Autoradiographical methods for the assessment of radionuclides in hot particles on filter samples.

Three different autoradiographical methods were tested for detection, localisation and quantification of radionuclides in hot particles deposited on air filters. With all methods, hot particles could successfully be localised on air filters. Two methods, a X-ray film technique and a digital autoradiography technique using a microchannel array detector, have been examined with particles of known activity and with particles on air filter samples of the Chernobyl area to be able to quantify the 90Sr activity in the hot particles consistently. The results obtained in this study suggest that the digital autoradiography system is a very useful tool having a high efficiency with a low measurement uncertainty and allowing short exposure times for extensive measurement tasks.     

Alternative radiochemical heavy ion activation methods for the production and separation of thallium radionuclides.

Heavy ion activation of natural gold foil with a 7Li beam results in the formation of carrier-free 199-201Pb radionuclides along with their corresponding decay products, 199-201Tl, in the matrix. At 49 MeV projectile energy, the production of 199Tl through its precursor 199Pb is maximal, while that of other. thallium radionuclides is minimal. Another way for the direct production of carrier-free thallium radionuclides is to irradiate natural platinum foil with a 7Li beam; on this case, production of 199Tl is maximal at 43 MeV projectile energy. The carrier-free thallium radionuclides have been separated from the bulk target matrix gold and platinum by liquid-liquid extraction using trioctylamine as a liquid anion exchanger.     

Use of alanine for dosimetry intercomparisons among Italian radiotherapy centers.

A pilot program of postal dosimetry intercomparison among 16 Italian Radiotherapy Centers was performed using the ISS Alanine/EPR dosimetry as a transfer system. Dosimeters were irradiated at 10 Gy with high-energy photon beams, both in reference condition in a water phantom and in an anthropomorphic phantom during the simulated treatment of rectum cancer. Intercomparison design along with alanine performances analyzing the different contributions to the combined uncertainty in dose assessment are reported. Main results of the pilot intercomparison, terminated in 2002, are also presented.     

Establishing measurement traceability for national laboratories: Results of an IAEA comparison of I

A radioactivity measurement comparison for solutions of ¹³¹I was conducted by the International Atomic Energy Agency for participants in one of its Cooperative Research Projects aimed at enhancing quality assurance practices in nuclear medicine. The comparison solutions were prepared from a single master stock solution and distributed to the participating laboratories, who measured the activity concentration of the solution using either the laboratory's radionuclide activity calibrator or primary standardization methods. From the 7 results received, a Comparison Reference Value was calculated to be 37.35(78) MBq g⁻¹ at the reference time. Degrees of equivalence, as defined by the Mutual Recognition Agreement (MRA) of the Comité International des Poids et Mesures (CIPM), were calculated for each laboratory, demonstrating that equivalence to within ±4% could be achieved. The comparison has been registered as a supplementary comparison with the CIPM, Consultative Committee for Ionizing Radiation, Section II—measurement of radionuclides (CCRI(II)) for the purposes of allowing the participants to establish traceability to international standards for this radionuclide.     

An intercomparison of non-radiometric methods for the measurement of low levels of radionuclides

Instrumental methods of elemental analysis are outlined and their applicability to the measurement of low levels of radionuclides is discussed. Problem types in the field of low-level radionuclide measurement are described and the non-radiometric methods suited to the various type of radio-analytical problem outlined. Analysis of well characterised samples provides illustrative examples of the advantages and disadvantages of non-radiometric methods.     

S values for radionuclides localized within the skeleton.

