| 1. |
|
|
| 2. |
- Andersson, Martin, et al.
(författare)
-
An internal radiation dosimetry computer program, IDAC 2.0, for estimation of patient doses from radiopharmaceuticals
- 2014
-
Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 162:3, s. 299-305
-
Tidskriftsartikel (refereegranskat)abstract
- The internal dosimetry computer program internal dose assessment by computer (IDAC) for calculations of absorbed doses to organs and tissues as well as effective doses to patients from examinations with radiopharmaceuticals has been developed. The new version, IDAC2.0, incorporates the International Commission on Radiation Protection (ICRP)/ICRU computational adult male and female voxel phantoms and decay data from the ICRP publication 107. Instead of only 25 source and target regions, calculation can now be made with 63 source regions to 73 target regions. The major advantage of having the new phantom is that the calculations of the effective doses can be made with the latest tissue weighting factors of ICRP publication 103. IDAC2.0 uses the ICRP human alimentary tract (HAT) model for orally administrated activity and for excretion through the gastrointestinal tract and effective doses have been recalculated for radiopharmaceuticals that are orally administered. The results of the program are consistent with published data using the same specific absorption fractions and also compared with published data from the same computational phantoms but with segmentation of organs leading to another set of specific absorption fractions. The effective dose is recalculated for all the 34 radiopharmaceuticals that are administered orally and has been published by the ICRP. Using the new HAT model, new tissue weighting factors and the new adult computational voxel phantoms lead to an average effective dose of half of its earlier estimated value. The reduction mainly depends on electron transport simulations to walled organs and the transition from the stylised phantom with unrealistic interorgan distances to more realistic voxel phantoms.
|
|
| 3. |
- Andersson, Martin, et al.
(författare)
-
An upgrade of the internal dosimetry computer program IDAC
- 2012
-
Ingår i: Medical Physics in the Baltic States. - : Kaunas University of Technology. - 1822-5721. ; , s. 120-123
-
Konferensbidrag (refereegranskat)abstract
- A full update of the internal dosimetry computer program IDAC has been conducted. The new update is based on new and more accurate computational phantoms to calculate effective dose and absorbed dose to organs and tissues. The new ICRP Adult Reference Computational Phantoms has been adopted as well as the latest of the ICRP standardized biokinetic models. The updated computer program includes a user-friendly graphical user interface.
|
|
| 4. |
- Andersson, Martin, et al.
(författare)
-
Effective dose to adult patients from 338 radiopharmaceuticals estimated using ICRP biokinetic data, ICRP/ICRU computational reference phantoms and ICRP 2007 tissue weighting factors
- 2014
-
Ingår i: EJNMMI Physics. - : Springer. - 2197-7364. ; 1:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Effective dose represents the potential risk to a population of stochastic effects of ionizing radiation (mainly lethal cancer). In recent years, there have been a number of revisions and updates influencing the way to estimate the effective dose. The aim of this work was to recalculate the effective dose values for the 338 different radiopharmaceuticals previously published by the International Commission on Radiological Protection (ICRP).Method: The new estimations are based on information on the cumulated activities per unit administered activity in various organs and tissues and for the various radiopharmaceuticals obtained from the ICRP publications 53, 80 and 106. The effective dose for adults was calculated using the new ICRP/International Commission on Radiation Units (ICRU) reference voxel phantoms and decay data from the ICRP publication 107. The ICRP human alimentary tract model has also been applied at the recalculations. The effective dose was calculated using the new tissue weighting factors from ICRP publications 103 and the prior factors from ICRP publication 60. The results of the new calculations were compared with the effective dose values published by the ICRP, which were generated with the Medical Internal Radiation Dose (MIRD) adult phantom and the tissue weighting factors from ICRP publication 60.Results: For 79% of the radiopharmaceuticals, the new calculations gave a lower effective dose per unit administered activity than earlier estimated. As a mean for all radiopharmaceuticals, the effective dose was 25% lower. The use of the new adult computational voxel phantoms has a larger impact on the change of effective doses than the change to new tissue weighting factors.Conclusion: The use of the new computational voxel phantoms and the new weighting factors has generated new effective dose estimations. These are supposed to result in more realistic estimations of the radiation risk to a population undergoing nuclear medicine investigations than hitherto available values.
|
|
| 5. |
- Andersson, Martin, et al.
