Introducing a Novel Method for Three Dimensional Dose Map by Optical Computed Tomography

Radiochromic gel is recently introduced as a three dimensional dosimeter that exhibits color changes by being exposed to ionizing radiation. Therefore, the read-out system of this dosimeter should be based on radiochromic response.
The aim of this study was to introduce a novel design of machine called optical computed tomography (OCT) and acquire the three dimensional dose distribution of ionizing radiation by using the Radon transform image reconstruction technique.
By assembling red light-emitting diode as a light source, two lenses, charge-coupled device (CCD) camera, step motor, matching liquid, radiochromic gel, and a base frame, a novel design of OCT was manufactured. Then a sample of radiochromic gel was irradiated and scanned by novel OCT. The acquired images were then reconstructed by using the Radon transform algorithm and consequently the dose distribution was mapped. Finally the results of this device were verified by an ion chamber.
By setting up the required accessories, a new design of OCT was constructed. The verification test showed that the results of novel OCT could be reliable by almost ± 3% deviations.
The results of this study confirmed that not only the Radon transform algorithm could be used for reconstructing computed tomography (CT) images, but also this technique could be applied for imaging the dose map of ionizing radiation obtained by OCT. Moreover, novel OCT- radiochromic gel could be considered as a proper system for acquiring three dimensional dose distribution of ionizing radiation.