Forensic identification of an individual in complex DNA mixtures

The identification of a suspect in a complex DNA mixture typed with standard short tandem repeat (STR) kits has proved difficult. In the current study we present the theoretical framework of a method aimed to resolve this problem in forensic cases. The method suggests genotyping a specially designed panel of 1000–3000 single nucleotide polymorphisms (SNPs), each with a relatively low (<0.1) minor allele frequency (MAF). The rationale of this method is that any individual will carry a specific set of dozens of rare alleles and the complex DNA mixture will carry this particular set only if the one individual is represented in the DNA mixture. The efficiency of the method is evaluated by estimating the probability that a random man will not be excluded (RMNE) from the mixture. When this probability, P(RMNE), is low, one can conclude that the suspect's DNA is present in the DNA mixture. Essentially, a P(RMNE) < 10⁻⁹ is considered as proof, whereas a P(RMNE) < 10⁻⁶ is considered strong evidence. For completeness, we also analyzed the method using the likelihood ratio (LR) approach. We have analyzed the method for a variety of conditions and found that generally the method will provide highly significant results even for complex mixtures combining up to 10 individuals. The method performs well even when close relatives (one or two brothers) are present in the complex DNA mixture and when contributors or suspects come from different populations. We have also found that the method can accurately identify the number of contributors to the mixture, something that in some instances has significant forensic value on its own.     

Emission probabilities for the 5.449-MeV alpha particles and 241-keV gamma rays in the 224Ra-220Rn decay

The emission probability P_α1 for the 5.449-MeV α particles, which in the decay of ²²⁴Ra populate the 241-keV level in ²²⁰Rn, was measured using ²²⁴Ra sources by recoil implantation from ²²⁸Th and Si surface-barrier detectors. Additionally, the 241-keV γ-ray emission probability, P_γ(241) was measured using ²²⁸Th sources and a calibrated high-purity Ge detector. A pair of deduced values, P_γ(241), P_α1, was obtained from the measured data of P_α1 and P_γ(241), respectively. The weighted mean of the measured and deduced data yielded the results of P_α1 = 0.0507 ± 0.0005 and P_γ(241) = 0.0400 ± 0.0007. The quoted overall uncertainties correspond to the 68% confidence limits for the mean with an effective number of degrees of freedom equal 5.     

乳腺癌根治术后双弧VMAT与IMRT计划的剂量学比较

目的 比较乳腺癌根治术后双弧的容积旋转调强放射治疗(VMAT)与5野的静态调强放射治疗(IMRT)2种计划之间的剂量学差异,评估VMAT技术在乳腺癌根治术后的剂量学特点与应用能力.方法 选取28例乳腺癌根治术后患者(左侧10例,右侧18例),分别制定双90度弧段的VMAT与5野的IMRT 2种计划,主要的计划评估参数为靶区的肿瘤控制概率(TCP)、适形指数(CI)、均匀指数(HI)以及接受相应处方剂量水平照射体积百分比V₉₅、V₁₁₀,危及器官(OAR)评估包括患侧肺的正常组织并发症概率(NTCP)、D_mean、V₅、V₂₀、V₃₀,心脏的NTCP值、D_mean、V₂₅,健侧乳腺的D_mean、机器跳数(MU)以及治疗时间.结果 VMAT计划与IMRT计划的TCP值分别为(96±2)%、(90±2)%(t=-6.28,P<0.01);HI值分别为0.15±0.04,0.22±0.02(t=13.29,P<0.05);肿瘤位于左侧时,心脏NTCP值在VMAT计划与IMRT计划中分别为(1.0±0.12)%,(1.7±0.13)%(t=2.14,P<0.05);肿瘤位于右侧时,2种计划心脏的NTCP差异无统计学意义,平均剂量分别为(3.27±0.26)、(6.0±0.47)Gy(t=9.21, P<0.01);VMAT计划在MU少于IMRT计划(t=9.58,P<0.01),治疗时间短于IMRT计划(t=8.40,P<0.05).结论 乳腺癌根治术后,VMAT计划具有更强的临床应用能力,且表现出更优的剂量学特点.     

