Extrinsic Versus Intrinsic Uniformity Correction for  -Cameras

Bolstad, Randy; Brown, Jody; Grantham, Vesper

doi:10.2967/jnmt.110.084814

Cited by 2 publications

(4 citation statements)

References 10 publications

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“…As a result, imperfections in the collimator will influence the uniformity more for EM1 than EM2. The cause of ring artifacts has been studied to some degree [27]; however, the above speculation has, to our knowledge, not been carefully investigated. It is, thus, strongly encouraged to carry out extrinsic uniformity correction before imaging with 161 Tb.…”

Section: Discussionmentioning

confidence: 99%

“…Due to ring artifacts that can occur in SPECT images, a uniformity map was created using 161 Tb. Artifacts may appear in SPECT images due to non-uniformity in the response over the detector surface [27]. Such artifacts may be reduced by acquiring an image of a uniform flood source and weighing the response in each pixel, such that the signal is uniform across all pixels.…”

Section: Energy Calibration Uniformity Measurements and Sensitivitymentioning

confidence: 99%

“…Such artifacts may be reduced by acquiring an image of a uniform flood source and weighing the response in each pixel, such that the signal is uniform across all pixels. Uniformity correction maps can be either intrinsic, which consider the detector head uniformities, or extrinsic, which also incorporate the collimator [27].…”

Section: Energy Calibration Uniformity Measurements and Sensitivitymentioning

confidence: 99%

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Establishment of a clinical SPECT/CT protocol for imaging of 161Tb

et al. 2020

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Background: It has been proposed, and preclinically demonstrated, that 161 Tb is a better alternative to 177 Lu for the treatment of small prostate cancer lesions due to its high emission of low-energy electrons. 161 Tb also emits photons suitable for single-photon emission computed tomography (SPECT) imaging. This study aims to establish a SPECT protocol for 161 Tb imaging in the clinic. Materials and methods: Optimal settings using various γ-camera collimators and energy windows were explored by imaging a Jaszczak phantom, including hollowsphere inserts, filled with 161 Tb. The collimators examined were extended low-energy general purpose (ELEGP), medium-energy general purpose (MEGP), and low-energy high resolution (LEHR), respectively. In addition, three ordered subset expectation maximization (OSEM) algorithms were investigated: attenuation-corrected OSEM (A-OSEM); attenuation and dual-or triple-energy window scatter-corrected OSEM (AS-OSEM); and attenuation, scatter, and collimator-detector response-corrected OSEM (ASC-OSEM), where the latter utilized Monte Carlo-based reconstruction. Uniformity corrections, using intrinsic and extrinsic correction maps, were also investigated. Image quality was assessed by estimated recovery coefficients (RC), noise, and signalto-noise ratio (SNR). Sensitivity was determined using a circular flat phantom. Results: The best RC and SNR were obtained at an energy window between 67.1 and 82.1 keV. Ring artifacts, caused by non-uniformity, were removed with extrinsic uniformity correction for the energy window between 67.1 and 82.1 keV, but not with intrinsic correction. Analyzing the lower energy window between 48.9 and 62.9 keV, the ring artifacts remained after uniformity corrections. The recovery was similar for the different collimators when using a specific OSEM reconstruction. Recovery and SNR were highest for ASC-OSEM, followed by AS-OSEM and A-OSEM. When using the optimized parameter setting, the resolution of 161 Tb was higher than for 177 Lu (8.4 ± 0.7 vs. 10.4 ± 0.6 mm, respectively). The sensitivities for 161 Tb and 177 Lu were 7.41 and 8.46 cps/MBq, respectively.

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Section: Discussionmentioning

confidence: 99%

Section: Energy Calibration Uniformity Measurements and Sensitivitymentioning

confidence: 99%

Section: Energy Calibration Uniformity Measurements and Sensitivitymentioning

confidence: 99%

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Establishment of a clinical SPECT/CT protocol for imaging of 161Tb

et al. 2020

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“…Among them are daily checks of uniformity and spatial resolution, and center-of-rotation and SPECT phantom evaluations. [9] Non-uniformity level of gamma cameras is difficult to determine, because reproducibility of quality control measurements and service adjustments are not well-established. Adjustment precision of gamma cameras could be performed by assessing the uniformity of 10 gamma cameras immediately after service adjustment at monthly intervals over a period of one year.…”

Section: Discussionmentioning

confidence: 99%

SPECT Gama Kemera Sistemi için Çekim Parametre Değişikliğinin Görüntü Kalitesine Etkisi

Gül¹

2018

Journal of Contemporary Medicine

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S ingle photon emission computed tomography (SPECT) is a major non-invasive diagnostic tool in nuclear medicine departments today. Collimated cameras, originally proposed by Hal Anger, have mostly been used for routine clinical applications. [1] As a result of mechanical collimation, system's geometrical properties limit and fix detection efficiency and energy acceptance. In conventional nuclear medicine applications, gamma rays emitted from various radiopharmaceuticals, especially 99m Technetium (99m Tc), are detected by systems called gamma cameras. Presently used gamma camera systems have Introduction: Quality control testing of a SPECT gamma camera is crucial in assessing the suitability of the camera for use in nuclear medicine department. The aim of the present study was to investigate the effect of gamma camera acquisition parameters on image quality. Methods: Camera scanning was carried out using a doubleheaded gamma camera on a total of 48 patients (29 female and 19 male, mean age: 47.4±11.1) referred to our department for myocardial perfusion scintigraphy and thyroid scintigraphy. Then, camera acquisition parameters were changed (for myocardial perfusion scintigraphy from 64x64 to 128x128 matrix change and for thyroid scintigraphy from 5 cm to 10 cm distance change), and scanning was repeated and images were analyzed. Results: Left ventricle ejection fraction (EF) value in 64x64 matrix was calculated to be 62.7±8.8%. EF value of 48.9±10.3% was obtained in 128x128 matrix for the same patients. 99mTc-pertechnetate uptake percentage was 3.8±2.3% in measurements carried out at a distance of 10 cm. On the other hand, a higher uptake percentage of 6.2±3.6% was found for the same patients measured at a distance of 5 cm. Discussion and Conclusion: In order to obtain proper imaging in SPECT gamma camera system, correct acquisition parameters should be used along with quality control tests for intrinsic floodfield uniformity and relative sensitivity.

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Extrinsic Versus Intrinsic Uniformity Correction for -Cameras

Abstract: Extrinsic uniformity correction may significantly improve the overall image quality by taking into account nonuniformities that arise from the collimator. This method will result in fewer image artifacts and improved image quality, thereby improving patient care.

Cited by 2 publications

References 10 publications

Establishment of a clinical SPECT/CT protocol for imaging of 161Tb

Establishment of a clinical SPECT/CT protocol for imaging of 161Tb

SPECT Gama Kemera Sistemi için Çekim Parametre Değişikliğinin Görüntü Kalitesine Etkisi

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