Development and characterization of an all-in-one gamma probe with auto-peak detection for sentinel lymph node biopsy based on NEMA NU3-2004 standard.

BACKGROUND: A gamma probe is a handheld device used for intraoperative interventions following interstitial injection of a radiotracer to locate regional lymph nodes through the external detection of radiation. This work reports on the design and performance evaluation of a novel fully integrated gamma probe (GammaPen), recently developed by our group. MATERIALS AND METHODS: GammaPen is an all-in-one pocket gamma probe with low weight and adequate dimensions, consisting of a detector, a control unit and output all together. The detector module consists of a cylindrical Thallium-activated Cesium Iodide [CsI (Tl)] crystal optically coupled to a Silicon photomultiplier (SiPM), shielded using Tungsten housing on side and back faces. The electronics of the probe consists of two small boards to handle signal processing and analog peak detection tasks. A number of parameters, including probe sensitivity in air/water, spatial resolution in air/water, angular resolution in air/water, and side and back shielding effectiveness, were measured to evaluate the performance of the probe based on NEMA NU3-2004 standards. RESULTS: The sensitivity of the probe in air at distances of 10, 30, and 50 mm is 18784, 3500, and 1575 cps/MBq. The sensitivity in scattering medium was also measured at distances of 10, 30, and 50 mm as 17,680, 3050, and 1104 cps/MBq. The spatial and angular resolutions in scattering medium were 47 mm and 87 degree at 30 mm distance from the probe, while they were 40 mm and 77 degree in air. The detector shielding effectiveness and leakage sensitivity are 99.91% and 0.09%, respectively. CONCLUSION: The performance characterization showed that GammaPen can be used effectively for sentinel lymph node localization. The probe was successfully used in several surgical interventions by an experienced surgeon confirming its suitability in a clinical setting.

The new IAEA-372 grass-certified reference material for (40)K and (137)Cs.

A new grass-certified reference material characterized for (137)Cs and (40)K has been issued by the International Atomic Energy Agency. Characterization of this material was conducted by a group of national metrological institutes and expert laboratories. The paper describes the process for assigning the certified reference value to the material.

EC intercomparisons for laboratories monitoring environmental radioactivity.

International measurement comparisons are organised regularly for EU laboratories involved in monitoring radioactivity, with emphasis on meeting routine measurement conditions. Using the recent comparison of 137Cs in air filters as an example, the whole cycle is described: establishment of traceable reference values, spiking of individual filters for the comparison and their quality assurance, treatment and measurement of filters in the participating laboratories and evaluation of comparison results. The treatment of an individual result, deviating widely from the reference value, is discussed. Monte-Carlo simulations allow to estimate the maximum errors possibly made due to a non-suitable measurement geometry.

An evaluation of the frequency shift caused by collisions with background gas in the primary frequency standard NPL-CsF2.

Collisions between cold cesium atoms and background gas atoms at ambient temperature reduce the cold atom signal in a fountain clock and at the same time produce a shift in the measured clock frequency. We evaluate the shift in the NPL-CsF2 cesium fountain primary frequency standard based on measurements of the fractional loss of cold atoms from the atomic cloud during the interrogation time combined with a model by Gibble that quantifies the relationship between the loss and the frequency shift.

Matrix elimination ion chromatography method for the determination of trace levels of anionic impurities in high purity cesium iodide.

In the present study an ion chromatographic method based on matrix elimination has been developed for the determination of anionic impurities in high purity cesium iodide crystals. The presence of impurities has a detrimental effect on the characteristics of detectors based on cesium iodide crystals. In particular, oxygen-containing anions inhibit the resolving power of scintillators and decrease the optical absorption. The quantitative determination of anions (fluoride, chloride, bromide, nitrate, phosphate, and sulphate) simultaneously in the high-purity cesium iodide crystals has not been carried out before. The large concentration of iodide poses a challenge in the determination of anions (especially phosphate and sulphate); hence, matrix elimination is accomplished by adopting a sample pretreatment technique. The method is validated for linearity, accuracy, and precision. The limit of detection for different anions is in the range of 0.3-3 µg/g, and the relative standard deviation is in the range of 4-6% for the overall method.

Uncertainty of inductively coupled plasma mass spectrometry based measurements: an application to the analysis of urinary barium, cesium, antimony and tungsten.

The wide use of barium (Ba), cesium (Cs), antimony (Sb) and tungsten (W) in many industrial and agricultural fields causes the increased release of these metals into the environment, laying the basis for health risk. To assess the exposure for the general population, the development of adequate and reliable analytical techniques becomes compulsory. This study refers to the quantification of urinary Ba, Cs, Sb and W levels by both quadrupole (Q) and sector field (SF) inductively coupled plasma mass spectrometry (ICP-MS). The two procedures were compared for their performances and their measurement uncertainties. The limits of detection were (Q and SF) 23.0 and 5.21 ng L(-1) for Ba; 21.1 and 7.52 ng L(-1) for Cs; 1.09 and 0.43 ng L(-1) for Sb; and 0.36 and 0.49 ng L(-1) for W. The trueness was better than 93.3% and the precision less than 12% for both techniques. Relative expanded uncertainties of the analytical procedures, at the median levels found in the general population, were below 5% for all the elements with both ICP-MS techniques. The uncertainties related to the calibration and repeatability were the parameters most influencing the final analytical performance. The urinary median values observed in healthy subjects from central Italy were 1146, 4301, 60.8 and 48.5 ng L(-1) for Ba, Cs, Sb and W, respectively.

[Photometric analysis of sodium and cesium iodides in the air of the work area]. / Fotometricheskoe opredelenie iodidov natriia i tseziia v vozdukhe rabochei zony.

The contributors propose a photometric technique for detecting sodium and caesium iodides in the working zone air. The technique is based on the oxidation of I-ions with bromine water, interacting of the educed iodine and redundant potassium iodide with concomitant formation of complex I3- ions, followed by 350-365 mm photometric measurements of the product. Air sample taking is performed by condensating on AFA--VP filtres. The lower limit of I-ions content measurements is 5 micrograms. The measurement range for sodium and caesium iodides is 0.2-50 mg/m3. Data is provided for the reproduction of the technique which can be used both in special laboratory and industrial conditions.