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1.
Article in Chinese | WPRIM | ID: wpr-1022955

ABSTRACT

Objective To compare the effects of two arc(TA)and dual arc(DA)techniques on the dose distribution to the planning target volume(PTV)and organs at risk(OAR)in volumetric modulated arc therapy(VMAT)for lower mid-thoracic esophageal cancer.Methods Ten patients with lower mid-thoracic esophageal cancer who received radiation therapy at some hospital from July 2020 to June 2022 were selected retrospectively.A TA radiation therapy plan and a DA radiation therapy plan were developed for each patient using the Ray Arc module of RayStation 4.7.5.4 planning system,and the two kinds of radiation plans were compared in terms of dosimetric parameters including D2,D5,D50,D95,D98,homogeneity index(HI),conformity index(CI),beam-on time and total monitor unit for PTV and lung V5,V10,V20,V30 and Dmean and heartV30,V40 and Dmean and spine cord Dmax for OAR.SPSS 22.0 was used for statistical analysis.Results TA and DA radiation therapy plans had no significant differences in PTV CI,HI,D2,D5,D50,D95 and beam-on time(P>0.05),and DA plan had D98 and total monitor unit higher obviously than those of TA plan(P<0.05).In terms of OARs protection,DA plan had heart V30,V40 and Dmean slightly lower than those of TA plan with non-significantly differences(P>0.05),while lung V5,V30 and Dmean and spine cordDmax significantly lower(P<0.05).Conclusion DA technique gains advantages over TA technique in PTV dose distribution and dose to OAR,and the involvement of DA technique in preparing the VMAT plan for esophageal cancer contributes to enhancing the treatment efficacy.[Chinese Medical Equipment Journal,2024,45(1):62-66]

2.
Article in Chinese | WPRIM | ID: wpr-1027383

ABSTRACT

Objective:To investigate the incidence of radiation pneumonitis (RP) induced by 125I seed implantation for the treatment of malignant lung tumors and analyze related dosimetric parameters. Methods:A retrospective analysis was conducted on 31 cases of malignant lung tumors treated with 125I seed implantation from January 2017 to December 2022 at Hebei Provincial Tumor Radioactive Seeds Implantation Diagnosis and Treatment Center. These cases consisted of eight patients with squamous cell carcinoma, 10 patients with adenocarcinoma, and 13 patients with metastatic cancer in other sites. At 1-6 months after treatment, these patients received postoperative chest CT scans, with the efficacy evaluated based on the Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1), including the objective response rate (ORR) and the disease control rate (DCR). The efficacy of RP was evaluated using the Radiation Therapy Oncology Group (RTOG) criteria. Postoperative dosimetric parameters, including D90 (minimum peripheral dose received by 90% of the target volume), V8 (percentage of lung volume receiving 8 Gy), V32 (percentage of lung volume receiving 32 Gy), and Dmean (mean radiation dose) of the affected lung, were statistically analyzed. The relationships of the RP occurrence with postoperative D90, V8, V32, and Dmean were analyzed by comparison with relevant external radiotherapy data, to identify the parameters that are correlated closely with RP occurrence. Results:All the patients underwent successful surgeries. The postoperative efficacy evaluation after six months showed complete response (CR) in 11 cases, partial response (PR) in 11 cases, stable disease (SD) in eight cases, and progressive disease (PD) in one case, with an overall response rate (ORR) of 71.0%, and a disease control rate (DCR) of 96.8%. Three patients suffered RP, with an incidence rate of 9.7%. Postoperative V8, V32, and Dmean could not serve as predictive indicators for RP. Follow-up observation revealed that three RP cases (3/5) exhibited postoperative D90 exceeding 170 Gy and no RP cases (0/26) showed postoperative D90 below 170 Gy. Conclusions:In the treatment of malignant lung tumors with 125I seed implantation, there is a certain correlation between RP and postoperative D90, while there is no correlation between it and V8, V32, and Dmean.