Identifying common donors in DNA mixtures,with applications to database searches

Several methods exist to compute the likelihood ratio LR(M, g) evaluating the possible contribution of a person of interest with genotype g to a mixed trace M. In this paper we generalize this LR to a likelihood ratio LR(M₁, M₂) involving two possibly mixed traces M₁ and M₂, where the question is whether there is a donor in common to both traces. In case one of the traces is in fact a single genotype, then this likelihood ratio reduces to the usual LR(M, g). We explain how our method conceptually is a logical consequence of the fact that LR calculations of the form LR(M, g) can be equivalently regarded as a probabilistic deconvolution of the mixture.Based on simulated data, and using a semi-continuous mixture evaluation model, we derive ROC curves of our method applied to various types of mixtures. From these data we conclude that searches for a common donor are often feasible in the sense that a very small false positive rate can be combined with a high probability to detect a common donor if there is one. We also show how database searches comparing all traces to each other can be carried out efficiently, as illustrated by the application of the method to the mixed traces in the Dutch DNA database.     

NOCIt: A computational method to infer the number of contributors to DNA samples analyzed by STR genotyping

Repetitive sequences in the human genome called short tandem repeats (STRs) are used in human identification for forensic purposes. Interpretation of DNA profiles generated using STRs is often problematic because of uncertainty in the number of contributors to the sample. Existing methods to identify the number of contributors work on the number of peaks observed and/or allele frequencies. We have developed a computational method called NOCIt that calculates the a posteriori probability (APP) on the number of contributors. NOCIt works on single source calibration data consisting of known genotypes to compute the APP for an unknown sample. The method takes into account signal peak heights, population allele frequencies, allele dropout and stutter—a commonly occurring PCR artifact. We tested the performance of NOCIt using 278 experimental and 40 simulated DNA mixtures consisting of one to five contributors with total DNA mass from 0.016 to 0.25 ng. NOCIt correctly identified the number of contributors in 83% of the experimental samples and in 85% of the simulated mixtures, while the accuracy of the best pre-existing method to determine the number of contributors was 72% for the experimental samples and 73% for the simulated mixtures. Moreover, NOCIt calculated the APP for the true number of contributors to be at least 1% in 95% of the experimental samples and in all the simulated mixtures.     

Decay data of 141Ce

A 4πβ-gamma coincidence system and several efficiency calibrated semiconductor spectrometers were used to determine the following ¹⁴¹Ce/¹⁴¹Pr decay data: 1. The β-transition probability to the 145 keV level of ¹⁴¹Pr, b₁. 2. The total conversion coefficient of the 145 keV transition to the ground state of ¹⁴¹Pr, α_T. 3. The gamma-ray emission probability of the 145 keV photons, P_γ. The results are b₁ = 0.697(6), α_T = 0.452(8), P_γ = 0.480(5). The value of b₁ is in agreement with most of the values reported in the literature for this quantity. The value found for α_T is higher than all experimental values determined previously but agrees well with the theoretically calculated value for an M1 transition with 0.48% E2 admixture (α_T = 0.4565). The value for P_γ agrees with the value determined by Hansen et al. (1979), P_γ = 0.482(3). In addition, emission probabilities of K and L x-rays following the decay of ¹⁴¹Ce are determined experimentally.     

The effect of lipophilicity on the hepatobiliary properties of iminodiacetic acid derivatives in the conditions of hyperbilirubinemia

The partition coefficients (log P) of theoretically possible alkyliodinated iminodiacetic acid (IDA) derivatives and commercial IDA derivatives were calculated using two computer programs: ChemSketch Log P and ChemOffice Ultra. Newly synthesized ligands (DIETHYLIODIDA and DIISOPROPYLIODIDA) with the highest calculated log P were labeled with technetium-99m. The biodistribution and the influence of bilirubin on their biokinetics were investigated in rats and compared to corresponding results for commercial ^99mTc-BROMIDA. Log P of ^99mTc-complexes of synthesized ligands were determined experimentally as well as the protein binding. In comparison to ^99mTc-BROMIDA, ^99mTc-DIETHYLIODIDA has: (a) better biliary excretion (2.76±0.15%ID/g versus 1.83±0.10%ID/g); (b) faster hepatic clearance (2.90±0.21%ID/g versus 7.47±0.70%ID/g) and decreased biliary excretion (for 14% versus 22%) in conditions of hyperbilirubinemia after 15 min. It is proved that ^99mTc-DIISOPROPYLIODIDA has a prolonged hepatic transit time and decreased biliary excretion.     

