Mikko Faarinen

Biokinetics and radiation dosimetry for patients undergoing a glycerol tri[1-14C]oleate fat malabsorption breath test.

The glycerol tri[1-14C]olein test for fat malabsorption was carried out in two male volunteers and measurements of the loss of 14C in expired air, urine and faeces and the retention of 14C in biopsy samples of abdominal fat were made using accelerator mass spectrometry. Exhalation accounted for 73% and 55% of the administered activity and could be described by three-component exponential functions with halftimes of about 1h, 2 days and 150 days, respectively. Urinary excretion accounted for 24% of the administered activity, almost all during the first 24h after administration; about 2% was excreted in the faeces in 48h. The halftime of retention of 14C in fat ranged from 137 to 620 days. Absorbed dose calculations indicate that for a normal adult the largest dose, 1.5-7.0mGy/MBq is received by the adipose tissue, and that the effective dose is 0.3-0.5mSv/MBq. It is concluded that no restrictions need to be placed on radiation safety grounds on the administration of 0.05-0.1MBq 14C-triolein for the triolein breath test.

Detection of 59Ni at the Lund AMS facility

Abstract In the use of small tandem accelerators for accelerator mass spectrometry (AMS), interfering isobars are often troublesome, especially when heavier isotopes such as 59Ni are to be measured. One way to reduce this problem is to combine AMS with the detection of characteristic projectile X-rays. After analysis in the AMS system, the ions are stopped in a suitable target and it is possible to identify the ions by atomic number and thereby separate the isobars. In order to lower the detection limit in the case of 59Ni in stainless steel samples, it is necessary to chemically reduce the content of 59Co in the sample. Further improvements in the reduction of the X-ray background and in the chemical reduction of cobalt have led to nearly a factor of 10 lower detection limit of 59Ni at the Lund AMS facility compared to what has been reported earlier. The content of 59Ni in some steel samples obtained from Swedish nuclear power plants has been measured and the results are presented here.

AMS studies of the long-term turnover of -labelled fat in man

Abstract To estimate the biokinetics of 14 C -labelled fatty acids and the associated radiation absorbed dose to man, long-term retention of 14 C from oral intake of glycerol tri[1- 14 C ]oleate (triolein) has been studied using accelerator mass spectrometry (AMS). As a complement to earlier reported data for three individuals, we present here results for one person from measurements up to 4.6 yr after administration, now also including 14 C -levels in fat, muscle and bone. In this subject, a total of 44% of the administered activity was recovered in the exhaled air. Fasting increased the exhalation of 14 C . The “excess” 14 CO 2 due to fasting had a half-life of about 400 d. AMS measurements on fat, muscle and bone biopsies taken from the same subject 4.5 yr after ingestion indicated that a small fraction of the administered activity was still present in fat. Also, bone tissue had a higher 14 C specific activity than the current environmental level. No significantly increased level was found in the muscle sample.

The charge state distribution of a carbon beam measured at the lund pelletron accelerator with the newly installed terminal pumping system in use

Charge state distributions for (12) C and C-13 ions have been measured at the Lund Pelletron tandem accelerator for the N-2 gas stripper with a newly installed terminal pumping system in use. A comparison of the results obtained for the ion energies between 1.5 and 2.8 MeV with the foil stripper and the gas stripper without terminal pumping demonstrates the great improvement of the stripping process achieved with the new terminal pumping

Dating of some Romanian fossil bones by combined nuclear methods

A set of fossil bones from Romania has been analysed by accelerator mass spectrometry and by neutron activation analysis in order to estimate their age. The temporal attributing of Malu Rosu archaeological settlement has been extensively analyzed. The radiocarbon age, determined by accelerator mass spectrometry, for this site is 5510±200 BP. This is in agreement with the age of 6000±2000 BP, obtained by the dating method based on fluorine content, determined by neutron activation analysis.

26Al investigations at the AMS-laboratory in Lund

At the accelerator mass spectrometry (AMS) laboratory in Lund, a facility for (26)Al analysis is under development. The sensitivity is expected to be several orders of magnitude higher than with standard mass spectrometry. The planned biomedical program includes studies of aluminium uptake, distribution and retention in man. The initial work has been concentrated on the construction and testing of a new dedicated injector for the accelerator and on the preparation of biological samples for aluminium analysis. The current quality of the facility is presented and the first experimental results reported.

Characteristic X-ray production in heavy ion collisions

The characteristic K X-ray production from projectile and solid target atoms in heavy ion collisions have been measured using a high-resolution Ge-detector. Ni projectiles in the energy range 15–25 MeV have been used to irradiate various thick targets made of materials in the Z range 22–32. In this energy region, the transition from predominantly quasi-molecular excitation to predominantly Coulomb excitation occurs. These measurements have been done in connection with our programme with a fairly new analytical technique, a combination of accelerator mass spectrometry (AMS) and the detection of characteristic X-rays. From the measurements, experimental K X-ray cross-sections have been extracted. Comparisons with other experimental data as well as with theoretical values are presented.

Some examples of the application of an analitical technique to ion-optical calculations for a new injector of the Lund Pelletron accelerator

Abstract The 3UDH Pelletron tandem accelerator in Lund is being developed to be more suitable for accelerator mass spectrometry of heavy ions. This development includes the installation of an electrostatic and a magnetic analyzer in a new injector aimed to obtain better mass and energy separation. In the present paper some applications of the first-order analytical calculation technique, used at the design stage of the new injector, are discussed. The estimation of the maximum possible opening of the analyzer slits was carried out, followed by the calculation of the analyzer acceptances. The values of the acceptances for the two transversal planes, as well as their contours are given. Some results of more detailed numerical calculation of the ion beam transport through the analyzers are reported.

Biokinetic and dosimetric investigations of 14C-labeled substances in man using AMS

Up to now, radiation dose estimates from radiopharmaceuticals, labeled with pure β-emitting radionuclides, e.g., 14C or 3H have been very uncertain. Using accelerator mass spectrometry (AMS) we have derived new and improved data for 14C-triolein and 14C-urea and are currently running a program related to the biokinetics and dosimetry of 14C-glycocholic acid and 14C-xylose. The results of our investigations have made it possible to widen the indications for the clinical use of the 14C-urea test for Helicobacter pylori infection in children. The use of ultra-low activities, which is possible with AMS (down to 1/1000 of that used for liquid scintillation counting), has opened the possibility for metabolic investigations on children as well as on other sensitive patient groups like new-borns, and pregnant or breast-feeding women. Using the full potential of AMS, new 14C-labeled drugs could be tested on humans at a much earlier stage than today, avoiding uncertain extrapolations from animal models.

Environmental radiation protection studies related to nuclear industries, using AMS

14C is produced in nuclear reactors during normal operation and part of it is continuously released into the environment. Because of the biological importance of carbon and the long physical half-life of 14C it is of interest to study these releases. The 14C activity concentrations in the air and vegetation around some Swedish as well as foreign nuclear facilities have been measured by accelerator mass spectrometry (AMS). 59Ni is produced by neutron activation in the stainless steel close to the core of a nuclear reactor. The 59Ni levels have been measured in order to be able to classify the different parts of the reactor with respect to their content of long-lived radionuclides before final storage. The technique used to measure 59Ni at a small accelerator such as the Lund facility has been developed over the past few years and material from the Swedish nuclear industry has been analyzed.