Validation of rapid methods for the determination of radiostrontium in milk

A rapid method of ⁸⁹Sr and ⁹⁰Sr comprising ion chromatography for preconcentration and Sr extraction chromatography for separation of Sr from Ca, Ba and Y was validated with spiked milk samples. An ⁸⁹Sr/⁹⁰Sr activity ratio of up to 12 showed the relative bias was within ±20%. The separation time of Sr was 7 h and the chemical recovery of Sr ranged from 80% to 95%. The detection limit for 500 mL milk and 90 min counting time was 0.1 Bq L⁻¹.     

Metal deposition at the bone–cartilage interface in articular cartilage

There is a growing interest being shown in the changes occurring in elemental distribution at the bone–cartilage interface, the changes either being a result of mechanical damage or disease. In particular, such investigations have tended to concern the elemental alterations associated with the osteoarthritic wear and tear damage occurring to the cartilage and subchondral bone of synovial joints or that associated with disease processes such as rheumatic arthritis. Present studies examine sections of femoral head obtained from total hip replacement surgery, use being made of micro-proton-induced X-ray emission (μ-PIXE) and the Rutherford back scattering (RBS) techniques. Enhancements of Zn, Ca and P have been observed at the bone–cartilage interface. Further, the concentration of Zn in spongy bone underlying the subchondral surface of a section of the femoral head has been measured, obtaining 136 μg g⁻¹ bone, the presence of Ca and P at the same position being 0.235 and 0.0451 g g⁻¹ bone, respectively. These values are slightly different to figures recently published by other authors using similar techniques.     

Production of medical radioisotopes with linear accelerators

In this study, we discuss producing radioisotopes using linear electron accelerators and address production and separation issues of photoneutron (γ,n) and photoproton (γ,p) reactions. While (γ,n) reactions typically result in greater yields, separating product nuclides from the target is challenging since the chemical properties of both are the same. Yields of (γ,p) reactions are typically lower than (γ,n) ones, however they have the advantage that target and product nuclides belong to different chemical species so their separation is often not such an intricate problem. In this paper we consider two examples, ¹⁰⁰Mo(γ,n)⁹⁹Mo and ⁶⁸Zn(γ,p)⁶⁷Cu, of photonuclear reactions. Monte-Carlo simulations of the yields are benchmarked with experimental data obtained at the Idaho Accelerator Center using a 44 MeV linear electron accelerator. We propose using a kinematic recoil method for photoneutron production. This technique requires ¹⁰⁰Mo target material to be in the form of nanoparticles coated with a catcher material. During irradiation, ⁹⁹Mo atoms recoil and get trapped in the coating layer. After irradiation, the coating is dissolved and ⁹⁹Mo is collected. At the same time, ¹⁰⁰Mo nanoparticles can be reused. For the photoproduction method, ⁶⁷Cu can be separated from the target nuclides, ⁶⁸Zn, using standard exchange chromatography methods. Monte-Carlo simulations were performed and the ⁹⁹Mo activity was predicted to be about 7 MBq/(g^⁎kW^⁎h) while ⁶⁷Cu activity was predicted to be about 1 MBq/(g^⁎kW^⁎h). Experimental data confirm the predicted activity for both cases which proves that photonuclear reactions can be used to produce radioisotopes. Lists of medical isotopes which might be obtained using photonuclear reactions have been compiled and are included as well.     

Solid phase extraction of radioyttrium from irradiated strontium target using nanostructure ion imprinted polymer formed with 1-hydroxy-4-(prop-2-enyloxy)-9,10-anthraquinone

A new complex of 1-hydroxy-4-(prop-2-enyloxy)-9,10-anthraquinone and Y(III) was synthesized and used as the functional monomer for a novel Y(III) nanostructure ion-imprinted polymer. This polymer was used as a sorbent for fast and selective separation. The separation method was based on radioyttrium sorption from aqueous HCl solution containing strontium onto ion-imprinted polymer. Influence of various parameters such as pH, mass sorbent, nature, concentration and volume of eluent was investigated. The radioyttrium recovery yield was 99.8% and Sr content was estimated to be 3 µg mL⁻¹.     

