Clinical experience using a video‐guided spirometry system for deep inhalation breath‐hold radiotherapy of left‐sided breast cancer

Abstract

The purpose was to report clinical experience of a video‐guided spirometry system in applying deep inhalation breath‐hold (DIBH) radiotherapy for left‐sided breast cancer, and to study the systematic and random uncertainties, intra‐ and interfraction motion and impact on cardiac dose associated with DIBH. The data from 28 left‐sided breast cancer patients treated with spirometer‐guided DIBH radiation were studied. Dosimetric comparisons between free‐breathing (FB) and DIBH plans were performed. The distance between the heart and chest wall measured on the digitally reconstructed radiographs (DRR) and MV portal images, dDRR(DIBH) and dport(DIBH), respectively, was compared as a measure of DIBH setup uncertainty. The difference (Δd) between dDRR(DIBH) and dport(DIBH) was defined as the systematic uncertainty. The standard deviation of Δd for each patient was defined as the random uncertainty. MV cine images during radiation were acquired. Affine registrations of the cine images acquired during one fraction and multiple fractions were performed to study the intra‐ and interfraction motion of the chest wall. The median chest wall motion was used as the metric for intra‐ and interfraction analysis. Breast motions in superior–inferior (SI) direction and “AP” (defined on the DRR or MV portal image as the direction perpendicular to the SI direction) are reported. Systematic and random uncertainties of 3.8 mm and 2 mm, respectively, were found for this spirometer‐guided DIBH treatment. MV cine analysis showed that intrafraction chest wall motions during DIBH were 0.3 mm in “AP” and 0.6 mm in SI. The interfraction chest wall motions were 3.6 mm in “AP” and 3.4 mm in SI. Utilization of DIBH with this spirometry system led to a statistically significant reduction of cardiac dose relative to FB treatment. The DIBH using video‐guided spirometry provided reproducible cardiac sparing with minimal intra‐ and interfraction chest wall motion, and thus is a valuable adjunct to modern breast treatment techniques.PACS number: 87.55.kh, 87.55.ne, 87.55.tg

Single‐institution report of setup margins of voluntary deep‐inspiration breath‐hold (DIBH) whole breast radiotherapy implemented with real‐time surface imaging

“… and Yang et al. , which both use x‐ray monitoring of left‐sided DIBH. The use of surface imaging in this study achieved a comparable setup margin to those in aforementioned peer works.…”

“…Image guidance is frequently used to detect large setup errors and refine patient positioning in the setting of radiotherapy . Modalities such as electronic portal imaging devices, cone‐beam CT (CBCT), and surface imaging have been implemented to verify setup accuracy of DIBH patients . However, daily shifts in patient setup are inevitable even with image guidance.…”

Evaluation of target and cardiac position during visually monitored deep inspiration breath‐hold for breast radiotherapy

“…Mean heart shifts of 13 mm between FB and DIBH in the μ direction have been previously reported. (8) Therefore, the expected change in MHD between FB and DIBH is on the order of 10 mm. The clinical implications of a small portion of the heart entering the primary beam as measured on a cine image are unknown; (5) however, we found that larger (> 10 mm) in-treatment MHD measurements were uncommon, and were most likely in patients where a portion of the heart was planned in the field.…”

“…MHD measurements on the DRRs were consistently smaller than in the cine images due to known differences between heart identification in projected CT contours and the pericardial shadow on MV portal images. (8) For this reason, planned and treatment MHDs were not directly compared, except in examining the correlation between CW positioning errors and MHD differences from planning. We found that chest wall displacement from the planned position was not predictive of increased MHD during treatment.…”

“…There are numerous commercial methods of implementing DIBH including spirometry, (8) external markers, (9) and optical surface monitoring; (10) however, widescale implementation of these technologies can be resource intensive. It has been estimated that breast cancer radiotherapy represents approximately one-third of all work in radiation oncology, (11) and slightly over half of breast cancer patients have left-sided breast cancer.…”