Feasibility study of a wearable sensing device for activity monitoring in patients treated with 131I

In nuclear medicine therapy, treatment personalization increases the effectiveness of the treatment and reduces induced toxicity. The knowledge of the biokinetics of the administered radiopharmaceutical is fundamental for an accurate absorbed dose estimation and the Time Activity Curve (TAC) could be obtained using wearable sensors. In the hypothesis of a patient undergoing 131I treatment of hyperthyroidism, Monte Carlo (MC) simulations were carried out reproducing the ICRP110 male phantom to estimate the response of gamma sensors placed at the thyroid, and at the right and left kidney level. The initial biodistribution was set according to the indications of ICRP for 131I biokinetics. The contribution from the source organs (such as liver, spleen, kidneys, urinary bladder) to the sensors’ response was also computed. Results indicate that the signal registered by the sensor placed in front of the thyroid can be mainly attributed to this organ since about 97% of it comes from the thyroid while the contribution from the other organs is negligible. Regarding the sensors placed at the kidneys’ level, the observed signal cannot be uniquely attributed to these organs; further studies are needed to optimize the sensor design to reduce the contribution coming from the other source organs such as the liver and spleen, or proper signal unfolding procedures have to be developed.