Design and implementation of a mobile gamma spectrometry system to in vivo measure the accumulated activity of 131I in patients with thyroid diseases

Evolution of Portable Sensors for In-Vivo Dose and Time-Activity Curve Monitoring as Tools for Personalized Dosimetry in Molecular Radiotherapy

Treatment personalization in Molecular Radiotherapy (MRT) relies on pre- and post-treatment SPECT/ PET-based images and measurements to obtain a patient-specific absorbed dose-rate distribution map and its evolution over time. Unfortunately, the number of time points that are available per patient to investigate individual pharmacokinetics is often reduced by limited patient compliance or SPECT or PET/CT scanner availability for dosimetry in busy departments. The adoption of portable sensors for in-vivo dose monitoring during the entire treatment could improve the assessment of individual biokinetics in MRT and, thus, the treatment personalization. The evolution of portable devices, non-SPECT/PET-based options, already used for monitoring radionuclide activity transit and accumulation during therapy with radionuclides (i.e., MRT or brachytherapy), is presented to identify valuable ones, which combined with conventional nuclear medicine imaging systems could be effective in MRT. External probes, integration dosimeters and active detecting systems were included in the study. The devices and their technology, the range of applications, the features and limitations are discussed. Our overview of the available technologies encourages research and development of portable devices and dedicated algorithms for MRT patient-specific biokinetics study. This would represent a crucial advancement towards personalized treatment in MRT.

Capture of I131 from medical-based wastewater using the highly effective and recyclable adsorbent of g-C3N4 assembled with Mg-Co-Al-layered double hydroxide

This paper reports a very high capacity and recyclable Mg-Co-Al-layered double hydroxide@ g-C₃N₄ nanocomposite as the new adsorbent for remediation of radioisotope-containing medical-based solutions. In this work, a convenient solvothermal method was employed to synthesize a new nano-adsorbent, whose features were determined by energy dispersive X-ray (EDS/EDX), XRD, FESEM, TEM, TGA, BET, and FT-IR spectroscopy. The as-prepared nano-adsorbent was applied to capture the radioisotope iodine-131 mainly from the medical-based wastewater under different conditions of main influential parameters, (i.e. adsorbent dose, initial I₂ concentration, sonication time, and temperature). The process was evaluated by three models of RSM, CCD-ANFIS, and CCD-GRNN. Furthermore, comprehensive kinetic, isotherm, thermodynamic, reusability cycles and optimization (by GA and DF) studies were conducted to evaluate the behavior and adsorption mechanism of I₂ on the surface of Mg-Co-Al-LDH@ g-C₃N₄ nanocomposite. High removal efficiency (95.25%) of ¹³¹I in only 30 min (i.e. during 1/384 its half-life), along with an excellent capacity that has ever been reported (2200.70 mg/g) and recyclability (seven times without breakthrough in the efficiency), turns the nanocomposite to a very promising option in remediation of ¹³¹I-containing solutions. Besides, from the models studied, ANFIS described the process with the highest accuracy and reliability with R² > 0.999.

Estimation of blood and bone marrow doses of thyroid carcinoma patients treated with 131I through gamma spectrometry

¹³¹I therapy is the treatment for patients with differentiated thyroid carcinoma (DTC) to ablate remnant thyroid tissue after surgery. The aim of this study was to estimate the absorbed doses to the blood and bone marrow of patients with DTC using gamma spectrometry. The evaluation of the absorbed dose in blood and bone marrow is a good indicator of a patient's response and its radiological protection. The average of low activities administered (AAAL) to ten patients was 3.20 GBq and the average of high activities administered (AAAH) to eight patients was 4.95 GBq. The blood and bone marrow doses were determined according to Lassmann et al 2008, performing successive measurements of activity in blood samples and whole body. Blood samples of 2 ml were taken during the first 48 h; the first one was extracted 2 h after the administration of the capsule and the following ones were taken every 12 h. The whole-body measurements were made at regular intervals of time throughout the patient's isolation period using a mobile gamma spectrometry system located inside the isolation room of the Dr Hernán Henríquez Aravena Hospital. The average residence times in blood and whole-body were (6.9 ± 1.7) × 10^-4 h ml^-1 and (23.2 ± 4.5) h, respectively. The average doses in blood and bone marrow of patients with AAAL were (0.33 ± 0.09) Gy and (0.63 ± 0.18) Gy, respectively, and with AAAH were (0.48 ± 0.06) Gy and (0.87 ± 0.19) Gy, respectively. In all studied patients, the bone marrow doses were less than 2 Gy. The results were compared with the previously published values, finding some differences between the residence times and significant differences in the doses, which show the need to compare the different methodologies.