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.

Clinical study of intensity-modulated radiation therapy combined with camrelizumab in the treatment of advanced hepatocellular carcinoma / 局解手术学杂志

Objective To investigate the efficacy and safety of intensity-modulated radiation therapy combined with camrelizumab in the treatment of advanced hepatocellular carcinoma(HCC).Methods A total of 84 patients with advanced HCC admitted to our hospital from January to December 2020 were selected as the study objects,and were randomly divided into the observation group and the control group,with 42 cases in each group.Patients in the observation group received intensity-modulated radiation therapy combined with carrelli-zumab,and patients in the control group received intensity-modulated radiation therapy.The short-term efficacy,immune function and long-term survival rate of patietns in the two groups were compared,and the incidence of adverse reactions was recorded.Results The total effec-tive rates of the observation group 1 month and 3 months after treatment were significantly higher than those of the control group(P<0.05).The levels of CD3+,CD4+ and CD4+/CD8+ 1 month and 3 months after treatment were all increased in the two groups,while the levels of CD8+ in both two groups were decreased(P<0.05),and the levels of CD3+,CD4+ and CD4+/CD8+ in the observation group were higher than those in the control group(P<0.05),and the levels of CD8+ in the observation group were lower than those in the control group(P<0.05).The median survival time of patients in the observation group was significantly longer than that of patients in the control group(P<0.05).The incidence of cutaneous capillary hyperplasia in the observation group was higher than that in the control group(P<0.001),and there was no significant difference in the incidence of other adverse reactions between the two groups(P>0.05),and all of adverse reactions were grades 1 to 2.Conclusion Intensity-modulated radiation therapy combined with camrelizumab has a good effect on HCC,it can improve the immune function of the body,and control the development of the disease,with good safety.

A dosimetric study of 3D-printed individual phantom in intensity modulated radiation therapy plan for chest / 中国医学装备

Objective:To make an individual phantom that was printed by using three dimension(3D)technique,which could reflect the real situation of patient,and to analyze the computed tomography(CT)value and dose distribution of radiotherapy on each organ of the inside of the 3D-printed individual phantom.Methods:According to the localization of CT image of the patient,the empty shell of 3D structure of each organ were reconstructed and printed by using 3D technique.The CT value was used as basis to select the equivalent material of each organ to perform fill,which could obtain the individual phantom of chest that could appear the structural characteristics of patient.The treatment plan of patients were included in treatment plan group,and the plans which were transplanted to 3D-printed individual phantom from treatment plan of patients were included in phantom plan group.The dosimetric parameters of the plans of two groups were compared.Results:The average CT values of left and right lung,soft tissue,cancellous bone,compact bone and heart of the phantom plan group were respectively-709,-737,14,144,760 and 28 HU.The errors of the all CT values between phantom images and located images of patients were less than 16.7%.The exposure doses of normal tissues of radiotherapy plans on the images of two groups could meet the clinical requirements.The minimum dose(Dmin),mean dose(Dmean),the corresponding doses of 98%,50% and 2% target volumes(D98%,D50% and D2%),conformity index(CI),homogeneity index(HI),monitor unit(MU)of dosimetric parameters of the target region could meet the clinical requirements without statistically significant differences.There was significant differences in the maximum dose(Dmax)of the target region(t=2.678,P＜0.05).Among of these Dmax values,the Dmax value of phantom plan group was larger,which was(56.97±0.32)Gy.Conclusion:The CT value,tissue structure and spatial distribution of the phantom,which is finally designed,can emulate the chest of human body in radiotherapy.It has verified the feasibility that 3D-printed phantom is applied in measuring dose in the quality assurance of radiotherapy.

Value of flattening filter-free mode in deep inspiration breath-hold intensity-modulated radiotherapy after modified radical surgery for left breast cancer / 肿瘤研究与临床

