Monte Carlo‐based investigation of absorbed‐dose energy dependence of radiochromic films in high energy brachytherapy dosimetry

Mishra Subhalaxmi,T Palani Selvam

doi:10.1120/jacmp.v15i1.4448

Mishra Subhalaxmi, T Palani Selvam

Open Access

https://doi.org/10.1120/jacmp.v15i1.4448

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Abstract

Relative absorbed dose energy response correction, R, for various radiochromic films in water phantom is calculated by the use of the Monte Carlo‐based EGSnrc code system for high energy brachytherapy sources 60Co, 137Cs, 192Ir and 169Yb. The corrections are calculated along the transverse axis of the sources (1‐15 cm). The radiochromic films investigated are EBT, EBT2 (lot 020609 and lot 031109), RTQA, XRT, XRQA, and HS. For the 60Co source, the value of R is about unity and is independent of distance in the water phantom for films other than XRT and XRQA. The XRT and XRQA films showed distance‐dependent R values for this source (the values of R at 15 cm from the source in water are 1.845 and 2.495 for the films XRT and XRQA, respectively). In the case of 137Cs and 192Ir sources, XRT, XRQA, EBT2 (lot 031109), and HS films showed distant‐dependent R values. The rest of the films showed no energy dependence (HS film showed R values less than unity by about 5%, whereas the other films showed R values higher than unity). In the case of 169Yb source, the EBT film showed no energy dependence and EBT2 film (lot 031109) showed a distance‐independent R value of 1.041. The rest of the films showed distance‐dependent R values (increases with distance for the films other than HS). The solid phantoms PMMA and polystyrene enhance the R values for some films when compared the same in the water phantom.PACS number: 87.53.Jw

Highlights

352 Subhalaxmi et al.: Energy response of radiochromic films application, user can chose a suitable radiochromic film
In a previously published study, Monte Carlo-based relative absorbed-dose energy response correction as a function of depth in water was investigated for solid state detectors such as LiF, Li2B4O7, Si diode, diamond, Al2O3 for 125I and 169Yb brachytherapy sources.[15]. Influence of solid phantoms, such as polystyrene and polymethyl methacrylate (PMMA), was investigated in the work
The present study is aimed at calculating relative absorbed-dose energy response correction as a function of depth in water for the various radiochromic films for different brachytherapy sources such as 60Co, 137Cs, 192Ir, and 169Yb

Summary

Introduction

352 Subhalaxmi et al.: Energy response of radiochromic films application, user can chose a suitable radiochromic film. In a previously published study, Monte Carlo-based relative absorbed-dose energy response correction as a function of depth in water was investigated for solid state detectors such as LiF, Li2B4O7, Si diode, diamond, Al2O3 for 125I and 169Yb brachytherapy sources.[15] Influence of solid phantoms, such as polystyrene and polymethyl methacrylate (PMMA), was investigated in the work. The present study is aimed at calculating relative absorbed-dose energy response correction as a function of depth in water for the various radiochromic films for different brachytherapy sources such as 60Co, 137Cs, 192Ir, and 169Yb. This study includes the influence of solid phantoms polystyrene and PMMA on the correction. We have employed the Monte Carlo-based user codes DOSRZnrc and FLURZnrc[16] of the EGSnrc code system[17]

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Conclusion