The backwards comparability of wrist worn GENEActiv and waist worn ActiGraph accelerometer estimates of sedentary time in children

ObjectivesTo examine the backward comparability of a range of wrist-worn accelerometer estimates of sedentary time (ST) with ActiGraph 100 count min⁻¹ waist ST estimates.DesignCross-sectional, secondary data analysisMethodsOne hundred and eight 10–11-year-old children (65 girls) wore an ActiGraph GT3X+ accelerometer (AG) on their waist and a GENEActiv accelerometer (GA) on their non-dominant wrist for seven days. GA ST data were classified using a range of thresholds from 23 to 56 mg ST estimates were compared to AG ST 100 count min⁻¹ data. Agreement between the AG and GA thresholds was examined using Cronbach’s alpha, intraclass correlation coefficients (ICC), limits of agreement (LOA), Kappa values, percent agreement, mean absolute percent error (MAPE) and equivalency analysis.ResultsMean AG total ST was 492.4 min over the measurement period. Kappa values ranged from 0.31 to 0.39. Percent agreement ranged from 68 to 69.9%. Cronbach’s alpha values ranged from 0.88 to 0.93. ICCs ranged from 0.59 to 0.86. LOA were wide for all comparisons. Only the 34 mg threshold produced estimates that were equivalent at the group level to the AG ST 100 count min⁻¹ data though sensitivity and specificity values of ∼64% and ∼74% respectively were observed.ConclusionsWrist-based estimates of ST generated using the 34 mg threshold are comparable with those derived from the AG waist mounted 100 count min⁻¹ threshold at the group level. The 34 mg threshold could be applied to allow group-level comparisons of ST with evidence generated using the ActiGraph 100 count min⁻¹ method though it is important to consider the observed sensitivity and specificity results when interpreting findings.     

Age estimation by the Cameriere’s normalized measurements (CNM) of the single permanent mandibular tooth on a panoramic radiograph

In this study Cameriere’s normalized measurements (CNM) of a single mandibular tooth were evaluated for age estimation on a sample of ortopantomographies (OPTs) of 2223 Italian children aged between 4 and 15 years.Dental maturity was radiographically evaluated by CNM of the seven left permanent mandibular teeth (CNMi = Ai/Li, i = 1,…,7); in monoradicular teeth, the distance (Ai, i = 1,…,5) between the inner sides of the open apex was measured while in biradicular teeth (Ai, i = 6, 7), the sum of the distances between the inner sides of the two open apices was calculated. Ai was normalized by the tooth length (Li, i = 1,…,7).The intra- and inter-observer agreement of CNM measurements was almost perfect. Overall, analyzed mandibular teeth finished their development up to the age of 13, but the distribution of CNM varied among different locations. The final models included a tooth-specific CNM as the independent variable and explained from 76% (second molars) to 39% (first incisors) of the variance in chronological age. The bias and accuracy of these models, when applied to real-life data with no age limitation, were within acceptable range of differences in the forensic anthropology of children. Specifically, in all models mean of absolute differences between estimated and real age was within one year (0.67 for first incisors to 1.00 for canines).In conclusion this study showed that all mandibular teeth do not have equal applicability for age estimation suggesting that further evaluation on different samples is necessary to evaluate the usefulness of a single mandibular tooth for age estimation.     

Dietary supplementation with New Zealand blackcurrant extract enhances fat oxidation during submaximal exercise in the heat

ObjectivesThis study investigated the effect of 7 days’ supplementation with New Zealand blackcurrant extract on thermoregulation and substrate metabolism during running in the heat.DesignRandomized, double-blind, cross-over study.MethodsTwelve men and six women (mean ± SD: Age 27 ± 6 years, height 1.76 ± 0.10 m, mass 74 ± 12 kg, V̇O_2max 53.4 ± 7.0 mL kg⁻¹ min⁻¹) completed one assessment of maximal aerobic capacity and one familiarisation trial (18 °C, 40% relative humidity, RH), before ingesting 2 × 300 mg day⁻¹ capsules of CurraNZ™ (each containing 105 mg anthocyanin) or a visually matched placebo (2 × 300 mg microcrystalline cellulose M102) for 7 days (washout 14 days). On day 7 of each supplementation period, participants completed 60 min of fasted running at 65% V̇O_2max in hot ambient conditions (34 °C and 40% relative humidity).ResultsCarbohydrate oxidation was decreased in the NZBC trial [by 0.24 g min⁻¹ (95% CI: 0.21–0.27 g min^-1)] compared to placebo (p =  0.014, d = 0.46), and fat oxidation was increased in the NZBC trial [by 0.12 g min⁻¹ (95% CI: 0.10 to 0.15 g min⁻¹)], compared to placebo (p = 0.008, d = 0.57). NZBC did not influence heart rate (p = 0.963), rectal temperature (p = 0.380), skin temperature (p = 0.955), body temperature (p = 0.214) or physiological strain index (p = 0.705) during exercise.ConclusionsSeven-days intake of 600 mg NZBC extract increased fat oxidation without influencing cardiorespiratory or thermoregulatory variables during prolonged moderate intensity running in hot conditions.     