Objective:To investigate the value of flattening filter-free (FFF) mode in postoperative deep inspiration breath-hold (DIBH) intensigy-modulated radiotherapy for left breast cancer.Methods:A retrospective case series study was conducted. Clinical data of 21 patients with left breast cancer who underwent DIBH intensity-modulated radiotherapy after modified radical surgery in Meizhou People's Hospital from January 2021 to December 2022 were retrospectively analyzed. On the DIBH-mode CT of each patient, the 7-field intensity-modulation plan was designed using the plan developed in the 6 MV FFF-mode (FFF group) or the plan developed in the 6 MV flattening filter (FF)-mode (FF group). The target areas and organs at risk, dosimetric and biological parameters, and dose validation results were compared between the two plans.Results:Twenty-one patients were female with the age [ M ( Q1, Q3)] of 47 years old (32 years old, 61 years old). The percentage of target areas receiving 95% of the prescribed dose (V 95%) was (95.9±0.8)% and (95.7±1.9)% in the FF and FFF groups ( t = 2.98, P = 0.089), and the maximum dose was (5 401±251) cGy and (5 424±201) cGy ( t = 2.85, P = 0.181), the fitness indices were 0.88±0.05 and 0.87±0.06 ( t = 0.32, P = 0.562), the homogeneity indices were 1.06±0.01 and 1.07±0.02 ( t = 2.91, P = 0.009), the equivalent uniform doses (EUD) were (51.81±0.21) Gy and (51.97±0.20) Gy ( t = 0.51, P = 0.309), and the tumor control probability (TCP) was (99.68±0.01)% and (99.61±0.02)% ( t = 0.81, P = 0.560). The plans of the FFF group and the FF group were compliant, and the doses of all organs at risk to be irradiated were within the clinically acceptable range, and the radiation doses in the FFF group in the left lung [5 Gy irradiated volume (V 5 Gy), mean dose (D mean), EUD and normal tissue complication rate (NTCP)], right lung (V 5 Gy and D mean), heart (V 10 Gy, D mean, EUD and NTCP), and right breast (V 5 Gy, D mean and EUD) were differently lower than those in the FF group, and the differences were statistically significant (all P < 0.05). The monitor units in the FFF and FF groups were (984±132) MU and (751±145) MU ( t = -1.25, P < 0.001), and the total beam-on time was (1.4±0.3) min and (2.2±0.4) min ( t = 0.68, P < 0.001); individual field beam-on time was (12±7) s and (16±10) s ( t = 2.68, P = 0.001), and the beam-on time for each field in patients of the FFF group was less than 25 s; γ pass rates were (97.1±2.8)% and (97.6±2.1)% ( t = 0.59, P = 0.484). Conclusions:In the intensity-modulated radiotherapy of left breast cancer, the radiation dose of the energy to the critical organs in FFF mode is lower and has higher dose rate and shorter treatment time. FFF combined with DIBH technique has positive clinical significance in the intensity-modulated radiotherapy of breast cancer.

Construction of a comprehensive nutritional index and relationship with quality of life and survival in patients with nasopharyngeal carcinoma undergoing intensity-modulated radiation therapy / 中国实用护理杂志

Objective:To construct a comprehensive nutritional index after treatment of nasopharyngeal carcinoma patients with intensity-modulated radiation therapy (IMRT), and to analyze its relationship with quality of life and 3-year survival period, and aimed to provide some reference for the management of nasopharyngeal carcinoma patients.Methods:This was a prospective cohort study. The clinical data of 431 nasopharyngeal carcinoma patients who admitted to Beijing Tongren Hospital Affiliated to Capital Medical University from January 2017 to December 2021 were collected using convenience sampling method. To evaluate the nutritional status of the patients, the BMI, change in body weight, hemoglobin, lymphocyte count, and albumin level and other clinical data of the patients were collected before and after intensity-modulated radiation therapy. The comprehensive nutrition index after IMRT was constructed by principal component analysis. The Chinese version of European Organization for Reasearch and Treatment of Cancer quality of life questionnare-Core 30 (EORTC QLQ-C30) and Quality of life questionnaire head and neck cancer module(QLQ-H&N35) were used to evaluate the patients′ quality of life. The best diagnostic cutoff point for predicting patient death within 3 years using ROC, and based on the determined optimal diagnostic cutoff point, all patients were divided into a low comprehensive nutritional index group and a high comprehensive nutritional index group. And analyzed the Pearson correlation between comprehensive nutritional index and quality of life.Differences in 3-year survival between the two groups were compared using the Kaplan-Meier method and Log-rank test.Results:Using the diagnostic threshold of receiver operating characteristic, all patients were divided into low comprehensive nutrition index group ( n=280) and high comprehensive nutrition index group ( n=151).The BMI, percentage of weight change, albumin, hemoglobin, and lymphocyte count of nasopharyngeal carcinoma patients before intensity-modulated radiation therapy were (23.14 ± 2.87) kg/m 2, (1.08 ± 0.14)%, (44.02 ± 4.52) g/L, (147.28 ± 15.57)g/L, (1.76 ± 0.56)×10 9/L, and higher than after intensity-modulated radiation therapy (21.14 ± 4.07) kg/m 2, (0.97 ± 0.16)%, ( 38.99 ± 5.12) g/L, (113.87 ± 18.24)g/L, (0.50 ± 0.18)×10 9/L, respectively, the difference were statistically significant ( t values were 8.34 to 44.47, all P<0.05).The comprehensive nutritional index constructed using principal component analysis was correlated with multiple dimensions of EORTC QLQ-C30) and QLQ-H&N35, with statistically significant differences ( r values were -0.169 - 0.245, all P<0.05). Kaplan-Meier curves indicated that the 3-year survival rate of the high comprehensive nutritional index group was higher than that of the low comprehensive nutritional index group, with 87.42% and 79.29% respectively, and the difference was statistically significant ( χ2=4.53, P<0.05). Conclusions:The constructed comprehensive nutritional index could reflect the comprehensive nutritional status of nasopharyngeal carcinoma patients. Nasopharyngeal carcinoma patients with a low comprehensive nutritional index score had a worse quality of life and shorter 3-year survival. Active intervention and improvement of malnutrition in nasopharyngeal carcinoma patients should be undertaken to improve patient quality of life and improve survival.