Yield and purity of 82Sr produced via the natRb(p,xn)82Sr process

The recently reported cross-section data for the production of ⁸²Sr via the ^natRb(p,xn)⁸²Sr process were evaluated. For the ^natRb(p,xn)⁸⁵Sr process, cross-sections were measured experimentally over the proton energy range of 25–45 MeV, a region where very few data existed. An evaluation of the recently published data on the formation of ⁸⁵Sr was then also performed. From the recommended data curves, the integral yields of the desired radionuclide ⁸²Sr and the impurity ⁸⁵Sr were calculated. Yields were also determined experimentally over several energy ranges using thick ^natRbCl targets. The experimental and calculated yields were found to be in agreement within 15%. These integral tests add confidence to the evaluated cross-section data. For the production of ⁸²Sr, an incident proton energy of 60 MeV or above is recommended; the ⁸⁵Sr impurity then corresponds to <20%.     

Escape-peak to photopeak ratios in NaI(Tl) crystals

The ratio, R, of the iodine K x-ray escape-peak intensity to that of photopeak for various sizes of thin and thick NaI(Tl) scintillation crystals has been calculated for gamma-rays varying in energy from 35 to 200 keV for the case of cone geometry using Axel's formula for escape probability and by Monte Carlo method. The theoretical results are tested experimentally using 50.8 mm × 50.8 mm (2″ × 2″) and 50.8 mm × 1 mm (2″ × 0.04″) NaI(Tl) crystals for 59.54 keV gamma-rays from a ²⁴¹Am radioactive source. The ratios calculated for Axel's formula using the revised photon cross sections and fluorescence yields are lower compared to experimental values. The discrepancy between the experimental values and those calculated using Axel's formula are maximum for the thin crystal. The escape ratios calculated using Axel's formula are independent of crystal thickness and depend only on incident energy, whereas the experimental escape ratios depend both on thickness and on incident energy. The iodine K x-rays generated in a small crystal tend to escape with more frequency than x-rays generated in a larger crystal. Monte Carlo calculations agree closely with experiment.     

Diffusion weighted imaging and estimation of prognosis using apparent diffusion coefficient measurements in ischemic stroke

Objective

Estimation of the prognosis of infarction by using diffusion weighted imaging (DWI) and quantitative apparent diffusion coefficient (ADC) measurements.

Methods

23 patients having acute stroke symptoms with verified infarction in magnetic resonance imaging (MRI) were included in this study. Their MRI studies were performed between 6 and 12 h after the onset of their symptoms and were repeated on the fifth day. The infarction volumes were calculated by using DWI and the patients were divided into two groups as the ones having an expansion in the infarction area (group 1, n = 16) and the others having no expansion in the infarction area (group 2, n = 7). Quantitative ADC values were estimated. The groups were compared in terms of the ADC values on ADC maps obtained from DWI, performed during the between 6 and 12 h from the onset of the symptoms, referring to the core of the infarction (ADC_IC), ischemic penumbra (ADC_P) and the nonischemic parenchymal tissue (ADC_N). P values < 0.05 were accepted to be statistically significant.

Results

During the between 6 and 12 h mean infarction volume calculated by DWI was 23.3 cm³ for group 1 patients (ranging from 1.1 to 68.6) and this was found to be 40.3 cm³ (ranging from 1.8 to 91.5) on the fifth day. For the group 2 patients these values were found to be 42.1 cm³ (ranging from 1 to 94.7) and 41.9 (ranging from 1 to 94.7) for the same intervals respectively. A significant statistical result was failed to be demonstrated between the mean ADC_IC and ADC_N values (p = 0.350 and p = 0.229 respectively). However the comparison of the ADC_P values between the groups was found to be highly significant (p < 0.001). When the differences between the ADC_P and ADC_IC and ADC_N and ADC_P were compared the results proved to be statistically significant (p = 0.038 and p < 0.001 respectively).

Conclusions

We believe that ADC results that would be obtained from the core and the penumbra of the infarction area will be beneficial in the estimation of the infarction prognosis and in the planning of a treatment protocol.     

