Measurement of Fe solution activity by LSC-TDCR method

A solution of ⁵⁵Fe was measured by using liquid scintillation counting (LSC)-TDCR method. The measurement was performed within the frame of the CIPM CCRI(II)-K2.Fe-55 comparison during the year 2006. Two computation codes were used for the calculation of detection efficiency, the difference between the results being analyzed. The photomultipliers asymmetry and its influence on the results, as well as the long-term stability are also analyzed. The influence of the variation of kB value over the activity value is compared with the case of ³H standardization.     

National comparison of activity measurements of 131I, 60Co,and 133Ba in Indonesia

National comparisons of radioactivity measurements of ¹³¹I and ⁶⁰Co (in 2010) and of ¹³³Ba (in 2011) were carried out within the framework of the National Radiation Metrology Laboratory Program of Indonesia, coordinated by PTKMR-BATAN. Eleven laboratories took part in the comparison, and all measurements were made using gamma spectrometry, on point sources with an activity between 2000 Bq and 6000 Bq. Several laboratories reported values which were more than 10% different from the reference value for ¹³¹I and ¹³³Ba. Possible reasons for these differences are discussed. This program will be continued with other radionuclides to maintain and control quality assurance for the local laboratories.     

Calibration of Fe activity with a lithium-drifted silicon detector

NMIJ participated in the CCRI (II) key comparison of ⁵⁵Fe activity measurement. A planar-type Si(Li) detector and a liquid-scintillation counter were used to calibrate the activity. The calibration result obtained by the Si(Li) detector agreed with that obtained by the liquid-scintillation counter using the CIEMAT/NIST method within uncertainty. The result was reported to the BIPM in 2006. The activity of ⁵⁵Fe was also measured by using a 2π pressurized proportional counter. The result obtained by the 2π pressurized proportional counter agreed with the above results within uncertainty. The measurement by the Si(Li) detector was very simple and its procedure was a combination of conventional methods. The measurement by the liquid-scintillation counter is most popular to calibrate the activity of ⁵⁵Fe. However the Si(Li) detector is also useful.     

A procedure for the standardization of gamma reference sources for quality assurance in activity measurements of radiopharmaceuticals

A simplified procedure for the standardization of gamma reference sources, for use in quality assurance of activity measurements during production and application of radiopharmaceuticals in Cuban nuclear medicine laboratories, is described. The method is based on the reliable achievement of consistent measurements by both gamma-spectrometry and ionization chamber techniques, and allows to obtain reference sources with uncertainties lower than 2%. Experimental setup, validation procedure and typical results obtained for ^99mTc, ¹³¹I, ²⁰¹Tl and ¹⁵³Sm are described and discussed. The method will serve also as a secondary reference system for radioactivity measurements in the country.     

Comparisons of activity measurements with radionuclide calibrators

The correct administration to a patient of the prescribed activity of a radiopharmaceutical is an important factor to ensure the confidence in the diagnosis or the therapeutic efficiency, while at the same time keeping the unnecessary human exposure as low as possible.

Comparisons of activity measurements for ¹³¹I, ²⁰¹Tl and ^99mTc with radionuclide calibrators were organized the first time in Cuba during 2002 with the aim of obtaining information about the quality of administration of radiopharmaceuticals. Ten Cuban nuclear medicine departments and the laboratories involved in the production of these kinds of compounds participated in the comparison runs. The results presented in this paper facilitated the identification of several problems and initiated corrective actions. In addition, they indicate the necessity of establishing Quality Systems in nuclear medicine in Cuba.     

Standardization of Fe by tracing method

This work describes the procedure followed by the Laboratório de Metrologia Nuclear (LMN) for the standardization of ⁵⁵Fe by the tracing method. This technique was applied using two radionuclides, which decay by the electron capture process followed by a prompt gamma-ray, namely ⁵¹Cr and ⁵⁴Mn, as tracers. The calibration was performed in a 4πβ–γ coincidence system. The efficiency was obtained by selecting a gamma-ray window set at the 320 keV total absorption peak for ⁵¹Cr and at 834 keV for ⁵⁴Mn.     

