Premium
Quantifying lateral tissue heterogeneities in hadron therapy
Author(s) -
Pflugfelder D.,
Wilkens J. J.,
Szymanowski H.,
Oelfke U.
Publication year - 2007
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2710329
Subject(s) - monte carlo method , beam (structure) , dosimetry , sensitivity (control systems) , proton therapy , inverse , pencil (optics) , radiation treatment planning , optics , physics , computer science , algorithm , mathematics , nuclear medicine , radiation therapy , statistics , electronic engineering , radiology , geometry , medicine , engineering
In radiotherapy with scanned particle beams, tissue heterogeneities lateral to the beam direction are problematic in two ways: they pose a challenge to dose calculation algorithms, and they lead to a high sensitivity to setup errors. In order to quantify and avoid these problems, a heterogeneity numberH ias a method to quantify lateral tissue heterogeneities of single beam spot i is introduced. To evaluate this new concept, two kinds of potential errors were investigated for single beam spots: First, the dose calculation error has been obtained by comparing the dose distribution computed by a simple pencil beam algorithm to more accurate Monte Carlo simulations. The resulting error is clearly correlated withH i . Second, the analysis of the sensitivity to setup errors of single beam spots also showed a dependence onH i . From this data it is concluded thatH ican be used as a criterion to assess the risks of a compromised delivered dose due to lateral tissue heterogeneities. Furthermore, a method how to incorporate this information into the inverse planning process for intensity modulated proton therapy is presented. By suppressing beam spots with a high value ofH i , the unfavorable impact of lateral tissue heterogeneities can be reduced, leading to treatment plans which are more robust to dose calculation errors of the pencil beam algorithm. Additional possibilities to use the information ofH iare outlined in the discussion.