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  • 1
    Digitale Medien
    Digitale Medien
    ECAT ART — a continuously rotating PET camera: Performance characteristics, initial clinical studies, and installation considerations in a nuclear medicine department (1997)
    Springer
    European journal of nuclear medicine 24 (1997), S. 6-15 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Three-dimensional image reconstruction ; Partial-ring scanner ; Position emission tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Advances in fully three-dimensional (3D) image reconstruction techniques have permitted the development of a commercial, rotating, partial ring, fully 3D positron emission tomographic (PET) scanner, the ECAT ART. The system has less than one-half the number of bismuth germanate detectors compared with a full ring scanner with the equivalent field of view, resulting in reduced capital cost. The performance characteristics, implications for installation in a nuclear medicine department, and clinical utility of the scanner are presented in this report. The sensitivity (20 cm diameter×20 cm long cylindrical phantom, no scatter correction) is 11400 cps·kBq−1·ml−1. This compares with 5800 and 40500 cps·kBq−1·ml−1 in 2D and 3D respectively for the equivalent full ring scanner (ECAT EXACT). With an energy window of 350–650 keV the maximum noise equivalent count (NEC) rate was 27 kcps at a radioactivity concentration of ~15 kBq·ml−1 in the cylinder. Spatial resolution is ~6 mm full width at half maximum on axis degrading to just under 8 mm at a distance of 20 cm off axis. Installation and use within the nuclear medicine department does not appreciably increase background levels of radiation on gamma cameras in adjacent rooms and the dose rate to an operator in the same room is 2 µSv·h−1 for a typical fluorine-18 fluorodeoxyglucose (18F-FDG) study with an initial injected activity of 370 MBq. The scanner has been used for clinical imaging with18F-FDG for neurological and oncological applications. Its novel use for imaging iron-52 transferrin for localising erythropoietic activity demonstrates its sensitivity and resolution advantages over a conventional dual-headed gamma camera. The ECAT ART provides a viable alternative to conventional full ring PET scanners without compromising the performance required for clinical PET imaging.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01728302
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  • 2
    Digitale Medien
    Digitale Medien
    A method for calibrating three-dimensional positron emission tomography without scatter correction (1997)
    Springer
    European journal of nuclear medicine 24 (1997), S. 660-664 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Calibration ; Three-dimensional positron emission tomography ; Scatter correction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Calibration for three-dimensional positron emission tomography (3D PET) using a uniform cylinder and cross-calibration with aliquots requires correction for scatter and attenuation. Thus the accuracy of thecalibration is dependent on the scatter correction method, and on the applicability of the scatter correction for different regions of the body. A method has been developed which provides a calibration which does not require correction for scatter or attenuation, making it generally applicable and independent of the scatter correction. The method has been previously described for measurement of the absolute sensitivity of tomography devices. This approach has been extended to give a calibration of the PET camera “in air” in units of kBq/pixel. The reconstructed images are multiplied by this factor to, give accurate activity concentrations, after attenuation and scatter correction. The method has been used with a fully 3D filtered back-projection (reprojection) algorithm and iterative convolution-subtraction scatter correction on data from an ECAT 953B. Using this method 3D PET images have been calibrated te, within ±5% accuracy, but this is highly dependent on the accuracy of the scatter correction. The method described here is practical and provides a means of calibrating a 3D PET system without the need for correction for scatter or attenuation of the calibration data.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00841405
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  • 3
    Digitale Medien
    Digitale Medien
    A method for measuring the absolute sensitivity of positron emission tomographic scanners (1991)
    Springer
    European journal of nuclear medicine 18 (1991), S. 861-861 
    Details
    ISSN: 1619-7089
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00175069
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  • 4
    Digitale Medien
    Digitale Medien
    Performance comparison of a state-of-the-art neuro-SPET scanner and a dedicated neuro-PET scanner (1994)
    Springer