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.

The efficacy analysis of moderately hypofractionated IMRT combined with androgen deprivation therapy for locally advanced prostate cancer / 中华放射医学与防护杂志

Objective:To investigate the efficacy and adverse reactions of moderately hypofractionated intensity modulated radiation therapy (IMRT) combined with androgen deprivation therapy (ADT) for locally advanced prostate cancer (LAPC).Methods:This study retrospectively analyzed the medical records of 40 LAPC patients who were admitted in The Second Hospital of Dalian Medical University during 2014-2020. The planning gross target volume (PGTV) dose for prostate gland and seminal vesicle gland was 64.8-70.0 Gy/25-28 f, 2.4-2.8 Gy/f and the dose of PGTVnd in 20 cases with positive pelvic lymph nodes was 60.0-64.4 Gy/25-28 f, 2.3-2.4 Gy/f. The dose of planning target volume (PTV) for the drainage area of pelvic lymph nodes was 45.0-50.4 Gy/25-28 f. The enrolled patients were treated with long-term ADT, including neoadjuvant, simultaneous, and adjuvant therapies. The efficacy and adverse reactions were evaluated. The prognostic factors affecting the biochemical failure-free survival (BFFS) were analyzed.Results:The median follow-up time was 31 months. The 2- and 3-year overall survival (OS) rates were 100% and 96.9%, respectively. The 1-, 2-, and 3-year BFFS rates were 90%, 76.8% and 72%, respectively. The 1-, 2-, and 3-year distant metastasis-free survival (DMFS) rates were 92.2%, 82.8% and 75.1%, respectively. Gleason (GS) score ( χ2=10.00, P < 0.05) and adjacent tissue invasion ( χ2=8.85, P<0.05) were prognostic factors related to BFFS for LAPC. Adjacent tissue invasion and GS 9-10 were independent poor prognostic factors. The incidence of acute urinary adverse reaction and rectal injury (grade≥2) was 7.5% and 20%, respectively. The incidence of late urinary adverse reaction and rectal injury (grade≥2) was 12.5% and 17.5%, respectively. Adverse reactions at grade 3-4 did not occur. Conclusions:The moderately hypofractionated IMRT combined with ADT is feasible for LAPC treatment, achieving satisfactory survival effects. 70 Gy/25-28 f, 2.5-2.8 Gy/f is a safe and effective moderate hypofraction scheme. Adjacent tissue invasion and GS score are prognostic factors related to BFFS for LAPC.

Radiomics-based prediction of gamma pass rates for different intensity-modulated radiation therapy techniques for pelvic tumors / 中华放射医学与防护杂志

Objective:To explore the feasibility of a classification prediction model for gamma pass rates (GPRs) under different intensity-modulated radiation therapy techniques for pelvic tumors using a radiomics-based machine learning approach, and compare the classification performance of four integrated tree models.Methods:With a retrospective collection of 409 plans using different IMRT techniques, the three-dimensional dose validation results were adopted based on modality measurements, with a GPR criterion of 3%/2 mm and 10% dose threshold. Then prediction were built models by extracting radiomics features based on dose documentation. Four machine learning algorithms were used, namely random forest (RF), adaptive boosting (AdaBoost), extreme gradient boosting (XGBoost), and light gradient boosting machine (LightGBM). Their classification performance was evaluated by calculating sensitivity, specificity, F1 score, and AUC value. Results:The RF, AdaBoost, XGBoost, and LightGBM models had sensitivities of 0.96, 0.82, 0.93, and 0.89, specificities of 0.38, 0.54, 0.62, and 0.62, F1 scores of 0.86, 0.81, 0.88, and 0.86, and AUC values of 0.81, 0.77, 0.85, and 0.83, respectively. XGBoost model showed the highest sensitivity, specificity, F1 score, and AUC value, outperforming the other three models. Conclusions:To build a GPR classification prediction model using a radiomics-based machine learning approach is feasible for plans using different intensity-modulated radiotherapy techniques for pelvic tumors, providing a basis for future multi-institutional collaborative research on GPR prediction.

