A review study on application of gel dosimeters in low energy radiation dosimetry.

INTRODUCTION: The accuracy of dose delivered to tumors and surrounding normal tissues is vital in either radiotherapy using low energy photons and radiological techniques as well as radiotherapy with mega voltage energies. This systematic review focuses on applications of gel dosimetry in low energy radiation contexts applied either through radiotherapy or interventional radiology. METHODS: Literature was reviewed based on electronic databases: Google Scholar, Scopus, Embase, PubMed, Science Direct, Research Gate and IOP science. The search was conducted on relevant terms in the title and keywords. 82 articles related to our criteria has been extracted and included in the study. RESULTS: The findings demonstrated that almost all types of gel dosimeters had an acceptable accuracy and high resolution in low energy radiation contexts with their own limitations and advantages. CONCLUSION: Gel dosimeters compete well with other conventional dosimeters in terms of tissue equivalence and energy dependence; however, choosing the best gel dosimeter for use in low energy radiation dosimetry depends on their different limitation and advantages. There are some general features about each gel group which can help to select the suitable gel related to our work. For example, methacrylic acid based gel dosimeters show higher sensitivity compared to other types of gel dosimeters but have more toxicity and are dose rate dependent in the range of dose rates applied in low energy contexts. In addition, Fricke gel dosimeters exhibit less sensitivity while they are independent of dose rate and energy applied in low energy situations.

Bismuth oxide nanoparticles as agents of radiation dose enhancement in intraoperative radiotherapy.

PURPOSE: Intraoperative radiotherapy (IORT) technique is an advanced radio therapeutic method used for delivery of a single high-dose radiation during surgery while removing healthy tissues from the radiation field. Nowadays, growing attention is being paid to IORT for its low-energy (kilovoltage) delivery as it requires less radiation protection, but suffers several disadvantages, including high-dose delivery and prolonged treatment time. The application of nanoparticles with high atomic number and high attenuation coefficients in kilovoltage energy may help overcome the mentioned shortcomings. This study was designed to investigate and quantify the mean dose enhancement factor (DEF) in the presence of nanoparticles using IORT method. METHODS: Bismuth oxide nanoparticles (Bi2 O3 NPs), both in sheet and spherical formats, were synthesized using a novel hydrothermal method and characterized with x-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) analysis. Genipin-gelatin gel dosimeter (GENIPIN) was produced in three batches of pure with sheet and with spherical nanoparticles in concentration of 46.596 µg/ml, and irradiated with 50 kV x-rays. RESULTS: Samples were scanned by a spectrophotometer, which indicated a DEF of 3.28  ±  0.37 and 2.50  ±  0.23 for sheet and spherical NPs, respectively. According to the results of this study, GENIPIN is a suitable dosimeter for the evaluation of three-dimensional dose distribution in the presence Bi2 O3 NPs. CONCLUSION: As a result, IORT along with Bi2 O3 NPs has the potential to reduce treatment time and/or normal tissue dose; moreover, it could provide localized dose enhancement.