Temporal response of gafchromic EBT2 radiochromic film in proton beam irradiation

Li Zhao, Len Coutinho, Ning Cao, Chee Wai Cheng, Indra J. Das

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

4 Scopus citations

Abstract

Introduction: Gafchromic EBT2 is being used for radiation dosimetry including photon, electrons and recently in proton beams, based on its color changes from transparent to blue due to polymerization. It is critical to understand the temporal response of the polymerization after irradiation to proton beam. Materials and Methods: Five small pieces cut from one sheet (lot no. A08060905A) were irradiated with different doses (2 - 10 Gy) using a clinical proton beam in reference condition (range 16 cm, spread-out-bragg-peak 10 cm). An EPSON flatbed 10000XL was used for digitizing 48 bit color RGB images. The films were kept in the same position on the scanner for each scan. Within a 6-day period, measurements were taken every 3 minutes for the first hour, every 5 to 30 minutes for the first 1-12 hours and then randomly after 12 hours. Red, green and blue frequency read out of the scanner for each film was analyzed in ImageJ software. Results: A mathematical function (netOD =α + β (1-exp (- t/Ta)) + γ (1-exp (-t/Tb)) can be used to describe the temporal response. The polymerization is time dependent with two time constants, Ta (25 minutes) and Tb (1000 minutes). α, β, and γ are dose dependent parameters. The percentage of OD change per 10 minutes remains less than 1% after the first hour. A 7%-11% increase in netOD was observed within the first 12 h when irradiated within 10 Gy, comparable to 9% reported for EBT films. Conclusions and Discussion: The post-irradiation rapid polymerization effect is observed on EBT2 film with the growth of OD. This characteristic can be described by a double exponential function. It is recommended to apply this function for temporal coloration effect to improve the accuracy for radiation dosimetry using EBT2 film in proton beam.

Original languageEnglish (US)
Title of host publicationWorld Congress on Medical Physics and Biomedical Engineering
Pages1164-1167
Number of pages4
DOIs
StatePublished - Apr 16 2013
EventWorld Congress on Medical Physics and Biomedical Engineering - Beijing, China
Duration: May 26 2012May 31 2012

Publication series

NameIFMBE Proceedings
Volume39 IFMBE
ISSN (Print)1680-0737

Other

OtherWorld Congress on Medical Physics and Biomedical Engineering
CountryChina
CityBeijing
Period5/26/125/31/12

Keywords

  • EBT2 film
  • film dosimetry
  • gafchromic film
  • proton therapy
  • temporal response

ASJC Scopus subject areas

  • Biomedical Engineering
  • Bioengineering

Fingerprint Dive into the research topics of 'Temporal response of gafchromic EBT2 radiochromic film in proton beam irradiation'. Together they form a unique fingerprint.

  • Cite this

    Zhao, L., Coutinho, L., Cao, N., Cheng, C. W., & Das, I. J. (2013). Temporal response of gafchromic EBT2 radiochromic film in proton beam irradiation. In World Congress on Medical Physics and Biomedical Engineering (pp. 1164-1167). (IFMBE Proceedings; Vol. 39 IFMBE). https://doi.org/10.1007/978-3-642-29305-4_305