Natural gamma-ray spectrometry as a tool for radiation dose and radon hazard modelling

We reviewed the calibration procedures of gamma-ray spectrometry with particular emphasis to factors that affect accuracy, detection limits and background radiation in field measurements for dosimetric and radon potential mapping. Gamma-ray spectra were acquired in western Liguria (Italy). The energy windows investigated are centred on the photopeaks of ²¹⁴Bi (1.76 MeV), ²⁰⁸Tl (2.62 MeV) and ⁴⁰K (1.46 MeV). The inferred absorbed dose rate and the radon flux are estimated to be lower than 60 nGy h⁻¹ and 22 Bq m⁻² h⁻¹, respectively.     

Thermoluminescence characteristics of Nd-doped SiO2 optical fibers irradiated with the 60Co gamma rays

Thermoluminescence (TL) properties (radiation sensitivity, dose response, signal fading) of Nd-doped SiO₂ optical fibers irradiated with 1.25 MeV photons to 1–50 Gy were studied. The peak of the glow curve is around 190 °C regardless of the dose. The dose response is linear up to 50 Gy. The radiation sensitivity is 219 nC mg⁻¹ Gy⁻¹. The fiber can be a potential candidate for photon radiotherapy dosimetry due to its high radiation sensitivity, linear dose response in a wide range, slow fading, and high spatial resolution due to the small size of the fiber.     

Whole-body biomechanical load in running-based sports: The validity of estimating ground reaction forces from segmental accelerations

ObjectivesUnlike physiological loads, the biomechanical loads of training in running-based sports are still largely unexplored. This study, therefore, aimed to assess the validity of estimating ground reaction forces (GRF), as a measure of external whole-body biomechanical loading, from segmental accelerations.MethodsFifteen team-sport athletes performed accelerations, decelerations, 90° cuts and straight running at different speeds including sprinting. Full-body kinematics and GRF were recorded with a three-dimensional motion capture system and a single force platform respectively. GRF profiles were estimated as the sum of the product of all fifteen segmental masses and accelerations, or a reduced number of segments.ResultsErrors for GRF profiles estimated from fifteen segmental accelerations were low (1–2 N kg⁻¹) for low-speed running, moderate (2–3 N kg⁻¹) for accelerations, 90° cuts and moderate-speed running, but very high (>4 N kg⁻¹) for decelerations and high-speed running. Similarly, impulse (2.3–11.1%), impact peak (9.2–28.5%) and loading rate (20.1–42.8%) errors varied across tasks. Moreover, mean errors increased from 3.26 ± 1.72 N kg⁻¹ to 6.76 ± 3.62 N kg⁻¹ across tasks when the number of segments was reduced.ConclusionsAccuracy of estimated GRF profiles and loading characteristics was dependent on task, and errors substantially increased when the number of segments was reduced. Using a direct mechanical approach to estimate GRF from segmental accelerations is thus unlikely to be a valid method to assess whole-body biomechanical loading across different dynamic and high-intensity activities. Researchers and practitioners should, therefore, be very cautious when interpreting accelerations from one or several segments, as these are unlikely to accurately represent external whole-body biomechanical loads.     