Research progress on the bone-marrow sparing intensity-modulated radiotherapy for cervical cancer / 中华放射肿瘤学杂志

The cisplatin-based concurrent chemoradiotherapy (CCRT) has been accepted as a standard treatment for most locally advanced cervical cancer. Compared with radiation therapy alone, CCRT can increase tumor control and survival rates, whereas it also can increase the incidence of acute hematological toxicity, which results in the treatment interruption or delay, and may even affect clinical efficacy and prognosis of patients. Therefore, how to reduce the incidence and severity of acute hematological toxicity induced by CCRT is a hot spot of clinical research. Previous studies have demonstrated that the occurrence of hematological toxicity is associated with the volume and dose of irradiated pelvic bone marrow. With the development of modern radiotherapy technology, precise radiotherapy technologies, such as intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT), not only guaranteed the enough dose for tumor, but also realized the protection of normal tissues. This article will focus on the feasibility of bone marrow sparing during CCRT for cervical cancer, and summarize the research progress in recent years.

Differential study of intensity modulated radiation therapy(IMRT)for cervical cancer in two different radiotherapy devices / 医疗卫生装备

Objective To investigate the differences between Elekta Synergy and Varian Halcyon accelerators in intensity modulated radiotherapy for cervical cancer.Methods Totally 60 cases of postoperative cervical cancer patients treated with radiotherapy in the radiotherapy center of some hospital from June 2021 to December 2022 were selected retrospectively,who were divided into a Halcyon group(30 cases)and a Synergy group(30 cases)according to the equipment involved.The Halcyon group with dynamic IMRT technique and the Synergy group with static IMRT technique were compared in terms of dosimetric parameters in the target area and organs at risk,gamma passing rate,setup error and treatment efficiency.SPSS 24.0 software was used for statistical analysis.Results The two groups had the dosimetric distributions meet clinical requirements.The Halcyon group behaved better than the Synergy group in target area homogeneity index,conformity index and gradient index(P＜0.001),which had lower irradiation dose in some endangered organs;the gamma passing rate was higher in the Halcyon group than that in the Synergy group(P＜0.01),while the dispersion was lower in the Halcyon group;there were no significant differences between the setup errors of the two groups in the left-right,head-foot,and up-down directions(P＞0.05);the two groups had no statistical differences in the number of monitor units(P＞0.05),while the Halcyon group had the plan execution time and total treatment time much shorter than those of the Synergy group(P＜0.001).Conclusion Halcyon accelerator gains advantages in dosimetric parameters and treatment efficiency over the traditional Synergy C-arm accelerator in intensity modulated radiotherapy for cervical cancer.[Chinese Medical Equipment Journal,2023,44(9):53-58]

Dosimetric difference between VMAT and dMLC-IMRT after breast-conserving surgery for left-sided breast cancer / 医疗卫生装备

Objective To investigate the dosimetric difference between volume modulated arc therapy(VMAT)and dynamic multi-leaf collimator intensity modulated radiation therapy(dMLC-IMRT)after breast-conserving surgery for left-sided breast cancer so as to optimize the treatment plan for the patient.Methods The clinical data of 15 patients admitted to the radiothe-rapy department of some hospital after breast-conserving surgery for left-sided breast cancer were selected retrospectively.Three groups of plans were designed for each patient,including continue volume modulated arc therapy(cVMAT),tangent volume modulated arc therapy(tVMAT)and dMLC-IMRT plans,and then compared in terms of the dosimetric parameters of the tumor target areas and organs at risk.SPSS 25.0 software was used for statistical analysis.Results The three groups had the dose distribution of the tumor target areas meet clinical requirements,which had significant differences between the values of D2,Dmean,conformity index(CI)and homogeneity index(HI),while the difference between the numbers of monitor units were not statistically significant.The dMLC-IMRT group had higher D2 value while lowerDmeanthan the cVMAT and tVMAT groups;for CI the cVMAT behaved the best in the three groups,followed by the tVMAT group.In the low-dose region,the cVMAT and tVMAT groups had larger illuminated volumes of the affected lung than the dMLC-IMRT group;the tVMAT group had the smallest illuminated volume of heart in the three groups,and the cVMAT group had the illuminated volume of heart slightly higher than that of the dMLC-IMRT group.In the high-dose region,the cVMAT and tVMAT groups had smaller illuminated volumes of the affected lung than the dMLC-IMRT group,and the illuminated volume of the affected lung of the tVMAT group was larger than that of the cVAMT group;the dMLC-IMAT group had the largest illuminated volume of heart in the three groups,and the differences between the tVMAT and cVMAT groups were not statistically significant.Conclusion In the design of intensity-modulated radiotherapy plans after breast-conserving surgery for left-sided breast cancer,VMAT behaves better than dMLC-IMRT in conformability to the tumor target area and protection of heart and lung at risk.[Chinese Medical Equipment Journal,2023,44(9):59-63]

