2021/11/11 by Nguyen Phuong Dang, Dang, Nguyen Phuong, Victor Gabriel Leandro Alves +5
Engineering · Medicine · Physics and Astronomy · #Advanced Radiotherapy Techniques #Advanced X-ray and CT Imaging #FOS: Physical sciences #Medical Physics (physics.med-ph) #Radiation Dose and Imaging
paper · pdf · doi:10.48550/arxiv.2111.06489
openalex publication_date 2021/11/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Purpose: To quantify the effectiveness of EPID-based cine transmission dosimetry to detect gross patient anatomic errors. Method and Materials: EPID image frames resulting from fluence transmitted through multiple patients anatomies are simulated for 100 msec delivery intervals for hypothetical 6 MV VMAT deliveries. Frames simulated through 10 head-and-neck CTs and 19 prostate CTs with and without 1-3 mm shift and 1-3 degree rotations were used to quantify expected in-tolerance clinical setup variations. Per-frame analysis methods to determine if simulated gross errors of (a) 10-20 mm patient miss alignment offsets and (b) 15-20 degree patient rotations could be reliably distinguished from the above baseline variations. For the prostate image sets, frames simulated through the reference CT are intercompared with (c) frames through 8-13 different CT's for the same patient to quantify expected inter-treatment frame variation. ROC analysis of per-frame error discrimination based upon (i) frame image differences, (ii) frame histogram comparisons, (iii) image feature matching, and (iv) image distance were used to quantify error detectability. Results: Each error detection method was able to distinguish gross patient miss-alignment and gross rotations from in-tolerance levels for both H&N and prostate datasets. The image distance algorithm is the best method based on AUC. Conclusion: In-field gross error detection was possible for gross patient miss-alignments and incorrect patients. For prostate cases, the methods used were able to distinguish different patients from daily patient variations.