Bilateral comparison between PTB and ENEA to check the performance of a commercial TDCR system for activity measurements

The only commercial TDCR counter from Hidex Oy (Finland), comprising three photomultiplier tubes, was tested at the two National Metrology Institutes (NMIs) PTB and ENEA. To this end, the two NMIs purchased a Hidex 300 SL TDCR counter (METRO version) each and carried out various tests at their laboratories. In addition, the two institutions agreed to organize a bilateral comparison in order to acquire information on the reproducibility of the results obtained with the counters. To achieve this, PTB prepared some ⁸⁹Sr liquid scintillation samples, which were first measured in various counters at PTB and then shipped to ENEA for comparative measurements.The aim of this paper is to summarize the findings on the counter characteristics and adjustments. In addition, the results of the bilateral comparison between PTB and ENEA are presented and the results from various commercial counters using the CIEMAT/NIST efficiency tracing and the TDCR method are discussed.     

建筑材料样品中放射性核素γ能谱测量比对

目的 通过全国省级疾病预防控制中心γ能谱实验室对建筑材料中放射性核素的测量比对,检验其测量结果的精确度和准确度,提高其对放射性核素的分析水平。方法 依据IAEA 2002年放射性核素国际比对方法,于2007年组织了15个单位对我国建筑材料样品中放射性核素γ能谱测量比对。结果 各参加比对单位提供的测量值与参考值符和较好,其中有50%的参加单位相对偏差小于5%,相对偏差小于10%的单位超过80%。结论 γ能谱分析建筑材料样品中放射性核素含量的方法是准确可靠的,可以满足GB 6566-2001《建筑材料放射性核素限量》标准的要求。     

A comparison of two-dimensional radiography and three-dimensional computed tomography in angular cephalometric measurements

Objectives

The objective of this study was to assess the reliability of three-dimensional (3D) cephalometric approaches by comparing this method with authenticated traditional two-dimensional (2D) cephalometry in angular cephalometric measurements.

Methods

CT images and lateral cephalometric radiographs of ten patients (five women, five men) were used in this study. Raw CT data of the patients were converted to 3D images with a 3D simulation program (Mimics 9.0, Leuven, Belgium). Lateral cephalometric radiographs were used manually for 2D measurements. The comparisons of the two methods were made using 14 cephalometric angular measurements. The Wilcoxon matched-pairs signed-ranks test (α _ 0.05) was used to determine the difference between the two methods. To assess the intra- and interobserver reproducibility, two sets of recordings made by each observer, in each modality were used. Dahlberg''s formula was used to determine the intraobserver reproducibility, and the Wilcoxon matched-pairs signed-rank test (α _ 0.05) was used to assess the interobserver reproducibility.

Results

The method errors of both observers ranged from 0.35° to 0.65°. In addition, there were no significant differences between the measurements of the two observers (P > 0.05). However, comparison of 2D and 3D parameters showed significant differences in U1-NA and U1-SN measurements (P < 0.05).

Conclusions

The 3D angular cephalometric analysis is a fairly reliable method, like the traditional 2D cephalometric analysis. Currently, the 3D system is likely to be more suitable for the diagnosis of cases with complex orthodontic anomalies. However, with the decrease in radiation exposure and costs in the future, 3D cephalometrics can be a suitable alternative method to 2D cephalometry.     

Theoretical foundation for a simple method for simultaneous measurements of the unattached fraction and activity median diameter of attached radon progeny

Calculation of lung dose from established lung dosimetry models requires use of the unattached fraction of potential alpha energy concentration (PAEC) of radon progeny and the activity median diameter (AMD) of attached radon progeny, in addition to the total PAEC. In the present work, for indoor environments without the nucleation mode of aerosols, a method based on the wire screen penetration theory using two wire screens and a filter is proposed for simultaneous measurements of these two parameters. It is shown that the traditional wire screen method can overestimate or sometimes underestimate the unattached fraction, depending on the properties of the wire screen and the true unattached fraction. The present method eliminates such uncertainties.     