3.
Article in Chinese | WPRIM | ID: wpr-1022867

ABSTRACT

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]

4.
Article in Chinese | WPRIM | ID: wpr-993147

ABSTRACT

Objective:To evaluate the effect of rotational errors (antero-posterior) on dosimetric parameters of positive lymph nodes in the long target volumetric modulated arc therapy (VMAT) plan for advanced cervical cancer and investigate its coping strategies.Methods:Clinical data of patients with cervical cancer complicated with para-aortic or inguinal lymph node metastasis admitted to Affiliated Hospital of North Sichuan Medical College were randomly selected and retrospectively analyzed. The target areas of the lymph nodes at different distances from the center of the plan were outlined according to the requirements. After designing the VMAT plan on the CT images of each case, the rotational errors (antero-posterior) were introduced by changing the parameters of the treatment couch, and the dose distribution was reconstructed by dose calculation with other parameters unchanged. Then, the external boundary of the original lymph node target was added according to d=2πr(α/360) ( r is the distance from the center of the lymph node to the plan center), re-planned, and the changes of dosimetric parameters in the target area of the original lymph node were analyzed after the corresponding rotational errors were introduced. Results:When the distance between the lymph node target area and the plan center was 6 cm with an error of 3°, the distance was 9 cm and 12 cm with an error of 2.5°, the distance was 15 cm with an error of 2°, and the distance was 18 cm with an error of 1.5°, the mean change of D 95% was more than 5%. When the rotational errors were ≤1°, the mean change of D 95% in lymph node target area was less than 5%, and when the lymph node was 18 cm away from the treatment plan center, the mean change was more than 3%, reaching 3.75%. When the rotational errors were 0.5° and the distance from the plan center was 18 cm (0.5°, 18 cm), the dose change of lymph node target was more than 5%, reaching 5.58%. At (1°, 15 cm), the V 100% change reached 8.96%, and at (1°, 18 cm), the V 100% change was 14.5%. The D 95% and V 100% parameters of the original lymph node target were changed by less than 1% after adding the external boundary of the original lymph node target and introducing corresponding rotational errors. Conclusions:In the long target area radiotherapy of cervical cancer, the variation of dosimetric parameters of lymph node target was increased with the increase of rotational errors and with the increase of distance from the plan center. It is recommended to increase the efferent boundary of lymph nodes in different positions to avoid underdose by d=2πr(α/360).

5.
Article in Chinese | WPRIM | ID: wpr-868539

ABSTRACT

Objective To evaluate the value of two oral mucosal contouring methods for predicting acute radiation-induced oral mucositis (A-ROM) in nasopharyngeal carcinoma (NPC) patients.Methods A total of 150 AJCC 7th stage Ⅱ-ⅣB NPCs receiving radical tomotherapy (TOMO) in Zhejiang Cancer Hospital from 2017 to 2019 were included in this prospective observational study.Oral cavity contour (OCC) and mucosal surface contour (MSC) were applied to delineate the oral mucosal structure.A-ROM grade was prospectively assessed and recorded weekly according to RTOG scoring criteria.The prediction value of two methods for A-ROM was statistically compared.Results The incidence rate of ≥ 3 grade A-ROM was 33.3%.In univariate analysis,V5,V10,V15,V45,V50,V55,V60,V65 and V70 of OCC and V5,V10,V50,V55,V60,V65,V70 and Dmean of MSC were significantly correlated with the risk of ≥3 grade A-ROM (all P<0.05).In binary logistic regression analysis,gender and smoking were significantly associated with the incidence of ≥3 grade A-ROM by using OCC (male vs.female:OR=0.141,95%CI=0.037-0.538,P=0.004;smoking vs.non-smoking:OR=5.109,95%CI=1.413-18.470,P=0.013).For MSC,gender,smoking,N stage and MSC-V55 were the independent predictors (male vs.female:OR=0.129,95%CI=0.032-0.519,P=0.004;smoking vs.non-smoking:OR=4.448,95%CI=1.224-16.164,P=0.023;N stage:OR=2.291,95%CI=1.268-4.137,P=0.006;MSC-V55:OR=1.432,95%CI=1.008-2.033,P=0.045).The cutoff value of MSC-V55 was 7.70%,the area under ROC curve was 0.754,the sensitivity and specificity were 0.680 and 0.740,retrospectively (all P<0.001).Conclusions Compared with OCC,MSC yields a higher prediction accuracy for the severity of A-ROM in nasopharyngeal carcinoma patients receiving TOMO treatment.

