Radiopharmaceutical Dosimetry Research Articles

Cell irradiation caused by diagnostic nuclear medicine procedures: dose heterogeneity and biological consequences.

Most radionuclides used for diagnostic imaging emit Auger electrons (technetium-99m, iodine-123, indium-111, gallium-67 and thallium-201). Their very short range in biological tissues may lead to dose heterogeneity at the cellular level with radiobiological consequences. This report describes the dosimetric models used to calculate the mean dose absorbed by the cell nucleus from Auger radionuclides. The techniques used to determine the biodistribution of radiopharmaceuticals at the subcellular level are also described and compared. Published examples of cellular dosimetry computations performed with radiotracers are reviewed in various clinical settings. Finally, the biological implications of the subcellular localization of Auger emitters are examined. While a number of efforts have been made to obtain dosimetric models and to estimate subcellular distribution of radioactivity, little is known of the cellular dosimetry of most radiopharmaceuticals used in diagnostic imaging. However, biological examples of selective radiotracer uptake have been shown, leading to extremely strong cell-cell dose heterogeneity. Furthermore, radiobiological experiments show that the biological effects of Auger emitters incorporated into DNA can be severe, with relative biological effectiveness greater than 1 compared with external X-rays. These findings clearly show that the assessment of biological risks associated with internal administration of diagnostic radiopharmaceuticals must focus not only on target organs as a whole, but also on the cellular level. This review proposes the most appropriate model for dosimetric computations (cellular or conventional) according to the subcellular distribution of radiotracers. The radionuclide of choice and the general strategy used to design new diagnostic radiopharmaceuticals are also discussed.

Book reviewThird International Radiopharmaceutical Dosimetry Symposium. Proceedings of a conference held at Oak Ridge, Tennessee, October 7–10, 1980. Edited and compiled by WatsonEvelyn E., Schlafke-StelsonAudrey T., CoffeyJack L. and CloutierRoger J., pp. xii + 669, 1981, HHS Publication FDA 81–8166 (BRG, Maryland, USA).

The Oak Ridge Laboratories have long been the repository of much that is known about internal dosimetry. This volume represents the proceedings of the Third International Symposium on Radiopharmaceutical Dosimetry which was held in October 1980. The papers are grouped together in the format of the conference.

Dosimetry of renal radiopharmaceuticals: the importance of bladder radioactivity and a simple aid for its estimation.

The contribution from radioactivity in bladder contents to dose commitments to the embryo, ovaries, red marrow, kidney, bladder wall and total body has been estimated for various renal radiopharmaceuticals, assuming a bladdervoiding period of 3.5 h. For hippuran and GFR agents this contribution is 70-97% of the embryo dose and 50-93% of the ovary dose. The embryo dose exceeds the ovary dose by a factor of two or more. For the radiopharmaceuticals with no significant kidney retention, the surface dose to the bladder wall is higher, by more than an order of magnitude, than doses to other organs and is largely responsible for the effective dose equivalent exceeding the estimated whole-body dose by factors of up to 25. Since the estimation of cumulated activity in bladder contents is necessary for bladder dosimetry, a nomogram based on a 3.5 h voiding period is presented as a convenient aid for this purpose.

Dosimetry of current radiopharmaceuticals used in renal investigation

Dosimetry of current radiopharmaceuticals used in renal investigation

Kinetics and dosimetry of radiopharmaceuticals utilized in evaluating liver, gall bladder and spleen

Kinetics and dosimetry of radiopharmaceuticals utilized in evaluating liver, gall bladder and spleen

Radiopharmaceutical dosimetry in pediatrics

The increasing use of radionuclides In diagnostic, procedures and the importance of minimizing radiation exposure in infants` and children necessitate accurate and detailed information concerning the radiation doses sustained from these procedures. This paper presents available information on the various parameters involved in radiopharmaceutical dosimetry in pediatrics. The age groups selected are the newborn and 1, 5, 10, and 15 yr. Measured and calculated parameters for these groups include: mass of whole body and target organs; effective halflives and cumulative activities for the various radiopharmaceuticals; equilibrium dose constants; and absorbed fractions for spheres and ellipsoids for target masses down to 1. Radiation doses to whole body and to certain target organs for the various radiopharmaceuticals are included. Some consideration is given to adjustment of the activities administered to children relative to that normally administered to adults.