Radiation exposure during transmission measurements: comparison between CT- and germanium-based techniques with a current PET scanner

In positron emission tomographic (PET) scanning, transmission measurements for attenuation correction are commonly performed by using external germanium-68 rod sources. Recently, combined PET and computed tomographic (CT) scanners have been developed in which the CT data can be used for both anatomical-metabolic image formation and attenuation correction of the PET data. The purpose of this study was to evaluate the difference between germanium- and CT-based transmission scanning in terms of their radiation doses by using the same measurement technique and to compare the doses that patients receive during brain, cardiac and whole-body scans. Measurement of absorbed doses to organs was conducted by using a Rando Alderson phantom with thermoluminescent dosimeters. Effective doses were calculated according to the guidelines in the International Commission on Radiation Protection Publication Number 60. Compared with radionuclide doses used in routine 2-[fluorine-18]-fluoro-2-deoxy-d-glucose PET imaging, doses absorbed during germanium-based transmission scans were almost negligible. On the other hand, absorbed doses from CT-based transmission scans were significantly higher, particularly with a whole-body scanning protocol. Effective doses were 8.81 mSv in the high-speed mode and 18.97 mSv in the high-quality mode for whole-body CT-based transmission scans. These measurements revealed that the doses received by a patient during CT-based transmission scanning are more than those received in a typical PET examination. Therefore, the radiation doses represent a limitation to the generalised use of CT-based transmission measurements with current PET/CT scanner systems.     

Factors associated with the impossibility to obtain reliable liver stiffness measurements by means of Acoustic Radiation Force Impulse (ARFI) elastography—Analysis of a cohort of 1031 subjects

Introduction

Acoustic Radiation Force Impulse (ARFI) elastography is a non-invasive technique for liver fibrosis assessment.

Aim

To assess the feasibility of ARFI elastography in a large cohort of subjects and to identify factors associated with impossibility to obtain reliable liver stiffness (LS) measurements by means of this technique.

Methods

Our retrospective study included 1031 adult subjects with or without chronic liver disease. In each subject LS was assessed by means of ARFI elastography. Failure of ARFI measurements was defined if no valid measurement was obtained after at least 10 shots and unreliable in the following situations: fewer than 10 valid shots; or median value of 10 valid measurements with a success rate (SR) < 60% and/or an interquartile range interval (IQR) ≥ 30%.

Results

Failure of LS measurements by means of ARFI was observed in 4 subjects (0.3%), unreliable measurements in 66 subjects (6.4%), so reliable measurements were obtained in 961 subjects (93.3%). In univariant analysis, the following risk factors were associated with failed and unreliable measurements: age over 58 years (OR = 0.49; 95% CI 0.30–0.80, p = 0.005), male gender (OR = 0.58; 95% CI 0.34–0.94, p = 0.04), BMI > 27.7 kg/m² (OR = 0.23, 95% CI 0.13–0.41, p < 0.0001). In multivariate analysis all the factors mentioned above were independently associated with the risk of failed and unreliable measurements.

Conclusions

Reliable LS measurements by means of ARFI elastography were obtained in 93.3% of cases. Older age, higher BMI and male gender were associated with the risk of failed and unreliable measurements, but their influence is limited as compared with Transient Elastography.     