6.
Article in Chinese | WPRIM | ID: wpr-798798

ABSTRACT

Objective@#To evaluate the value of two oral mucosal contouring methods for predicting acute radiation-induced oral mucositis (A-ROM) in nasopharyngeal carcinoma (NPC) patients.@*Methods@#A total of 150 AJCC 7th stage Ⅱ-IVB NPCs receiving radical tomotherapy (TOMO) in Zhejiang Cancer Hospital from 2017 to 2019 were included in this prospective observational study. Oral cavity contour (OCC) and mucosal surface contour (MSC) were applied to delineate the oral mucosal structure. A-ROM grade was prospectively assessed and recorded weekly according to RTOG scoring criteria. The prediction value of two methods for A-ROM was statistically compared.@*Results@#The incidence rate of ≥3 grade A-ROM was 33.3%. In univariate analysis, V5, V10, V15, V45, V50, V55, V60, V65 and V70 of OCC and V5, V10, V50, V55, V60, V65, V70 and Dmean of MSC were significantly correlated with the risk of ≥3 grade A-ROM (all P<0.05). In binary logistic regression analysis, gender and smoking were significantly associated with the incidence of ≥3 grade A-ROM by using OCC (male vs. female: OR=0.141, 95%CI=0.037-0.538, P=0.004; smoking vs.non-smoking: OR=5.109, 95%CI=1.413-18.470, P=0.013). For MSC, gender, smoking, N stage and MSC- V55 were the independent predictors (male vs. female: OR=0.129, 95%CI=0.032-0.519, P=0.004; smoking vs.non-smoking: OR=4.448, 95%CI=1.224-16.164, P=0.023; N stage: OR=2.291, 95%CI=1.268-4.137, P=0.006; MSC-V55: OR=1.432, 95%CI=1.008-2.033, P=0.045). The cutoff value of MSC-V55 was 7.70%, the area under ROC curve was 0.754, the sensitivity and specificity were 0.680 and 0.740, retrospectively (all P<0.001).@*Conclusions@#Compared with OCC, MSC yields a higher prediction accuracy for the severity of A-ROM in nasopharyngeal carcinoma patients receiving TOMO treatment.

7.
Article in Chinese | WPRIM | ID: wpr-708244

ABSTRACT

Objective To evaluate the effect of stainless steel applicator on dose distribution in GZP 60 Co brachytherapy source and to obtain the dosimetric parameters of the 60 Co source with stainless steel applicator. Methods Geant4 was employed to obtain the mean adsorption dose of the 60 Co brachytherapy source in the range of 0-10 cm, and the dosimetric parameters were calculated according to the formula proposed by AAPM reports TG43 and TG43U1. The 60 Co source was located in the center of a sphere water phantom with a radius of 30 cm. Results For channel 1 and 2 of GZP 60 Co source, the results of Λ with stainless steel applicator were 1. 014 cGyh-1 U-1( with a difference of 0. 5% compared with non-applicator) , the results of Λ with stainless steel applicator for channel 3 were 0. 998 cGyh-1 U-1 ( with a difference of 0. 1% compared with non-applicator) . The radial dose function in the range of 0. 5-10. 0 cm in a longitudinal direction was calculated and the fitting formula for the function was obtained. The polynomial function for the radial dose function and the anisotropy function with a of 0°-175° and an r of 0. 5-10. 0 cm were obtained. Conclusion The dosimetric parameters of the 60 Co source with stainless steel applicator are obtained, which provide more accurate reference data for clinical application. In clinical practice, the effect of stainless steel applicator on dose distribution should be considered.

