Joint EURADOS-EANM initiative for an advanced computational framework for the assessment of external dose rates from nuclear medicine patients.

Background: In order to ensure adequate radiation protection of critical groups such as staff, caregivers and the general public coming into proximity of nuclear medicine (NM) patients, it is necessary to consider the impact of the radiation emitted by the patients during their stay at the hospital or after leaving the hospital. Current risk assessments are based on ambient dose rate measurements in a single position at a specified distance from the patient and carried out at several time points after administration of the radiopharmaceutical to estimate the whole-body retention. The limitations of such an approach are addressed in this study by developing and validating a more advanced computational dosimetry approach using Monte Carlo (MC) simulations in combination with flexible and realistic computational phantoms and time activity distribution curves from reference biokinetic models.

Thyroid remnant ablation in patients with papillary cancer: a comparison of low, moderate, and high activities of radioiodine.

Objective: The consensus about optimal activities of I-131 for thyroid remnant ablation has not yet been achieved. The aim of this study was to compare ablation rates obtained with different I-131 activities.

Patients And Methods: The study included 466 patients divided into four groups according to I-131 activities given after total thyroidectomy for papillary thyroid cancer: group A [168 patients who received 888 MBq (24 mCi)], group B [125 patients who received 1480 MBq (40 mCi)], group C [65 patients who received 1850 MBq (50 mCi)], and group D [108 patients who received 4440 MBq (120 mCi)].

Thyroid stunning in vivo and in vitro.

Aim: To review published in-vivo and in-vitro quantitative dosimetric studies on thyroid stunning in order to derive novel data applicable in clinical practice.

Methods: A non-linear regression analysis was applied to describe the extent of thyroid stunning in thyroid remnants, as a function of the radiation absorbed dose of diagnostic radioiodine-131 (I), in thyroid cancer patients investigated in four in-vivo studies. The regression curves were fitted using individual patient absorbed doses or the mean absorbed doses for the groups of patients.

Tc-99m DTPA renal scintigraphy using deconvolution analysis with six functional images of the mean time to evaluate acute pyelonephritis.

In 38 children with proved P-fimbriated Escherichia coli acute pyelonephritis, Tc-99m DTPA dynamic renal scintigraphy in the zoom mode using deconvolution analysis was performed, and the results were compared with those of Tc-99m DMSA scans. From the dynamic study, six functional images of the mean time were generated. Each functional image was analyzed separately to search for focal areas of increased mean time within the kidney contour, especially over the kidney parenchyma.

Determination of small objects from pinhole scintigrams.

This study assessed the possibility of measuring the linear dimensions of small structures using pinhole scintigraphy. A number of glass objects were made with a spherical, cylindrical or conical shape. Their maximum dimensions (diameters and heights) were 3.

Radioiodine uptake in thyroid cancer patients after diagnostic application of low-dose 131I.

The aim of this study was to investigate the influence of the diagnostic administration of 74 MBq 131I on subsequent uptake of therapeutic radioiodine in thyroid cancer patients. Retention measurements were performed using a whole-body counter in 24 patients 6 weeks after total thyroidectomy. Profile scans were performed 2, 24, 48 and 72 h after the administration of the diagnostic dose and 72 h after the administration of the ablation-therapeutic dose (4.