Calculations of radiation absorbed dose to the active marrow are important to radionuclide therapies such as radioimmunotherapy and bone pain palliation. In diagnostic nuclear medicine, calculations of the effective dose for radiopharmaceutical procedures also require the assessment of radiation dose to the skeletal endosteum. We have previously reported the development of 2 3-dimensional electron transport models for assessing absorbed fractions to both marrow and endosteum in trabecular and cortical bone, respectively. Here, we extend these calculations to the assignment of radionuclide S values. METHODS: Data published in International Commission on Radiological Protection Publication 70 were used to develop tables of masses for total marrow space, active and inactive marrow, endosteum, and bone matrix within 22 skeletal sites in the adult. Using our site-specific tissue masses, along with electron absorbed fractions given by our 3-dimensional transport models, radionuclide S values (electron and beta particle components only) were subsequently calculated using the MIRD schema for 32P, 33P, 89Sr, 90Sr, 90Y, 117mSn, 153Sm, 169Er, 177Lu, and 186Re. Specific consideration was given to the trabecular active marrow as both a source and a target region. RESULTS: Site-specific radionuclide S values are reported for 22 skeletal sites, for 9 source-target tissue combinations within trabecular bone, and for 6 source-target tissue combinations within cortical bone. Skeletal-averaged S values are also provided. CONCLUSION: A fully documented model is presented for the adult for use in radionuclide dosimetry of the skeleton. The model is based on both the latest international recommendations for skeletal tissue masses and results from three-dimensional electron transport calculations within the skeleton. Comparisons are additionally made against the radionuclide S values published in MIRD Pamphlet No. 11 and those calculated using the MIRDOSE2 and MIRDOSE3 computer codes. Differences in these datasets vary with the source-target combination considered and may be attributed to 1 of 3 causes: (a) assumptions on reference target masses, (b) transport models used to assign absorbed fractions, and (c) implicit assumptions made in considering the trabecular active marrow as both a source and a target tissue.     

Transfer standard for beta decay radionuclides in radiotherapy.

The measurement of the activity of therapeutic radiopharmaceuticals prior to the administration to patients is normally achieved via the use of radionuclide calibrators. An accurate measurement of the activity of pure beta-emitters is complex. Calibration problems can be solved by combining a primary calibration with a 90Y reference solution and a 90Sr/90Y transfer standard with a solid source, simulating geometric effects caused by high energetic beta radiation. The recent development of a 90Sr/90Y transfer standard for this purpose is reported.     

Testing models for predicting the behaviour of radionuclides in aquatic systems.

The paper describes the main results of the international EMRAS model testing exercise for radionuclide transport in watershed-river and estuarine systems. The exercises included the following scenarios: multi-point source of (3)H discharge into the Loire River (France), radioactive contamination of the Dnieper-Southern Boug estuary (Ukraine), remobilisation of radionuclide contamination from the Pripyat River floodplain (Ukraine) following the Chernobyl accident, release of radionuclides into the Techa River (Russia) and behaviour of (226)Ra in the Huelva estuary (Spain).     

Biological intercomparisons of neutron beams used for radiotherapy generated by p(+)-->Be in hospital-based cyclotrons.

The new generation of hospital-based neutron therapy facilities involve cyclotrons using protons on beryllium. The spectrum of neutrons produced includes a large and variable proportion of low-energy neutrons that are poorly penetrating but biologically effective. Cells cultured in vitro were used to compare the three US facilities at Seattle, M.D. Anderson and UCLA, together with the UK facility at Clatterbridge. Cyclotrons were compared within a given experiment on the same day using cells from a common suspension. Among the three US facilities, the relative potency factor at a depth of 25 mm differs by about 11%, with Seattle the least and UCLA the most biologically effective. Clatterbridge was compared directly with M.D. Anderson and found to be less effective by about 5%; it has a slightly lower biological effectiveness than any of the US facilities. There is evidence for an increased biological effectiveness in the build-up region, which reduces the effective skin sparing potential. There is not much difference in build-up between the three US facilities. Using the proton-on-beryllium neutron production process results in a wide spectrum of neutrons with a large but variable low-energy component. The biological effectiveness of the beam depends on target design and thickness as well as the design of the collimating system. Consequently the biological effectiveness of neutron beams generated by this process must be assessed on an individual basis. It cannot be assumed that because cyclotrons have similar accelerating energies that the relative biological effectiveness will be the same.     

