Optimum energy window setting on Hg-201 x-rays photopeak for effective Tl-201 imaging

Kojima, Akira; Takaki, Akinobu; Noguchi, Takuro; Matsumoto, Masanori; Katsuda, Noboru; Tomiguchi, Seiji; Yamashita, Yasuyuki

doi:10.1007/bf02985046

Cited by 8 publications

(7 citation statements)

References 5 publications

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“…A similar investigation was previously performed (28); however, the phantom used in that study was a point source of activity in a cylinder filled with water as attenuation material.…”

Section: Discussionmentioning

confidence: 96%

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Optimized Energy Window Configuration for 201Tl Imaging

Kalantari¹,

Rajabi²,

Yaghoobi³

2008

Journal of Nuclear Medicine Technology

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A poor signal-to-noise ratio attributable to a low injected dose of thallium and the presence of scattered photons are the major impediments in the use of thallium as an imaging agent. Thallium decays in a complicated way and emits photons in a wide range of energies (68-82 keV). To increase the ratios of primary photons to scatter photons (primary-to-scatter ratios) and possibly increase system sensitivity, a new energy window for thallium was investigated. Methods: The NCAT phantom was used to simulate the distribution of activity and the attenuation coefficient in a typical patient torso. The phantom was imaged with a SPECT simulator in different energy window configurations. The energy spectra for primary photons and scatter photons were generated, and the most suitable energy windows were investigated. To evaluate the results of the simulation study, a physical phantom was imaged in different energy windows with a SPECT system. The images of the physical phantom were analyzed for the best-quality image and the corresponding window setting. To evaluate the windows determined in the simulation and phantom studies, SPECT images of 7 patients who had angiographically confirmed myocardial defects were acquired in different energy windows. The images were quantitatively compared on the basis of the calculated contrast, scatter-to-noise ratio, and sensitivity. The images were also qualitatively evaluated independently by 4 nuclear medicine specialists. Results: The simulation study showed that the conventional window setting (68 6 10% keV) is not the most suitable window configuration for 201 Tl imaging and that the optimum energy window is 77 6 15% keV. The images acquired in the latter window configuration yielded higher primary-to-scatter ratios, higher sensitivity (total counts), and better contrast than the images acquired in the conventional window configuration. The phantom study confirmed the results of the simulation study. In the clinical study, the images acquired in the suggested window showed a considerable increase in myocardium-to-defect contrast (1.541 6 0.368) and myocardium-to-cavity contrast (1.171 6 0.099) than those acquired in the conventional window configuration. Conclusion: The energy window configuration of 77 6 15% keV yields higher-quality images than the conventional window configuration.

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“…A similar investigation was previously performed (28); however, the phantom used in that study was a point source of activity in a cylinder filled with water as attenuation material.…”

Section: Discussionmentioning

confidence: 96%

“…In other words, the x-rays of 201 Tl are implicitly considered to be monoenergetic g-rays of 68 keV. From the physical point of view, this presumption is not quite valid because of the complex combination of primary and scattered photons in the x-ray spectrum (28).…”

Section: Discussionmentioning

confidence: 99%

Optimized Energy Window Configuration for 201Tl Imaging

Kalantari¹,

Rajabi²,

Yaghoobi³

2008

Journal of Nuclear Medicine Technology

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“…Several groups have proposed a shorter acquisition protocol that collects fewer angular projections and also a reduced time per projection [6,7]. Kojima et al proposed an off-peak window energy setting which increases the primary counts rate of 201 Tl, and also improves the image quality [8]. A new advanced reconstruction algorithm based on an iterative reconstruction method with resolution recovery controls the effects of noise [9,10,11].…”

Section: Discussionmentioning

confidence: 99%

The interpolated projection data estimation method improves the image quality of myocardial perfusion SPECT with a short acquisition time

et al. 2011

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The interpolated projection data estimation processing (IPDE) method increases the amount of projection data by interpolation of the projection data. We examined the usefulness of the IPDE method for 201 Tl myocardial perfusion imaging (MPI) single photon emission computed tomography (SPECT) with a short acquisition time. MethodsForty patients with suspected ischemic heart disease underwent stress 201 Tl-MPI SPECT.Both stress and delayed images were acquired by 4 cycles of 360° continuous rotation with a 90-direction setting for 14 min. The projection data used for reconstruction were 1) all cycle data (Tl-90-14min), 2) 2 cycles of data (Tl-90-7min), and 3) 2 cycles of data processed using the IPDE method (Tl-180IPDE-7min). This study compared the detection of the perfusion defect by the uptake score and the image quality of 201 Tl-MPI SPECT using the normalized mean square error (NMSE). ResultsThe uptake score of Tl-180IPDE-7min was significantly more concordant with Tl-90-14min in comparison to the Tl-90-7min (p<0.05). The NMSE of the Tl-180IPDE-7 min (1.85±1.06%) was significantly lower than that of the Tl-90-7min be useful as a supporting method for shortening the acquisition time of 201 Tl-MPI SPECT.

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“…Procedures of determining FWTM are similar to those of FWHM, while a tenth of the peak events are used to determine the peak area (Figure 1). Due to increased low-energy tailing in a peak brought on by charge trapping, the FWTM is considered as a stronger indicator of radiation dosimetry to the detector than the FWHM [12]. In this method, 95% of the peak events are integrated, but there is an intersection of the peak with Compton continuum in the low energy tail [9].…”

Section: -1-full Width At Half Maximummentioning

confidence: 99%

Review Article : Applicable methods of evaluating peak area of gamma ray spectra

Al-Musawi¹,

Jubair²,

Sulaiman³

2022

JUAPS

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Gamma ray spectra have interesting information about energy and intensity of gamma photons. Normally, this information is available in the peak area and background region. A full energy peak sits on a background continuum and produced by full energy absorption of high energy photons, while background region is produced by Compton scattering of the photons. The most essential concern of errors is in the method of determining the events in both peak and background areas. The uncertainty is low when the background counts are small relative to the peak counts. However, it becomes high when the counts of the peak area are low with respect to that of background. The detection threshold for the peak is ultimately determined by the uncertainty in the background counts. This depends on the technique used and the form of the produced spectra. This paper reviews different methods of determining peak area and their associated uncertainties in terms of the principle and application of the techniques used..

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Optimum energy window setting on Hg-201 x-rays photopeak for effective Tl-201 imaging

Cited by 8 publications

References 5 publications

Optimized Energy Window Configuration for 201Tl Imaging

Optimized Energy Window Configuration for 201Tl Imaging

The interpolated projection data estimation method improves the image quality of myocardial perfusion SPECT with a short acquisition time

Review Article : Applicable methods of evaluating peak area of gamma ray spectra

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