Skin-sparing reduction effects of thermoplastics used for patient immobilization in head and neck radiotherapy

Fiorino, Claudio; Cattaneo, Giovanni Mauro; Vecchio, Antonella Del; Fusca, M.; Longobardi, B.; Signorotto, P.; Calandrino, R.

doi:10.1016/0167-8140(94)90468-5

Cited by 15 publications

(7 citation statements)

References 13 publications

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“…Surface dose increases of 14% to 40% on phantoms under 2 mm of thermoplastic material with 6-MV photons have been reported (18)(19)(20)(21). Lee et al (22) showed that head-and-neck IMRT is not immune to this effect because both conventional and IMRT plans had a mean surface dose increase of 18% for 3-mm thermoplastic masks, an increase sufficient to cause substantial skin reactions.…”

Section: Introductionmentioning

confidence: 96%

Cone-Beam CT Assessment of Interfraction and Intrafraction Setup Error of Two Head-and-Neck Cancer Thermoplastic Masks

Velec

Waldron

O’Sullivan

et al. 2010

International Journal of Radiation Oncology*Biology*Physics

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Section: Introductionmentioning

confidence: 96%

Cone-Beam CT Assessment of Interfraction and Intrafraction Setup Error of Two Head-and-Neck Cancer Thermoplastic Masks

Velec

Waldron

O’Sullivan

et al. 2010

International Journal of Radiation Oncology*Biology*Physics

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“…Several groups have examined the effect of thermoplastic immobilization shells on surface dose for both photons and electrons and have concluded that they can significantly increase skin dose. 29,31,[50][51][52][53][54] Surface dose was found to decrease as the mask material was increasingly stretched which reduced the areal density and mask thickness (and reproducibility). For 6 MV photons, without stretching, the surface dose was 61% compared to 16% without a mask, but with stretching that increased the area of the mask by 125% or 525%, the surface dose changed to 48% or 29%, respectively.…”

Section: B3 Thermoplastic Shellsmentioning

confidence: 99%

Dosimetric effects caused by couch tops and immobilization devices: Report of AAPM Task Group 176

et al. 2014

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The dosimetric impact from devices external to the patient is a complex combination of increased skin dose, reduced tumor dose, and altered dose distribution. Although small monitor unit or dose corrections are routinely made for blocking trays, ion chamber correction factors, e.g., accounting for temperature and pressure, or tissue inhomogeneities, the dose perturbation of the treatment couch top or immobilization devices is often overlooked. These devices also increase skin dose, an effect which is also often ignored or underestimated. These concerns have grown recently due to the increased use of monolithic carbon fiber couch tops which are optimal for imaging for patient position verification but cause attenuation and increased skin dose compared to the "tennis racket" style couch top they often replace. Also, arc delivery techniques have replaced stationary gantry techniques which cause a greater fraction of the dose to be delivered from posterior angles. A host of immobilization devices are available and used to increase patient positioning reproducibility, and these also have attenuation and skin dose implications which are often ignored. This report of Task Group 176 serves to present a survey of published data that illustrates the magnitude of the dosimetric effects of a wide range of devices external to the patient. The report also provides methods for modeling couch tops in treatment planning systems so the physicist can accurately compute the dosimetric effects for indexed patient treatments. Both photon and proton beams are considered. A discussion on avoidance of high density structures during beam planning is also provided. An important aspect of this report are the recommendations the authors make to clinical physicists, treatment planning system vendors, and device vendors on how to make measurements of surface dose and attenuation and how to report these values. For the vendors, an appeal is made to work together to provide accurate couch top models in planning systems.

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“…The use of plastic masks in daily treatment might have a side effect of increasing the surface dose. The published studies reported that the partial reduction of the skin-sparing effect of high energy photon beams is related to the use of thermoplastic masks (3) . The reduction of the sparing effect leads to an increased risk of over-exposure of the skin that might result in acute radiation dermatitis, radiation burns or delayed effects (4) .…”

Section: Introductionmentioning

confidence: 99%

Investigation of surface and buildup region doses for 6 MV high energy photon beams in the presence of a thermoplastic mask

Kesen

Koksal

2020

Int J Radiat Res

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Background:The accuracy and the reproducibility of radiotherapy can be provided by using immobilization devices such as thermoplastic masks. In head and neck cancer radiotherapy, the patients are mostly immobilized by using thermoplastic masks. In this study, the effect of the thermoplastic mask to the surface and buildup region doses was investigated by using Markus parallel plate ion chamber, Gafchromic EBT3 film and MOSFET detector for the same field size and different beam angles. Materials and Methods: The measurements were made in a water equivalent solid phantom at the surface and in the buildup region of the 6 MV photon beams at 100 cm source-detector distance for 10 × 10 cm 2 field size and beam angles of 0°, 30°, 60° and 80° with and without thermoplastic mask. Results: The surface doses in 0.07 mm depth using 6MV photon beams without a thermoplastic mask for 10 × 10 cm 2 field size were found 20.3%, 18.8%, and 41.5% for Markus chamber, EBT3 film, and MOSFET detector, respectively. The surface doses using 6 MV photon beams with a thermoplastic mask for 10 × 10 cm 2 field size were found 38.4%, 51.7% and 50.2% for Markus chamber, EBT3 film, and MOSFET detector, respectively. Conclusion: The thermoplastic masks placed on the surface of the medium affect the surface and buildup region doses. The effect of thermoplastic masks to surface and buildup region doses should be determined before use clinically.

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Skin-sparing reduction effects of thermoplastics used for patient immobilization in head and neck radiotherapy

Cited by 15 publications

References 13 publications

Cone-Beam CT Assessment of Interfraction and Intrafraction Setup Error of Two Head-and-Neck Cancer Thermoplastic Masks

Cone-Beam CT Assessment of Interfraction and Intrafraction Setup Error of Two Head-and-Neck Cancer Thermoplastic Masks

Dosimetric effects caused by couch tops and immobilization devices: Report of AAPM Task Group 176

Investigation of surface and buildup region doses for 6 MV high energy photon beams in the presence of a thermoplastic mask

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