A Comparison of Manual and Automatic Methods for Calculating Cumulative Dose-Volume Histogram Parameters in Cervical Cancer Radiotherapy

Abstract

Background: The cumulative dose-volume histogram (DVH) parameters for organs at risk (OAR) and the target volume, obtained from external beam radiotherapy (EBRT) and brachytherapy (BT), are commonly calculated manually in clinical practice. Objectives: This study aims at comparing the manual and automatic methods for calculating cumulative DVH parameters of OAR and the target volume in patients with cervical cancer. Methods: The cumulative DVH of EBRT and BT methods for target volume and OAR, including rectum, bladder, and sigmoid was calculated manually, using the EQD2 (equivalent dose in 2 Gy fractions) formula. In the automatic method, dosimetric data were collected as DICOM files and entered into SagiPlan® BT software. Using the BED/EQD2 summation feature, the BT and EBRT plans were summed, and the cumulative DVH parameters were extracted. The results were compared with the manual method. Results: In 32 cervical cancer samples, dosimetric comparisons showed significant differences between manual (EQD2) and automatic (SagiPlan®) calculations for rectum (mean dose 69.15 vs. 71.92 Gy, P < 0.01), bladder (mean dose 81.87 vs. 84.47 Gy, P < 0.01), and sigmoid (mean dose 69.84 vs.73.15 Gy, P < 0.01). However, the cumulative dose to the target tissue was similar between the two methods (mean dose 86.9 vs. 86.91, P = 0.21). Automatic calculations indicated higher doses of the OARs, suggesting potential underestimation by manual methods. Conclusions: In clinical practice, when designing BT planning for cervical cancer, it is recommended to input the patient’s EBRT design data into the planning software to determine the cumulative dose received by the target and OARs.