Acceptance testing and clinical assessment of the in-vivo dose measurement EPIgray system / 中国医学装备

Objective:To assess the accuracy of dose reconstruction of the in-vivo dose verification EPIgray system in intensity-modulated radiation therapy(IMRT)and volumetric-modulated arc therapy(VMAT)through acceptance testing,and to explore the preliminarily clinical application of that.Methods:A total of 37 patients with cancer at various parts were selected for clinical testing.Referring to the suggestions of the acceptance manual of manufacturer and the American Association of Physicists in Medicine(AAPM)TG-119 report,the square field,strip field and intensity-modulated plan were adopted to test the precision of dose reconstruction of EPIgray system on phantom.The recognition ability of the system for error was researched through changed the thickness of homogeneous phantom and the skin distance of exposure source.A total of 37 patients with cancer at different parts who underwent VMAT were selected to conduct clinical test,and then,the consistence between the dose reconstruction of EPIgray system and the counted dose of treatment plan system were further analyzed.Results:In the tests of square field,EPIgray dose reconstruction demonstrated excellent linearity and higher accuracy.On the phantoms with different thicknesses of fields with different sizes,the highest precision of dose reconstruction of central axis of field was(0.10±0.39)%.The all precisions of dose reconstruction were within 3.0%besides the built region of dose and field edges.In the tests of IMRT and VMAT plan,the deviation of dose reconstruction was<5.0%.With the increasing of the complexity of plan and the heterogeneity of phantom,there was a slight decrease in the reconstruction precision,but all deviations of dose reconstruction were within the range of allowable deviations.In clinical testing of 37 patients,the average reconstruction deviation of the prescription dose point was(-0.6±4.8)%,and the average deviation of sampling points within the range of target area was(-2.1±2.7)%.The reconstruction deviations outside of field and that with large dose gradient were larger.Conclusion:The dose reconstructions of in-vivo dose verification system EPIgray has better consistency with treatment planning system in calculating dose,and the precision of dose reconstruction can meet the requirement of clinical application.

Effect of simultaneous integrated boost intensity-modulated radiation therapy on lateral lymph node metastasis in rectal cancer / 中华放射医学与防护杂志

Objective:To evaluate the efficacy and safety of simultaneous integrated boost intensity-modulated radiation therapy (SIB-IMRT) for rectal cancer with lateral lymph node metastasis (LLNM).Methods:From January 2016 to December 2022, 103 rectal cancer patients with LLNM were enrolled. The patients were divided into SIB-IMRT group (52 cases) and conventional chemoradiotherapy (CRT) group (51 cases) using the random number table method. The dose was 50 Gy for the pelvis with 60 Gy of SIB-IMRT for the LLNM in the SIB-IMRT group. The dose was 50 Gy for the pelvis in the CRT group. The primary endpoint was the lateral recurrence rate. The efficacy and adverse reactions of the two groups were compared.Results:The adverse reactions and surgical complications after neoadjuvant radiotherapy were comparable between the two groups. The response rates of LLNM treatment were 76.9% and 56.9%, respectively, in the two groups ( χ2=4.69, P=0.03). The SIB-IMRT group and CRT group had a local recurrence rate of 7.7% and 25.5% ( χ2=5.92, P=0.015), respectively, and a lateral recurrence rate of 3.8% and 23.5% ( χ2=8.49, P=0.004), respectively. Univariate analysis showed that the SIB-IMRT, short axis of lateral lymph nodes <5 mm after radiotherapy, and negative result in the postoperative lymph node pathological examination were factors associated with lateral recurrence. Multivariable regression analysis demonstrated that the SIB-IMRT ( HR=6.42, 95% CI: 1.40-29.49) and short axis of lateral lymph nodes <5 mm after radiotherapy ( HR=0.17, 95% CI: 0.04-0.66) were independent factors associated with lateral recurrence. The two groups had a 3-year disease-free survival of 73.25% and 62.6% ( P>0.05), respectively, and a 3-year overall survival of 87% and 82.5% ( P>0.05), respectively. Conclusions:The SIB-IMRT is safe and effective for rectal cancer with LLNM. The short axis of lateral lymph nodes <5 mm after neoadjuvant radiotherapy and SIB-IMRT is an independent risk factor for lateral recurrence.