    European journal of nuclear medicine 21 (1994), S. 381-387 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Single-photon emission tomography scanner ; Positron emission tomography scanner ; Brain imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The physical performances of two current state-of-the-art scanners dedicated to functional imaging of the brain, one a single-photon emission tomography (SPET) scanner and the other a positron emission tomography (PET) scanner, have been compared under identical conditions. The aim of the study was to compare the capabilities of the devices under conditions resembling the routine clinical environment, as well as to consider other issues such as radiation burden for some common investigations. Both systems have slightly less than 11-cm axial fields of view. The PET system can be operated in a septa-less (3D) mode as well as conventionally with septa (2D). The spatial resolution of both devices was less than 8 mm in all dimensions in scattering media. On average, the PET scanner's resolution was approximately 10%–15% better than the SPET system. Energy resolution on the SPET system was superior due the scintillator used [Nal(Tl)]. Sensitivity in air with a line source on the PET system was found to be ∼150 times greater in 3D and ∼25 times greater in 2D than with the SPET system. A normal subject was studied on each system in an attempt to obtain the highest quality data possible for a subjective comparison. It is clear that, while PET retains the advantages of more desirable radiopharmaceuticals and higher sensitivity, the quality obtainable from SPET devices has improved markedly. SPET may prove as useful for many clinical investigations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00171411
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  • 5
    Digitale Medien
    Digitale Medien
    Simultaneous emission and transmission measurements as an adjunct to dynamic planar gamma camera studies (1996)
    Springer
    European journal of nuclear medicine 23 (1996), S. 326-331 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Dynamic emission/transmission studies ; Single-photon emission tomography ; Patient movement
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Anatomical imaging provides useful information which complements functional imaging performed using a gamma camera. We have previously used transmission measurements in single-photon emission tomography acquired simultaneously with the emission scan using either a plane flood source or a moving line source for attenuation and scatter correction. This approach is equally applicable in planar imaging and provides useful information to assist in detecting patient motion and in defining regions of interest in dynamic studies. We have adapted a moving transmission line source to acquire dynamic geometric mean measurements in the study of the mucociliary clearance of inhaled technetium-99m labelled colloids with a single-headed rotating gamma camera. The line source makes a return pass for each emission acquisition frame (alternating anterior/posterior views), each pass being initiated by a signal from the gamma camera. The result is a dynamic sequence of emission and transmission measurements obtained from a single acquisition. In this application transmission measurements are used to define the lung outline for clearance determination and to check for subject movement throughout the duration of the study.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00837632
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  • 6
    Digitale Medien
    Digitale Medien
    Non-invasive measurement of left ventricular volumes and function by gated positron emission tomography (1996)
    Springer
    European journal of nuclear medicine 23 (1996), S. 1594-1602 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Left ventricular volumes ; Left ventricular function ; Positron emission tomography ; Gating
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract To date cardiac positron emission tomography (PET) studies have focussed on the measurement of myocardial blood flow, metabolism and receptors while left ventricular (LV) function and dimensions have been derived from other modalities. The main drawback of this approach is the difficulty of data co-registration, which limits clinical interpretation. The aim of this study was to evaluate whether it is possible to measure absolute cardiac volumes, and consequently LV function parameters such as ejection fraction, and wall motion with gated PET. Nineteen patients underwent a PET scan and planar radionuclide ventriculography (MUGA) within 9±9 days. A 9-min scan (16 gates/cardiac cycle) was acquired after inhalation of 3 MBq/ml of oxygen-15 labelled carbon monoxide at the rate of 500 m1/min over 4 min using a multislice PET camera. Noise reduction was performed on the gated image to enhance the definition of the ventricles before reslicing to the short-axis view. A threshold value was used to detect the edge of the LV at each gate. LV volumes at each gate were estimated by summing the volume of voxels within the LV boundary. PET measurements of LV volumes were as follows: LV end-diastolic volume ranged from 72 to 233 ml and LV end-systolic volume ranged from 24 to 203 ml. Phantom experiments supported the validity of this approach for estimating volumes. LV ejection fraction measured with MUGA was 38.4%±16.3% (range 15%–71%) and that measured with PET was 39.6%±17.7% (range 9%–72%) (P=NS). The LV ejection fraction measurements were highly correlated (r 2=0.824). These results indicate that: (1) absolute enddiastolic and end-systolic volumes can be quantified using gated PET and (2) LV ejection fraction can be accurately measured by gated PET simultaneously with the other physiological PET parameters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01249622
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  • 7
    Digitale Medien
    Digitale Medien
    A method for calibrating three-dimensional positron emission tomography without scatter correction (1997)
