Reduced lung dose and improved inspiration level reproducibility in visually guided DIBH compared to audio coached EIG radiotherapy for breast cancer patients

Abstract

Introduction. Patients with left-sided breast cancer with lymph node involvement have routinely been treated with enhanced inspiration gating (EIG) for a decade at our institution. In a transition from EIG to deep inspiration breath hold (DIBH) we compared the two techniques with focus on target coverage, dose to organs at risk and reproducibility of the inspiration level (IL). Material and methods. Twenty-four patients were computed tomography (CT) scanned with EIG and DIBH. For DIBH we used visual feedback and for EIG audio coaching, both during scan and treatment. Treatment plans for 50 Gy over 25 fractions were calculated. Seventeen of the patients were included in the analysis of reproducibility. They were audio coached for one minute before beam-on in DIBH at nine treatment sessions. These respiration curves were analysed with average maximum IL and standard deviation (SD) for the EIG part of the respiratory signal, and mean IL and SD for the DIBH. Comparison of dosimetric and respiration parameters were performed with the Wilcoxon signed rank-sum test. Results. In DIBH, the ipsilateral lung volume increased further compared to EIG (p Ͻ 0.0004, mean increase 11%). This lead to a 9% mean reduction (p ϭ 0.002) of the ipsilateral lung volume receiving 20 Gy (V 20 Gy). We found no other signifi cant dosimetric differences between the two methods. The reproducibility of the IL was better with the DIBH method, observed as a signifi cantly smaller SD in most patients (p Ͻ 0.04 for 16 of 17 patients). Conclusion. The DIBH method resulted in a signifi cantly larger lung volume and lower ipsilateral lung V 20 Gy compared to EIG. The IL for visually guided DIBH was more reproducible than audio-coached EIG. Based on these fi ndings, the DIBH technique is our new breathing adaptation standard for radiotherapy of patients with left-sided breast cancer with lymph node involvement.

Improving the reproducibility of voluntary deep inspiration breath hold technique during adjuvant left-sided breast cancer radiotherapy

“…Visual guidance with goggles or monitors improves the reproducibility of breath hold, as presented by Damkjaer et al [13,17]. Rong et al found that the RPM system alone is not sufficient to verify the BHL [18] and used three-dimensional (3D) surface imaging as a second method.…”

“…The marker block used can be placed either on the abdominal wall at the level of the diaphragm [5,6,12] or on bony sternum [8,13]. RPM measures the BHL only indirectly and in anterior-posterior (AP) dimension -thus the actual BHL must be re-verified in the treatment situation [9,10].…”

Image-guided radiotherapy and motion management in lung cancer

“…For both respiratory gating in free breathing and breath-hold techniques, it has been shown that reproducibility and stability can be enhanced by use of patient training and coaching techniques, using both audio and visual guidance 33,34 (see the Decision making strategies for motion management section).…”

Deep inspiration breath hold radiotherapy for locally advanced lung cancer: Comparison of different treatment techniques on target coverage, lung dose and treatment delivery time

“…Increased lung volume in deep inspiration breath hold (DIBH) facilitates a potential for lung toxicity decrease [6,7]. DIBH RT has been successfully applied for a decade, primarily for breast cancer RT [8,9]. However, it is generally feared that lung cancer patients will have poorer lung function and a lower compliance.…”