Evaluating fMRI methods for assessing hemispheric language dominance in healthy subjects

We evaluated two methods for quantifying the hemispheric language dominance in healthy subjects, by using a rhyme detection (deciding whether couple of words rhyme) and a word fluency (generating words starting with a given letter) task. One of methods called "flip method" (FM) was based on the direct statistical comparison between hemispheres' activity. The second one, the classical lateralization indices method (LIM), was based on calculating lateralization indices by taking into account the number of activated pixels within hemispheres. The main difference between methods is the statistical assessment of the inter-hemispheric difference: while FM shows if the difference between hemispheres' activity is statistically significant, LIM shows only that if there is a difference between hemispheres. The robustness of LIM and FM was assessed by calculating correlation coefficients between LIs obtained with each of these methods and manual lateralization indices MLI obtained with Edinburgh inventory. Our results showed significant correlation between LIs provided by each method and the MIL, suggesting that both methods are robust for quantifying hemispheric dominance for language in healthy subjects. In the present study we also evaluated the effect of spatial normalization, smoothing and "clustering" (NSC) on the intra-hemispheric location of activated regions and inter-hemispheric asymmetry of the activation. Our results have shown that NSC did not affect the hemispheric specialization but increased the value of the inter-hemispheric difference.     

Computer-aided methods for assessing lower limb deformities in orthopaedic surgery planning

Accurate, simple, and quick measurement of anatomical deformities at preoperative stage is clinically important for decision making in surgery planning. The deformities include excessive torsional, angular, and curvature deformation. This paper presents computer-aided methods for automatically measuring anatomical deformities of long bones of the lower limb. A three-dimensional bone model reconstructed from CT scan data of the patient is used as input. Anatomical landmarks on femur and tibia bone models are automatically identified using geometric algorithms. Medial axes of femur and tibia bones, and anatomical landmarks are used to generate functional and reference axes. These methods have been implemented in a software program and tested on a set of CT scan data. Overall, the performance of the computerized methodology was better or similar to the manual method and its results were reproducible.     

International intercomparisons of integrating radon detectors in the NIRS radon chamber

An international intercomparison of integrating detectors was conducted at NIRS (National Institute of Radiological Science, Japan) with a 24.4 m³ inner volume walk-in radon chamber that has systems to control radon concentration, temperature and humidity.During the first intercomparison (05.2007) four groups participated from four countries and for the second intercomparison (10.2007) 17 participants were involved from 11 countries.Most of detectors are in good agreement with each other when compared to the radon level provided by the radon chamber. It appeared that the 70% of detectors are unified within the 20% margin of uncertainty.     

Comparison of methods for assessing body composition changes during weight loss

PURPOSE: Four cross-sectional studies have reported that percent body fat (%BF) measured by dual-energy x-ray absorptiometry (DXA) is significantly higher compared with values obtained with air displacement plethysmography (ADP) using the Bod Pod(R) in normal-weight individuals. This study was performed to confirm these findings in an overweight population and to assess whether DXA and ADP detected similar changes in body composition after moderate weight loss. METHODS: Twelve women (42 +/- 8 yr) and 10 men (40 +/- 11 yr) had their %BF, fat mass (FM), and fat-free mass (FFM) measured using DXA and ADP before and after an 8-wk weight-loss program involving moderate energy restriction and exercise. RESULTS: Body weight decreased significantly in women (-4.3 +/- 3.4 kg) and men (-4.7 +/- 3.1 kg). There were significant method (ADP vs DXA) and time (pre and post) effects but no method by time or gender interactions. Methods were significantly different in estimating %BF, FM, and FFM with ADP estimates of %BF and FM being lower and estimates of FFM higher than corresponding DXA values (P = 0.000). There were significant correlations accounting for a high degree of the shared variance between DXA and ADP (r = 0.98 to 0.99) for %BF, FM, and FFM and lower correlations for the changes in %BF (r = 0.66), FM (r = 0.86), and FFM (r = 0.34). In response to weight loss, the mean changes in %BF, FM, and FFM were not significantly different between methods (P > 0.05). CONCLUSION: Both DXA and ADP measure changes in body composition after small to moderate weight loss to the same extent and with similar sensitivity.     