STRmix™ collaborative exercise on DNA mixture interpretation

An intra and inter-laboratory study using the probabilistic genotyping (PG) software STRmix™ is reported. Two complex mixtures from the PROVEDIt set, analysed on an Applied Biosystems™ 3500 Series Genetic Analyzer, were selected. 174 participants responded.For Sample 1 (low template, in the order of 200 rfu for major contributors) five participants described the comparison as inconclusive with respect to the POI or excluded him. Where LRs were assigned, the point estimates ranging from 2 × 10⁴ to 8 × 10⁶. For Sample 2 (in the order of 2000 rfu for major contributors), LRs ranged from 2 × 10²⁸ to 2 × 10²⁹. Where LRs were calculated, the differences between participants can be attributed to (from largest to smallest impact):

• •varying number of contributors (NoC),
• •the exclusion of some loci within the interpretation,
• •differences in local CE data analysis methods leading to variation in the peaks present and their heights in the input files used,
• •and run-to-run variation due to the random sampling inherent to all MCMC-based methods.

This study demonstrates a high level of repeatability and reproducibility among the participants. For those results that differed from the mode, the differences in LR were almost always minor or conservative.     

Mammographic features of calcifications in DCIS: correlation with oestrogen receptor and human epidermal growth factor receptor 2 status

Objective

This study investigated the correlation of oestrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) status with the probability of malignancy (POM) of mammographic calcifications in ductal carcinoma in situ (DCIS).

Methods

A total of 101 women (age range, 27–83 years) with pure DCIS that presented as mammographic calcifications were included. Three radiologists independently reviewed mammograms according to the BI-RADS lexicon and provided 100-point POM scores and a BI-RADS category. ER, HER2 and breast cancer subtypes were determined using immunohistochemistry (IHC) and fluorescence in situ hybridisation. Pairwise correlations between POM and IHC biomarker scores were calculated, and mammographic features were compared between breast cancer subtypes.

Results

HER2 level positively correlated with the POM score (P?<?0.0001) and BI-RADS category (P?<?0.0001), and ER level inversely correlated with the POM score (P?<?0.013) and BI-RADS category (P?<?0.010). Fine linear branching (P?=?0.004) and segmental (P?=?0.014) calcifications were significantly associated with HER2-positive cancers, and clustered calcifications were more frequently observed in ER-positive cancers (P?=?0.014).

Conclusion

HER2 status in DCIS correlated positively with the POM of mammographic calcifications, as determined by radiologists on the basis of the BI-RADS lexicon.

Key Points

? Prediction of malignancy on mammographic ductal carcinoma in situ is difficult. ? HER2 level correlated positively with the probability of malignancy assigned by radiologists. ? ER level correlated inversely with the probability of malignancy assigned by radiologists. ? HER2-positive DCIS more frequently exhibited fine linear branching or segmental calcifications. ? ER-positive DCIS more frequently exhibited clustered calcifications.     

Natural tritium measurements: Determination of the electrolytic enrichment factor of tritium

For the purpose of improving the accuracy and precision of tritium measurements in natural waters, this paper proposes a new method for the estimation of tritium concentration after electrolytic enrichment. The proposed method was based on the fact that there is a reliable correlation between the water electrolytic enrichment of deuterium and that of tritium. The constancy of the ratio, k, during the electrolysis, k = α(β − 1)/β(α − 1), was experimentally verified, where α and β are the separation factors of deuterium and tritium, respectively. The value of k depends only on the electrode materials and the type of cells. The value of k is far more constant than the values of βα and of log β/log α. When the value of k was experimentally measured beforehand, the initial concentration of sample water, (T/H)₀, could be estimated by the formula (T/H)₀ = (T/H)_f[(D/H)_f(D/H)₀]^−k, where (T/H)_f and (D/H)_f are the tritium and deuterium contents after the electrolysis, and (D/H)₀ is the deuterium content before the electrolysis.     

Complex DNA mixture analysis in a forensic context: Evaluating the probative value using a likelihood ratio model

