza y cuello es el séptimo más común a nivel mundial. Las opciones terapéuticas para su manejo incluyen la radioterapia, la cual debe procurar un equilibrio entre la eliminación del tumor y la preservación del tejido sano porque su aplicación implica el riesgo de desarrollar una osteorradionecrosis de los maxilares. Objetivo: Valorar si el riesgo de que se produzca osteorradionecrosis de los maxilares varía en función del tipo de radioterapia. Métodos: Diseño documental, retrospectivo basado en los principios de las revisiones sistemáticas exploratorias según lo establece la lista de chequeo PRISMA Extension for Scoping Reviews (PRISMA-ScR). Se realizaron búsquedas en inglés y español en PubMed, LILACS, ScienceDirect, Tripdatabase y Epistemonikos. Resultados: En total se incluyeron 12 estudios publicados entre 2016 y 2022 con diversos diseños de investigación; el estudio de cohorte retrospectivo fue el que tuvo mayor representación. Se analizaron distintas opciones de radioterapia y sus protocolos, entre ellos, la radioterapia de intensidad modulada, la terapia de protones de intensidad modulada, la radioterapia corporal estereotáctica y la radioterapia tridimensional. La literatura refiere que los protocolos que implican dosis totales más bajas representan un menor riesgo de osteorradionecrosis. Conclusiones: El riesgo de osteorradionecrosis de los maxilares debe atribuirse, en mayor medida, a la dosis total de radiación recibida por el paciente y a la dosis por fracción que al tipo de radioterapia(AU)
Introduction: Head and neck cancer is the seventh most common cancer worldwide. Therapeutic options for its management include radiotherapy, which should seek a balance between tumor elimination and preservation of healthy tissue because its application implies the risk of developing osteoradionecrosis of the jaws. Objective: To assess whether the risk of developing osteoradionecrosis of the jaws varies according to the type of radiotherapy. Methods : Documentary, retrospective design based on the principles of exploratory systematic reviews as established by the PRISMA Extension for Scoping Reviews (PRISMA-ScR) checklist. PubMed, LILACS, ScienceDirect, Tripdatabase and Epistemonikos were searched in English and Spanish. Results: In total, 12 studies published between 2016 and 2022 with various research designs were included; the retrospective cohort study had the highest representation. Different radiotherapy options and their protocols were analyzed, including intensity-modulated radiotherapy, intensity-modulated proton therapy, stereotactic body radiotherapy, and three-dimensional radiotherapy. The literature refers that protocols involving lower total doses represent a lower risk of osteoradionecrosis. Conclusions: The risk of osteoradionecrosis of the jaws should be attributed, to a greater extent, to the total radiation dose received by the patient and the dose per fraction than to the type of radiotherapy(AU)
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Humanos , Osteorradionecrosis , Radioterapia de Intensidad Modulada , Terapia de Protones , Neoplasias de Cabeza y Cuello , Investigación , Proyectos de Investigación , Estudios de Cohortes , Guías como AsuntoRESUMEN
Objective To investigate the effect of couch rotation angle on non-coplanar static intensity-modulated radiotherapy (IMRT) plan for gastric cancer and to provide a reference for clinical planning. Methods A retrospective analysis was conducted on patients who recently underwent postoperative IMRT for gastric cancer. Twenty patients who received radiotherapy in the centre of Radiation Oncology of Huanggang Central Hospital from August 2022 to January 2023 were selected. That were selected to receive a seven-field coplanar static IMRT plan based on a couch rotation angle of 0° as the control group. Then, based on the coplanar IMRT plan, only the couch rotation angle of gantry angles 30° and 330° was changed to 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, and 90°, respectively, and nine different non-coplanar plans were established. The homogeneity index (HI), conformity index (CI) of the target volume, and monitor unit (MU), as well as Dmean, V20, and V30 of the left and right kidneys, Dmax, Dmean, V10, V20, and V30 of the spinal cord, and Dmax, Dmean, V10, V20, V30, and V40 of the small intestine and liver were compared among the 10 plans. The MU and the dosimetric parameters of the target volumes and When the couch rotation angle was 60°, the minimum HI and maximum CI of the target volume were 0.0714±0.0089 and 0.9271±0.0108, respectively, and the minimum MU was 438±26, with the best homogeneity and conformity in the target volume and the shortest machine treatment time (P＜0.05). When the couch rotation angle was 10°, the Dmax of the small intestine was lowest, being (4620.73±99.27) cGy. When the couch rotation angle was 60°, the Dmean of the left and right kidneys was lowest, being (1246.30±130.35) cGy and (1001.52±103.33) cGy, respectively; the V20 of the left and right kidneys was lowest, being 22.87±6.29 and 19.69±1.84, respectively; the V10 and V30 of the spinal cord were lowest, being 40.08±4.92 and 1.68±0.34, respectively (P＜0.05). Conclusion The couch rotation angle has some influence on the postoperative treatment planning for patients with gastric cancer. In the design of non-coplanar plan for gastric cancer, the couch rotation angle of 60° contributes to establishing a better radiotherapy plan.
