Date Approved

9-23-2024

Embargo Period

9-24-2024

Document Type

Thesis

Degree Name

Master of Science (M.S.)

Department

Biomedical Engineering

College

Henry M. Rowan College of Engineering

Advisor

Sebastian Vega, Ph.D.

Committee Member 1

Erik Brewer, Ph.D.

Committee Member 2

Leonard Kim, D.A.B.R.

Keywords

radiation dosimeters, Fricke hydrogels

Subject(s)

Radiation dosimetry

Disciplines

Biomedical Engineering and Bioengineering | Chemical Engineering | Engineering

Abstract

Hydrogel-based radiation dosimeters are used to calibrate and validate radiation delivered by linear accelerators used in radiotherapy. Specifically, Fricke hydrogel-based dosimeters containing ferrous ion complexes oxidize upon exposure to radiation, leading to a change in optical density that can be measured via a color change in a photometric reagent. While gelatin-based Fricke hydrogels are routinely used to measure radiation, these hydrogels are unstable at body temperature, and it is currently not possible to noninvasively measure radiation dose inside a patient. This study reports the synthesis and characterization of self-forming hydrogels containing Fricke components that are stable at body temperature. The effects of varying individual Fricke hydrogel components on the sensitivity (measured by change in optical density) to radiation dose were systematically studied. Self-forming hydrogels were prepared using xylenol orange (XO) in the range of 0.05 to 0.5 mM, ferrous ammonium sulfate (Mohr’s salt) in the range of 0.1 to 1 mM, and sulfuric acid (H2SO4) in the range of 0 to 100 mM. The minimum concentration of Fricke components to create self-forming hydrogels that are sensitive to radiation dose (0 to 40 Gy) at room and body temperature was found to be XO (0.2 mM), H2SO4, (25 mM) and Mohr’s salt (0.5 mM). To assess self-forming hydrogel biocompatibility, human mesenchymal stem cells (MSCs) cultured in medium were exposed to cylindrical hydrogels containing Fricke components, and MSCs co-cultured with self-forming hydrogels containing the optimized formulation remained highly viable. Plans for a preclinical study using a rodent tumor model are underway, bringing this technology one step closer to clinical practice.

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