Dual radioisotopes simultaneous SPECT of 99mTc-tetrofosmin and 123I-BMIPP using a semiconductor detector.

Document Type : Original Article

Authors

1 Department of Nuclear Medicine Technology, Gunma Prefectural College of Health Sciences, Maebashi, Japan

2 Department of Radiology, Ehime University Graduate School of Medicine, Toon, Japan

3 Department of Radiological Technology, Ehime University Hospital, Toon, Japan

Abstract

Objective(s): The energy resolution of a cadmium-zinc-telluride (CZT) solid-state semiconductor detector is about 5%, and is superior to the resolution of the conventional Anger type detector which is 10%. Also, the window width of the high-energy part and of the low-energy part of a photo peak window can be changed separately. In this study, we used a semiconductor detector and examined the effects of changing energy window widths for 99mTc and 123 I simultaneous SPECT.
Methods: The energy “centerline” for 99mTc was set at 140.5 keV and that for 123I at 159.0 keV. For 99mTc, the “low-energy-window width” was set to values that varied from 3% to 10% of 140.5 keV and the “high-energy-window width” were independently set to values that varied from 3% to 6% of 140.5 keV. For 123I, the “low energy-window-width” varied from 3% to 6% of 159.0 keV and the high-energy-window width from 3% to 10% of 159 keV. In this study we imaged the cardiac phantom, using single or dual radionuclide, changing energy window width, and comparing SPECT counts as well as crosstalk ratio.
Results: The contamination to the 123I window from 99mTc (the crosstalk) was only 1% or less with cutoffs of 4% at lower part and 6% at upper part of 159KeV. On the other hand, the crosstalk from 123I photons into the 99mTc window mostly exceeded 20%. Therefore, in order to suppress the rate of contamination to 20% or less, 99mTc window cutoffs were set at 3% in upper part and 7% at lower part of 140.5 KeV. The semiconductor detector improves separation accuracy of the acquisition inherently at dual radionuclide imaging. In, this phantom study we simulated dual radionuclide simultaneous SPECT by 99mTc-tetrofosmin
and 123 I-BMIPP.
Conclusion: We suggest that dual radionuclide simultaneous SPECT of 99mTc and 123I using a CZT semiconductor detector is possible employing the recommended windows.

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1. Dobbeleir AA, Hambys ASE, Franken PR. Influence of methodology on the presence and extent of mismatching between 99mTc-MIBI and 123I-BMIPP in myocardial viability studies. J Nucl Med. 1999; 40: 707-14.
2. Tamaki N, Tadamura E, Kawamoto M Magata Y, Yonekura Y, Fujibayashi Y, et al. Decreased uptake of iodinated branched fatty acid analog indicates metabolic alterations in ischemic myocardium. J Nucl Med. 1995; 36:1974-80.
3. Kumita S, Mizumura S, Kijima T, Machida M, Kumazaki T, Tetsuou Y, et al. ECG-gated dual isotope myocardial SPECT with 99mTc-MIBI and 123I-BMIPP in patiens with ischemic heart disease. Kaku Igaku. 1995; 32:547-55.
4. National Electric Manufacturers Association (NEMA). Performance Measurements of Scintillation Cameras. Standards publication NU-1–1994. Washington, DC: NEMA; 1994.
5. NEMA Standard Publication NU 1-2001, Performance Measurements of Scintillation Cameras. USA, Rosslyn: National Electrical Manufacturers Association; 2001.
6. Mizumura S, Kumita S, Kumazaki T. A study of the simultaneous acquisition of dual energy SPECT with 99mTc and 123I: Evaluation of optimal window setting with myocardial phantom. Kaku Igaku. 1995;32(2):183-90.
7. Hirata M, Monzen H, Suzuki T, Ogasawara M, Nakanishi A, Sumi N, et al. Evaluation of a new protocol for two-isotope 123I-BMIPP/99mTc-TF single photon emission computed tomography (SPECT) to detect myocardial damage within one hour. Jpn J Med Phys. 2009; 29:3-11.
8. Inoue T. Basic study of dual radionuclide data acquisition with Tc-99m and I-123 to establish quantitative brain SPECT. Ehime Medical Journal 1993; 12:228-37.
9. Bocher M, Blevis IM, Tsukerman L, Shrem Y, Kovalski G, Volokh L. A fast cardiac gamma camera with dynamic SPECT capabilities: design, system validation and future potential. Eur J Nucl Med. 2010; 37:1887-902.
10. Takahashi Y, Miyagawa M, Nishiyama Y, Ishimura H, Mochizuki T. Performance of a semiconductor SPECT system: comparison with a conventional Anger-type SPECT instrument. Ann Nucl Med. 2013; 27:11-6.
11. Jaszcak RJ, Greer KL.Improved SPECT quantification using compensation for scattered photons. J Nucl Med. 1984; 25: 893-900.
12. Kubo A, Nakamura K, Hashimoto J, Sammiya T, Iwanaga S, Hashimoto S, et al. Phase I clinical trial of a new myocardial imaging agent, 99mTc-PPN1011. Kaku Igaku. 1992;29(10):1165-76.
13. Torizuka K, Yonekura Y, Nishimura T, Tamaki N, Uehara T, Ikekubo K, et al. A Phase 1 study of betamethyl- p-(123I)-iodophenyl-pentadecanoic acid (123I-BMIPP). Kaku Igaku. 1991;28(7):681-90.
14. Hatakeyama R. Heart phantom with liver object. A new textbook of nuclear medicine technology 2001; 1: 243-246. (in Japanese)