Detection of post-exercise stunning by early gated SPECT myocardial perfusion imaging: Results from the IAEA multi-center study

Background

Transient post-ischemic LV dysfunction due to myocardial stunning in patients with coronary artery disease can be missed by conventional gated SPECT (GSPECT) acquisitions. The aim of this IAEA-sponsored multi-center study was to determine whether early post-exercise imaging is more likely to detect stunning than conventional without adversely affecting image quality or perfusion information.

Methods and Results

Patients undergoing exercise/rest GSPECT were enrolled in this international multicenter study. Post-exercise studies were acquired at 15 ± 5 minutes after radiotracer injection (Stress-1) and repeated at 60 ± 15 minutes (Stress-2). Rest studies (R) were acquired at 60 minutes post injection. A core laboratory quantitatively assessed perfusion pattern and LV blinded to the acquisition time. Ischemia was defined as summed stress score (SDS) ≥4, and stunning was defined as the difference between rest and post-stress LVEF (Δ-LVEF). In the 229 patients enrolled into the study, both image quality and perfusion information were similar between Stress-1 and Stress-2. Post-stress LVEF was associated with both ischemia and time of acquisition, with a significant correlation between SDS and Δ-LVEF, which was stronger at Stress-1 than Stress-2 in the ischemic compared to the non-ischemic population (r = 0.23 vs 0.08, P = 0.10).

Conclusions

Early post-exercise imaging is feasible, and can potentially improve the detection of post-ischemic stunning without compromising image quality and perfusion data     

间接性门静脉DSA的时间-视频密度曲线对肝功能状态的评估价值

目的 初步探讨肝门静脉DSA的时间-视频密度曲线(TVDC)参数对肝功能状态评估的价值.方法 收集2007年7月-2008年10月进行介入诊疗的肝癌(HCC)患者42例,其中男35例,女7例,平均年龄56岁(28～76岁),肿块平均10.38 cm(5.5～15.5 cm).按肝功能Child-Pugh分级将患者分成A...     

Results of an IAEA inter-comparison exercise to assess 137Cs and total 210Pb analytical performance in soil

Fallout radionuclides (FRNs) such as ²¹⁰Pb and ¹³⁷Cs have been widely used to assess soil erosion and sedimentation processes. It is of major importance to obtain accurate analytical results of FRNs by gamma analysis before any data treatment through conversion model and to allow subsequent comparison of erosion and sedimentation rates from different case studies.Therefore, IAEA organized an inter-comparison exercise to assess the validity and reliability of the analytical results of ¹³⁷Cs and total ²¹⁰Pb using γ-spectrometry in the various laboratories participating in the IAEA Co-ordinated Research Project on “Assess the effectiveness of soil conservation measures for sustainable watershed management using fallout radionuclides”.Reference materials were distributed to 14 participating laboratories and, using a rating system, their analytical results were compared to the reference values assigned.In the case of ¹³⁷Cs, the analytical results were satisfactory with 66% of the laboratories producing acceptable results. Only the sample with low ¹³⁷Cs activity (2.6±0.2 Bq kg⁻¹) gave less accurate results with more than 25% not acceptable results. The total ²¹⁰Pb analysis indicated a clear need for corrective actions in the analysis process as only 36% of the laboratories involved in the proficiency test was able to access total ²¹⁰Pb with occurrence (bias ⩽10%). This inter-laboratory test underlines that further inter-comparison exercises should be organized by IAEA or regional laboratories to ensure the quality of the analytical data produced in Member States. As a result of the above-mentioned proficiency test, some recommendations have been provided to improve accurate gamma measurement of both ¹³⁷Cs and total ²¹⁰Pb.