Heart rate-index estimates aerobic metabolism in professional soccer players

ObjectivesThis study aimed at proposing a new heart rate (HR) method to track aerobic metabolism in soccer by: (i) validating a recently developed HR index (HR_index) in professional soccer players, (ii) comparing HR_index vs the most common HR parameters and (iii) testing the agreement between measured and estimated VO₂ values using HR_index.Designcross-sectional.Methods184 professional soccer players performed a step incremental running test on a treadmill while VO₂ and HR were recorded. HR_index was calculated (actual HR/resting HR) and its relationship with VO₂ was compared with the relationships with the metabolism of actual HR, net HR, and % of HR reserve. Finally, HR_index was used to predict VO₂ = ((HR_index · 6) − 5) · 3.5) and measured and estimated VO₂ were compared by 2W RM-ANOVA and Bland–Altman analysis.ResultsHR_index/VO₂ relationship explained 85% of the variability in data, showing a higher performance than actual HR (77%) and similar values to the other parameters. Measured and estimated VO₂ were not significantly different ≤14 km h⁻¹, whereas at speeds ≥14 km h⁻¹ measured VO₂ was higher than estimated VO₂. Finally, measured and estimated VO₂ were highly correlated (R² = 0.85, p = 0.000), and showed no significant bias (bias = −1.03, z = −0.69, precision = 3.75 ml kg min⁻¹).ConclusionsWe validated the HR_index/VO₂ relationship in professional soccer players. HR_index showed better agreement with metabolism than actual HR and similar agreement to the other HR parameters. HR_index allowed to estimate VO₂, but at very high-intensity HR_index underestimated VO₂. Future studies should test this in real game conditions. HR_index could offer a time-efficient and easy-to-use “field” method to monitor aerobic metabolism in soccer.     

44gSc production using a water target on a 13 MeV cyclotron

IntroductionAccess to promising radiometals as isotopes for novel molecular imaging agents requires that they are routinely available and inexpensive to obtain. Proximity to a cyclotron center outfitted with solid target hardware, or to an isotope generator for the metal of interest is necessary, both of which can introduce significant hurdles in development of less common isotopes. Herein, we describe the production of ⁴⁴Sc (t_1/2 = 3.97 h, E_avg,β⁺ = 1.47 MeV, branching ratio = 94.27%) in a solution target and an automated loading system which allows a quick turn-around between different radiometallic isotopes and therefore greatly improves their availability for tracer development. Experimental yields are compared to theoretical calculations.MethodsSolutions containing a high concentration (1.44–1.55 g/mL) of natural-abundance calcium nitrate tetrahydrate (Ca(NO₃)₂ · 4 H₂O) were irradiated on a 13 MeV proton-beam cyclotron using a standard liquid target. ^44gSc was produced via the ⁴⁴Ca(p,n)^44gSc reaction.Results^44gSc was produced for the first time in a solution target with yields sufficient for early radiochemical studies. Saturation yields of up to 4.6 ± 0.3 MBq/μA were achieved using 7.6 ± 0.3 μA proton beams for 60.0 ± 0.2 minutes (number of runs n = 3). Experimental data and calculation results are in fair agreement. Scandium was isolated from the target mixture via solid-phase extraction with 88 ± 6% (n = 5) efficiency and successfully used for radiolabelling experiments. The demonstration of the production of ⁴⁴Sc in a liquid target greatly improves its availability for tracer development.     

Dietary intakes of professional Australian football league women’s (AFLW) athletes during a preseason training week

ObjectivesIn 2016 the Australian football league introduced the first women’s league, integrating part-time female athletes into the professional sporting environment. This study aims to assess the dietary intakes of professional Australian football league women’s (AFLW) athletes to highlight key focus areas for nutrition and additionally provide nutrition recommendations for dietitians working with these athletes.DesignCross-sectional study.MethodsDietary intake data was collected from 23 players from the same club competing in the Australian football league women’s, during a preseason week. Dietary intakes were assessed using three day estimated food records.ResultsMajority of athletes did not meet recommendations for carbohydrate (96%, n = 22), iron (87%, n = 20) and calcium (61%, n = 14). In comparison, majority of athletes met protein (74%, n = 17) and fat (78%, n = 18) recommendations. No significant difference was found in energy intake on main training, light training and recovery days (p > 0.05). Energy and carbohydrate intakes reported by AFLW athletes (1884 ± 457 kcal day⁻¹ and 2.7 ± 0.7 g kg⁻¹ day⁻¹) were consistent with values reported in previous studies that included professional female athletes.ConclusionsThis research highlights that further exploration of the factors that influence dietary intake is required to support athletes to meet energy and carbohydrate recommendations required for desired training and performance outcomes.     

