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

Annie Xiao,Jennie Crosby,Martha Malin,Steven J Chmura,Yasmin Hasan,Hyejoo Kang,Maxine Washington,Hania A Al‐Hallaq

doi:10.1002/acm2.12368

Annie Xiao, Jennie Crosby + Show 6 more

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https://doi.org/10.1002/acm2.12368

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Abstract

PurposeWe calculated setup margins for whole breast radiotherapy during voluntary deep‐inspiration breath‐hold (vDIBH) using real‐time surface imaging (SI).Methods and MaterialsPatients (n = 58) with a 27‐to‐31 split between right‐ and left‐sided cancers were analyzed. Treatment beams were gated using AlignRT by registering the whole breast region‐of‐interest to the surface generated from the simulation CT scan. AlignRT recorded (three‐dimensional) 3D displacements and the beam‐on‐state every 0.3 s. Means and standard deviations of the displacements during vDIBH for each fraction were used to calculate setup margins. Intra‐DIBH stability and the intrafraction reproducibility were estimated from the medians of the 5th to 95th percentile range of the translations in each breath‐hold and fraction, respectively.ResultsA total of 7269 breath‐holds were detected over 1305 fractions in which a median dose of 200 cGy was delivered. Each fraction was monitored for 5.95 ± 2.44 min. Calculated setup margins were 4.8 mm (A/P), 4.9 mm (S/I), and 6.4 mm (L/R). The intra‐DIBH stability and the intrafraction reproducibility were ≤0.7 mm and ≤2.2 mm, respectively. The isotropic margin according to SI (9.2 mm) was comparable to other institutions’ calculations that relied on x‐ray imaging and/or spirometry for patients with left‐sided cancer (9.8–11.0 mm). Likewise, intra‐DIBH variability and intrafraction reproducibility of breast surface measured with SI agreed with spirometry‐based positioning to within 1.2 and 0.36 mm, respectively.ConclusionsWe demonstrated that intra‐DIBH variability, intrafraction reproducibility, and setup margins are similar to those reported by peer studies who utilized spirometry‐based positioning.

Highlights

Adjuvant whole breast radiotherapy (WBRT) following lumpectomy improves local control and in some populations overall survival in the treatment of invasive breast cancer.[1,2] collateral toxicities to the heart and lungs remain a significant challenge.[3,4] Deep-inspiration breath-hold (DIBH) harnesses the advantage of organ motion during the respiratory cycle to minimize overlap of the heart and lungs with the treatment fields.[5]
Alderliesten et al.[13] compared voluntary DIBH (vDIBH) setup errors quantified by surface imaging (SI) to daily cone-beam CT (CBCT) for left-sided breast cancer patients; combining these errors using Eq (1) yields setup margins of 4.6 mm (A/P), 4.8 mm (S/I), and 5.2 (L/R), which are comparable to our results in a setup margin of 4.8 mm (A/P) (4.9 mm) and S/I (4.7 mm) but not in L/R (6.2 mm)
When comparing intra-DIBH and intrafraction variability in the breast surface achieved by vDIBH to Fassi et al.[9], we found slightly better intra-DIBH stability in vDIBH over spirometric-DIBH, and comparable intrafraction reproducibility regardless of breathhold technique indicating that vDIBH measures up to spirometry

Summary

Introduction

Adjuvant whole breast radiotherapy (WBRT) following lumpectomy improves local control and in some populations overall survival in the treatment of invasive breast cancer.[1,2] collateral toxicities to the heart and lungs remain a significant challenge.[3,4] Deep-inspiration breath-hold (DIBH) harnesses the advantage of organ motion during the respiratory cycle to minimize overlap of the heart and lungs with the treatment fields.[5]. Surface imaging has the added benefit of being noninvasive and voluntary

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