Relative biological effectiveness (RBE) and out-of-field cell survival responses to passive scattering and pencil beam scanning proton beam deliveries

Authors

Karl T. Butterworth, Queen's University of BelfastFollow
Conor K. Mcgarry, Queen's University of Belfast,Belfast Health and Social Care Trust
Ben Clasie, Massachusetts General Hospital,Harvard Medical School, Boston
Alejandro Carabe-Fernandez, Massachusetts General Hospital,Harvard Medical School, Boston
Jan Schuemann, Massachusetts General Hospital,Harvard Medical School, Boston
Nicolas Depauw, University of WollongongFollow
Shikui Tang, Harvard Medical School, Boston,Massachusetts General Hospital
Stephen J. Mcmahon, Queen's University of Belfast
Giuseppe Schettino, Queen's University of Belfast
Joe M. O'Sullivan, Belfast Health and Social Care Trust
Hsaio-Ming Lu, Harvard Medical School, Boston,Massachusetts General HospitalFollow
Hanne Kooy, Massachusetts General Hospital
Harald Paganetti, Massachusetts General Hospital
Alan R. Hounsell, Queen's University of Belfast,Belfast Health and Social Care Trust
Kathryn D. Held, Massachusetts General Hospital,Harvard Medical School, Boston
Kevin M. Prise, Queen's University of Belfast

RIS ID

68817

Publication Details

Butterworth, K. T., Mcgarry, C. K., Clasie, B., Carabe-Fernandez, A., Schuemann, J., Depauw, N., Tang, S., Mcmahon, S. J., Schettino, G., O'Sullivan, J. M., Lu, H., Kooy, H., Paganetti, H., Hounsell, A. R., Held, K. D. & Prise, K. M. (2012). Relative biological effectiveness (RBE) and out-of-field cell survival responses to passive scattering and pencil beam scanning proton beam deliveries. Physics in Medicine and Biology, 57 (20), 6671-6680.

Abstract

The relative biological effectiveness (RBE) of passive scattered (PS) and pencil beam scanned (PBS) proton beam delivery techniques for uniform beam configurations was determined by clonogenic survival. The radiobiological impact of modulated beam configurations on cell survival occurring in- or out-of-field for both delivery techniques was determined with intercellular communication intact or physically inhibited. Cell survival responses were compared to those observed using a 6 MV photon beam produced with a linear accelerator. DU-145 cells showed no significant difference in survival response to proton beams delivered by PS and PBS or 6 MV photons taking into account a RBE of 1.1 for protons at the centre of the spread out Bragg peak. Significant out-of-field effects similar to those observed for 6 MV photons were observed for both PS and PBS proton deliveries with cell survival decreasing to 50-60% survival for scattered doses of 0.05 and 0.03 Gy for passive scattered and pencil beam scanned beams respectively. The observed out-of-field responses were shown to be dependent on intercellular communication between the in- and out-of-field cell populations. These data demonstrate, for the first time, a similar RBE between passive and actively scanned proton beams and confirm that out-of-field effects may be important determinants of cell survival following exposure to modulated photon and proton fields.