Articles producció científica> Ciències Mèdiques Bàsiques

Dosimetric leaf gap and leaf trailing effect in a double-stacked multileaf collimator

  • Dades identificatives

    Identificador: imarina:9334293
    Autors:
    Hernandez, VSaez, JAngerud, ACayez, RKhamphan, CNguyen, DVieillevigne, LFeygelman, V
    Resum:
    Purpose To investigate (i) the dosimetric leaf gap (DLG) and the effect of the "trailing distance" between leaves from different multileaf collimator (MLC) layers in Halcyon systems and (ii) the ability of the currently available treatment planning systems (TPSs) to approximate this effect.Methods DICOM plans with transmission beams and sweeping gap tests were created in Python for measuring the DLG for each MLC layer independently and for both layers combined. In clinical Halcyon plans both MLC layers are interchangeably used and leaves from different layers are offset, thus forming a trailing pattern. To characterize the impact of such configuration, new tests called "trailing sweeping gaps" were designed and created where the leaves from one layer follow the leaves from the other layer at a fixed "trailing distance" t between the tips. Measurements were carried out on five Halcyons SX2 from different institutions and calculations from both the Eclipse and RayStation TPSs were compared with measurements.Results The dose accumulated during a sweeping gap delivery progressively increased with the trailing distance t. We call this "the trailing effect." It is most pronounced for t between 0 and 5 mm, although some changes were obtained up to 20 mm. The dose variation was independent of the gap size. The measured DLG values also increased with t up to 20 mm, again with the steepest variation between 0 and 5 mm. Measured DLG values were negative at t = 0 (the leaves from both layers at the same position) but changed sign for t >= 1 mm, in line with the positive DLG sign usually observed with single-layer rounded-end MLCs. The Eclipse TPS does not explicitly model the leaf tip and, as a consequence, could not predict the dose reduction due to the trailing effect. This resul
  • Altres:

    Autor segons l'article: Hernandez, V; Saez, J; Angerud, A; Cayez, R; Khamphan, C; Nguyen, D; Vieillevigne, L; Feygelman, V
    Departament: Ciències Mèdiques Bàsiques
    Autor/s de la URV: Hernandez Masgrau, Victor
    Paraules clau: Transmission Trailing effect System Stacked mlc Radiotherapy, intensity-modulated Radiotherapy planning, computer-assisted Radiotherapy dosage Radiometry Plant leaves Mlc model Halcyon Dosimetric leaf gap
    Resum: Purpose To investigate (i) the dosimetric leaf gap (DLG) and the effect of the "trailing distance" between leaves from different multileaf collimator (MLC) layers in Halcyon systems and (ii) the ability of the currently available treatment planning systems (TPSs) to approximate this effect.Methods DICOM plans with transmission beams and sweeping gap tests were created in Python for measuring the DLG for each MLC layer independently and for both layers combined. In clinical Halcyon plans both MLC layers are interchangeably used and leaves from different layers are offset, thus forming a trailing pattern. To characterize the impact of such configuration, new tests called "trailing sweeping gaps" were designed and created where the leaves from one layer follow the leaves from the other layer at a fixed "trailing distance" t between the tips. Measurements were carried out on five Halcyons SX2 from different institutions and calculations from both the Eclipse and RayStation TPSs were compared with measurements.Results The dose accumulated during a sweeping gap delivery progressively increased with the trailing distance t. We call this "the trailing effect." It is most pronounced for t between 0 and 5 mm, although some changes were obtained up to 20 mm. The dose variation was independent of the gap size. The measured DLG values also increased with t up to 20 mm, again with the steepest variation between 0 and 5 mm. Measured DLG values were negative at t = 0 (the leaves from both layers at the same position) but changed sign for t >= 1 mm, in line with the positive DLG sign usually observed with single-layer rounded-end MLCs. The Eclipse TPS does not explicitly model the leaf tip and, as a consequence, could not predict the dose reduction due to the trailing effect. This resulted in dose discrepancies up to +10% and -8% for the 5 mm sweeping gap and up to +/- 5% for the 10 mm one depending on the distance t. RayStation implements a simple model of the leaf tip that was able to approximate the trailing effect and improved the agreement with measured doses. In particular, with a prototype version of RayStation that assigned a higher transmission at the leaf tip the agreement with measured doses was within +/- 3% even for the 5 mm gap. The five Halcyon systems behaved very similarly but differences in the DLG around 0.2 mm were found across different treatment units and between MLC layers from the same system. The DLG for the proximal layer was consistently higher than for the distal layer, with differences ranging between 0.10 mm and 0.24 mm.Conclusions The trailing distance between the leaves from different layers substantially affected the doses delivered by sweeping gaps and the measured DLG values. Stacked MLCs introduce a new level of complexity in TPSs, which ideally need to implement an explicit model of the leaf tip in order to reproduce the trailing effect. Dynamic tests called "trailing sweeping gaps" were designed that are useful for characterizing and commissioning dual-layer MLC systems.
    Àrees temàtiques: Radiology, nuclear medicine and imaging Radiology, nuclear medicine & medical imaging Medicine (miscellaneous) Medicina ii Medicina i Interdisciplinar General medicine Engenharias iv Engenharias ii Ciências biológicas iii Ciências biológicas ii Ciências biológicas i Ciência da computação Biotecnología Biophysics Astronomia / física Antropologia / arqueologia
    Accès a la llicència d'ús: https://creativecommons.org/licenses/by/3.0/es/
    Adreça de correu electrònic de l'autor: victor.hernandez@urv.cat
    Identificador de l'autor: 0000-0003-3770-8486
    Data d'alta del registre: 2024-07-27
    Versió de l'article dipositat: info:eu-repo/semantics/acceptedVersion
    Enllaç font original: https://aapm.onlinelibrary.wiley.com/doi/full/10.1002/mp.14914
    URL Document de llicència: https://repositori.urv.cat/ca/proteccio-de-dades/
    Referència a l'article segons font original: Medical Physics. 48 (7): 3413-3424
    Referència de l'ítem segons les normes APA: Hernandez, V; Saez, J; Angerud, A; Cayez, R; Khamphan, C; Nguyen, D; Vieillevigne, L; Feygelman, V (2021). Dosimetric leaf gap and leaf trailing effect in a double-stacked multileaf collimator. Medical Physics, 48(7), 3413-3424. DOI: 10.1002/mp.14914
    DOI de l'article: 10.1002/mp.14914
    Entitat: Universitat Rovira i Virgili
    Any de publicació de la revista: 2021
    Tipus de publicació: Journal Publications
  • Paraules clau:

    Biophysics,Medicine (Miscellaneous),Radiology, Nuclear Medicine & Medical Imaging,Radiology, Nuclear Medicine and Imaging
    Transmission
    Trailing effect
    System
    Stacked mlc
    Radiotherapy, intensity-modulated
    Radiotherapy planning, computer-assisted
    Radiotherapy dosage
    Radiometry
    Plant leaves
    Mlc model
    Halcyon
    Dosimetric leaf gap
    Radiology, nuclear medicine and imaging
    Radiology, nuclear medicine & medical imaging
    Medicine (miscellaneous)
    Medicina ii
    Medicina i
    Interdisciplinar
    General medicine
    Engenharias iv
    Engenharias ii
    Ciências biológicas iii
    Ciências biológicas ii
    Ciências biológicas i
    Ciência da computação
    Biotecnología
    Biophysics
    Astronomia / física
    Antropologia / arqueologia
  • Documents:

  • Cerca a google

    Search to google scholar