Effects on skin dose from unwanted air gaps under bolus in photon beam radiotherapy

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Author(s)

  • Martin J. Butson
  • Tsang Cheung
  • Peter Yu
  • Peter Metcalfe

Detail(s)

Original languageEnglish
Pages (from-to)201-204
Journal / PublicationRadiation Measurements
Volume32
Issue number3
Publication statusPublished - Jun 2000

Abstract

The dose under small air gaps located under bolus material of up to 10 mm have been measured with an Attix parallel plate ionization chamber and radiochromic film. For a 6 MV x-ray beam with 10 mm bolus, an air gap of 2 mm produced no reduction in skin dose when measured with the Attix chamber. An air gap of 4 mm will introduce a reduction of dose to the basal layer of approximately 0-4% depending on field size, angle of incidence and other patient specific parameters and a reduction of up to 10% could be seen at the basal cell layer for a 10 mm air gap. The 10% reduction was for a small x-ray field at 60 degrees angle of incidence and was a reduction in dose from 100% of Dmax down to 90% of Dmax. Results at oblique angles of incidence show that larger reductions in dose are seen with increasing angle of incidence. Radiochromic film results agree with the Attix chamber results measuring 2% +2% decrease for a 4 mm gap and 4% +2% for a 10 mm gap at normal incidence. Clinically, results show that small air gaps can reduce skin dose, however, at least 90% of maximum dose is still delivered for air gaps up to 10 mm.

Citation Format(s)

Effects on skin dose from unwanted air gaps under bolus in photon beam radiotherapy. / Butson, Martin J.; Cheung, Tsang; Yu, Peter et al.
In: Radiation Measurements, Vol. 32, No. 3, 06.2000, p. 201-204.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review