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CC BY 4.0 · World J Nucl Med 2023; 22(03): 217-225
DOI: 10.1055/s-0043-1771287
Original Article

Impact of Wolfmet Tungsten Alloys as Parallel-Hole Collimator Material on Single-Photon Emission Computed Tomography Image Quality and Functional Parameters: A Simulating Medical Imaging Nuclear Detectors Monte Carlo Study

Maryam Darami
1   Medical Radiation Sciences Research Team, Tabriz University of Medical Sciences, Tabriz, Iran
,
Babak Mahmoudian
2   Department of Nuclear Medicine, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
,
Michael Ljungberg
3   Medical Radiation Physics, Lund University, Lund, Sweden
,
Jalil Pirayesh Islamian 
4   Department of Medical Physics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
› Institutsangaben
Funding This work was financially supported by a grant from the Medical Radiation Sciences Research Team, Tabriz University of Medical Sciences, Tabriz, Iran (Grant no # 65077).
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Abstract

Objectives Collimators have a significant role in image quality and detectability in single-photon emission computed tomography (SPECT) imaging. Using an appropriate alloy that effectively absorbs scattered photons, without induced secondary x-rays, and with proper rigidity and weight may provide an effective approach to the image improvement that conventionally collimators made of lead (Pb).

Materials and Methods A Siemens E.CAM SPECT imaging system equipped with low-energy high-resolution (LEHR) collimator was simulated by the Simulating Medical Imaging Nuclear Detectors Monte Carlo program. Experimental and simulated data were compared based on a 2-mm 99mTc point source in an acrylic cylindrical Deluxe phantom (Data Spectrum, Inc). Seven types of tungsten (W) alloys (Wolfmet), with W content from 90 to 97% by weight, were then used as collimator materials of the simulated system. Camera parameters, such as energy- and spatial resolution, image contrast, and collimator-related parameters, such as fraction of septal penetration, scatter-to-primary ratios, and percentage of induced secondary x-rays, due to interactions in the collimator, were evaluated.

Results Acceptable conformity was found for the simulated and experiment systems in terms of energy spectra, 10.113 and 10.140%, full width at half-maximum (FWHM) of the point spread function (PSF) curves, 8.78 and 9.06 mm, sensitivity, 78.46 and 78.34 cps/MBq, and contrast in images of 19.1 mm cold spheres in the Deluxe phantom, 79.17 and 78.97%, respectively. Results on the parameters of the simulated system with LEHR collimator made from the alloys showed that the alloy consisting of 90% W, 6% nickel, and 4% copper provided an FWHM of 8.76 mm, resulting in a 0.2% improvement in spatial resolution. Furthermore, all the Wolfmet collimators showed a 48% reduction in the amount of X-rays production compared to the Pb.

Conclusion A Wolfmet LEHR collimator, made by a combination of W (90%), Ni (6%), and Cu (6%) provides a better image quality and detectability compared to the Pb.

Keywords

Wolfmet - collimator - image quality - SPECT - SIMIND - tungsten

Authors' Contribution

M.D. was responsible for writing—original draft, visualization, methodology, investigation, data curation, and conceptualization. B.M was responsible for writing—review and editing, supervision, formal analysis, and conceptualization. M.L. was responsible for providing materials for SIMIND simulation, review, and editing. J.P.I. was responsible for writing—review and editing, supervision, funding acquisition, and conceptualization.




Publikationsverlauf

Artikel online veröffentlicht:
06. September 2023

© 2023. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)

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