| 1. |
- Ballantyne, Kaye N., et al.
(författare)
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Toward Male Individualization with Rapidly Mutating Y-Chromosomal Short Tandem Repeats
- 2014
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Ingår i: Human Mutation. - : John Wiley & Sons. - 1059-7794 .- 1098-1004. ; 35:8, s. 1021-1032
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Tidskriftsartikel (refereegranskat)abstract
- Relevant for various areas of human genetics, Y-chromosomal short tandem repeats (Y-STRs) are commonly used for testing close paternal relationships among individuals and populations, and for male lineage identification. However, even the widely used 17-loci Yfiler set cannot resolve individuals and populations completely. Here, 52 centers generated quality-controlled data of 13 rapidly mutating (RM) Y-STRs in 14,644 related and unrelated males from 111 worldwide populations. Strikingly, greater than99% of the 12,272 unrelated males were completely individualized. Haplotype diversity was extremely high (global: 0.9999985, regional: 0.99836-0.9999988). Haplotype sharing between populations was almost absent except for six (0.05%) of the 12,156 haplotypes. Haplotype sharing within populations was generally rare (0.8% nonunique haplotypes), significantly lower in urban (0.9%) than rural (2.1%) and highest in endogamous groups (14.3%). Analysis of molecular variance revealed 99.98% of variation within populations, 0.018% among populations within groups, and 0.002% among groups. Of the 2,372 newly and 156 previously typed male relative pairs, 29% were differentiated including 27% of the 2,378 father-son pairs. Relative to Yfiler, haplotype diversity was increased in 86% of the populations tested and overall male relative differentiation was raised by 23.5%. Our study demonstrates the value of RMY-STRs in identifying and separating unrelated and related males and provides a reference database.
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| 2. |
- Andersson, Martin, et al.
(författare)
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An internal radiation dosimetry computer program, IDAC 2.0, for estimation of patient doses from radiopharmaceuticals
- 2014
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 162:3, s. 299-305
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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.
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| 3. |
- Andersson, Martin, et al.
(författare)
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An upgrade of the internal dosimetry computer program IDAC
- 2012
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Ingår i: Medical Physics in the Baltic States. - : Kaunas University of Technology. - 1822-5721. ; , s. 120-123
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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.
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| 4. |
- Andersson, Martin, et al.
(författare)
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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
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Ingår i: EJNMMI Physics. - : Springer. - 2197-7364. ; 1:1
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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.
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| 5. |
- Andersson, Martin, et al.
(författare)
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Improved estimates of the radiation absorbed dose to the urinary bladder wall
- 2014
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Ingår i: Physics in Medicine and Biology. - : Institute of Physics Publishing (IOPP). - 0031-9155 .- 1361-6560. ; 59:9, s. 2173-2182
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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.
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| 6. |
- Minarik, David, et al.
(författare)
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90Y Bremsstrahlung Imaging for Absorbed-Dose Assessment in High-Dose Radioimmunotherapy.
- 2010
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 2159-662X. ; 51:12, s. 1974-1978
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Tidskriftsartikel (refereegranskat)abstract
- This feasibility study demonstrates (90)Y quantitative bremsstrahlung imaging of patients undergoing high-dose myeloablative (90)Y-ibritumomab treatment. METHODS: The study includes pretherapy (111)In SPECT/CT and planar whole-body (WB) imaging at 7 d and therapy (90)Y SPECT/CT at 6 d and (90)Y WB imaging at 1 d. Time-activity curves and organ-absorbed doses derived from (90)Y SPECT images were compared with pretherapy (111)In estimates. Organ activities derived from (90)Y WB images at the first day were compared with corresponding pretherapy estimates. RESULTS: Pretherapy (111)In images from 3 patients were similar to the (90)Y images. Differences between absorbed-dose estimates from pretherapy (111)In and (90)Y therapy were within 25%, except for the lungs. Corresponding activity differences derived from WB images were within 25%. Differences were ascribed to incomplete compensation methods and real differences in pharmacokinetics between pretherapy and therapy. CONCLUSION: Quantitative bremsstrahlung imaging to estimate organ activities and absorbed doses is feasible.
