Evaluation of image-guided and surface-guided radiotherapy for breast cancer patients treated in deep inspiration breath-hold: A single institution experience.

Joan Penninkhof,Britt Kunnen,Sandra Quint,Maarten Dirkx,Kimm Fremeijer,Nienke Hoffmans-Holtzer,Kirsten Offereins-Van Harten,Cynthia Van Wanrooij,Margreet Baaijens,Annemarie Swaak

doi:10.1016/j.tipsro.2022.02.001

Abstract

Nowadays, deep inspiratory breath-hold is a common technique to reduce heart dose in left-sided breast radiotherapy. This study evaluates the evolution of the breath-hold technique in our institute, from portal imaging during dose delivery to continuous monitoring with surface-guided radiotherapy (SGRT). Setup data and portal imaging results were analyzed for 98 patients treated before 2014, and SGRT data for 228 patients treated between 2018 and 2020. For the pre-SGRT group, systematic and random setup errors were calculated for different correction protocols. Residual errors and reproducibility of breath-holds were evaluated for both groups. The benefit of using SGRT for initial positioning was evaluated for another cohort of 47 patients. Online correction reduced the population mean error from 3.9mm (no corrections) to 1.4mm. Despite online setup correction, deviationsgreater than3mm were observed in about 10% and 20% of the treatment beams in ventral-dorsal and cranial-caudal directions, respectively. However, these percentages were much smaller than with offline protocols or no corrections. Mean absolute differences between breath-holds within a fraction were smaller in the SGRT-group (1.69mm) than in the pre-SGRT-group (2.10mm), and further improved with addition of visual feedback (1.30mm). SGRT for positioning did not improve setup accuracy, but slightly reduced the time for imaging and setup correction, allowing completion within 3.5min for 95% of fractions. For accurate radiotherapy breast treatments using deep inspiration breath-hold, daily imaging and correction is required. SGRT provides accurate information on patient positioning during treatment and improves patient compliance with visual feedback.

Highlights

Nowadays, deep inspiratory breath-hold is a common technique to reduce heart dose in left-sided breast radiotherapy
By using online cone-beam CT (CBCT) corrections, the population mean error reduced from 3.9 mm to 1.4 mm
The random error without corrections was 2.3 mm in ventral-dorsal direction (U) and 2.7 mm in cranial-caudal direction (V); this was reduced to 1.3 mm in U and 1.6 mm in V after online CBCT correction

Summary

Introduction

Deep inspiratory breath-hold is a common technique to reduce heart dose in left-sided breast radiotherapy. Deviations greater than 3 mm were observed in about 10% and 20% of the treatment beams in ventral-dorsal and cranial-caudal directions, respectively These percentages were much smaller than with offline protocols or no corrections. Radiation therapy after lumpectomy has become the standard treatment for breast cancer patients It reduces the risk of local recur rence with a factor of 3–4 compared to no radiotherapy [1]. When a patient inhales deeply, the volume of the lungs increases, and the heart is pushed down and away from the Abbreviations: DIBH, Deep inspiratory breath-hold; SGRT, surface-guided radiotherapy; DRRs, digitally reconstructed radiographs; CT, computer tomography; CBCT, cone-beam CT; OTM, online treatment monitor; (U, V), ventral-dorsal and cranial-caudal direction in the tangential beam, respectively; NAL, no-action-level setup correction protocol; eNAL, extended NAL setup correction protocol; VRT, anterior-posterior direction; LNG, cranial-caudal direction; LAT, medio-lateral direction

Methods

Results

Conclusion