Monte Carlo and Lambertian light guide models of the light output from scintillation crystals at megavoltage energies

Evans, Philip M; Mosleh-Shirazi, M Amin; Harris, Emma J; Seco, Joao

doi:10.1118/1.2199597

Title: Monte Carlo and Lambertian light guide models of the light output from scintillation crystals at megavoltage energies

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Abstract

A new model of the light output from single-crystal scintillators in megavoltage energy x-ray beams has been developed, based on the concept of a Lambertian light guide model (LLG). This was evaluated in comparison with a Monte Carlo (MC) model of optical photon transport, previously developed and reported in the literature, which was used as a gold standard. The LLG model was developed to enable optimization of scintillator detector design. In both models the dose deposition and light propagation were decoupled, the scintillators were cuboids, split into a series of cells as a function of depth, with Lambertian side and entrance faces, and a specular exit face. The signal in a sensor placed 1 and 1000 mm beyond the exit face was calculated. Cesium iodide (CSI) crystals of 1.5 and 3 mm square cross section and 1, 5, and 10 mm depth were modeled. Both models were also used to determine detector signal and optical gain factor as a function of CsI scintillator thickness, from 2 to 10 mm. Results showed a variation in light output with position of dose deposition of a factor of up to approximately 5, for long, thin scintillators (such as 10x1.5x1.5 mm{sup 3}). For short,more »« less

Authors:

Evans, Philip M; Mosleh-Shirazi, M Amin; Harris, Emma J; Seco, Joao ^[1]

Joint Physics Department, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Downs Road, Sutton, Surrey, SM2 5PT (United Kingdom)

Publication Date:: Thu Jun 15 00:00:00 EDT 2006

OSTI Identifier:: 20853192

Resource Type:: Journal Article

Journal Name:: Medical Physics

Additional Journal Information:: Journal Volume: 33; Journal Issue: 6; Other Information: DOI: 10.1118/1.2199597; (c) 2006 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405

Country of Publication:: United States

Language:: English

Subject:: 61 RADIATION PROTECTION AND DOSIMETRY; CESIUM IODIDES; CROSS SECTIONS; DOSEMETERS; LIGHT TRANSMISSION; MONOCRYSTALS; MONTE CARLO METHOD; OPTICAL FIBERS; OPTIMIZATION; PARAMETRIC ANALYSIS; PHOTON TRANSPORT; QUANTUM EFFICIENCY; SCINTILLATIONS; SOLID SCINTILLATION DETECTORS

Citation Formats


                    Evans, Philip M, Mosleh-Shirazi, M Amin, Harris, Emma J, and Seco, Joao. Monte Carlo and Lambertian light guide models of the light output from scintillation crystals at megavoltage energies.  United States: N. p., 2006. 
        Web.  doi:10.1118/1.2199597.

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                    Evans, Philip M, Mosleh-Shirazi, M Amin, Harris, Emma J, & Seco, Joao. Monte Carlo and Lambertian light guide models of the light output from scintillation crystals at megavoltage energies.  United States.  https://doi.org/10.1118/1.2199597

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                    Evans, Philip M, Mosleh-Shirazi, M Amin, Harris, Emma J, and Seco, Joao. 2006.  
        "Monte Carlo and Lambertian light guide models of the light output from scintillation crystals at megavoltage energies".  United States.  https://doi.org/10.1118/1.2199597.

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@article{osti_20853192,

  title        = {Monte Carlo and Lambertian light guide models of the light output from scintillation crystals at megavoltage energies},

  author       = {Evans, Philip M and Mosleh-Shirazi, M Amin and Harris, Emma J and Seco, Joao},

  abstractNote = {A new model of the light output from single-crystal scintillators in megavoltage energy x-ray beams has been developed, based on the concept of a Lambertian light guide model (LLG). This was evaluated in comparison with a Monte Carlo (MC) model of optical photon transport, previously developed and reported in the literature, which was used as a gold standard. The LLG model was developed to enable optimization of scintillator detector design. In both models the dose deposition and light propagation were decoupled, the scintillators were cuboids, split into a series of cells as a function of depth, with Lambertian side and entrance faces, and a specular exit face. The signal in a sensor placed 1 and 1000 mm beyond the exit face was calculated. Cesium iodide (CSI) crystals of 1.5 and 3 mm square cross section and 1, 5, and 10 mm depth were modeled. Both models were also used to determine detector signal and optical gain factor as a function of CsI scintillator thickness, from 2 to 10 mm. Results showed a variation in light output with position of dose deposition of a factor of up to approximately 5, for long, thin scintillators (such as 10x1.5x1.5 mm{sup 3}). For short, fat scintillators (such as 1x3x3 mm{sup 3}) the light output was more uniform with depth. MC and LLG generally agreed to within 5%. Results for a sensor distance of 1 mm showed an increase in light output the closer the light originates to the exit face, while a distance of 1000 mm showed a decrease in light output the closer the light originates to the exit face. For a sensor distance of 1 mm, the ratio of signal for a 10 mm scintillator to that for a 2 mm scintillator was 1.98, whereas for the 1000 mm distance the ratio was 3.00. The ratio of quantum efficiency (QE) between 10 and 2 mm thicknesses was 4.62. We conclude that these models may be used for detector optimization, with the light guide model suitable for parametric study.},

  doi          = {10.1118/1.2199597},

  url          = {https://www.osti.gov/biblio/20853192},
  journal      = {Medical Physics},

  issn         = {0094-2405},

  number       = 6,

  volume       = 33,

  place        = {United States},

  year         = {Thu Jun 15 00:00:00 EDT 2006},

  month        = {Thu Jun 15 00:00:00 EDT 2006}

}

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