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Objective To analyze the effect of the fixed-jaw technique on dosimetric parameters during dynamic intensity-modulated radiotherapy (DIMRT) planning. Methods Ten patients each with nasopharyngeal carcinoma, postoperative cervical cancer, and right breast cancer after radical surgery were selected for this study; all patients underwent DIMRT in our hospital in 2020. After administration at the prescribed dose, two methods were used to design the radiotherapy plan for each patient: split-field technique (SFT) and fixed-jaw technique (FJT). The two plans were compared for the differences in the dosimetric parameters and plan verification pass rate. Results Compared with SFT, FJT showed significant decreases (P <0.05) in the following parameters for patients with nasopharyngeal carcinoma, postoperative cervical cancer, and right breast cancer after radical surgery: number of radiation fields (down by 41.5%, 47.3%, and 34.9%, respectively, t = 7.954, 24.2, and 4.949, respectively), total number of monitor units (MUs) (down by 5.6%, 5.3%, and 13.5%, respectively, t = 3.211, 2.423, and 5.481, respectively), and actual beam-on time (down by 25.3%, 23.8%, and 13.6%, respectively, t = 5.814, 9.208, and 5.655, respectively). There were significant differences in some of the dosimetric parameters for all three types of cancer patients between the two plans (P <0.05). There were no significant differences in the plan verification pass rate (P >0.05). Conclusion FJT can reduce the total number of MUs and actual beam-on time while meeting the requirements for clinically prescribed doses in DIMRT planning.
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@#Performing external beam radiotherapy alone without chemotherapy or brachytherapy for locally advanced cervical cancer with multiple lymph node metastases is challenging. The purpose of this case report is to present the efficacy of high‑dose adaptive extended‑field intensity‑modulated radiotherapy (IMRT) with simultaneous integrated boost (SIB) in treating locally advanced cervical cancer with multiple lymph node metastases. A 67‑year‑old woman with locally advanced squamous cell carcinoma of the uterine cervix was treated by external beam radiotherapy alone due to the refusal of chemotherapy and intracavitary brachytherapy. In order to maximize the efficacy of treatment, extended‑field radiotherapy that includes the paraaortic lymph nodes as well as an adaptive IMRT‑SIB plan, was applied. The treatment was successful, resulting in complete tumor disappearance without severe adverse events. In conclusion, high‑dose adaptive IMRT‑SIB may be an alternative treatment option for locally advanced cervical cancer with multiple lymph node metastases.
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Dosis de Radiación , Neoplasias del Cuello UterinoRESUMEN
Objective:To assess the feasibility of the designed dual-isocenter IMRT plans based on Halcyon 3.0 linear accelerator in postoperative radiotherapy of radical mastectomy for left side of breast cancer.Methods:A total of sixteen patients received the postoperative radiotherapy of radical mastectomy for left side of breast cancer at Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine from December 2022 to June 2023 were retrospectively selected.The dual-isocenter plans based respectively on Halcyon 3.0 linear accelerator and Truebeam linear accelerator were designed,and the dosimetric parameters included conformity index(CI)values of target region,homogeneity index(HI)values and doses to organs at risk(OAR)of the two plans were calculated as statistic method.And then,the dosimetric performance of Halcyon 3.0 dual-isocenter plan was compared and analyzed.Utilizing two dose verification tools,ArcCHECK and Portal Dosimetry,to assess the precision of beam delivery of Halcyon 3.0 dual-isocenter plan.Results:The Halcyon dual-isocenter plan and the Truebeam single-isocenter plan had similar plan quality.There were not statistically significant differences(P>0.05)in dosimetric parameters such as CI,HI,exposure dose to 2%of the target volume(D2%)and exposure dose to 98%of the target volume(D98%).Compared to the average monitor unit(MU)of Truebeam single-isocenter plan,the MU values of Halcyon 3.0 dual-isocenter plan increased by 366 MU,while the difference was not statistically significant(P>0.05).The Halcyon 3.0 dual-isocenter plan provided comprehensive protection for OAR,which was better than that of the Truebeam single-isocenter plan.The values of the left side of lung volume(V20)that were covered by 20 Gy dose of the Halcyon 3.0 dual-isocenter plan and the Truebeam single-isocenter plan were respectively 20.41%±1.56%and 24.88%±2.95%,and the difference was statistically significant(t=6.413,P<0.05).There were not significant differences in other OAR dosimetric parameters between the two kinds of plans(P>0.05).The verification pass rates of the Halcyon 3.0 dual-isocenter plans on the ArcCHECK and Portal Dosimetry platforms were respectively 97.6%-98.9%and 98.1%-100%when the ratio of dose tolerance(DT)to distance to agreement(DTA)was set at 2%/2 mm.The verification pass rates of the Halcyon 3.0 dual-isocenter plans on the ArcCHECK and Portal Dosimetry platforms were respectively 99.1%-100%and 99.7%-100%when DT/DTA was set at 3%/3 mm.The beam delivery precision of the Halcyon 3.0 dual-isocenter plan could meet verification standards of clinical treatments.Conclusion:The Halcyon 3.0 dual-isocenter IMRT plan demonstrates a higher feasibility in the postoperative radiotherapy of radical mastectomy for left side of breast cancer.The precision of dose delivery of plan is high,and the dose of target area is sufficient,uniform and favorable conformability.It can effectively limit the OAR exposure dose at the same time.