The interpretation of mixed DNA profiles obtained from low template DNA samples has proven to be a particularly difficult task in forensic casework. Newly developed likelihood ratio (LR) models that account for PCR-related stochastic effects, such as allelic drop-out, drop-in and stutters, have enabled the analysis of complex cases that would otherwise have been reported as inconclusive. In such samples, there are uncertainties about the number of contributors, and the correct sets of propositions to consider. Using experimental samples, where the genotypes of the donors are known, we evaluated the feasibility and the relevance of the interpretation of high order mixtures, of three, four and five donors.The relative risks of analyzing high order mixtures of three, four, and five donors, were established by comparison of a ‘gold standard’ LR, to the LR that would be obtained in casework. The ‘gold standard’ LR is the ideal LR: since the genotypes and number of contributors are known, it follows that the parameters needed to compute the LR can be determined per contributor. The ‘casework LR’ was calculated as used in standard practice, where unknown donors are assumed; the parameters were estimated from the available data. Both LRs were calculated using the basic standard model, also termed the drop-out/drop-in model, implemented in the LRmix module of the R package Forensim.We show how our results furthered the understanding of the relevance of analyzing high order mixtures in a forensic context. Limitations are highlighted, and it is illustrated how our study serves as a guide to implement likelihood ratio interpretation of complex DNA profiles in forensic casework.     

Decay data of 123Tem

Measurements of coincidences between conversion electrons of the 88 keV transition in the ¹²³Te^m decay and subsequent 159 keV quanta have been made with a 4πβ-γ coincidence system equipped with a pressurized proportional counter (PPC) in the beta channel. With ¹²³Te^m sources prepared for activity determination, a detection probability for conversion electrons, ϵ, very close to ϵ = 1 was achieved. The following data have been derived from the slope of a polynomial fit to n_βn_γ/n_c vs (1 − ϵ)/ϵ by varying ϵ by discrimination and taking into account the γ sensitivity of the PPC (n_β, n_γ, n_c are the counting rates in the β, γ and coincidence channel): the total conversion coefficient of the 159 keV transition α_t = 0.1895(13), the γ-ray emission probability of the 159 keV photons p = 0.8407(9). These data agree with the theoretically calculated values, and with less accurate values determined experimentally by other authors.     

Quantitative perfusion computed tomography measurements of cerebral hemodynamics: correlation with digital subtraction angiography identified primary and secondary cerebral collaterals in internal carotid artery occlusive disease

Background

The aim of the present study was to assess hemodynamic variations in symptomatic unilateral internal carotid artery occlusion (ICAO) patients with primary collateral flow via circle of Willis or secondary collateral flow via ophthalmic artery and/or leptomeningeal collaterals.

Methods

Thirty-eight patients with a symptomatic unilateral ICAO were enrolled in the study. Based on digital subtraction angiography (DSA) findings, patients were classified into 2 groups: primary collateral (n = 14) and secondary collateral (n = 24) groups. Collateral flow hemodynamics were investigated with perfusion computed tomography (PCT) by measuring the cerebral blood flow (CBF), cerebral blood volume (CBV) and time to peak (TTP) in the hemispheres ipsilateral and contralateral to ICAO. Based on the measurements, the ipsilateral to contralateral ratio for each parameter was calculated and compared.

Results

Irrespective of the collateral patterns, ipsilateral CBF was not significantly different from that of the contralateral hemisphere (P = 0.285); ipsilateral CBV and TTP was significantly increased compared with those of the contralateral hemisphere (P = 0.000 and P = 0.000 for CBV and TTP, respectively). Furthermore, patients with secondary collaterals had significantly larger ipsilateral-to-contralateral ratios for both CBV (rCBV, P = 0.0197) and TTP (rTTP, P = 0.000) than those of patients with only primary collaterals. These two groups showed no difference in ipsilateral-to-contralateral ratio for CBF (rCBF, P = 0.312).

Conclusion

Patients with symptomatic unilateral ICAO in our study were in an autoregulatory vasodilatation status. Moreover, secondary collaterals in ICAO patients were correlated with ipsilateral CBV and delayed TTP that suggested severe hemodynamic impairment, presumably increasing the risk of ischemic events.     

Comparison of Feeding-Artery-Only versus Nidus-Plus-Feeding-Artery Embolization of Pulmonary Arteriovenous Malformations

