ABSTRACT
Objective:To investigate the clinical effects of pelvic radiotherapy on improving the patient′s position variability by using stretching exercises before radiotherapy.Methods:The study period was from January 2017 to May 2019. The study subjects were patients with pelvic malignancies who visited Zhejiang Cancer Hospital during this period and needed radiotherapy. A total of 278 patients were divided into study group and control group according to the random number table method, with 139 cases in each group. The study group performed hip joint stretching and rotation exercises before radiotherapy, while the control group had no special intervention. By comparing the changes in the sacral slope angle (SSA) of the patients between the two groups, the position variability during radiotherapy was reflected. The effects of complications, compliance, and degree of benefit were analyzed.Results:The daily compliance of the study group was above 95%. No patients reported adverse events such as dyskinesias and related pain and falls. The SSA change in the study group patients was significantly reduced ( P<0.05). The daily SSA and baseline SCT in the study group were significantly lower ( P<0.05). The average change in the study group was (0.95 ± 0.24)°(0.52°-1.33°), while the average change in the control group was (2.31 ± 1.05)°(1.17°-5.26°),and there was significant difference ( P<0.05). The comparison of the average differences between the treatment days showed that the average change in the study group was (0.96 ± 0.64)°(0.72°-1.28°)and in the control group was (2.09 ± 1.12)°(0.94°-3.28°),and there was significant difference ( P<0.05). Pearson correlation analysis was used to evaluate its correlation to the overall change of each patient. The reliability between the two assessors showed moderately positive correlation ( r=0.52, P=0.18), and there was also a moderately positive correlation in the control group ( r=0.59, P=0.26). The patients in the study group scored (7.12 ± 0.16) scores on the degree of benefit of participating in the study group. Conclusions:The stretching exercise before radiotherapy can effectively reduce the position variability of patients with pelvic radiotherapy, which is beneficial to improve the effect of diagnosis and treatment.
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Objective To evaluate the inter-fraction setup error during the treatment with megavoltage computed tomography (MVCT) and provide theoretical basis for clinical target volume-planning target volume (CTV-PTV) margins for nasopharyngeal carcinoma (NPC) patients treated with tomotherapy.Methods Thirty-seven consecutive NPC patients treated with tomotherapy were prospectively enrolled for the study between February 2015 and September 2015.For each patient,one MVCT scan was obtained after conventional positioning,online correction and tomotherapy delivery daily,and the scan was registered to the planning CT to determine inter-fraction setup error.The expanding margin for PTV (MPTV) was calculated with the recipe:MPTV =2.5∑ + 0.76 (∑:systematic error;6:random error).Results The average absolute errors of the inter-fraction were (2.102 ± 0.040 6) mm,(1.490 ± 0.034 8) mm,(1.306 ± 0.335) mm and (1.392 ± 0.038 4) ° in the three dimensions.Gradual increases in both inter-fraction three-dimensional displacement were observed with time and treatment (P ＜ 0.05).The total MPTV ac counting for inter-error were 3.467 5 mm,2.979 5 mm and 2.888 5 mm.Conclusions Tomotherapy irradiation technology personalized MPTV should be adopted for the design of tomotherapy plan.Displacement increased as a function of time.
ABSTRACT
Objective To explore the inter-fraction setup errors and affecting factors from data of daily fan-beam megavoltage computed tomography(MVCT). Methods A total of 37consecutive NPC patients treated with tomotherapy were hospitalized during the period of February 2015 to September 2015. For each patient,one MVCT scan was obtained after conventional positioning ,online correction and tomotherapy delivery daily ,and the scans were put into the planning computed tomography to determine inter-fraction setup errors. The MPTV was calculated with the equation:MPTV=2.5∑+0.7σ(∑:systematic error;σ:random error). Results The average absolute errors of the inter-fraction were(2.102 ± 0.0406)mm,(1.490 ± 0.0348)mm,(1.306 ± 0.335)mm and(1.392 ± 0.0384)° at three dimensions. The total MPTV accounting for inter-error was 3.4675 mm,2.9795 mm,and 2.8885 mm. Gradual increases in both inter-fraction three-dimensional displacement were observed with time and treatment(P < 0.05). Univariate analysis revealed that weight loss and retraction of neck lymph nodes were affecting factors of set-up errors. Conclusions 3 mm margins uniformly expended from clinical target volume to planning target volume may not be suitable. The personalized margin should be adopted for the design of IMRT planning. Displacement increases as a treatment course is prolonged.
ABSTRACT
Objective To assess the variation in patient setup corrections for three different anatomic treat-ment sites using daily pretreatment megavoltage CT(MVCT)in helical tomotherapy,and to analyze alternative refer-ence margins for specific tumor site.Methods Sixty patients treated for three anatomical sites on helical tomotherapy were analyzed.Daily MVCT was carried out for registration and setup corrections before each treatment fraction.Setup errors and rotational setup corrections from 587 head and neck,500 thoracic,371 abdomen and gynecology MCVT imaging were input to statistical analysis.Incidences of three dimensional vector error lengths were calculated for each anatomic site.Overall distribution histograms of the three -dimensionally error was presented using GraphPad Prism 5.The distributions of systematic and random setup errors were quantitative analyzed and the additional margins required were also taken into account.Results 1 458 MVCT scans were implemented for sixty patients.Head and neck had lower frequencies of translational setup errors than others.Frequency of at least 3mm three -dimensional setup errors for head and neck,thoracic,abdomen and gynecology was 55.3%,70.8%,79.8%,respectively.This fre-quency decreased to 17.5%,40.6%,47.2% if 3D vector distance ≥5mm was scored.Overall systematic errors ranged from -1.4mm to 2.7mm,abdomen and gynecology had the largest setup errors in the vertical direction which was statistically significant(χ2 =19.3,P <0.05).The suggested margins should be increased by 4 -7 mm in three -dimensional direction for head and neck,9 -14mm for thoracic,10 -17mm for abdomen and gynecology.Conclusion Differences in setup corrections are perceived between head and neck,thoracic,abdomen and gynecology.The accura-cy of patient positioning can be improved if pre -treatment daily MVCT scans are put into use.Results from setup cor-rection can provide evidence for tumor treatment margin and improve the accuracy of regular radiotherapy.