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Objective:To explore the effect of oral contrast agent on the dose distribution and verification pass rate of radiotherapy plan when female patients with pelvic tumor underwent oral contrast agent to assist the delineations for tumors and organ at risk(OAR).Methods:A total of 15 female patients with pelvic tumor were selected.The original computed tomography(CT)images of each patient were the images with oral contrast agent.Based on these images,a 7-field static intensity-modulated radiotherapy plan was designed as plan 1.The intestinal CT values of the original images were modified to simulate the situations without oral contrast agent to obtain new images.The same optimization parameters of plan 1 was used to design a 7-field static intensity-modulated radiotherapy plan as plan 2.The two kinds of plans were normalized to a degree which 95%of volume was covered by 100%dose at the central point of target region.The 9 parameters of dose distribution included the maximum dose(Dmax),and two verification parameters were calculated as statistical method,and then,the effect of contrast agent was assessed.Results:The Dmax values of the target regions of plan 1 and plan 2 were respectively(5457.9±46.41)and(5455.8±46.33).The mean dose(Dmean)values of them were respectively(5185.4±24.39)and(5189.4±22.78).The conformity index(CI)values of them were respectively 1.03±0.03 and(1.03±0.03).The γ(3%/3 mm)pass rates of them were respectively(99.17±0.44)and(98.93±0.81)(P=0.177).The γ(2%/2 mm)pass rates of them were(95.46±1.27)and(94.88±1.87)(P=0.143).The differences of the dose and verification parameters between the designed two plans on the basis of the images with and without oral contrast agent were not statistical significance(P>0.05).Conclusion:Contrast agent does not have statistical effect on the dose distribution and verification pass rate of static intensity-modulated radiotherapy plan for female patients with pelvic tumor.
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Objective:To develop the method based on deep learning to predict the dose distribution of breast-conserving postoperative intensity-modulated radiotherapy(IMRT) for breast cancer, and to evaluate accuracy of the prediction model.Methods:The data of 110 left-sided breast-conserving postoperative IMRT for breast cancer patients were reviewed, among them, 80 cases were randomly selected for training set, 10 cases for validation set and the remaining 20 cases were used as test set.Firstly, the four-channel characteristics of the patients′ computed tomography(CT) images, regions of interest, distances between voxel and planning target volume(PTV), and corresponding dose distributions were taken as input data.The established U-Net was used for training and obtaining prediction model which was utilized to perform dose prediction on the test set, in order to verify the influence of the features of distance between voxel and PTV in dose prediction, and to compare the dose prediction result with the actual manual planned dose.Results:By incorporating the features of distance between voxel and PTV, the model achieved higher accuracy in predicting the dose distribution.The dose scores and dose volume histogram(DVH) scores of the testing set, consisting of 20 patients, were 2.10±0.18 and 2.28±0.08, respectively, and the predicted dose distribution was closer to the manually planned distribution( t=2.52, 2.40, P<0.05). The deviation between the predicted doses of the PTV and the organ at risk (OAR) and the manually planned doses were within 4%, the average dose to the contralateral breast was increased by 13 cGy, all of them within the clinically acceptable range. Except for the statistically significant differences in D2, D98( Di represents the dose received by i%of the PTV volume), Dmean(mean dose) of PTV 60 and V5( Vi was the volume percentage of OAR receiving i Gy dose.), Dmeanof the ipsilateral lung ( t=3.74, 2.91, 2.99, 3.47, 2.29, P < 0.05), there were no statistically significant differences in other parameters. Conclusions:The deep learning-based method can accurately predict the dose distribution of breast-conserving postoperative IMRT for breast cancer, and it has been proven through experiments that by incorporating the features of distance between voxel and PTV can effectively improve the prediction accuracy, which helps physicists to improve the quality and consistency of treatment planning.
