Objectif Experimental studies of the biokinetics of radiolabelled HM-PAO, meta-iodobenzyl guanidine (MIBG) and methoxy isobutyl isonitrile (MIBI) and of the excretion of radionuclides in breast milk have been carried out. The biokinetics of technetium-99m HM-PAO have been studied in 8 children aged betwen 7 weeks and 18 years. There is a strong age dependence on the uptake in the brain with 20% for the very young children and 5% for the adults. The uptake in the lungs, liver, kidneys and intestines showed no age dependence. The organs or tissues receiving the highest absorbed doses are the gall bladder wall, bladder wall, kidneys, liver and upper large intestine wall. The effective dose (equivalent) per activity unit for a new born (0.11 u5v/MBq) is more than one order of magnitude higher than the value for an adult (0.008 uSv/MBq). It was found that, if the same activity per unit body weight is given to patients of various ages, this gives equal image quality.The biokinetics and dosimetry of iodine-131 MIBG in 2 patients of 3.5 years and 7 years have been studied. The clearance from blood was very rapid. Bone marrow aspiration was done at 24 hours post injection and the activity in the bone marrow measured. The study is ongoing.10 adult patients who were undergoing myocardial perfusion imaging with technetium-99m MIBI were followed with respect to the biodistribution and retention of technetium-99m. The upper large intestine, lower large intestine, kidneys and gallbladder receive the highest absorbed doses. The effective dose was estimated as 0.01 mSv/MBq. For a full investigation, at rest and during stress, 2 injections have to be given making a total effective dose of 13 mSv. New data has been collected concerning the excretion of technetium-99m labelled radionuclides in breast milk. The activity concentration is relatively independent of the total milk volume.Dosimetric studies of a recently developed myocardial perfusion imaging agent, technetium-99m-P53, a lipophilic technetium phosphine cation, have been carried out. Healthy male volunteers were investigated at rest and, more than 7 days later, after exercising to 85% of peak heart rate. The measurements included: quantitative whole body imaging with anterior and posterior views on 8 occasions between 5 minutes and 48 hours post injection; monitoring of whole blood and plasma clearance up to 24 hours; and total urinary and faecal clearance up to 48 hours. Whole blood acvtivity fell rapidly to less than 0.2% of administered activity per litre within 30 minutes. Whole body retention fell rapidly during the first hour and was only about 20% after 48 hours. After exercise, whole body retention was consistently about 10% higher than that at rest, largely as a result of enhanced upfalse in the leg muscles. Excreted activity was roughly shared equally between the urinary and faecal routes and approximately 80% of the administered activity was accounted for in the 48 hours excreta. Residence times were determined for the heart, liver, lungs, kidneys, salivary glands, gall bladder, urinary bladder and gastrointestinal tract and for the remaining body. At rest, the highest dose estimate was to the gall bladder (49 uGy/MBq), followed by the gastrointestinal tract (17 to 39 uGy/MBq), urinary bladder (19 uGy/MBq) and salivary glands (12 uGy/MBq) with all other organs receiving less than 10 uGy/MBq. After exercise, doses to these organs were reduced to about 70% of those at rest but total body doses were similar in both studies. The effective dose was 8.9 uSv/MBq at rest and 7.1 uSv/MBq after exercise, assuming a bladder voiding period of 3.5 hours.Similar studies have been initiated on technetium-99m-S12, an antibody against arthrosclerotic plaque.Tools are being developed to simulate the transport of radiation within the body. The method chosen uses Monte Carlo techniques. The necessary geometric information concerning the positions, sizes and forms of the important tissues and organs is taken form a computer tomography investiagtion of a 7 week old baby. For the simulation of the radiation transport, an existing computer code was used which was developed for the dosimetry of external irradiations (ie for diagnostic radiology). The program was modified to allow the use of arbitrary internal sources in any tissue of interest. The code was developed and tested on a parallel computer especially well suited for Monte Carlo simulations. The computational power guarantees the possibility to reduce statistical uncertainties as far as necessary (at present below 10%). The calculations will enable comparison of the results of this method with that using mathematical anthropomorphic phantoms and a decision as to whether the improvements, which may be expected especially for children, are sufficiently substantial to continue with the development of other voxel phantoms (other ages) for internal dosimetry.Patient dose from radiopharmaceuticals The accuracy of the current data on absorbed dose from radiopharmaceuticals into patients, specifically to children of various ages, will be improved. This will be done by: improving the biokinetic data for selected radiopharmaceuticals by repeated uptake and retention measurements on patients; special attention will be given to new radiopharmaceuticals recently taken into clinical use and biokinetics for children; improving the physical basis for the dose calculations by using detailed voxel-phantoms based on CT/MR data for Monte Carlo calculations of new S-values, especially for children. The results will be used to quantify organ doses as well as effective dose equivalents. The results will help to compare different radionuclides for labelling in view of balancing diagnostic benefit and radiation dose, and to determine the appropriate activity to be administered in order to avoid unnecessary radiation exposure of the patient. Champ scientifique natural scienceschemical sciencesinorganic chemistrytransition metalsmedical and health sciencesclinical medicineradiologynatural sciencescomputer and information sciencescomputational sciencenatural scienceschemical sciencesnuclear chemistryradiation chemistry Programme(s) FP2-RADPROT 7C - Specific multiannual research and training programme (Euratom) in the field of radiation protection, 1990-1991 Thème(s) Data not available Appel à propositions Data not available Régime de financement CSC - Cost-sharing contracts Coordinateur LUND UNIVERSITY Contribution de l’UE Aucune donnée Adresse 3,Lasarettet 221 00 LUND Suède Voir sur la carte Coût total Aucune donnée Participants (2) Trier par ordre alphabétique Trier par contribution de l’UE Tout développer Tout réduire GSF - FORSCHUNGSZENTRUM FUER UMWELT UND GESUNDHEIT GMBH Allemagne Contribution de l’UE Aucune donnée Adresse Ingolstaedter Landstrasse 1 85764 NEUHERBERG Voir sur la carte Liens Site web Opens in new window Coût total Aucune donnée MRC Clinical Research Centre Royaume-Uni Contribution de l’UE Aucune donnée Adresse Watford Road HA1 3UJ Harrow Voir sur la carte Coût total Aucune donnée