8.
Article in Chinese | WPRIM | ID: wpr-485381

ABSTRACT

Objective To compare the dosimetric parameters of volumetric modulated arc therapy(VMAT),fixed field intensity modulated radiation therapy(IMRT)and three-dimensional conformal radiotherapy(3D-CRT)in the radiotherapy for the patients with locally recurrent nasopharyngeal carcinoma, and to analyze their characteristics. Methods Twelve patients with locally recurrent nasopharyngeal carcinoma were treated with VMAT, IMRT and 3D-CRT plan designed by Pinnacle 9.2 and Preciseplan 2.03 treatment planning system.The dosimetric parameters of targeted volumes and organs at risk were compared between three groups. Results The conformation indexes (CI)of VMAT and IMRT plans were similar,and they were both better than 3D-CRT plan,the difference was significant(P0.05).The monitor units(MU)and beam time in 3D-CRT group were better than those in other two groups,and VMRT group was better than IMRT group,the statistical differences were observed between three groups (P0.05).The doses of the spinal cord,optic nerve,optic chiasm and temporal lobe of brain in VMAT and IMRT groups were better than those in 3D-CRT group,there were statistical differences between them(P0.05).Conclusion There are differences of the targeted dose distribution between the three kinds of radiation technology, while VMAT and IMRT plans can cover the targeted areas and reduce the received doses of organs at risk.The CI,MU and beam time of VMAT plan are better than those of IMRT plan. 3D-CRT plan only has advantage in the MU and beam time.

9.
Article in Chinese | WPRIM | ID: wpr-424811

ABSTRACT

Objective To compare the dosimetric characteristics of intensity-modulated arc therapy( IMAT ),fixed-gantry intensity-modulated radiotherapy ( IMRT ) and 3-dimensional conformal radiotherapy (3D-CRT) for the thoracic esophageal cancer.Methods A total of 15 patients with thoracic esophageal cancer were enrolled.3D-CRT,5-field IMRT( IMRT5 ),7-field IMRT( IMRT7 ),9-field IMRT ( IMRT9 ),single arc ( Arc1 ) and double arc ( Arc2 ) RapidArc plans were generated for each patient.All plans were prescribed 40 Gy in 20 fractions and 19.6 Gy in 14 fractions to PTV at 95% isodose line.Results RapidArc and all IMRT treatment plans in dosimetric parameters of target volumes were obviously better compared to 3-dimentional conformal treatments( t =5.77,3.52,P < 0.05 ).The result of V95 of PTV for 3D-CRT,IMRT5,IMRT7,IMRT9,Arc1 and Arc2 plans was 91.55 ±2.90,96.66 ±1.05,96.87 ± 1.23,96.81 ± 1.16,94.98 ± 1.41 and 95.93 ± 1.32,respectively.The best conformation index in PTV was observed in the RapidArc plans ( t =3.76,10.01,P < 0.05 ),and the best homogeneity index in PTV was observed in the IMRT plans( t =3.93,3.37,P < 0.05 ).In terms of organ sparing,no statistical difference was observed between IMRT and RapidArc plans( P > 0.05 ),while 3D-CRT provided the lowest number of V1 cGy and V5 cGy for total lung.Compared with the IMRT treatment plans,the number of monitor units was lower in all 3D-CRT and RapidArc cases with differences of 75%.Conclusions All the IMRT and RapidArc plans could offer high quality treatment for patients.3D-CRT might show advantage in low-dose region to organs at risk.Compared with IMRT,no obvious advantage in PTV dosimetric parameters could be observed in RapidArc plans.

10.
Article in Chinese | WPRIM | ID: wpr-580537

ABSTRACT

The ?-radioactive seed brachytherapy source has been widely employed in the implantation therapy for the prostatic carcinoma and the ophthalmic lesions.In this study the dosimetric parameters for characterization of a low-energy interstitial brachytherapy source 125I were calculated according to dose calculation formalism recommended by AAPM TG-43U1.For data processing,a 0.28 cm active length was used for the geometry function.The dosimetry parameter air-Kerma strength,dose rate constant,radial dose function and anisotropy function were estimated by means of the EGS5 Monte Carlo code.The results obtained from this study are in good agreement with the corresponding values recommended by TG-43U1 and with the data reported by Dolan,et al.

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