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Objective:To design a method to introduce random six-dimensional setup error (6D-SE) into the intensity-modulated radiotherapy (IMRT) planning for rectal cancer and evaluate its dosimetric effect.Methods:A total of 21 IMRT plans for patients with rectal cancer were randomly selected as reference plans [2 Gy per fraction for a total of 50 Gy; a 5 mm uniform margin around the clinical target volume (CTV) was taken as the planning target volume (PTV)]. For each fraction of the reference plan, a randomly generated 6D-SE was introduced by adjusting the geometrical parameters of the radiation field, and the dose was recalculated. The overall dose distribution with 6D-SE was obtained by adding up the dose of each fraction. A treatment simulation program that could complete the above workflow was developed using the Varian Eclipse scripting API (ESAPI). 6D-SEs that obey two preset distributions [distribution 1: translational error obey N(0, 4 2), and rotational error obey N(0, 2 2); distribution 2: translational error obey N(0, 2 2), and rotational error obey N(0, 1 2)] were introduced into the reference plans, and the dosimetric effects were assessed. Results:When the reference plans, error distribution 1, and error distribution 2 were applied, the Dmin values of the CTV were (49.4±0.41), (47.56±0.76), and (49.17±0.64) Gy, respectively; the D98% values of the CTV were (50.23±0.07), (49.98±0.10), and (50.27±0.09) Gy, respectively; the D98% values of the primary target area (the kernel part of the target area, excluding the margins) were (50.25±0.08), (50.42±0.13), and (50.33±0.10) Gy, respectively; the D98% values of the marginal area were (50.22±0.10), (49.88±0.11), and (50.26±0.10) Gy, respectively. In addition, compared with the result of the reference plans, the result of errors 1 and 2 showed no significant changes in the mean dose of the bladder and femoral heads ( P>0.05), despite slight decreases in the conformity index of the dose distribution with limited clinical significance. Conclusion:The proposed method and the treatment simulation program developed thereupon can introduce the 6D-SE obeying different distributions into the IMRT plans for rectal cancer on demand and provide overall dosimetric changes.
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Objective:To explore the effect of clinical target volume (CTV) optimization on long-term survival and late xerostomia of patients with nasopharyngeal carcinoma (NPC).Methods:Clinical data of 763 patients with NPC treated with intensity-modulated radiotherapy (IMRT) in the Jiangsu Cancer Hospital from January 2015 to November 2018 were retrospectively analyzed. All patients were divided into the modified and conventional CTV groups. Propensity score matching (PSM) was applied to balance the distribution of baseline features. The degree of xerostomia was evaluated by Radiation Therapy Oncology Group (RTOG) / European Organisation for Research and Treatment of Cancer (EORTC) standard and Jiangsu Cancer Hospital Multi-dimensional Radiotherapy-Induced Xerostomia scale. Survival analysis was performed by Kaplan-Meier method. The difference of xerostomia between two groups was compared by rank-sum test. The dose parameters of salivary glands were compared by independent sample t-test. Prognostic factors of survival and xerostomia were assessed by univariate / multivariate regression analyses. Results:There were no significant differences in overall survival, local recurrence-free survival, distant metastasis-free survival and progression-free survival between conventional and modified CTV groups before and after PSM. There were no significant differences in the incidence of late xerostomia above grade 2 of RTOG/EORTC standard between two groups. Using multi-dimensional scale criteria, NPC patients in the modified CTV group developed less late xerostomia than those in the conventional CTV group ( P<0.05). D mean and V 26 Gy of bilateral parotid glands, D mean and V 39 Gy of bilateral submandibular glands, and D mean of sublingual glands and mouths were reduced after optimization of CTV (all P<0.001). Univariate analysis showed that clinical staging, T staging and N staging were the independent prognostic factors of overall survival. Multivariate analysis demonstrated that clinical staging was the independent prognostic factor of overall survival. The risk factor for xerostomia during night sleep was the D mean of sublingual glands. Conclusion:The optimization of CTV in IIb region in NPC treated with IMRT can better protect salivary glands and reduce the incidence of late radiation-induced xerostomia on the premise of ensuring long-term survival.
