On the Use of the Fricke-Pluronic F-127 Gel Dosimeter for Radiation Isocenter Testing of a Medical Linear Accelerator

Abstract

This work presents a Fricke-XO-Pluronic F-127 2D radiochromic dosimeter with a flat-bed scanner for 2D reading and a dedicated data processing software package as a tool for performing coincidence testing of the radiation and mechanical isocenter of a medical accelerator. The optimal irradiation parameters were determined as follows: monitor units per beam and multi-leaf collimator gap, which are ≤750–≤2500 MU and 2–5 mm, respectively, for a cuboidal container with dimensions of 12 × 12 × 0.3 cm3. Despite the diffusion of Fe3+ ions occurring during irradiation, 2D reading can be performed at least 3 h after irradiation, without affecting the calculation performance of the coincidence test. The test was successfully performed for various irradiation settings. Overall, the Fricke-XO-Pluronic F-127 dosimeter has proven to be a potential tool for the coincidence testing of medical accelerators.

An Optical Reusable 2D Radiochromic Gel-Based System for Ionising Radiation Measurements in Radiotherapy

“…Also, the irradiated dark blue zones are unstable and disperse over time after irradiation. This can be seen with the naked eye just 2.5 h after irradiation and storage at room temperature (see Figure 2 in [ 20 ]). Therefore, the Fricke–XO–Pluronic F-127 cannot be used as a reusable dosimeter.…”

“…To date, we have investigated two radiochromic gel dosimeters as 2D systems for routine medical linear accelerator (X-ray radiation) testing–coincidence of mechanical and radiation isocenters: NBT–Pluronic F-127 in current work and Fricke–XO–Pluronic F-127 reported elsewhere [ 20 ]. There is only one similarity between these dosimeters: the Pluronic F-127 matrix.…”

“…Unlike the NBT–Pluronic F-127 dosimeter, the Fricke–XO–Pluronic F-127 is significantly less stable after preparation and irradiation. After preparation, the entire gel dosimeter changes color from light yellowish-brownish to dark blue-purple, especially when the sides of the dosimeter in the plastic frame are in contact with air (see Figure 2 in [ 20 ]). This conversion can be observed with the naked eye approximately 2.5 h after preparation and storage at room temperature.…”

“…Therefore, the Fricke–XO–Pluronic F-127 cannot be used as a reusable dosimeter. However, this does not disqualify it from use in radiotherapy dosimetry on account that 2D scanning is performed shortly after irradiation and preparation [ 20 ]. The advantage of Fricke–XO–Pluronic F-127 is a strong signal after irradiation even with 500 MU (see Figure 2 in [ 20 ]).…”

“…Although the changes occurring in the dosimeter after irradiation are irreversible, this work presents an approach to reusing the dosimeter in the coincidence test. The features of the NBT–Pluronic F-127 dosimeter proposed in this work are discussed in comparison to the Fricke-XO–Pluronic F-127 dosimeter, which has recently been reported elsewhere [ 20 ].…”