Effects of changes in bladder volumes derived from CT simulation on set-up errors during radiotherapy for prostate cancer / 中华放射医学与防护杂志

Objective:To explore the effects of bladder volumes from CT simulation on bladder volume consistency and set-up errors during radiotherapy for prostate cancer, aiming to provide a reference for clinical practice.Methods:A retrospective analysis was conducted for of 66 prostate cancer patients treated with intensity-modulated radiation therapy in the Sun Yat-sen University Cancer Center from August 2015 to November 2020. They underwent CT scan or radiotherapy after voluntarily holding in urine. Cone beam computed tomography (CBCT) scans were performed for them to measure their set-up errors in left-right (L-R), superior-inferior (S-I), and anterior-posterior (A-P) directions before each treatment. The bladder contours of the patients were delineated on CT simulation images and CBCT images. Accordingly, bladder volumes were calculated. Based on the calculated bladder volumes derived from the CT simulation images, the patients were divided into three groups: 18 cases in the 200-300 ml group, 24 cases in the 300-400 ml group, and 24 cases in the >400 ml group. Finally, this study analyzed the effects of bladder volumes derived from CT simulation on set-up errors and the changes of CBCT-derived bladder volumes relative to planned volumes during radiotherapy.Results:The bladder volumes in the 200-300 ml, 300-400 ml, and >400 ml groups during radiotherapy were reduced by 15%, 26%, and 32%, respectively. The pairwise comparison indicates statistically significant differences in the changes of bladder volumes among the three groups ( Z=3.43, 7.97, 4.83, P<0.05). Regarding the three-dimensional set-up errors, there were statistically significant differences in S-I set-up errors among the three groups ( H=26.72, P<0.05), but there was no statistically significant difference in L-R and A-P set-up errors ( P>0.05) among these groups. The 200-300 ml, 300-400 ml, and >400 ml groups exhibited S-I set-up errors of 0.00 (-0.20, 0.20) cm, 0.00 (-0.20, 0.30) cm, and -0.10 (-0.30, 0.20) cm, respectively. Therefore, the >400 ml group displayed larger the S-I set-up errors than other two groups, with statistically significant differences ( Z=4.17, 4.66, P< 0.05), while there was no statistically significant differences in S-I set-up errors between other two groups ( P> 0.05). Conclusions:Controlling the bladder filling volumes at 200-300 ml in CT simulation is beneficial for maintaining bladder volume consistency and reducing set-up errors of patients during radiotherapy.

Comparison of dosimetric differences in unintended irradiation of ipsilateral axillary region between intensity modulated proton and photon therapy for whole breast irradiation / 肿瘤

Objective:This study aimed to compare the dosimetric differences in unintended irradiation to the ipsilateral axillary region between intensity-modulated radiation therapy(IMRT)and intensity-modulated proton therapy(IMPT)in patients receiving whole breast irradiation(WBI). Methods:A total of 20 patients with early breast cancer who received WBI at our center between August and September 2022 were included in this study.One IMPT plan and one IMRT plan were formulated for each patient,with prescription dose of 4005 cGy(RBE)in 1 5 fractions.Dosimetric parameters of axillary lymph nodes(ALN)level Ⅰ,Ⅱ,Ⅲ,Rotter's lymph nodes(RN),and the axillary-lateral thoracic vascular junction(ALTJ)were compared between IMPT and IMRT plans. Results:All plans met the criteria of CTV V95％Dose≥95％.IMPT showed significantly better conformity index(0.97 vs 0.95,P=0.0003)and homogeneity index(0.05 vs 0.07,P=0.0301)compared to IMRT.The mean dose of the heart[27.48 vs 114.74 cGy(RBE),P＜0.0001]and ipsilateral lung[356.66 vs 498.89 cGy(RBE),P＜0.0001]were significantly lower in the IMPT plan compared to the IMRT plan.The mean dose,V50％Dose,V80％Dose,V90％Dose,and V95％Dose of ALNⅠ,ALN Ⅱ,ALN Ⅲ and RN in the IMPT plan were significantly lower than those in the IMRT plan(all P＜0.01),with the most significant difference observed in the dosimetric parameters of the axillary region inferior to the axillary vein[mean dose:79.75 vs 995.31 cGy(RBE),P＜0.0001].The mean dose and serial dosimetric parameters(V5,V10,V15,V20,V25,V30,and V35)of the ALTJ were also significantly lower in IMPT plans compared to IMRT plans. Conclusion:IMPT demonstrates lower unintended irradiation dose in the inferior axillary region and reduces dose volume in the ALTJ region compared to IMRT.When employing IMPT,the clinical target volume(CTV)should be delineated based on the individual locoregional recurrence risk for patients with positive sentinel lymph nodes who omitted axillary lymph node dissection.For high-risk patients,the axillary region should be included in the CTV to ensure efficacy,while for low-risk patients,excluding the axillary region can help mitigate the risk of breast cancer-related lymphedema.