(författare)
-
Improved estimates of the radiation absorbed dose to the urinary bladder wall
- 2014
-
Ingår i: Physics in Medicine and Biology. - : Institute of Physics Publishing (IOPP). - 0031-9155 .- 1361-6560. ; 59:9, s. 2173-2182
-
Tidskriftsartikel (refereegranskat)abstract
- Specific absorbed fractions (SAFs) have been calculated as a function of the content in the urinary bladder in order to allow more realistic calculations of the absorbed dose to the bladder wall. The SAFs were calculated using the urinary bladder anatomy from the ICRP male and female adult reference computational phantoms. The urinary bladder and its content were approximated by a sphere with a wall of constant mass, where the thickness of the wall depended on the amount of urine in the bladder. SAFs were calculated for males and females with 17 different urinary bladder volumes from 10 to 800 mL, using the Monte Carlo computer program MCNP5, at 25 energies of mono-energetic photons and electrons ranging from 10 KeV to 10 MeV. The decay was assumed to be homogeneously distributed in the urinary bladder content and the urinary bladder wall, and the mean absorbed dose to the urinary bladder wall was calculated. The Monte Carlo simulations were validated against measurements made with thermoluminescent dosimeters. The SAFs obtained for a urine volume of 200 mL were compared to the values calculated for the urinary bladder wall using the adult reference computational phantoms. The mean absorbed dose to the urinary wall from F-18-FDG was found to be 77 mu Gy/MBq formales and 86 mu Gy/MBq for females, while for (99)mTc-DTPA the mean absorbed doses were 80 mu Gy/MBq for males and 86 mu Gy/MBq for females. Compared to calculations using a constant value of the SAF from the adult reference computational phantoms, the mean absorbed doses to the bladder wall were 60% higher for F-18-FDG and 30% higher for (99)mTc-DTPA using the new SAFs.
|
|
| 6. |
- Aurumskjöld, Marie-Louise, et al.
(författare)
-
A PHANTOM STUDY SHOWING THE IMPORTANCE OF COMPRESSION IN CONVENTIONAL DIAGNOSTIC X-RAY EXAMINATIONS.
- 2010
-
Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; Apr 7, s. 78-80
-
Tidskriftsartikel (refereegranskat)abstract
- Compression was earlier an important and well-managed part of the clinical routine, but during the past 15-20 y the use has diminished, except for mammography, where it is a prerequisite for having images of high quality and low radiation dose. According to national and European regulations and recommendations, it is important to apply the compression technique to obtain the optimal image quality and radiation dose in common conventional diagnostic examinations. Current experience of compression technique is, however, based on studies carried out a long time ago and with analogue imaging techniques. An anthropomorphic phantom was used to show the importance of compression in conventional X-ray examinations. The patient thicknesses on volunteers with and without compression was measured. This measurement was done to investigate compression potential on patients and to select suitable phantom thicknesses. The X-ray examinations that were included in the study were abdomen overview, lumbar spine and the pelvis. The results from the phantom study showed a large dependency of the kerma-area product value on the phantom thickness. The phantom study suggests that there is a potential for significant reduction of radiation dose to the patient by using compression also with modern X-ray techniques. A dose reduction of up to 50 % or even more may be obtained.
|
|
| 7. |
- Bernhardsson, Christian, et al.
(författare)
-
Comparative Measurements of the External Radiation Exposure in a 137Cs Contaminated Village in Belarus Based on Optically Stimulated Luminescence in NaCl and Thermoluminescence in LiF.
