Determination of monitor unit check tolerances based on a comparison with measurement and treatment planning system data.
Med Dosim
; 38(1): 81-7, 2013.
Article
en En
| MEDLINE
| ID: mdl-23219518
ABSTRACT
This work describes the experimental validation of treatment planning system monitor unit (MU) calculations against measurement for a range of scenarios. This, together with a comparison of treatment planning system MUs and an independent MU check method, allows the derivation of confidence intervals for the check process. Data were collected for open and 60° motorized wedge fields using an Elekta Synergy linac at 6 and 8MV using homogeneous and heterogeneous phantoms. Masterplan (Version 4.0) pencil-beam and collapsed cone algorithms were used for the primary MU calculations with full inhomogeneity correction. Results show that both algorithms agree with measurement to acceptable tolerance levels in the majority of the cases studied. The confidence interval for the pencil-beam algorithm MU against an independent check was determined as + 1.6% to -3.4%. This is modified to + 2.3% to -2.5% when data collected with low-density heterogeneities are removed as this algorithm is not used clinically for these cases. The corresponding interval for the collapsed cone algorithm was + 1.2% to -4.3%, indicating that an offset tolerance for the independent check is appropriate. Analysis of clinical conformal treatment plan data generated using the pencil-beam algorithm (1393 beams) returned 93% of beams within the independent check tolerance. Similarly, using the collapsed cone algorithm as the primary MU calculation, 77% (of 1434 beams) were within the confidence interval.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Radiometría
/
Algoritmos
/
Planificación de la Radioterapia Asistida por Computador
/
Radioterapia Conformacional
Tipo de estudio:
Diagnostic_studies
/
Evaluation_studies
Idioma:
En
Revista:
Med Dosim
Asunto de la revista:
RADIOTERAPIA
Año:
2013
Tipo del documento:
Article
País de afiliación:
Reino Unido