Performance of a commercial Macro Monte Carlo dose calculation algorithm for determining output factors of clinical electron fields.
Technol Cancer Res Treat
; 8(4): 307-14, 2009 Aug.
Article
em En
| MEDLINE
| ID: mdl-19645523
ABSTRACT
We compare measured output factors of clinical electron fields to those calculated by a commercial treatment planning system based on an electron Monte Carlo algorithm. The measured data is comprised of 195 fields with energies 6 to 18 MeV, applicator sizes 6 x 6 cm(2) to 25 x 25 cm(2), and source to surface distances (SSDs) of 97 to 107 cm. Due to a scarcity of clinical fields for the highest energies and the largest applicator sizes, additional measurements were made at arbitrarily chosen large field sizes at previously not used energies, for a total of 223 output factors. The difference between calculation and measurement ranged from -2.9% to 3.9%, with a mean difference of -0.2%. Half of the field shapes had a difference with magnitude less than 0.8%. Only 7 (3%) of the field shapes were outliers, having differences greater than 2%. All outliers had field widths at the normalization point < 3.5 cm, were applied at SSDs > 100 cm, were inserts for the 25 _ 25 cm(2) applicator, or had more than one of these characteristics. For narrow and elongated fields the TPS slightly overestimated output factors, whereas for field shapes with aspect ratio close to 1 the TPS slightly underestimated the output factors. No strong dependence of the difference on energy was observed.
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Base de dados:
MEDLINE
Assunto principal:
Planejamento da Radioterapia Assistida por Computador
/
Método de Monte Carlo
/
Elétrons
Tipo de estudo:
Health_economic_evaluation
/
Prognostic_studies
Limite:
Humans
Idioma:
En
Ano de publicação:
2009
Tipo de documento:
Article