    Springer
    European journal of nuclear medicine 24 (1997), S. 660-664 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Key words: Calibration ; Three-dimensional positron emission tomography ; Scatter correction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Calibration for three-dimensional positron emission tomography (3D PET) using a uniform cylinder and cross-calibration with aliquots requires correction for scatter and attenuation. Thus the accuracy of the calibration is dependent on the scatter correction method, and on the applicability of the scatter correction for different regions of the body. A method has been developed which provides a calibration which does not require correction for scatter or attenuation, making it generally applicable and independent of the scatter correction. The method has been previously described for measurement of the absolute sensitivity of tomographic devices. This approach has been extended to give a calibration of the PET camera ”in air” in units of kBq/pixel. The reconstructed images are multiplied by this factor to give accurate activity concentrations, after attenuation and scatter correction. The method has been used with a fully 3D filtered backprojection (reprojection) algorithm and iterative convolution-subtraction scatter correction on data from an ECAT 953B. Using this method 3D PET images have been calibrated to within ±5% accuracy, but this is highly dependent on the accuracy of the scatter correction. The method described here is practical and provides a means of calibrating a 3D PET system without the need for correction for scatter or attenuation of the calibration data.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00841405
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  • 8
    Digitale Medien
    Digitale Medien
    A method for measuring the absolute sensitivity of positron emission tomographic scanners (1991)
    Springer
    European journal of nuclear medicine 18 (1991), S. 374-379 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Positron emission tomography (PET) ; Quantitation ; Sensitivity ; Calibration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A need exists to measure the absolute sensitivity of a positron emission tomographic (PET) scanner in units of counts. s−1.MBq−1. At present sensitivity is generally determined by measurement of a radionuclide of known concentration distributed in a water-filled cylindrical phantom, usually 20 cm in diameter. The measurement is confounded by self-attenuation of the source and scatter within the cylinder and does not give a true absolute sensitivity measurement. Due to variations in the magnitude and treatment of these factors, meaningful comparison between different manufacturer's scanners is difficult, as are comparisons between different acquisition geometries (e.g. with and without interplane septa present). A method has been developed in our laboratory that provides measurements of absolute sensitivity in air for a scanner independent of attenuation and scatter within the source. The method involves measurements of a thin-line source of fluorine 18 contained within an aluminium housing to which successive aluminium sleeves are added. The extrapolation of these measurements allows an effective counts. s−1.MBq−1 measurement to be made for zero thickness of aluminium. Measurements have yielded absolute sensitivities of 3 926 ± 61 counts. s−1.MBq−1 (0.39% efficiency), 5079±26 counts. s−1.MBq−1 (0.51%), and 32312±544 counts. s−1.MBq−1 (3.2%) for a whole-body PET scanner with interplane septa and for a NeuroPET operating with and without interplane septa, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02258426
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  • 9
    Digitale Medien
    Digitale Medien
    Transmission scanning in emission tomography (1998)
    Springer
    European journal of nuclear medicine 25 (1998), S. 774-787 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Key words: Attenuation correction ; Transmission scans ; Single-photon emission tomography ; Positron emission tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Attenuation correction in single-photon (SPET) and positron emission (PET) tomography is now accepted as a vital component for the production of artefact-free, quantitative data. The most accurate attenuation correction methods are based on measured transmission scans acquired before, during, or after the emission scan. Alternative methods use segmented images, assumed attenuation coefficients or consistency criteria to compensate for photon attenuation in reconstructed images. This review examines the methods of acquiring transmission scans in both SPET and PET and the manner in which these data are used. While attenuation correction gives an exact correction in PET, as opposed to an approximate one in SPET, the magnitude of the correction factors required in PET is far greater than in SPET. Transmission scans also have a number of other potential applications in emission tomography apart from attenuation correction, such as scatter correction, inter-study spatial co-registration and alignment, and motion detection and correction. The ability to acquire high-quality transmission data in a practical clinical protocol is now an essential part of the practice of nuclear medicine.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002590050282
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