Dose effect of fluence-smoothing on intensity modulated planning after rectal cancer surgery / 中国辐射卫生

Objective To compare the dosimetric differences of four fluence smoothing (FS) levels of the Monaco system in intensity-modulated radiation therapy (IMRT) after rectal cancer surgery, and to provide a reference for FS selection in clinical practice. Methods A total of 15 postoperative patients with rectal cancer admitted in 2020 were selected. Under the same optimal conditions, FS was set to Off, Low, Medium, and High for IMRT planning. The data were analyzed by SPSS 20.0 software. The dosimetric parameters of planning target volume and organs at risk (OARs), the number of Segments, the number of monitor units (MUs), the estimated total delivery time (ETDT), and the gamma pass rate were compared between the four FS levels. Results The four FS levels resulted in clinically acceptable dosimetric parameters of the planning target volume and OARs, and there was no significant difference in dose distribution between FS levels. From FS-Off to FS-High, number of Segments, number of Mus, and ETDT decreased by 15.2%, 11.8%, and 6.7%, respectively, whereas gamma pass rate increased by 1.6%. Conclusion The IMRT plans at four FS levels can meet the clinical requirements. Considering the planning quality and execution efficiency, FS-High is recommended for postoperative IMRT of patients with rectal cancer.

Influence of normal tissue objective on intensity modulated radiation therapy for rectal cancer based on the Eclipse treatment planning system / 中国辐射卫生

Objective To analyze the dosimetric effect of the optimization tool, normal tissue objective (NTO), in Eclipse on the intensity modulated radiation therapy (IMRT) for postoperative patients with rectal cancer. Methods Twenty postoperative patients with rectal cancer were randomly selected. Based on the Eclipse treatment planning system, three IMRT plans were formulated for each patient, with manual NTO as the control group, and automatic NTO and no NTO as the other two groups. The dosimetric parameters of the target volume and organs at risk (OAR) and the monitor units (MU) were compared between the automatic NTO and no NTO groups and the control group under the same optimization conditions. Results Compared with the control group, the automatic NTO group showed a worse conformity index (CI) (t = 3.248, P < 0.05), a 0.6% higher Dmean of normal tissues (t = -3.678, P < 0.05), and no significant difference in the dose to OAR and the MU (P > 0.05); the no NTO group showed a worse CI (t = 16.716, P < 0.05), a better homogeneity index (t = 6.594, P < 0.05), a 3.19% higher Dmean of normal tissues (t = -8.560, P < 0.05), no significant difference in the dose to OAR except the small intestine with higher Dmax (P > 0.05), and a 3.95% increase in the MU. Conclusion From the dosimetry results of the target volume and OAR, the plans with manual NTO and automatic NTO, and without NTO can meet clinical needs, but the plan without NTO increases the hot spots outside the target volume and the MU as well as the Dmean of normal tissues. Manual NTO has no obvious advantages over automatic NTO which is recommended for the fixed-field IMRT of rectal cancer.