Dose-response between frequency of breaks in sedentary time and glucose control in type 2 diabetes: A proof of concept study

ObjectivesThis study aimed to investigate dose-response between frequency of breaks in sedentary time and glucose control.DesignRandomised three-treatment, two-period balanced incomplete block trial.MethodsTwelve adults with type 2 diabetes (age, 60 ± 11 years; body mass index, 30.2 ± 4.7 kg/m²) participated in two of the following treatment conditions: sitting for 7 h interrupted by 3 min light-intensity walking breaks every (1) 60 min (Condition 1), (2) 30 min (Condition 2), and (3) 15 min (Condition 3). Postprandial glucose incremental area under the curves (iAUCs) and 21-h glucose total area under the curve (AUC) were measured using continuous glucose monitoring. Standardised meals were provided.ResultsCompared with Condition 1 (6.7 ± 0.8 mmol L⁻¹ × 3.5 h⁻¹), post-breakfast glucose iAUC was reduced for Condition 3 (3.5 ± 0.9 mmol L⁻¹ × 3.5 h⁻¹, p ˂ 0.04). Post-lunch glucose iAUC was lower in Condition 3 (1.3 ± 0.9 mmol L⁻¹ × 3.5 h⁻¹, p ˂ 0.03) and Condition 2 (2.1 ± 0.7 mmol L⁻¹ × 3.5 h⁻¹, p ˂ 0.05) relative to Condition 1 (4.6 ± 0.8 mmol L⁻¹ × 3.5 h⁻¹). Condition 3 (1.0 ± 0.7 mmol L⁻¹ × 3.5 h⁻¹, p = 0.02) and Condition 2 (1.6 ± 0.6 mmol L⁻¹ × 3.5 h⁻¹, p ˂ 0.04) attenuated post-dinner glucose iAUC compared with Condition 1 (4.0 ± 0.7 mmol L⁻¹ × 3.5 h⁻¹). Cumulative 10.5-h postprandial glucose iAUC was lower in Condition 3 than Condition 1 (p = 0.02). Condition 3 reduced 21-h glucose AUC compared with Condition 1 (p < 0.001) and Condition 2 (p = 0.002). However, post-breakfast glucose iAUC, cumulative 10.5-h postprandial glucose iAUC and 21-h glucose AUC were not different between Condition 2 and Condition 1 (p ˃ 0.05).ConclusionsThere could be dose-response between frequency of breaks in sedentary time and glucose. Interrupting sedentary time every 15 min could produce better glucose control.     

Handling interferences in 89Sr and 90Sr measurements of reactor coolant water: A method based on strontium separation chemistry

Measurements for determining the activity of ⁸⁹Sr and ⁹⁰Sr in reactor coolant water are associated with limitations due to interferences from radionuclides with similar chemical properties and β⁻-energies. From a measurement bias point-of-view these interferences would result mainly in an overestimated activity concentration of ⁹⁰Sr.In order to address the interference problem, a common and well-known method was used in order to show the need for sufficient decontamination. An improvement was achieved by taking the sample through two initial strontium separations in order to increase the decontamination factor. This method determines the activity concentration of ⁸⁹Sr and ⁹⁰Sr, via its daughter nuclide ⁹⁰Y, by Cherenkov counting. This work is primarily based on theoretical calculations of strontium-, yttrium- and other potential interfering radionuclide ratios after instant fission. The work done to confirm the theoretical calculations were carried through on spiked strontium standard solutions and fresh reactor coolant water. The reactor coolant water was known to contain interferences at a composition resembling that of instant fission. The detection limit for double separation was calculated to 0.17 Bq/kg for ⁹⁰Sr and 0.38 Bq/kg for ⁸⁹Sr. When using methods that solely rely on strontium resins, this paper shows that the decontamination factor (DF) is significantly higher when using double separation than that of a single separation. The paper also shows that the DF of an initial double strontium separation is as effective when it comes to removing high ratio interferences as separations done with both Sr- and Ln-resin (EiChrom Technologies, Inc., 2003, Tovedal et al., 2009b). However, ‘old’ samples, where e.g. ¹⁴⁰Ba and ⁸⁹Sr has decayed, does not benefit from double separation. Furthermore, samples with low ratios of interfering radionuclides does not benefit from using this method either, seeing as this is a more time consuming method due to the double separations.     