Reproducibility of linear tumor measurements using PACS: comparison of caliper method with edge-tracing method

The aim of this study was to evaluate inter- and intra-observer reproducibility when making electronic caliper linear tumor measurements on picture archiving and communications systems (PACS) and compare them with linear measurements obtained from circumferential tracing of tumor perimeter. Three radiologists measured 64 masses from 30 patients on body CT scans in two separate settings. Long axis and perpendicular short axis were measured using electronic calipers. The edge of each tumor was traced electronically and the long and short axes were calculated by computer software. The reproducibility of a measurement was evaluated by computing and comparing the absolute value of the mean difference between initial and subsequent measurements. The mean differences ±95% confidence interval (CI) between two measurements of the long by short axis were 3.8±2.6×3.1±1.8 mm when the caliper method was used and 3.5±2.0×3.2±1.5 mm when the tumor tracing method was used. There was no statistically significant difference in individual intra-observer reproducibility of tumor axes measurements. Neither long- nor short-axis single-dimension measurements resulted in significantly greater or lesser intra-observer reproducibility. When comparing caliper and tracing measurements, the overall mean difference (3.42±1.8 vs 3.38±1.4 mm) was not statistically significant. There was close correlation between the individual measurements made by each observer whether these were made by electronic calipers and when these were calculated from electronic tracings (Pearson correlations between 0.79 and 0.949). Current PACS systems allow reproducible linear, long or short axis, tumor measurements. There is no significant difference in reproducibility of measurements whether these are made directly with electronic calipers or calculated from tumor edge tracings.     

Results of an international comparison for the activity measurement of 177Lu

An international Key Comparison of (177)Lu has recently been carried out. Twelve laboratories performed assays for radioactivity content on aliquots of a common master solution of (177)Lu, leading to eleven results submitted for entry into the Key Comparison Database of the Mutual Recognition Arrangement. A proposed Comparison Reference Value (CRV) was calculated to be 3.288(4)MBq/g using all eleven results. Degrees of equivalence and their uncertainties were calculated for each laboratory based on the CRV. Most of the values reported by the participating laboratories were within 0.6% of the CRV.     

Investigation of the reproducibility and reliability of sagittal vertebral inclination measurements from MR images of the spine

In this study, sagittal vertebral inclination (SVI) was systematically evaluated for 28 vertebrae (segments between T4 and L5) in magnetic resonance (MR) images of one normal and one scoliotic subject to compare the performance of manual and computerized measurements, and identify the most reproducible and reliable measurements. Manual measurements were performed by three observers, who identified on two occasions the distinctive anatomical landmarks required to evaluate SVI by six measurement methods, i.e. the superior tangents, inferior tangents, anterior tangents, posterior tangents, mid-endplate lines and mid-wall lines. Computerized measurements were performed by automatically evaluating SVI from the symmetry of vertebral anatomical structures in two-dimensional (2D) sagittal cross-sections and in three-dimensional (3D) volumetric images. The mid-wall lines and posterior tangents proved to be the manual measurements with the lowest intra-observer (standard deviation, SD, of 1.4° and 1.7°, respectively) and inter-observer variability (SD of 1.9° and 2.4°, respectively). The strongest inter-method agreement was found between the mid-wall lines and posterior tangents (SD of 2.0°). Computerized measurements in 2D and in 3D resulted in intra-observer (SD of 2.8° and 3.1°, respectively) and inter-observer variability (SD of 3.8° and 5.2°, respectively) that were comparable to those of the superior tangents (SD of 2.6° and 3.7°) and inferior tangents (SD of 3.2° and 4.5°), which represent standard Cobb angle measurements. It can be concluded that computerized measurements of SVI should be based on the inclination of vertebral body walls.     

Results of an international comparison for the determination of radionuclide activity in bilberry material

Radioactivity found in wild food products has assumed greater importance when assessing the total exposure of the population. For this reason, IRMM has been developing a reference material for the activity concentration of three radionuclides in bilberry samples. In order to characterise this new material, a CCRI(II) supplementary comparison was organised. The difficulties encountered in this comparison are discussed, in particular the efficiency calibration for volume sources of gamma-ray emitters, and comparison reference values for (137)Cs and (40)K are calculated.     