- 2012
-
Ingår i: Health Physics. - 1538-5159. ; 103:6, s. 740-749
-
Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: Laboratory studies have shown that ordinary household salt (NaCl) exhibits several promising properties for retrospective dosimetry; e.g., a linear dose response and a low detection limit, down to a few mGy or even less. In an attempt to test NaCl as a dosimeter outside the laboratory, the first results from the use of NaCl as a dosimeter under normal environmental conditions are reported here. For this purpose, special dosimeter kits with NaCl and lithium fluoride (LiF) chips were designed. The dosimeter kits were positioned at different locations in a Chernobyl Cs-contaminated village in Belarus during the summers of 2008, 2009, and 2010. The results from the two luminescent detectors were also compared with those of measurements carried out with a handheld 75 cm NaI(Tl) detector and with a 8 dm high pressure ionization chamber. The radiation level in the village was inhomogeneous, and depending on the type of house and countermeasures carried out, the ambient dose rate inside and around the houses varied between 0.05 μSv h and 0.50 μSv h. Based on the different measurements, the annual external effective dose to a hypothetical adult population in the village was estimated as 1-1.5 mSv y. Detector readings from the two luminescent materials correlated relatively strongly to that of the ambient survey NaI(Tl) detector. After three repeated surveys using similar dosimeter kits for prospective dosimetry, the potential use of ordinary household salt as a complement to other techniques for retrospective dose estimations is more evident, and shortcomings of the technique have been identified.
|
|
| 8. |
- Bernhardsson, Christian, et al.
(författare)
-
Measurements of long-term external and internal radiation exposure of inhabitants of some villages of the Bryansk region of Russia after the Chernobyl accident
- 2011
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 1879-1026 .- 0048-9697. ; 409:22, s. 4811-4817
-
Tidskriftsartikel (refereegranskat)abstract
- A Nordic-Soviet programme was initiated in 1990 to evaluate the external and internal radiation exposure of the inhabitants of several villages in the Bryansk region of Russia. This area was one of the number of areas particularly affected by the nuclear accident at the Chernobyl Nuclear Power Plant in 1986. Measurements were carried out yearly until 1998 and after that more irregularly; in 2000, 2006 and 2008 respectively. The effective dose estimates were based on individual thermoluminescent dosemeters and on in vivo measurements of the whole body content of (137)Cs (and (134)Cs during the first years of the programme). The decrease in total effective dose during the almost 2 decade follow-up was due to a continuous decrease in the dominating external exposure and a less decreasing but highly variable exposure from internal irradiation. In 2008, the observed average effective dose (i.e. the sum of external and internal exposure) from Chernobyl (137)Cs to the residents was estimated to be 0.3mSvy(-1). This corresponds to 8% of the estimated annual dose in 1990 and to 1% of the estimated annual dose in 1986. As a mean for the population group and for the period of the present study (2006-2008), the average yearly effective dose from Chernobyl cesium was comparable to the absorbed dose obtained annually from external exposure to cosmic radiation plus internal exposure to naturally occurring radionuclides in the human body. Our data indicate that the effective dose from internal exposure is becoming increasingly important as the body burdens of Chernobyl (137)Cs are decreasing more slowly than the external exposure. However, over the years there have been large individual variations in both the external and internal effective doses, as well as differences between the villages investigated. These variations and differences are presented and discussed in this paper.
|
|
| 9. |
|
|
| 10. |
- Bernhardsson, Christian, et al.
(författare)
-
Variation in gamma dose rate in different locations following the Chernobyl accident
- 2013
-
Ingår i: Medical Physics in the Baltic States : Proceedings of the 11th International Conference on Medical Physics - Proceedings of the 11th International Conference on Medical Physics. - 1822-5721. ; , s. 127-130
-
Konferensbidrag (refereegranskat)abstract
- Radionuclides from the Chernobyl accident were released and dispersed during a limited period of time, but under different weather conditions. As a result the radionuclides were unevenly distributed on the ground. During the years the initial deposition has been altered at some locations by different processes, but remains relatively unchanged in others. Here we report on the current inhomogeneous radionuclide distribution, on both large- and small scales (1 cm2 – 10ths of km2), which on average varies a factor of 4.
|
|
