(652h) Colorimetric Detection of Therapeutic Levels of Ionizing Radiation Using Plasmonic Nanoparticle Gels

Radiotherapy has evolved into a highly complex and efficient treatment modality for ablation of malignant tumors. Treatments are typically administered in fractions of 2 Gy each (1 Gy = 1 Joule energy absorbed / kg), leading to a cumulative dose of 20-70 Gy depending on the disease. Despite several technological advances, determination of the dose delivered to the tumor and adjacent tissues remains a challenge due to complex fabrication, cumbersome operation, and high costs associated with current dosimeters. Advances in molecular and nanoscale systems can lead to novel platforms for the detection of therapeutic levels of ionizing radiation in radiotherapy. Here, we describe fundamental studies and development of a novel gel-based colorimetric nanosensor for detecting therapeutic levels of X-rays (1-10 Gy) administered in clinical radiotherapy. Following exposure to X-rays, surfactant micelles, incorporated together with gold salts in a gel, were able to convert the monovalent gold ions (Au1) to nanoparticles within the matrix, resulting in the formation of a maroon-colored plasmonic gel. Differences in color intensity of the gel following irradiation were used as a quantitative indicator of the radiation dose employed. The gel-based nanosensor was able to detect doses as low as 0.5 Gy, and demonstrated a linear detection range of 0.5 â?? 5 Gy, which shows its application in the fractionated radiotherapy regime. Importantly, the gel-based dosimeter was able to report on the spatial distribution of the dose, indicating its use for identifying tissue regions that may receive higher-than-intended doses. The gel was also able to successfully detect therapeutic levels of radiation doses administered to anthropomorphic tissue phantoms. The range of detection, ease of fabrication, simplicity associated with colorimetric detection and relatively lower costs indicate that this technology can be potentially translated to different radiotherapy applications in the clinic.