We compared Doppler spectral parameters in acute inflammatory, reactive, lymphomatous, and metastatic lymph nodes, and evaluated pulsed Doppler sonography as a method for distinguishing between different causes of cervical lymphadenopathy. Spectral Doppler analysis with measurements of resistance index (RI), pulsatility index (PI), peak systolic velocity (PSV), and end-diastolic velocity (EDV) was performed in 197 patients with cervical lymphadenopathy. Results of Doppler analysis were compared with findings of cytology and histology or with clinical presentation and follow-up. Student's t-test was used to assess statistical significance of differences in Doppler parameters between groups of patients. Significant differences for RI and PI were shown between all groups of patients except between lymphomatous and reactive nodes. Specificity of 100% for metastatic nodal involvement was shown for cutoff values RI>0.80 and PI>1.80. A positive predictive value (PPV) of 100% for acute lymphadenitis was shown for cutoff values RI<0.50 and PI<0.60. An EDV>9 cm/s has 100% negative predictive value for nodal metastasis, and EDV<1 cm/s has 100% specificity and PPV for metastasis. Although there exist differences in RI, PI, PSV, and EDV between different nodal diseases, none of these parameters offer both good sensitivity and good specificity, and only extreme cutoff values may occasionally be helpful in differential diagnosis. Doppler spectral analysis is a valuable noninvasive adjunct which can help in differentiation between metastatic, lymphomatous, acute inflammatory, and reactive lymphadenopathy, but cannot obviate biopsy in the majority of cases.
The aim of this work was to determine important dosimetric characteristics of several types of the most interesting tissue-equivalent thermoluminescent detectors (TLDs). Special attention was given to the determination of energy dependence for medium and low energy X rays. The following types of TLDs were investigated: (a) two new types based on lithium borate: Li2B4O7:Cu,In and Li,B4O7:Cu,In,Ag; (b) two types of the recently developed highly sensitive LiF:Mg,Cu,P material: TLD-700H and GR 200A and (c) two well known types of LiF:Mg,Ti detectors: TLD-100 and TLD-700. In order to determine their photon energy response characteristics, TLDs previously calibrated with 137Cs gamma rays were simultaneously irradiated with X ray beams in the range of effective energies between 33 and 116 keV. Measured energy responses (relative to air), normalised to those to 137Cs photons were compared with calculated data. Although the deviations of the measured data from the 'theoretical' predictions are different for all the investigated TLDs, there is no large difference in 'tissue-equivalency' between them.
The aim of this work was to determine energy dependence characteristics in terms of values of the personal dose equivalent, HP(10). The following types of thermoluminescent detectors (TLDs) were investigated: (a) two new types based on lithium borate, Li2B4O7:Cu,In and Li2B4O7:Cu,In,Ag; (b) two types based on the highly sensitive material LiF:Mg,Cu,P, TLD-700H and GR 200A; (c) two well-known types of LiF:Mg,Ti detector, TLD-100 and TLD-700 and (d) highly sensitive Al2O3:C detectors. TLDs previously calibrated with 137Cs gamma rays were simultaneously irradiated with X ray beams in the range of mean energies between 33 and 116 keV. The irradiations were performed with detectors in polymethyl methacrylate (PMMA) holders placed on a 30 cm x 30 cm x 15 cm water phantom with PMMA walls (ISO phantom). Measured energy responses were compared with calculated data for HP(10) values. The results confirmed the satisfactory tissue equivalent characteristics of all investigated TLDs except Al2O3:C, which (due to its large energy dependence) is suitable for personal dosimetry only with an appropriate filter.
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