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Objective:To explore the feasibility and validity of constructing an intensity-modulated radiotherapy gamma pass rate prediction model after combining the SHAP values with the extreme gradient boosting tree (XGBoost) algorithm feature selection technique, and to deliver corresponding model interpretation.Methods:The dose validation results of 196 patients with pelvic tumors receiving fixed-field intensity-modulated radiotherapy using modality-based measurements with a gamma pass rate criterion of 3%/2 mm and 10% dose threshold in Hunan Provincial Tumor Hospital from November 2020 to November 2021 were retrospectively analyzed. Prediction models were constructed by extracting radiomic features based on dose files and using SHAP values combined with the XGBoost algorithm for feature filtering. Four machine learning classification models were constructed when the number of features was 50, 80, 110 and 140, respectively. The area under the receiver operating characteristic curve (AUC), recall rate and F1 score were calculated to assess the classification performance of the prediction models.Results:The AUC of prediction model constructed with 110 features selected based on the SHAP-valued features was 0.81, the recall rate was 0.93 and the F1 score was 0.82, which were all better than the other 3 models.Conclusion:For intensity-modulated radiotherapy of pelvic tumor, SHAP values can be used in combination with the XGBoost algorithm to select the optimal subset of radiomic features to construct predictive models of gamma pass rates, and deliver an interpretation of the model output by SHAP values, which may provide value in understanding the prediction by machine learning-dependent models.
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Objective:To construct a predictive nomogram incorporating pretreatment CT-based radiomics for radiation pneumonitis (RP) in esophageal cancer (EC) patients treated with intensity-modulated radiotherapy (IMRT), and to evaluate the value of CT radiomics in predicting RP.Methods:Clinical data of 267 EC patients sequentially treated with IMRT in Quanzhou First Hospital affiliated to Fujian Medical University from January 2019 to December 2021 were prospectively analyzed. Among them, the first 206 patients were assigned into the training cohort and the last 61 patients were enrolled in the validation cohort. Radiomics features of bilateral lungs were extracted by radiotherapy CT simulation. Univariate analysis was performed to screen the potential predictive variables for symptomatic RP. Machine learning algorithms, such as least absolute shrinkage and selection operator (LASSO), extreme gradient boosting (XGboost), and support vector machine (SVM), were performed for radiomic features selection, respectively. The best classifier was chosen to construct a radiomic signature (RS). Clinical, radiomics and combined nomogram predictive model were developed, respectively. The predictive efficiency and clinical benefits of three models were compared by calculating the area under the receiver operating characteristic (ROC) curve (AUC), calibration curve and decision curve analysis (DCA), and then validated in the validation cohort. Multivariate logistic regression analysis was conducted. Different ROC curves were compared by Delong test.Results:Cardiovascular disease, minimum internal diameter of esophagus and adjuvant chemotherapy and RS were the independent related factors of RP. The AUC of clinical, radiomics and combined models were 0.772, 0.745, 0.842 in the training cohort, and 0.851, 0.811, 0.901 in the validation cohort, respectively. DCA showed that combined radiomic model yielded better clinical benefits compared with clinical model.Conclusion:Radiomics features from pretreatment CT have the potential of improving the efficiency of RP prediction models for EC patients treated with IMRT.
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Objective:Based on radiomics characteristics, different machine learning classification models are constructed to predict the gamma pass rate of dose verification in intensity-modulated radiotherapy for pelvic tumors, and to explore the best prediction model.Methods:The results of three-dimensional dose verification based on phantom measurement were retrospectively analyzed in 196 patients with pelvic tumor intensity-modulated radiotherapy plans. The gamma pass rate standard was 3%/2 mm and 10% dose threshold. Prediction models were constructed by extracting radiomic features based on dose documentation. Four machine learning algorithms, random forest, support vector machine, adaptive boosting, and gradient boosting decision tree were used to calculate the AUC value, sensitivity, and specificity respectively. The classification performance of the four prediction models was evaluated.Results:The sensitivity and specificity of the random forest, support vector machine, adaptive boosting, and gradient boosting decision tree models were 0.93, 0.85, 0.93, 0.96, 0.38, 0.69, 0.46, and 0.46, respectively. The AUC values were 0.81 and 0.82 for the random forest and adaptive boosting models, respectively, and 0.87 for the support vector machine and gradient boosting decision tree models.Conclusions:Machine learning method based on radiomics can be used to construct a prediction model of gamma pass rate for specific dosimetric verification of pelvic intensity-modulated radiotherapy. The classification performance of the support vector machine model and gradient boosting decision tree model is better than that of the random forest model and adaptive boosting model.