Presence of a radioactive gas in archaeological excavations,determination and mitigation

During recent archaeological discovery and excavation of a tunnel build approximately 2000 years ago by the Teotihuacans under the feathered serpent temple, in Mexico, abnormal radon concentrations up to 700 Bq m⁻³ were measured at several excavation stages. The tunnel is at 15 m below the earth surface with a vertical rectangular entrance of 4×4 m², a semi cylindrical shape of 3 m in diameter, with a probable length of 100 m.This study supports the assumption that at the opening of the tunnel radon concentration was around 5500 Bq m⁻³; however, although natural convection in the tunnel atmosphere naturally pups radon out, it build up to a maximum concentration of 2000 Bq m⁻³. This paper presents the identification of the radon problem in this archaeological site, dose determination, and the mitigation actions that reduced the radon concentration down to 40 Bq m⁻³ that ensure a negligible radon risk for archaeologist.     

Radiation surveillance using an unmanned aerial vehicle

Radiation surveillance equipment was mounted in a small unmanned aerial vehicle. The equipment consists of a commercial CsI detector for count rate measurement and a specially designed sampling unit for airborne radioactive particles. Field and flight tests were performed for the CsI detector in the area where ¹³⁷Cs fallout from the Chernobyl accident is 23–45 kBq m⁻². A 3-GBq ¹³⁷Cs point source could be detected at the altitude of 50 m using a flight speed of 70 km h⁻¹ and data acquisition interval of 1 s. Respective response for ¹⁹²Ir point source is 1 GBq. During the flight, the detector reacts fast to ambient external dose rate rise of 0.1 μSv h⁻¹, which gives for the activity concentration of ¹³¹I less than 1 kBq m⁻³. Operation of the sampler equipped with different type of filters was investigated using wind-tunnel experiments and field tests with the aid of radon progeny. Air flow rate through the sampler is 0.2–0.7 m³ h⁻¹ at a flight speed of 70 km h⁻¹ depending on the filter type in question. The tests showed that the sampler is able to collect airborne radioactive particles. Minimum detectable concentration for transuranium nuclides, such as ²³⁹Pu, is of the order of 0.2 Bq m⁻³ or less when alpha spectrometry with no radiochemical sample processing is used for activity determination immediately after the flight. When a gamma-ray spectrometer is used, minimum detectable concentrations for several fission products such as ¹³⁷Cs and ¹³¹I are of the order of 1 Bq m⁻³.     

Differentiation and diagnosis of benign and malignant testicular lesions using 18F-FDG PET/CT

ObjectivesThe purpose of this study was to evaluate the differential diagnostic value of ¹⁸F-fluorodeoxy glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) for benign and malignant testicular lesions.MethodsThe PET/CT scans of 53 patients with testicular lesions confirmed by biopsy or surgical pathology were retrospectively analyzed. There were 32 cases of malignant tumors and 21 cases of benign lesions. Differences in the maximum standardized uptake value (SUVmax) measurements and the SUVmax lesion/background ratios between benign and malignant lesions were analyzed. The diagnostic value of this PET/CT modality for the differential diagnosis of benign versus malignant testicular lesions was calculated.ResultsThe differences in the SUVmax measurements and the SUVmax lesion/background ratios between benign and malignant lesions were statistically significant (SUVmax: Z = −4.295, p = 0.000; SUVmax lesion/background ratio: Z = −5.219, p = 0.000); specifically, both of these indicators were higher in malignant lesions compared to benign lesions. An SUVmax of 3.75 was the optimal cutoff value to differentiate between benign and malignant testicular lesions. The diagnostic sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of this PET/CT modality in the differential diagnosis of benign versus malignant testicular lesions were 90.6%, 80.9%, 86.8%, 87.9%, and 85.0%, respectively.Conclusions¹⁸F-FDG PET/CT can accurately identify benign and malignant testicular lesions.     

A rapid method for determining 89Sr and 90Sr by Cerenkov counting

A new combination of simple preparation techniques for determining ⁸⁹Sr and ⁹⁰Sr in water and milk samples using alginate has been developed and tested. By means of Cerenkov counting without a long ingrowth period for ⁹⁰Y, results can be obtained within 4 days. The detection limit is about 1 Bq/l for a sample volume of 0.2 l. Milk samples can be prepared without ashing. A Liquid Scintillation Counter TRI-Carb 3170TR/SL in low-level mode has been used for counting.