ABSTRACT
This work aims at assessing the performance of a portable detection system, equipped with an NaI(Tl) scintillation detector for in vivo thyroid monitoring, which was properly calibrated using an anthropomorphic neck phantom. The anthropomorphic physical phantoms commonly used for the efficiency calibration of in vivo counters often present certain limitations regarding the geometry and the activity distribution. Therefore, the feasibility of these detection systems for in vivo monitoring should be assessed whenever possible. To accomplish this assessment, patients to whom (99m)Tc and (123)I marked radiopharmaceuticals have been administered in the framework of nuclear medicine diagnostic procedures were monitored. As the biokinetic models of the administered radiopharmaceuticals are known, the time-dependent activity functions in the critical organs after administration are easily quantified. The measured activities in the thyroid using the NaI(Tl) scintillation detector were compared with the estimated activities using the biokinetic models, in order to reach conclusion about the applicability of the portable scintillation counter for in vivo thyroid monitoring. The state-of-the-art Monte Carlo computer program PENELOPE and two voxel phantoms (male and female) were used to evaluate the overall uncertainties influencing the thyroid monitoring. A computational parametric study was performed to quantify the influence of several parameters in the activity quantification (neck-detector distance, thyroid shape, thyroid size and overlying tissue thickness), which allowed one to gain insight and to better understand the discrepancies between the calculated and measured activities.
Subject(s)
Iodine Radioisotopes , Occupational Exposure , Radiation Monitoring , Sodium Iodide/administration & dosage , Thyroid Gland/radiation effects , Uncertainty , Computer Simulation , Humans , Monte Carlo Method , Phantoms, Imaging , Radiopharmaceuticals , Scintillation Counting , Thyroid Gland/anatomy & histologyABSTRACT
Scintigraphy using Tc-99m MDP and Tl-201 was performed in a patient with polyostotic Paget's disease and sarcomatous degeneration in the right iliac bone. Tc-99m MDP imaging showed abnormal uptake in both types of lesions. Tl-201 imaging showed increased uptake in the sarcomatous lesion and absent uptake in pagetic lesions. This result supports the idea that Tl-201 scintigraphy may have a potential role to play in the differentiation of Paget's disease from malignancy. To the authors' knowledge, Tl-201 has never been reported for the detection of sarcomatous change of pagetic bone.
Subject(s)
Bone Neoplasms/diagnostic imaging , Ilium/diagnostic imaging , Osteitis Deformans/diagnostic imaging , Osteosarcoma/diagnostic imaging , Thallium Radioisotopes , Bone and Bones/diagnostic imaging , Female , Humans , Middle Aged , Radionuclide Imaging , Technetium Tc 99m MedronateABSTRACT
To evaluate the safety of intravenous dipyridamole thallium-201 imaging as an alternative to exercise thallium imaging in the evaluation of coronary artery disease, clinical data from 140 patients were retrospectively analyzed. Adverse effects were experienced by 39 patients (27.9%) with a total number of 52 effects: chest pain (23), dizziness (13), headache (7), nausea (7), dyspnea (2). All patients presented complete relief of symptoms. In 15 patients administration of aminophylline was necessary. Major effects (fatal and non fatal myocardial infarction and acute bronchospasm) were not registered. Vital sign data change observed after infusion of dipyridamole was: decreased blood pressure and increased pulse rate. Patient's age and incidence of coronary artery disease did not differ significantly in the subgroup of patients with adverse effects versus the group of patients without it.
