Increasing the sensitivity of the dosimetry system for high energy x-rays, using gafchromic EBT film and a flat-bed scanner with sharp cut filters

Hirofumi Hato, Hideki Aoyama, Yoshiharu Azuma, Sachiko Goto, Tetsuhiro Sumimoto

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Abstract

To increase the sensitivity of the dosimetry system for high energy x-rays, using Gafchromic EBT film (International Specialty Products) and a flat-bed scanner with transparency unit (ES-2200 or Expression 1680, Epson, Inc.), the optimal sharp cut (SC) filters like optical filters to be added to the scanner were investigated. Gafchromic EBT film (EBT) has the absorption spectrum with a maximum absorption band centered at 636 nm. Consequently the response of EBT will be enhanced by measurement with red light and can be very significantly increased by using a red filter while making scanner measurements. In our research, employed SC filters were SC filter 54, 56, 58, 60 and 62 (product made from Fuji film). SC filters are defined as filters that cut off as much as possible of the wavelength light shorter than a specific wavelength, while transmitting as much of longer wavelength light as possible, within a wavelength range of 350 nm to 800 nm. Generally, it is ideal to use a narrow band pass filter. However we didn't employ the filter because the transmissivity of the filter of film type is low or the thickness of glass type filter is large, so it is unsuitable for a flat-bed scanner. Film pieces of EBT were exposed to the following doses: 0.3 – 10.0 Gy with the 6 MV x-rays from a linear accelerator. The irradiated film pieces to which the SC filter was added were scanned and the scan data of red channel was converted into optical density. Furthermore the optical density was divided by the absorbed dose and the value was estimated as sensitivity. EBT with SC filter 62 with 50% of transmissivity at 620 nm was about 1.48 times more sensitive on the average than without a SC filter.

Original languageEnglish
Title of host publicationIFMBE Proceedings
EditorsSun I. Kim, Tae Suk Suh
PublisherSpringer Verlag
Pages2138-2141
Number of pages4
Edition1
ISBN (Print)9783540368397
DOIs
Publication statusPublished - 2007
Event10th World Congress on Medical Physics and Biomedical Engineering, WC 2006 - Seoul, Korea, Republic of
Duration: Aug 27 2006Sep 1 2006

Publication series

NameIFMBE Proceedings
Number1
Volume14
ISSN (Print)1680-0737
ISSN (Electronic)1433-9277

Other

Other10th World Congress on Medical Physics and Biomedical Engineering, WC 2006
CountryKorea, Republic of
CitySeoul
Period8/27/069/1/06

Keywords

  • Absorption spectrum
  • Gafchromic EBT film
  • High energy x-rays
  • Sensitivity of dosimetry system
  • Sharp cut filter

ASJC Scopus subject areas

  • Bioengineering
  • Biomedical Engineering

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