Voluntary breath-holding for breast cancer radiotherapy is consistent and stable.
OBJECTIVE
To evaluate breath-hold stability and constancy for a voluntary breath-hold (VBH) technique in a retrospective analysis.


METHODS
Movie loop sequences of electronic portal image data from multiple breath holds in a cohort of 19 patients were used to assess within and between breath-hold stability. In vivo dosimetry data based on electronic portal imaging (EPI) were analysed for 31 VBH patients plus a cohort of free-breathing (FB) patients to provide a reference. A phantom experiment simulated the impact on dose of FB, breath hold and unplanned release of breath hold.


RESULTS
165/174 (93%) movie loop data sets had no detectable displacement. For the remaining 12, median displacement = 1.5 mm and maximum displacement = 3 mm (one patient on one fraction). In vivo dosimetry data analysis showed a median dose difference measured to planned of -0.2% (VBH) and -0.1% (FB). Dose distribution evaluation (γ) pass rates were 84% (VBH) and 91% (FB) including the lung region; 93% and 96% with a lung override. Unplanned release of phantom breath-hold position changed median dose by ≤1% and degraded γ pass rates to 79-62%. Failing regions were mostly in the periphery of the treated volume.


CONCLUSIONS
The data confirmed that multiple VBHs using visual monitoring are stable; in vivo dose verification via EPI was within expected and acceptable levels.


CONCLUSIONS
These data provide further reassurance that VBH is a safe technique for cardiac sparing breast radiotherapy and support its rapid, widespread implementation.
1 Physics Department, The Royal Marsden NHS Foundation Trust, Sutton, UK.
Ruth
R
Colgan
1 Physics Department, The Royal Marsden NHS Foundation Trust, Sutton, UK.
Matthew
M
James
2 Southampton Oncology Centre, University Hospital Southampton NHS Foundation Trust, Southampton, UK.
Frederick R
FR
Bartlett
3 Department of Radiotherapy, The Royal Marsden NHS Foundation Trust, Sutton, UK.
Anna M
AM
Kirby
1 Physics Department, The Royal Marsden NHS Foundation Trust, Sutton, UK.
Ellen M
EM
Donovan
D001943:Breast Neoplasms / Q000532:radiotherapy*; D062485:Breath Holding; D015331:Cohort Studies; D005260:Female; D006801:Humans; D019047:Phantoms, Imaging; D011879:Radiotherapy Dosage; D012119:Respiration; D012189:Retrospective Studies; D014743:Videotape Recording