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| 7. |
- Minarik, David
(författare)
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Activity quantification based on scintillation camera imaging - Application to 111In/90Y radioimmunotherapy
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Radionuclide therapy (RNT), is important for the treatment of certain benign and malignant diseases. 90Y-Zevalin™ therapy has become an established method of treating patients with non-Hodgkin B-cell lymphoma. Several observ¬ations regarding the outcome of therapy have prompted the use of higher absorbed doses by administering larger amounts of activity than those indicated in standard protocols. This type of treatment, which generally requires bone marrow support, increases the risk of deterministic effects on healthy organs and, therefore, requires the use of reliable patient-specific internal dosimetry. An important part of patient-specific dosimetry is the quantification of the activity of the radiopharmaceutical by means of scintillation camera imaging. The aim of the work presented in this thesis was thus to develop quantitative scintillation camera imaging methods in 2 and 3 dimensions. A method for planar activity quantification and absorbed dose assess¬ment is presented and evaluated (Paper I). The planar quantification method requires a narrow-beam, patient-specific attenuation map, which can be obtained through a transmission study using an external radionuclide source. This method has clear drawbacks, which prompted investigations of the use of a whole-body X-ray image for attenuation correction. The method is based on acquiring a whole-body X-ray image using the CT unit on a hybrid SPECT/CT system (Paper II). 90Y only emits β-particles, and has previously been considered difficult to image. The radionuclide 111Indium has therefore been used as a substitute tracer for imaging purposes. However, free unbound 111In and 90Y behave differently in vivo. It would thus be of interest to be able to image 90Y alone, without an admixture of 111In. This could be done by detecting the bremsstrahlung that is produced when β-particles interact with tissue. The feasibility of quantitative bremsstrahlung SPECT (paper III) and quantitative planar whole-body imaging (paper IV) have been investigated by means of simulations and measure¬ments using phantoms. The feasibility of these 90Y bremsstrahlung imaging procedures has also been investigated using data from patients undergoing 90Y-Zevalin treatment for B-cell lymphoma (Paper V).
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| 8. |
- Nakajima, K., et al.
(författare)
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Improved quantification of small hearts for gated myocardial perfusion imaging
- 2013
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Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 40:8, s. 1163-1170
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Tidskriftsartikel (refereegranskat)abstract
- In patients with a small heart, defined as an end-systolic volume (ESV) of a parts per thousand currency sign20 mL calculated using the Quantitative Gated SPECT (QGS) program, underestimation of ESV and overestimation of ejection fraction (EF) using gated myocardial perfusion imaging are considered errors caused by inappropriate delineation of the left ventricle (LV). The aim of this study was to develop a new method for delineation of the LV and to evaluate it in studies using a digital phantom, normal subjects and patients. The active shape-based method for LV delineation, EXINI heart (ExH), was adjusted to more accurately process small hearts. In small hearts, due to the partial volume effect and the short distance to the opposite ventricular wall, the endocardial and the epicardial surfaces are shifted in the epicardial direction depending on the midventricular volume. The adjusted method was evaluated using digital XCAT phantoms with Monte Carlo simulation (8 virtual patients), a Japanese multicentre normal database (69 patients) and consecutive Japanese patients (116 patients). The LV volumes, EF and diastolic parameters derived from ExH and QGS were compared. The digital phantom studies showed a mean ESV of 87 % +/- 9 % of the true volume calculated using ExH and 22 % +/- 18 % calculated using QGS. In the normal database, QGS gave higher EFs in women than in men (71.4 +/- 6.0 % vs. 67.2 +/- 6.0 %, p = 0.0058), but ExH gave comparable EFs (70.7 +/- 4.9 % and 71.4 +/- 5 % in men and women, respectively, p = ns). QGS gave higher EFs in subjects with a small heart than in those with a normal-sized heart (74.5 +/- 5.1 % vs. 66.1 +/- 4.9 %), but ExH gave comparable values (70.0 +/- 5.9 % vs. 71.6 +/- 4.2 %, respectively, p = ns). In consecutive patients, the average EFs with QGS in patients with ESV > 20 mL, 11-20 mL and a parts per thousand currency sign10 mL were 57.9 %, 71.9 % and 83.2 %, but with ExH the differences among these groups were smaller (65.2 %, 67.8 % and 71.5 %, respectively). The volume-dependent edge correction algorithm was able to effectively reduce the effects on ESV and EF of a small heart. The uniform normal values might be applicable to both men and women and to both small and normal-sized hearts.
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