Proton therapy is currently on the rise and is thus considered for treating lung cancer patients. The majority of proton therapy patients are currently being treated with passive scattered proton therapy. As newer facilities are being designed for pencil beam scanning only and existing facilities are upgrading towards beam scanning, it can be expected that beam scanning will be the method of choice in the future. Dosimetric effects of motion are potentially more severe in proton therapy than in conventional therapy due to the sharp distal dose fall-off. Furthermore, proton beam scanning can cause interplay effects between pencil beam motion and target motion. Before beam scanning can be used clinically for lung treatments it is mandatory that we understand dosimetric effects when treating moving targets with a time-dependent delivery system. This study needs to be done now, before beam scanning becomes established! Consequently, we propose to apply four-dimensional Monte Carlo to study potential interplay effects between pencil beam motion and target motion when treating moving targets with proton beam scanning. We expect that there could be under-dosage of the tumor or dose changes in organs at risk in excess of 30% depending on motion parameters and beam delivery parameters. Thus, for certain delivery and motion parameters, proton beam scanning might not be used (not even with gated delivery) instead of standard passive scattered proton beam therapy. The impact of interplay effects can be influenced by varying beam delivery parameters, e.g. pencil beam spot size, re-painting strategy, etc. We also propose to study the biological impact of scanned beam delivery with high local dose rate.

Public Health Relevance

Proton therapy is currently on the rise and is thus considered for treating lung cancer. However, proton beam scanning can cause interplay effects between pencil beam motion and target motion. Before beam scanning can be used clinically for lung treatments it is mandatory that we understand dosimetric effects when treating moving targets with a time-dependent delivery system. This study needs to be done now, before beam scanning becomes clinically established! Consequently, we propose to apply four-dimensional Monte Carlo to study potential interplay effects between pencil beam motion and target motion when treating moving targets with proton beam scanning.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
5R01CA111590-08
Application #
8657827
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Deye, James
Project Start
Project End
Budget Start
Budget End
Support Year
8
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02199
Grassberger, Clemens; Dowdell, Stephen; Sharp, Greg et al. (2015) Motion mitigation for lung cancer patients treated with active scanning proton therapy. Med Phys 42:2462-9
Grassberger, C; Lomax, Anthony; Paganetti, H (2015) Characterizing a proton beam scanning system for Monte Carlo dose calculation in patients. Phys Med Biol 60:633-45
Phillips, Justin; Gueorguiev, Gueorgui; Shackleford, James A et al. (2014) Computing proton dose to irregularly moving targets. Phys Med Biol 59:4261-73
Grassberger, Clemens; Daartz, Juliane; Dowdell, Stephen et al. (2014) Quantification of proton dose calculation accuracy in the lung. Int J Radiat Oncol Biol Phys 89:424-30
Dowdell, S; Grassberger, C; Sharp, G C et al. (2013) Interplay effects in proton scanning for lung: a 4D Monte Carlo study assessing the impact of tumor and beam delivery parameters. Phys Med Biol 58:4137-56
Grassberger, Clemens; Dowdell, Stephen; Lomax, Antony et al. (2013) Motion interplay as a function of patient parameters and spot size in spot scanning proton therapy for lung cancer. Int J Radiat Oncol Biol Phys 86:380-6
Dowdell, Stephen; Grassberger, Clemens; Paganetti, Harald (2013) Four-dimensional Monte Carlo simulations demonstrating how the extent of intensity-modulation impacts motion effects in proton therapy lung treatments. Med Phys 40:121713
McGurk, Ross; Seco, Joao; Riboldi, Marco et al. (2010) Extension of the NCAT phantom for the investigation of intra-fraction respiratory motion in IMRT using 4D Monte Carlo. Phys Med Biol 55:1475-90
Nohadani, Omid; Seco, Joao; Martin, Benjamin C et al. (2009) Dosimetry robustness with stochastic optimization. Phys Med Biol 54:3421-32
Seco, Joao; Sharp, Greg C; Wu, Ziji et al. (2008) Dosimetric impact of motion in free-breathing and gated lung radiotherapy: a 4D Monte Carlo study of intrafraction and interfraction effects. Med Phys 35:356-66

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