Extending the linear-quadratic model for large fraction doses pertinent to stereotactic radiotherapy. Phys Med Biol 2004 Oct 21;49(20):4825-35
Date
11/30/2004Pubmed ID
15566178DOI
10.1088/0031-9155/49/20/012Scopus ID
2-s2.0-7244258926 (requires institutional sign-in at Scopus site) 272 CitationsAbstract
Ongoing clinical trials designed to explore the use of extracranial stereotactic radiosurgery (ESR) for different tumour sites use large doses per fraction (15, 20, 30 Gy or even larger). The question of whether the linear-quadratic (LQ) model is appropriate to describe radiation response for such large fraction doses has been raised and has not been answered definitively. It has been proposed that mechanism-based models, such as the lethal-potentially lethal (LPL) model, could be more appropriate for such large fraction/acute doses. However, such models are not well characterized with clinical data and they are generally not easy to use. The purpose of this work is to modify the LQ model to more accurately describe radiation response for high fraction/acute doses. A new parameter is introduced in the modified LQ (MLQ) model. The new parameter introduced is characterized based both on in vitro cell survival data of several human tumour cell lines and in vivo animal iso-effect curves. The MLQ model produces a better fit to the iso-effect data than the LQ model. For a high single dose irradiation, the prediction of the MLQ is consistent with that from the LPL model. Unlike the LPL model, the MLQ model retains the simplicity of the LQ model and uses the well-characterized alpha and beta parameters. This work indicates that the standard LQ model can lead to erroneous results when used to calculate iso-effects with large fraction doses, such as those used for ESR. We present a solution to this problem.
Author List
Guerrero M, Li XAMESH terms used to index this publication - Major topics in bold
AnimalsBody Burden
Cell Proliferation
Cell Survival
Computer Simulation
Dose-Response Relationship, Radiation
Humans
Linear Models
Mice
Models, Biological
Neoplasms
Organ Specificity
Radiosurgery
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted
Radiotherapy, Computer-Assisted
Rats
Reproducibility of Results
Sensitivity and Specificity
Treatment Outcome
Tumor Stem Cell Assay