Nuclear Data Sheets for A = 176

Browne, E.; Junde, Huo

doi:10.1006/ndsh.1998.0014

Cited by 49 publications

(19 citation statements)

References 136 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The 4.5% difference between the results obtained by the two methods is compatible with the uncertainty of I reported by Browne & Junde (1998). This argument is supported by the fact that the present result at kT ¼ 25 keV of 1094 AE 32 mbarn nicely agrees with the value of 1101 AE 24 mbarn reported by Zhao & Käppeler (1991) via -ray spectroscopy.…”

Section: Resultssupporting

confidence: 92%

“…This comparison is most important since the decay intensity of the 88 keV line had been revised recently. While Zhao & Käppeler (1991) had used a value of I ¼ 8:90% AE 0:15% (Browne 1990), the most recent reference contains a 3 times more uncertain value of 8:90% AE 0:44% (Browne & Junde 1998). However, this additional uncertainty can be avoided by normalization of the present measurement to the data based on spectroscopy of the decay electrons as discussed in x 3.3.…”

Section: Self-absorption Correctionmentioning

confidence: 98%

“…For 176 Lu, the analysis was based on the most intense line in the decay of the isomeric state with E ¼ 88:36 keV. The decay properties of all relevant states used in the analysis were adopted from Chunmei (1995) and Browne & Junde (1998), as listed in Table 1.…”

Section: Overviewmentioning

confidence: 99%

See 2 more Smart Citations

¹⁷⁶Lu/¹⁷⁶Hf: A Sensitive Test ofs‐Process Temperature and Neutron Density in AGB Stars

Heil

Winckler

Dababneh

et al. 2008

ApJ

View full text Add to dashboard Cite

The s-process branching at A ¼ 176 has been analyzed on the basis of significantly improved experimental cross sections. This work reports on activation measurements of the partial (n; ) cross section of 176 Lu feeding the isomeric state in 176 Lu. In total, six irradiations were performed at the Karlsruhe 3.7 MV pulsed Van de Graaff accelerator, and the induced activities were measured with HPGe clover detectors. In combination with previous data, partial cross sections of 3185 AE 156 and 1153 AE 30 mbarn were deduced at kT ¼ 5:1 and 25 keV, respectively. With these results and a recent time-of-flight measurement of the total stellar (n; ) cross section, the isomeric ratio was found to be constant in the relevant thermal energy range of the main s-process component. Based on these new data, a comprehensive analysis of the branching at 176 Lu was carried out for testing the temperature and neutron density conditions during He shell flashes in thermally pulsing low-mass asymptotic giant branch stars. It was found that the long-standing problem of the mother/daughter ratio of the two s-only isotopes 176 Lu and 176 Hf could be solved, if the temperaturedependent -decay half-life of 176 Lu was considered with sufficient resolution over the temperature profile of the convective He shell flashes.

show abstract

Section: Resultssupporting

confidence: 92%

Section: Self-absorption Correctionmentioning

confidence: 98%

See 1 more Smart Citation

¹⁷⁶Lu/¹⁷⁶Hf: A Sensitive Test ofs‐Process Temperature and Neutron Density in AGB Stars

Heil

Winckler

Dababneh

et al. 2008

ApJ

View full text Add to dashboard Cite

show abstract

“…However, in the scintillation crystal Lu 2 SiO 5 , about 2.59% of the lutetium element is 176 Lu and has an intrinsic emission, [25][26][27][28] which results in the formation of "true" coincidences. These true coincidences generate a system background, possibly masking out low uptake regions.…”

Section: Iib Analytical Cnr Calculationmentioning

confidence: 99%

Estimation of the minimum detectable activity of preclinical PET imaging systems with an analytical method

Bao

Chatziioannou

2010

Medical Physics

View full text Add to dashboard Cite

Purpose:The traditional figures of merit used in the evaluation of positron emission tomography ͑PET͒ systems, including system sensitivity and spatial resolution, do not directly reflect the minimum detectable activity ͑MDA͒ performance, despite the fact that it is one of the most important tasks for a PET system. MDA, as a combination of the more traditional PET system parameters, is directly related to lesion detection. However, MDA evaluation is task specific and cannot be done by a single measurement. Therefore, a simple method to evaluate system detectability needs to be developed. Methods: In this work, an analytical method of MDA estimation was developed, taking into account system sensitivity, spatial resolution, source properties, and noise propagation in image reconstruction by using the Rose criterion and/or the Curie equation as the detection standard. In the implementation, the source background, as well as the intrinsic activity background from the scintillation material of the system, was also taken into consideration. The accuracy of this method was evaluated in two commercially available preclinical PET systems, with phantom experiments that were designed to closely mimic in vivo tumor uptake without introducing finite boundaries between the source and the background. Results: The lesion contrast-to-noise ratio calculated by the analytical evaluation showed good agreement with that obtained from the experiments. Visual assessment of the reconstructed images at the detection limit ͑based on analytical evaluation͒ also was in agreement with the Rose criterion. The MDA performance was quantitatively compared between the two preclinical PET systems and showed different detection limits under different imaging conditions, suggesting that the detection limit of a PET system strongly depends on the lesion properties and acquisition settings. Conclusions: An analytical method of evaluating the PET system detectability was developed and validated by experiments. Overall, the analytical MDA calculation provides a simple way to evaluate the signal detectability of a PET system and can be used for comparing different systems. It also provides guidelines for designing new PET tomographs as well as optimizing data acquisition protocols.

