Implementation and initial characterization of acquisition orbits about a pendulous breast using the ASET system

Archer, C.N.; Tornai, Martin P.; Bowsher, J.E.; Metzler, S.; Pieper, B.C.; Jaszczak, R.J.; MacDonald, L.R.; Patt, Bradley E.; Iwanczyk, Jan S.

doi:10.1109/nssmic.2001.1008581

Cited by 3 publications

(6 citation statements)

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“…1) [4][5][6]. Note that reconstructed results in [6] indicate that complex orbits such as the CPA do indeed sufÞciently sample the volume of interest when the activity is fully within the cameraÕ s Þeld-ofview (FOV) for each projection angle and provide near equal resolution recovery to that of a standard vertical-axis-of-rotation (VAOR) orbit with this mammotomography system. In previous studies with a mini-cold rod resolution phantom, 3.1 mm rods are discernible with both VAOR and CPA orbits at a radiusof-rotation (ROR) of 5.6 cm [6].…”

Section: Introductionmentioning

confidence: 95%

“…Combined, the three degrees of motion permit fully automated contiguous orbits of the camera center on the set of concentric inverted hemispheres [1], [2]. Due to some physical constraints, the camera could not be optimally mounted on the gantry as in previous experiments [6]. The radius-of-rotation (ROR) is deÞned as the perpendicular distance between the detector face and the COR.…”

Section: Aset System Descriptionmentioning

confidence: 99%

“…5(a)), which is ∼1/2 the volume investigated in our initial studies [6]. Three lesions, 8 mm inner diameter (0.236 ml volume each) (Data Spectrum, Corp., Hillsborough, NC) were placed according to the schematic in Fig.…”

Section: Breast Alonementioning

confidence: 99%

“…Note that reconstructed results in [6] indicate that complex orbits such as the CPA do indeed sufÞciently sample the volume of interest when the activity is fully within the cameraÕ s Þeld-ofview (FOV) for each projection angle and provide near equal resolution recovery to that of a standard vertical-axis-of-rotation (VAOR) orbit with this mammotomography system. In previous studies with a mini-cold rod resolution phantom, 3.1 mm rods are discernible with both VAOR and CPA orbits at a radiusof-rotation (ROR) of 5.6 cm [6]. The VAOR orbit is, however, limited by the placement of the camera adjacent to the torso; the projection of the camera center is closer to the nipple than the chest wall, which for a parallel-hole collimator results in a reduced imaged volume.…”

Section: Introductionmentioning

confidence: 99%

“…A particular orbit that meets OrlovÕ s sampling criteria for sufÞcient data collection [3] for activity reconstruction of the breast is the circle-plus-arc (CPA) (Fig. 1) [4][5][6]. Note that reconstructed results in [6] indicate that complex orbits such as the CPA do indeed sufÞciently sample the volume of interest when the activity is fully within the cameraÕ s Þeld-ofview (FOV) for each projection angle and provide near equal resolution recovery to that of a standard vertical-axis-of-rotation (VAOR) orbit with this mammotomography system.…”

Section: Introductionmentioning

confidence: 99%

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Initial investigation of circle-plus-arc orbit variants with a dedicated emission mammotomograph

Archer

Tornai

Bowsher³

et al.

2002 IEEE Nuclear Science Symposium Conference Record

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A dedicated emission mammotomograph, uniquely capable of imaging in a hemisphere, is utilized to image the breast by way of complex acquisition orbits, completely sampling most of the breast. Orbits such as the circle-plus-arc (CPA) in particular provide for extended viewing times in a specific portion of the breast. This is advantageous in that as a diagnostic rather than screening imaging tool, a long duration of the camera trajectory may be distinctly positioned in the quadrant where the lesion is suspected. However, orbit modifications that distribute the scan time more evenly over the breast may also be effective. As the trajectories conform to the shape of the breast, including dynamic radius-of-rotation control, resolution degradation is minimized. However, for both the arc and the circular portion of the orbit, increased background contamination may result since the line-ofsight of the single photon camera can view unscattered primary radiation, particularly from cardiac and hepatic sources. The effect of azimuthal position of the arc, as well as the degree of the arc, on image quality is investigated by measurements of lesion signal-to-noise ratios and contrasts. Additionally, because the resolution characteristics of the CPA are not uniform throughout breast quadrants, the implementation of a modified orbit, in the shape of a 3D cloverleaf is investigated through measurements of the breast phantom alone with lesions of varying radioactive concentrations, and with additional torso backgrounds. These initial results indicate that polar tilt does affect image quality, with low polar tilt showing little variation in SNRs and contrasts, while increasing tilt decreases SNRs and contrasts by ∼2x when torso background is present. Considering the effect of azimuthal arc location, θ=45 o yields the highest SNRs and contrasts for the locations at which SNR was evaluated. Both cloverleaf orbits yield comparable SNRs and contrasts to the CPA orbits.

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