Respiratory gating for proton beam scanning versus photon 3D-CRT for breast cancer radiotherapy
2016 (English)In: Acta Oncologica, ISSN 0284-186X, E-ISSN 1651-226X, Vol. 55, no 5, 577-583 p.Article in journal (Refereed) Published
Background Respiratory gating and proton therapy have both been proposed to reduce the cardiopulmonary burden in breast cancer radiotherapy. This study aims to investigate the additional benefit of proton radiotherapy for breast cancer with and without respiratory gating.Material and methods Twenty left-sided patients were planned on computed tomography (CT)-datasets acquired during enhanced inspiration gating (EIG) and free-breathing (FB), using photon three-dimensional conformal radiation therapy (3D-CRT) and scanned proton beams. Ten patients received treatment to the whole breast only (WBO) and 10 were treated to the breast and the regional lymph nodes (BRN). Dosimetric parameters characterizing the coverage of target volumes and the cardiopulmonary burden were compared using a paired, two-tailed Student's t-test.Results Protons ensured comparable or better target coverage than photons in all patients during both EIG and FB. The heterogeneity index decreased from 12% with photons to about 5% with protons. The mean dose to the ipsilateral lung was reduced in BRN patients from 12Gy to 7Gy(RBE) in EIG and from 14Gy to 6-7Gy (RBE) in FB, while for WBO patients all values were about 5-6Gy (RBE). The mean dose to heart decreased by a factor of four in WBO patients [from 1.1Gy to 0.3Gy (RBE) in EIG and from 2.1Gy to 0.5Gy (RBE) in FB] and 10 in BRN patients [from 2.1Gy to 0.2Gy (RBE) in EIG and from 3.4Gy to 0.3Gy (RBE) in FB]. Similarly, the mean and the near maximum dose to the left anterior descending artery (LAD) were significantly lower (p<0.05) with protons in comparison with photons.Conclusion Proton spot scanning has a high potential to reduce the irradiation of organs at risk and other normal tissues for most patients, beyond what could be achieved with EIG and photon therapy. The largest dose sparing has been seen for BRN patients, both in terms of cardiopulmonary burden and integral dose.
Place, publisher, year, edition, pages
2016. Vol. 55, no 5, 577-583 p.
Cancer and Oncology
IdentifiersURN: urn:nbn:se:uu:diva-298013DOI: 10.3109/0284186X.2015.1120883ISI: 000375566700008PubMedID: 27027913OAI: oai:DiVA.org:uu-298013DiVA: diva2:1039684