Author, as appears in the article.: Hernandez, V; Vera-Sánchez, JA; Vieillevigne, L; Saez, J
Department: Ciències Mèdiques Bàsiques
URV's Author/s: Hernandez Masgrau, Victor
Keywords: Tps modelling Tps commissioning Tongue and groove Spatial dependence Radiotherapy, intensity-modulated Radiotherapy planning, computer-assisted Radiotherapy dosage Radiometry Quality-assurance Modulated arc therapy Models, biological Mlc transmission Mlc Imrt delivery Humans Dose calculation Calculation algorithm Acuros xb Accuracy Aaa
Abstract: Adequate modelling of the multi-leaf collimator (MLC) by treatment planning systems (TPS) is essential for accurate dose calculations in intensity-modulated radiation-therapy. For this reason modern TPSs incorporate MLC characteristics such as the leaf end curvature, MLC transmission and the tongue-and-groove. However, the modelling of the tongue-and-groove is often neglected during TPS commissioning and it is not known how accurate it is. This study evaluates the dosimetric consequences of the tongue-and-groove effect for two different MLC models using both film dosimetry and ionisation chambers. A set of comprehensive tests are presented that evaluate the ability of TPSs to accurately model this effect in (a) static fields, (b) sliding window beams and (c) VMAT arcs. The tests proposed are useful for the commissioning of TPSs and for the validation of major upgrades. With the ECLIPSE TPS, relevant differences were found between calculations and measurements for beams with dynamic MLCs in the presence of the TG effect, especially for the High Definition MLC, small gap sizes and the 1 mm calculation grid. For this combination, dose differences as high as 10% and 7% were obtained for dynamic MLC gaps of 5 mm and 10 mm, respectively. These differences indicate inadequate modelling of the tongue-and-groove effect, which might not be identified without the proposed tests. In particular, the TPS tended to underestimate the calculated dose, which may require tuning of other configuration parameters in the TPS (such as the dosimetric leaf gap) in order to maximise the agreement between calculations and measurements in clinical plans. In conclusion, a need for better modelling of the MLC by TPSs is demonstrated, one of the relevant aspects being the tongue-and-groove effect. This would improve the accuracy of TPS calculations, especially for plans using small MLC gaps, such as plans with small target volumes or high complexities. Improved modelling of the MLC would also reduce the need for tuning parameters in the TPS, facilitating a more comprehensive configuration and commissioning of TPSs.
Thematic Areas: Saúde coletiva Radiology, nuclear medicine and imaging Radiology, nuclear medicine & medical imaging Radiological and ultrasound technology Psicología Odontología Medicina ii Medicina i Matemática / probabilidade e estatística Interdisciplinar General medicine Engineering, biomedical Engenharias iv Engenharias iii Engenharias ii Ciências biológicas ii Ciências biológicas i Ciência da computação Astronomia / física
licence for use: https://creativecommons.org/licenses/by/3.0/es/
Author's mail: victor.hernandez@urv.cat
Author identifier: 0000-0003-3770-8486
Record's date: 2024-09-07
Papper version: info:eu-repo/semantics/acceptedVersion
Licence document URL: https://repositori.urv.cat/ca/proteccio-de-dades/
Papper original source: Physics In Medicine And Biology. 62 (16): 6688-6707
APA: Hernandez, V; Vera-Sánchez, JA; Vieillevigne, L; Saez, J (2017). Commissioning of the tongue-and-groove modelling in treatment planning systems: from static fields to VMAT treatments. Physics In Medicine And Biology, 62(16), 6688-6707. DOI: 10.1088/1361-6560/aa7b1a
Entity: Universitat Rovira i Virgili
Journal publication year: 2017
Publication Type: Journal Publications
Repositori URV