Sensitivity and specificity of Monte Carlo based independent secondary dose computation for detecting modulation-related dose errors in intensity modulated radiotherapy.
Z Med Phys
; 2023 Oct 25.
Article
en En
| MEDLINE
| ID: mdl-37891103
ABSTRACT
BACKGROUND:
The recent availability of Monte Carlo based independent secondary dose calculation (ISDC) for patient-specific quality assurance (QA) of modulated radiotherapy requires the definition of appropriate, more sensitive action levels, since contemporary recommendations were defined for less accurate ISDC dose algorithms.PURPOSE:
The objective is to establish an optimum action level and measure the efficacy of a Monte Carlo ISDC software for pre-treatment QA of intensity modulated radiotherapy treatments.METHODS:
The treatment planning system and the ISDC were commissioned by their vendors from independent base data sets, replicating a typical real-world scenario. In order to apply Receiver-Operator-Characteristics (ROC), a set of treatment plans for various case classes was created that consisted of 190 clinical treatment plans and 190 manipulated treatment plans with dose errors in the range of 1.5-2.5%. All 380 treatment plans were evaluated with ISDC in the patient geometry. ROC analysis was performed for a number of Gamma (dose-difference/distance-to-agreement) criteria. QA methods were ranked according to Area under the ROC curve (AUC) and optimum action levels were derived via Youden's J statistics.RESULTS:
Overall, for original treatment plans, the mean Gamma pass rate (GPR) for Gamma(1%, 1â¯mm) was close to 90%, although with some variation across case classes. The best QA criterion was Gamma(2%, 1â¯mm) with GPRâ¯>â¯90% and an AUC of 0.928. Gamma criteria with small distance-to-agreement had consistently higher AUC. GPR of original treatment plans depended on their modulation degree. An action level in terms of Gamma(1%, 1â¯mm) GPR that decreases with modulation degree was the most efficient criterion with sensitivityâ¯=â¯0.91 and specificityâ¯=â¯0.95, compared with Gamma(3%, 3â¯mm) GPRâ¯>â¯99%, sensitivityâ¯=â¯0.73 and specificityâ¯=â¯0.91 as a commonly used action level.CONCLUSIONS:
ISDC with Monte Carlo proves highly efficient to catch errors in the treatment planning process. For a Monte Carlo based TPS, dose-difference criteria of 2% or less, and distance-to-agreement criteria of 1â¯mm, achieve the largest AUC in ROC analysis.
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Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
Z Med Phys
Asunto de la revista:
RADIOTERAPIA
Año:
2023
Tipo del documento:
Article