# Cumulative dose assessment with transformer‐based deformable image registration addition for cervical cancer patients

## TL;DR

This study introduces a new transformer-based method for accurately assessing cumulative radiation doses in cervical cancer patients undergoing combined therapies.

## Contribution

A novel mix-transformer structure-based deformable image registration (MTDIR) network is proposed for improved dose accumulation in cervical cancer treatment.

## Key findings

- MTDIR achieved higher mean DSC and lower HDmean values for bladder and rectum registration compared to VoxelMorph and Velocity.
- The proposed method outperformed existing techniques in both EBRT-ICBT and ICBT-ICBT CT scan registrations.
- MTDIR-based dose addition showed better accuracy in cumulative dose assessment for cervical cancer patients.

## Abstract

Based on the combination mode of internal and external radiotherapy for cervical cancer, this study aimed to investigate an accurate transformer‐based deformable image registration (DIR) method for cumulative dose assessment.

According to a retrospective analysis conducted on 180 patients with cervical cancer who underwent intracavitary brachytherapy (ICBT) and external beam radiation therapy (EBRT), this study proposed a mix‐transformer structure‐based deformable image registration (MTDIR) network for registering CT scans of ICBT and EBRT, followed by dose accumulation and assessment. The mean dice similarity coefficient (DSC) and Hausdorff distance (HD) of the rectum and bladder were computed to compare the performance of MTDIR with that of the state‐of‐the‐art VoxelMorph method and the DIR method provided by velocity. Additionally, the cumulative dose of the bladder and rectum from four methods was calculated: direct DVH parameter addition (DA), DIR‐based dose addition provided by Velocity (VA), VoxelMorph‐based dose addition (VoA), and MTDIR‐based dose addition (MA).

The mean DSC values of MTDIR, VoxelMorph, and Velocity for the bladder were 0.78, 0.75, and 0.72 for the registration between CT scans of EBRT and the last ICBT, respectively. The mean DSC values of the rectum were also equal to 0.58, 0.56, and 0.52. The mean HDmean values of MTDIR, VoxelMorph, and Velocity for the bladder were 4.81, 5.16, and 5.43, and the mean HDmean values of the rectum were 5.41, 5.81, and 6.93, respectively. For the registration between CT scans of ICBT, the mean DSC values of MTDIR, VoxelMorph, and Velocity for the bladder were obtained 0.82, 0.80, and 0.77, and the mean DSC values for the rectum were equal to 0.70, 0.68, and 0.63, respectively. The mean HDmean values of MTDIR, VoxelMorph, and Velocity for the bladder were 4.22, 4.58, and 4.79, and the mean HDmean values of the rectum were obtained 4.86, 5.17, and 5.64, respectively. The results generally suggested that MTDIR outperformed VoxelMorph and Velocity.

The study findings demonstrated that the model developed based on parameters obtained from the proposed method exhibited higher registration accuracy.