show abstract

“…The lutetium used in LSO contains 2.6% 176 Lu, which decays by b 2 -decay (mean b 2 -energy of 420 keV). As shown in Figure 1, the b 2 -decay is followed by the prompt emission of g-rays of energy 307 keV (94%), 202 keV (78%), and 88 keV (15%) (11). The b 2 -particle is detected in the crystal in which it was emitted but the g-ray may escape and be detected in another crystal, causing a valid coincident count that lacks the collinearity possessed by the 511-keV photons associated with positron decay.…”

mentioning

confidence: 96%

Imaging of Weak-Source Distributions in LSO-Based Small-Animal PET Scanners

Goertzen

Suk²,

Thompson³

2007

Journal of Nuclear Medicine

View full text Add to dashboard Cite

Lutetium oxyorthosilicate (LSO)-or lutetium-yttrium oxyorthosilicate (LYSO)-based PET scanners have intrinsic radioactivity in the scintillator crystals due to the presence of 176 Lu, which decays by b-emission followed by one or more prompt g-ray emissions. This leads to intrinsic true counts that can influence the image when scanning low levels of activity. An evaluation of the effects of this intrinsic activity for low levels of activity and different energy windows is performed on an LSO-based small-animal PET scanner. Methods: Intrinsic count rate and sensitivity were measured for a range of lower-level discriminators (LLDs) ranging from 100 to 750 keV. The noise equivalent count rate (NECR) as a function of LLD for activity levels from 100 Bq to 100 kBq was estimated using a combination of measurement and previously published data for this scanner. Phantom imaging was performed using three 68 Ge sources of strength 55, 220, and 940 Bq and LLD levels of 250, 350, and 400 keV. The images were assessed using a contrast-to-noise ratio (CNR) analysis and by comparing the observed ratio of source activities to the true ratio value. Results: The intrinsic true count rate is reduced from 940 counts per second (cps) for a 250-to 750-keV energy window to ,2 cps for a 400-to 750-keV window. There is a corresponding 2-fold drop in sensitivity for detected true events for external positron sources for these 2 energy windows. The NECR versus LLD curves showed a highly peaked shape, with the optimum LLD being approximately 425 keV. The phantom image results were dominated by the intrinsic true counts when an energy window of 250-750 keV was used. The intrinsic true counts were almost completely removed by raising the LLD to 400 keV. The CNR for each of the sources was higher for the narrow energy window and the 55 Bq could be easily visualized in images acquired with LLD levels of 350 and 400 keV but not when the 250-keV LLD was used. Images acquired with an LLD of 400 keV and reconstructed with 2-dimensional filtered backprojection were the most quantitatively accurate. Conclusion: It is possible to visualize sources of ,1 kBq in LSO-based animal PET systems by raising the LLD to 400 keV to exclude the majority of the counts due to the intrinsic activity present in the LSO. PET scanner performance is usually optimized for a specific imaging task based on the results of noise equivalent count rate (NECR) measurements (1-4). The usual measure reported is the peak NECR value and the activity at which the peak occurs and, in general, the energy window is chosen to maximize the value of the peak NECR. When the imaging task involves very low levels of injected activity, such as cell trafficking studies (5) or gene expression imaging (6), the scanner is operating at a count rate far less than the peak NECR value.When low activity levels are being imaged, there is a very limited number of true counts that can be acquired so that one would consider using a wider energy window to increase the sensitivity (7). However, the choice...

show abstract

Nuclear Data Sheets for A = 176

Cited by 49 publications

References 136 publications

¹⁷⁶Lu/¹⁷⁶Hf: A Sensitive Test ofs‐Process Temperature and Neutron Density in AGB Stars

¹⁷⁶Lu/¹⁷⁶Hf: A Sensitive Test ofs‐Process Temperature and Neutron Density in AGB Stars

Estimation of the minimum detectable activity of preclinical PET imaging systems with an analytical method

Imaging of Weak-Source Distributions in LSO-Based Small-Animal PET Scanners

Contact Info

Product

Resources

About

Nuclear Data Sheets for A = 176

Cited by 49 publications

References 136 publications

176Lu/176Hf: A Sensitive Test ofs‐Process Temperature and Neutron Density in AGB Stars

176Lu/176Hf: A Sensitive Test ofs‐Process Temperature and Neutron Density in AGB Stars

Estimation of the minimum detectable activity of preclinical PET imaging systems with an analytical method

Imaging of Weak-Source Distributions in LSO-Based Small-Animal PET Scanners

Contact Info

Product

Resources

About

¹⁷⁶Lu/¹⁷⁶Hf: A Sensitive Test ofs‐Process Temperature and Neutron Density in AGB Stars

¹⁷⁶Lu/¹⁷⁶Hf: A Sensitive Test ofs‐Process Temperature and Neutron Density in AGB Stars