Accuracy of MRI volume measurements of breast lesions: comparison between automated, semiautomated and manual assessment

The aim of this study was to investigate the efficacy of a dedicated software tool for automated and semiautomated volume measurement in contrast-enhanced (CE) magnetic resonance mammography (MRM). Ninety-six breast lesions with histopathological workup (27 benign, 69 malignant) were re-evaluated by different volume measurement techniques. Volumes of all lesions were extracted automatically (AVM) and semiautomatically (SAVM) from CE 3D MRM and compared with manual 3D contour segmentation (manual volume measurement, MVM, reference measurement technique) and volume estimates based on maximum diameter measurement (MDM). Compared with MVM as reference method MDM, AVM and SAVM underestimated lesion volumes by 63.8%, 30.9% and 21.5%, respectively, with significantly different accuracy for benign (102.4%, 18.4% and 11.4%) and malignant (54.9%, 33.0% and 23.1%) lesions (p < 0.05). Inter- and intraobserver reproducibility was best for AVM (mean difference ± 2SD, 1.0 ± 9.7% and 1.8 ± 12.1%) followed by SAVM (4.3 ± 25.7% and 4.3 ± 7.9%), MVM (2.3 ± 38.2% and 8.6 ± 31.8%) and MDM (33.9 ± 128.4% and 9.3 ± 55.9%). SAVM is more accurate for volume assessment of breast lesions than MDM and AVM. Volume measurement is less accurate for malignant than benign lesions.     

通过国际合作探索中国特色转化医学之路

转化医学是现代医学发展的重要方向。我国的转化医学尚处于发展阶段,亟需加强国际交流与合作。在国际合作中,既需要学习国外转化医学的发展历程,认清其本质属性和发展规律;也需要把握我国国情和发展现状,制定符合国情的转化医学发展方针。本文通过论述转化医学的发展历程,提出转化医学发展的一般规律,阐释国际合作交流在我国转化医学发展中的作用;以协和转化医学中心为例,论述我国当前转化医学发展的现状;并分析现阶段我国转化医学存在的问题,提出借助国际合作探索中国特色转化医学发展之路的建议。     

222Rn-220Rn累积探测器参加日本组织的国际比对结果分析

目的 通过参加国际比对,提高²²²Rn和²²⁰Rn累积测量的水平,保证测量的质量。方法 将本实验室的LD-P型²²²Rn-²²⁰Rn探测器寄往日本放射线医学综合研究所(National Institute of Radiological Science,NIRS),参加²²²Rn-²²⁰Rn累积探测器的国际比对。²²²Rn比对在NIRS的标准²²²Rn室进行,按暴露量分低、中、高3个水平;²²⁰Rn比对在NIRS的²²⁰Rn室进行,也分低、中、高3个水平。暴露结束后将探测器寄回本实验室进行蚀刻、分析,然后把测量结果报给NIRS,最后NIRS将暴露的参考值反馈回本实验室。结果 LD-P探测器²²²Rn比对测量低、中、高3个暴露水平的测量值与参考值的相对偏差(RPD)分别为-13.8%、-14.4% 和-17.1%;²²⁰Rn比对测量低、中、高3个暴露水平的测量值与参考值的RPD分别为-14.4%、 8.9%和-3.2%。结论 本次比对LD-P探测器²²²Rn和²²⁰Rn的测量结果均在NIRS规定的RPD为20%的一级标准范围内。     

Sex identification on the basis of hand and foot measurements in Indo-Mauritian population--a model based approach

Identification is the foremost issue in crime investigation. A few studies have been performed so far in order to identify sex on the basis of single foot or hand of the victim. Moreover, these studies provide only crude measures to indicate sex and there exists no concrete methodology to predict sex using the available information. In the present paper, we have developed statistical models to identify sex based on the dimensions of foot and hand. The models containing both length and breadth of hand or foot as independent variables are capable of predicting sex in Indo-Mauritian population with fairly high accuracy as compared to those containing hand or foot indices.