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. 2015 Sep 8;16(5):427–434.
doi: 10.1120/jacmp.v16i5.5664.

Ultraviolet exposure of Gafchromic XR-RV3 and XR-SP2 films

Toshizo Katsuda  1 , Rumi Gotanda, Tatsuhiro Gotanda, Takuya Akagawa, Nobuyoshi Tanki, Tadao Kuwano, Kouichi Yabunaka
Affiliations

Ultraviolet exposure of Gafchromic XR-RV3 and XR-SP2 films

Toshizo Katsuda et al. J Appl Clin Med Phys. .

Abstract

Gafchromic film has been used for X-ray dose measurement in diagnostic examinations. Their use has been initiated for three-dimensional X-ray dose measurement by using the high-resolution characteristics of Gafchromic films in computed tomography. However, it is necessary to solve the problem of nonuniform thickness in the active layers of Gafchromic films. A double exposure technique using X-rays is performed in therapeutic radiology; it is difficult to use in a diagnostic examination because of the heel effect. Therefore, it is suggested that ultraviolet (UV) rays be substituted for X-rays. However, the appropriate UV wavelength is unknown. In this study, we aimed to determine which UV wavelengths are effective to expose Gafchromic XR-RV3 and XR-SP2. UV lamps with peak wavelengths of 245 nm, 310 nm, and 365 nm were used. The three UV wavelengths were used to irradiate Gafchromic XR-RV3 and XR-SP2 films for 60 min, and irradiation was repeated every 60 min for 600 min thereafter. Films were scanned after each irradiation period on a flatbed scanner. The images were split into their red-green-blue components, and red images were stored using ImageJ version 1.44o image analysis software. Regions of interest (ROI), 0.5 inches in diameter, were placed at the centers of the subtracted Gafchromic film images, and graphs of UV irradiation duration and mean pixel values were plotted. There were reactions to UV-A on both Gafchromic XR-RV3 and XR-SP2; those to UV-B were moderate. However, UV-C demonstrated few reactions with Gafchromic XR-RV3 and XR-SP2. From these results, irradiation with UV-A may be able to correct nonuniformity errors. Uniform UV-A irradiation of Gafchromic films with large areas is possible, and UV rays can be used as a substitute for X-rays in the double exposure technique.

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Figures

Figure 1
Figure 1
Placements of Gafchromic XR‐SP2 and XR‐RV3. The black circles indicate the measured ROIs for the pixel values.
Figure 2
Figure 2
The setup arrangement for ultraviolet (UV) exposure. A lateral view (top) and frontal view (bottom) are shown.
Figure 3
Figure 3
Results of UV‐A, B, and C exposure to Gafchromic XR‐RV3. Marker (black circle, black square, and black triangle) show the scanning timing of each irradiated Gafchromic film.
Figure 4
Figure 4
The different reactions of UV‐A between the Gafchromic XR‐RV3 and XR‐SP2. Marker (black circle, black square, and black triangle) show the scanning timing of each irradiated Gafchromic film.
Figure 5
Figure 5
Results of UV‐A, B, and C exposure to Gafchromic XR‐SP2. Marker (black circle, black square, and black triangle) show the scanning timing of each irradiated Gafchromic film.
See this image and copyright information in PMC

References

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