Application of 3D printed personalized breast bracket in IMRT for breast cancer / 中华放射肿瘤学杂志

Objective:By comparing the positioning errors caused by 3D printed personalized breast bracket and common headrest in intensity-modulated radiation therapy (IMRT), the fixation effect of 3D printed personalized breast bracket in IMRT was analyzed.Methods:Thirty-two breast cancer patients from January to July 2021 were randomly divided into a the 3D printed breast bracket group and common headrest group. All patients in two groups were kept in supine position, head tilted to the healthy side, the affected hand held the grip bar on the same side of the horizontal bar, the healthy hand held the opposite side of the vertical bar, and the chest and mandible were fixed with thermoplastic film. CBCT scan was performed weekly, and gray level registration was carried out according to the three registration regions of interest: breast or chest wall field, supraclavicular and inferior field, and axillary field. The positioning errors in the left and right, head and foot, abdomen and back directions were analyzed between two groups.Results:In the 3D printed breast bracket group, the positioning errors of breast or chest wall field, supraclavicular and inferior field and axillary field in the left and right, head and foot, abdomen and back directions were (1.75±1.26), (1.77±1.11) and (1.70±1.08) mm, (1.75±1.25), (1.72±1.09) and (1.70±1.05) mm,(1.86±1.34), (2.14±2.13) and (1.66±1.19) mm, respectively.In the common headrest group, the positioning errors of breast or chest wall field, supraclavicular and inferior field and axillary field in the left and right, the head and feet, the abdomen and back directions were (2.54±1.84), (2.73±3.62) and (2.18±2.45) mm, (3.25±2.02), (3.52±2.26) and (2.62±2.83) mm, (3.25±2.05), (4.44±2.90) and (3.10±3.18) mm, respectively.The positioning errors significantly differed between two groups (all P<0.05). Conclusions:The positioning error of 3D printed personalized breast bracket fixation is less than that of common headrest fixation. The positioning consistency of 3D printed personalized breast bracket in the three target areas of breast or chest wall field, supraclavicular and inferior field and axillary field is better than that of common headrest.

Meta-analysis of efficacy and safety of induction chemotherapy combined with radiotherapy±concurrent chemotherapy for nasopharyngeal carcinoma patients in the era of intensity-modulated radiation therapy / 中华放射肿瘤学杂志

Objective:To compare the efficacy and adverse events of induction chemotherapy combined with radiotherapy alone (IC+ RT) and induction chemotherapy combined with concurrent chemoradiotherapy (IC+ CCRT) for nasopharyngeal carcinoma in the era of intensity-modulated radiation therapy in this Meta-analysis.Methods:Retrospective or randomized controlled clinical studies published between 2010 and 2020 were searched from the Cochrane Library, PubMed, and Web of Science databases. The selected studies included nasopharyngeal carcinoma patients treated with IC+ CCRT or IC+ RT. STATA 12 software was used to combine the hazard ratio (HR), risk ratio (RR) and 95% confidence interval (CI), and random or fixed effect models were used for statistical analysis.Results:A total of 2483 patients from eight retrospective studies were included. The overall survival in the IC+ CCRT group was similar to that in the IC+ RT group ( HR=0.78, 95% CI: 0.58-1.04, P=0.091). However, the distant metastasis-free survival ( HR=0.56, 95% CI: 0.42-0.74, P<0.001) and progression-free survival ( HR=0.65, 95% CI: 0.54-0.77, P<0.001) were improved in the IC+ CCRT group compared with those in the IC+ RT group. In terms of adverse reactions, the acute adverse reactions in the IC+ CCRT group were increased significantly compared with those in the IC+ RT group. Conclusions:In the treatment of nasopharyngeal carcinoma, the overall survival of two treatment modes is similar, but the distant metastasis-free survival and progression-free survival in the IC+ CCRT group are better than those in the IC+ RT group, whereas the incidence of adverse reactions is also increased. IC+ CCRT may be a recommended treatment for nasopharyngeal carcinoma patients, but more research is needed.

Advances in bowel delineation and dose-volume constraint in intensity modulated radiation therapy and 3D conformal radiation therapy for pelvic tumors / 中华放射医学与防护杂志

Intestinal injury is an important toxic response during radiation therapy of pelvic tumors. With the widespread use of precision radiotherapy techniques such as intensity modulated radiation therapy (IMRT), the dose exposed to normal tissues and organs has been significantly reduced. However, the toxic response of the bowel still limits the increase of the dose to the target volume. Therefore, the protection of important organs at risk (OAR), such as the bowel, becomes more and more important while giving adequate irradiated dose to the target volume. Most current studies used loop to contour bowel. For patients who underwent IMRT, the meaningful dose-volume predictors of grade 2 acute intestinal adverse events using bowel loop (small loop + big bowel) delineation included V45 Gy < 50 cm 3,V50 Gy < 13 cm 3, and V55 Gy < 3 cm 3, and the corresponding predicators using bowel bag delineation were V40 Gy < 170 cm 3,V45 Gy < 100 cm 3, and V50 Gy < 33 cm 3.