PurposeTo compare coil embolotherapy outcomes of feeding-artery-only versus nidus-plus-feeding-artery technique for treating pulmonary arteriovenous malformations (PAVMs).Materials and MethodsA total of 219 treatment-naïve PAVMs embolized in 90 patients at a single center from 2008 to 2018 met inclusion criteria for retrospective evaluation. Of the patients, 87% had a diagnosis of hereditary hemorrhagic telangiectasia (HHT). Feeding artery (FA) diameters ≥2 mm were treated. Coil embolization techniques were classified on the basis of embolic deployment zone: (i) distal feeding artery (DFA) technique (coil-to-nidus distance ≤ 1 cm) or (ii) nidus plus feeding artery (NiFA) technique. Successful embolization predictors were assessed using a multivariate linear regression model with input from patient- and PAVM-specific variables.ResultsTreatment success was achieved in 192 of 219 PAVMs (87.7%) over a mean follow-up period of 19 months. Statistically significant predictors of success in the linear regression model included simple angioarchitecture, NiFA embolization technique, and shorter follow-up duration. Stratified by technique, success rates were 99 of 105 (94.3%) and 93 of 114 (81.6%) PAVMs for NiFA and DFA, respectively (P = .007). On average, NiFA-embolized PAVMs had a larger FA diameter (3.6 mm vs 2.7 mm, P < .001) and comprised more complex PAVMs (48% vs 22%, P < .001) than DFA. Treatment success was not significantly associated with sac size or FA diameter.ConclusionsCoil embolization of both the nidus and FA was associated with a higher persistent occlusion rate than FA embolization alone.     

Assessing the Risk of Intracranial Aneurysm Rupture Using Morphological and Hemodynamic Biomarkers Evaluated from Magnetic Resonance Fluid Dynamics and Computational Fluid Dynamics

Purpose:Evaluate in vivo hemodynamic and morphological biomarkers of intracranial aneurysms, using magnetic resonance fluid dynamics (MRFD) and MR-based patient specific computational fluid dynamics (CFD) in order to assess the risk of rupture.Methods:Forty-eight intracranial aneurysms (10 ruptured, 38 unruptured) were scrutinized for six morphological and 10 hemodynamic biomarkers. Morphological biomarkers were calculated based on 3D time-of-flight magnetic resonance angiography (3D TOF MRA) in MRFD analysis. Hemodynamic biomarkers were assessed using both MRFD and CFD analyses. MRFD was performed using 3D TOF MRA and 3D cine phase-contrast magnetic resonance imaging (3D cine PC MRI). CFD was performed utilizing patient specific inflow–outflow boundary conditions derived from 3D cine PC MRI. Univariate analysis was carried out to identify statistically significant biomarkers for aneurysm rupture and receiver operating characteristic (ROC) analysis was performed for the significant biomarkers. Binary logistic regression was performed to identify independent predictive biomarkers.Results:Morphological biomarker analysis revealed that aneurysm size [P = 0.021], volume [P = 0.035] and size ratio [P = 0.039] were statistically significantly different between the two groups. In hemodynamic biomarker analysis, MRFD results indicated that ruptured aneurysms had higher oscillatory shear index (OSI) [OSI.max, P = 0.037] and higher relative residence time (RRT) [RRT.ave, P = 0.035] compared with unruptured aneurysms. Correspondingly CFD analysis demonstrated significant differences for both average and maximum OSI [OSI.ave, P = 0.008; OSI.max, P = 0.01] and maximum RRT [RRT.max, P = 0.045]. ROC analysis revealed AUC values greater than 0.7 for all significant biomarkers. Aneurysm volume [AUC, 0.718; 95% CI, 0.491–0.946] and average OSI obtained from CFD [AUC, 0.774; 95% CI, 0.586–0.961] were retained in the respective logistic regression models.Conclusion:Both morphological and hemodynamic biomarkers have significant influence on intracranial aneurysm rupture. Aneurysm size, volume, size ratio, OSI and RRT could be potential biomarkers to assess aneurysm rupture risk.     

A method for determination mass absorption coefficient of gamma rays by Compton scattering

A method was proposed for determination mass absorption coefficient of gamma rays for compounds, alloys and mixtures. It is based on simulating interaction processes of gamma rays with target elements having atomic numbers from Z=1 to Z=92 using the MCSHAPE software. Intensities of Compton scattered gamma rays at saturation thicknesses and at a scattering angle of 90° were calculated for incident gamma rays of different energies. The obtained results showed that the intensity of Compton scattered gamma rays at saturations and mass absorption coefficients can be described by mathematical formulas. These were used to determine mass absorption coefficients for compound, alloys and mixtures with the knowledge of their Compton scattered intensities. The method was tested by calculating mass absorption coefficients for some compounds, alloys and mixtures. There is a good agreement between obtained results and calculated ones using WinXom software. The advantages and limitations of the method were discussed.