Investigation of EBT 3 radiochromic film's response to humidity

• Published in: Journal of applied clinical medical physics Vol. 19; no. 3; pp. 283 - 290
• Main Authors: León‐Marroquín, Elsa Y., Lárraga‐Gutiérrez, José M., Herrera‐González, J. Alfredo, Camacho‐López, Miguel A., Villarreal Barajas, José E., García‐Garduño, Olivia A.
• Format: Journal Article
• Language: English
• Published: Malden Massachusetts John Wiley & Sons, Inc 01.05.2018
• Subjects: Dosimetry; Humidity; Investigations; Radiation therapy; Calgary Alberta Canada
• ISSN: 1526-9914; 1526-9914
• DOI: 10.1002/acm2.12337

Abstract Purpose The aim of this work is to investigate the effects of immersing EBT 3 radiochromic film in water and to evaluate its contribution to the total uncertainty in dose determination. Materials and methods We used 3 cm × 3 cm EBT 3 radiochromic films irradiated in the range of 0–70 Gy to study the impact of water immersion on the change in net optical density. These films were placed in a water container for a period of 24 h. The net optical density was measured before (0 h) and after of the immersion in water (1, 3, 6, 12, 18, and 24 h). The absorbance spectrum of the EBT 3 radiochromic film was measured at 0 h and 24 h after immersion in water. The uncertainty in dose determination due to the effects of keeping the EBT 3 radiochromic film submerged in water at 0, 1, and 24 h were recorded in the red, green, and blue channels. Results We observed an increase in the net optical density as an effect on the film due to its immersion in water. The penetration of the water at the edges of the radiochromic film was observed to be a function of time during which the film remained in the water. On the other hand, the penetration of water at the edges of the film was found to be independent of irradiation dose. Conclusions EBT 3 radiochromic film is found more resistant to water penetration through the edges than its predecessors. However, there is evidence that suggest that liquid water damage the Nylon cover layer of the film by changing its optical properties. Therefore, it is recommended to build a new calibration curve for radiochromic films for a specific situation involving dose measurements in liquid water.