Intrafraction motion monitoring to determine PTV margins in early stage breast cancer patients receiving neoadjuvant partial breast SABR

Matthew Mouawad; Owen Lailey; Per Poulsen; Melissa O'Neil; Muriel Brackstone; Michael Lock; Brian Yaremko; Olga Shmuilovich; Anat Kornecki; Ilanit Ben Nachum; Giulio Muscedere; Kalan Lynn; Scott Karnas; Frank S Prato; R Terry Thompson; Stewart Gaede

doi:10.1016/j.radonc.2021.02.021

Intrafraction motion monitoring to determine PTV margins in early stage breast cancer patients receiving neoadjuvant partial breast SABR

Radiother Oncol. 2021 May:158:276-284. doi: 10.1016/j.radonc.2021.02.021. Epub 2021 Feb 24.

Authors

Matthew Mouawad¹, Owen Lailey², Per Poulsen³, Melissa O'Neil⁴, Muriel Brackstone⁵, Michael Lock⁶, Brian Yaremko⁷, Olga Shmuilovich⁸, Anat Kornecki⁹, Ilanit Ben Nachum¹⁰, Giulio Muscedere¹¹, Kalan Lynn¹², Scott Karnas¹³, Frank S Prato¹⁴, R Terry Thompson¹⁵, Stewart Gaede¹⁶

Affiliations

¹ Medical Biophysics, Western University, London, Canada; London Health Sciences Centre, London, Canada. Electronic address: mmouawad@uwo.ca.
² London Health Sciences Centre, London, Canada.
³ Danish Center for Particle Therapy and Department of Oncology, Aarhus University Hospital, Denmark. Electronic address: per.poulsen@rm.dk.
⁴ London Health Sciences Centre, London, Canada. Electronic address: melissa.ONeil@lhsc.on.ca.
⁵ Medical Biophysics, Western University, London, Canada; London Health Sciences Centre, London, Canada; Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada. Electronic address: Muriel.Brackstone@lhsc.on.ca.
⁶ London Health Sciences Centre, London, Canada; Department of Oncology, Western University, London, Canada. Electronic address: Michael.Lock@lhsc.on.ca.
⁷ London Health Sciences Centre, London, Canada; Department of Oncology, Western University, London, Canada. Electronic address: Brian.Yaremko@lhsc.on.ca.
⁸ Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada; Department of Medical Imaging, Western University, London, Canada. Electronic address: Olga.Shmuilovich@lhsc.on.ca.
⁹ Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada; Department of Medical Imaging, Western University, London, Canada. Electronic address: Anat.Kornecki@sjhc.london.on.ca.
¹⁰ Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada; Department of Medical Imaging, Western University, London, Canada. Electronic address: Ilanit.BenNachum@sjhc.london.on.ca.
¹¹ Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada; Department of Medical Imaging, Western University, London, Canada. Electronic address: Giulio.Muscedere@sjhc.london.on.ca.
¹² London Health Sciences Centre, London, Canada; Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada. Electronic address: Kalan.Lynn@lhsc.on.ca.
¹³ London Health Sciences Centre, London, Canada. Electronic address: Scott.Karnas@lhsc.on.ca.
¹⁴ Medical Biophysics, Western University, London, Canada; Lawson Health Research Institute, London, Canada; St. Joseph's Health Care, London, Canada; Department of Medical Imaging, Western University, London, Canada. Electronic address: prato@lawsonimaging.ca.
¹⁵ Medical Biophysics, Western University, London, Canada; Lawson Health Research Institute, London, Canada. Electronic address: thompson@lawsonimaging.ca.
¹⁶ Medical Biophysics, Western University, London, Canada; London Health Sciences Centre, London, Canada; Lawson Health Research Institute, London, Canada; Department of Oncology, Western University, London, Canada. Electronic address: Stewart.Gaede@lhsc.on.ca.

PMID: 33636230
DOI: 10.1016/j.radonc.2021.02.021

Abstract

Background and purpose: To quantify intra-fraction tumor motion using imageguidance and implanted fiducial markers to determine if a 5 mm planning-target-volume (PTV) margin is sufficient for early stage breast cancer patients receiving neoadjuvant stereotactic ablative radiotherapy (SABR).

Materials and methods: A HydroMark© (Mammotome) fiducial was implanted at the time of biopsy adjacent to the tumor. Sixty-one patients with 62 tumours were treated prone using a 5 mm PTV margin. Motion was quantified using two methods (separate patient groups): 1) difference in 3D fiducial position pre- and post-treatment cone-beam CTs (CBCTs) in 18 patients receiving 21 Gy/1fraction (fx); 2) acquiring 2D triggered-kVimages to quantify 3D intra-fraction motion using a 2D-to-3D estimation method for 44 tumours receiving 21 Gy/1fx (n = 22) or 30 Gy/3fx (n = 22). For 2), motion was quantified by calculating the magnitude of intra-fraction positional deviation from the pretreatment CBCT. PTV margins were derived using van Herkian analysis.

Results: The average ± standard deviation magnitude of motion across patients was 1.3 ± 1.15 mm Left/Right (L/R), 1.0 ± 0.9 mm Inferiorly/Superiorly (I/S), and 1.8 ± 1.5 mm Anteriorly/Posteriorly (A/P). 85/105 (81%) treatment fractions had dominant anterior motion. 6/62patients (9.7%) had mean intra-fraction motion during any fraction > 5 mm in any direction, with 4 in the anterior direction. Estimated PTV margins for single and three-fx patients in the L/R, I/S, and A/P directions were 6.0x4.1x5.9 mm and 4.5x2.9x4.3 mm, respectively.

Conclusion: Our results suggest that a 5 mm PTV margin is sufficient for the I/S and A/P directions if a lateral kV image is acquired immediately before treatment. For the L/R direction, either further immobilization or a larger margin is required.

Keywords: Breast cancer; Intra-fraction motion; PTV; SABR; Triggered Imaging; Van Herk.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Breast Neoplasms* / diagnostic imaging
Breast Neoplasms* / radiotherapy
Breast Neoplasms* / surgery
Cone-Beam Computed Tomography
Fiducial Markers
Humans
Neoadjuvant Therapy
Radiosurgery*
Radiotherapy Planning, Computer-Assisted
Radiotherapy, Image-Guided*

Grants and funding

149080/CIHR/Canada