Fricke gel dosimeter with improved sensitivity for low‐dose‐level measurements

Abstract

Fricke solution has a wide range of applications as radiation detector and dosimetry. It is particularly appreciated in terms of relevant comparative advantages, like tissue‐equivalence when prepared in aqueous media like gel matrix, continuous mapping capability, independence of dose rate and incident direction, as well as linear dose response. This work presents the development and characterization of an improved Fricke gel system, based on modified chemical compositions, making possible its application in clinical radiology due to its improved sensitivity. Properties of standard Fricke gel dosimeter for high‐dose levels are used as a starting point, and suitable chemical modifications are introduced and carefully investigated in order to attain high resolution for low‐dose ranges, like those corresponding to radiology interventions. The developed Fricke gel radiation dosimeter system achieves the expected typical dose‐dependency, showing linear response in the dose range from 20 up to 4000 mGy. Systematic investigations including several chemical compositions are carried out in order to obtain an adequate dosimeter response for low‐dose levels. A suitable composition from among those studied is selected as a good candidate for low‐dose‐level radiation dosimetry consisting of a modified Fricke solution fixed to a gel matrix containing benzoic acid along with sulfuric acid, ferrous sulfate, Xylenol orange, and tridistilled water. Dosimeter samples are prepared in standard vials for in‐phantom irradiation and further characterization by spectrophotometry measuring visible light transmission and absorbance before and after irradiation. Samples are irradiated using typical X‐ray tubes for radiology and calibrated Farmer‐type ionization chamber is used as reference to measure dose rates inside phantoms at vial locations. Once sensitive material composition is optimized, dose‐response curves show significant improvement regarding overall sensitivity for low dose levels. The aim of this work consists of implementing the optimized gel dosimeter to perform direct measurements of absorbed dose in samples irradiated during microcomputed tomography scanning in order to preliminary assess dose levels for further scanning of small animals for further applications in veterinary and paleontology. As a first attempt, dose distributions were measured in water‐equivalent phantoms having dimensions comparable to small animals, 100 to 1000 cm3, approximately. According to the obtained results, it is found that the proposed method shows satisfactory reliability and adequate performance for a promising gel dosimetry system.PACS number(s): 87.53.Bn, 87.57.uq, 87.59.‐e

Carbon Dots based Tissue Equivalent Dosimeter as an Ionizing Radiation Sensor

“…This system guarantees consistent and reproducible measurements, making it a reference in absolute dose calculations. In clinical applications, the Fricke dosimeter has an effective atomic number close to that of the soft tissue of the human body and is therefore tissue equivalent [33] . When incorporated into a gel matrix, it maintains its properties, which becomes advantageous for three‐dimensional (3D) dosimetry.…”

Evaluation of ferrous benzoic methylthymol-blue gel as a dosimeter via magnetic resonance imaging

“…High uncertainty in measuring low doses (below 1 Gy for radiation therapy energies) is recognized as one of the main disadvantages of gel dosimeters [26]. The number of ions transformed per 100 eV of absorbed energy, G value, is defined as an indicator that shows the performance of Fricke gel dosimeters [27]. Clearly, changes in the concentration of components or the addition of new media can cause changes in the G-value.…”

Measurement of tissue-radiation dosage using a thermal steady-state elastic shear wave

“…The detection sensitivity at 1 cGy in this method is 10-fold higher for detection sensitivity than the conventional biodosimeter at 100 mGy based on chromosome aberration analysis and optical 3-D dosimeter. 1,2,26 Moreover, by directly monitoring the change in the TIESW profile in real time, it is capable of measuring the transit stage of the dermis during ionizing radiation. In addition, from the positive or negative slope of linear dependence between the absorbed dose and the oscillation frequency of the TIESW in these experiments, it was possible to predict the recovery abilities of a living porcine dermis treated with ionizing radiation.…”