Geometric and dosimetric analysis of automatic segmentation of organs at risk for radiotherapy on nasopharyngeal carcinoma
Objective To analyze the geometric and dosimetric accuracy of automatic segmentation of organs at risk(OAR)in volumetric modulated arc therapy(VMAT)for nasopharyngeal carcinoma and exam the correlation between geometry and dosimetry of OAR delineation,and provide reference for OAR delineation in radiotherapy patients.Methods A total of 120 patients with nasopharyngeal carcinoma were retrospectively enrolled,which included 84 males and 36 females,aged 11-82 years old with median age of 55 years old.The lesion was located between skull base and soft palate,with vertical diameter and transverse diameter of 3-4 cm,respectively,and anteroposterior diameter was 2-3 cm.A total of 85 patients were se-lected by random number method and trained by AccuLearning deep learning training platform to form AS model,and the AS model was imported into AccuContour software.The AS contouring model was used to automatically delineate 18 OAR in 35 untrained nasopharyngeal carcinoma radiotherapy patients.The geometric measurements of AS and manually segmontation(MS)OAR were compared,which included Dice similarity coefficient(DSC),Jacquard coefficient(JAC),deviation of centroid(DC),Hausdorff distance(HD95),average symmetric surface distance(ASSD),and relative absolute volume difference(RAVD).Under the same VMAT plan,the OAR dosimetric parameters delineated by AS and MS were compared by dose volume histogram(DVH).The correlation between geometric index and dosimetry absolute difference was analyzed by double-tailed Spearman.Results The OAR contouring outlined by AS and MS were different.The mandible was the best delineation quali-ty in DSC,JAC and RAVD,of which mean±standard deviation was 0.94±0.01,0.88±0.02 and 6.34±4.13,respectively.The results of HD95 and ASSD of left lens were the best,of which mean±standard deviation was 2.04±0.91 and 0.22± 0.12,respectively.The best mean±standard deviation of DC was 0.93±0.77 in the right eyeball.The worst performance in DSC and JAC was the optic chiasm,of which mean±standard deviation was 0.75±0.06 and 0.60±0.07,respectively.The worst de-lineated OAR in DC and HD95 was the left temporal lobe,of which mean±standard deviation was 5.22±2.30 and 11.89±3.82,respectively.The oral cavity was the worst ASSD,of which mean±standard deviation was 1.30±0.41.The right crystalline lens was the worst RAVD,of which mean±standard deviation was 29.03±16.51.The mean value of MS dose parameters for all OAR was lower than that for AS,but dose value for AS was not exceed the dose limit.The paired t-test showed that there was no signifi-cant difference in dosimetric parameters of the most OAR,but only in pinal cord and brainstem was statistically significant.The two-tailed Spearman correlation test showed that there was the strong correlation between non-OAR geometric parameters and Absolute dose difference(ΔDose).Conclusion It is demonstrated that AccuContour automatic contouring software could contour OAR with certain accuracy for nasopharyngeal carcinoma radiotherapy,which improves the work efficiency for clinicians,and there is no strong correlation between AS geometric index and dose difference.
NETL
NSTL
万方数据
维普
