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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Asia Oceania Journal of Nuclear Medicine and Biology
- نوع مقاله: Journal Article
- کلمات کلیدی: specific binding ratio,partial volume effect,Southampton method
- چکیده:
- چکیده انگلیسی: Objective(s): The partial volume effect (PVE) of single-photon emission computed tomography (SPECT) on corpus striatum imaging is caused by the underestimation of specific binding ratio (SBR). A large ROI (region of interest) set using the Southampton method is independent of PVE for SBR. The present study aimed to determine the optimal ROI size with contrast and SBR for striatum images and validate the Southampton method using a three-dimensional mathematical cylinder (3D-MAC) phantom.
Methods: We used ROIs sizes of 27, 36, 44, 51, 61, 68, and 76 mm for targets with diameters 40, 20, and 10 mm on reference and processed images reconstructed using the 3D-MAC phantom. Contrast values and SBR were compared with the theoretical values to obtain the optimal ROI size.
Results: The contrast values in the ROI with diameters of 51 (target: 40 mm in diameter) and 44 (target: 20 mm in diameter) mm matched the theoretical values. However, this value did not correspond with the 10-mm-diameter target. The SBR matched the theoretical value with an ROI of > 44 mm in the 20-mm-diameter target;but, it was under- and overestimated under any other conditions.
Conclusion: These results suggested that an ROI should be 4-2 folds larger than the target size without PVE, and that the Southampton method was remarkably accurate.- انتشار مقاله: 26-07-1396
- نویسندگان: Hideo Onishi,Takayuki SAKAI,Osamu SHIROMOTO,Hizuru Amijima
- مشاهده
- جایگاه : پژوهشی
- مجله: Asia Oceania Journal of Nuclear Medicine and Biology
- نوع مقاله: Journal Article
- کلمات کلیدی: Bilinear scaling,CTAC,Attenuation Coefficient,effective atomic number
- چکیده:
- چکیده انگلیسی: Objective: In this study, we aimed to validate the accuracy of computed tomography-based attenuation correction (CTAC) using the bilinear scaling method.
Methods: The measured attenuation coefficient (μm) was compared to a theoretical attenuation coefficient (μt ) using four different CT scanners and an RMI 467 phantom. The effective energy of the CT beam X-rays was calculated, using the aluminum half-value layer method, and was used in conjunction with an attenuation map to convert the CT numbers to μm values for the photon energy of 140 keV. We measured the CT number of the RMI 467 phantom for each of four scanners, and compared the μm and μt values for the effective energies of the CT beam X-rays, effective atomic numbers, and physical densities.
Results: The μm values for CT beam X-rays with low effective energies decreased in high construction elements, compared with CT beam X-rays of high effective energies . As the physical density increased, the μm values elevated linearly. Compared with other scanners, the μm values obtained from the scanner with CT beam X-rays of the maximal effective energy increased once the effective atomic number exceeded 10.00. The μm value of soft tissue was equivalent to the μt value. However, the ratios of the maximal differences between the μm value and the μt value were 25.4% (lung) and 21.5% (bone) respectively. Additionally, the maximal differences in the μm values were 6.0% in the bone tissue for each scanner.
Conclusion: The bilinear scaling method could accurately convert CT numbers to μ values within the soft tissues.- انتشار مقاله: 10-07-1394
- نویسندگان: Nobuhiro Yada,Hideo Onishi
- مشاهده