Optimizing Orientation of SPECT and Cone Beam CT Detectors Through Quantification of Cross Contamination in a Dual Modality Mammotomography System

McKinley³

et al. 2009

Phys. Med. Biol.

A compact dedicated 3D breast SPECT-CT (mammotomography) system is currently under development. In its initial prototype, the cone-beam CT sub-system is restricted to a fixed-tilt circular rotation around the patient’s pendant breast. This study evaluated stationary-tilt angles for the CT subsystem that will enable maximal volumetric sampling and viewing of the breast and chest wall. Images of geometric/anthropomorphic phantoms were acquired using various fixed-tilt circular and 3D sinusoidal trajectories. The iteratively reconstructed images showed more distortion and attenuation coefficient inaccuracy from tilted cone-beam orbits than from the complex trajectory. Additionally, line profiles illustrated cupping artifacts in planes distal to the central plane of the tilted cone-beam, otherwise not apparent for images acquired with complex trajectories. This indicates that undersampled cone-beam data may be an additional cause of cupping artifacts. High-frequency objects could be distinguished for all trajectories, but their shapes and locations were corrupted by out-of-plane frequency information. Although more acrylic balls were visualized with a fixed-tilt and nearly flat cone-beam at the posterior of the breast, 3D complex trajectories have less distortion and more complete sampling throughout the reconstruction volume. While complex trajectories would ideally be preferred, negatively fixed-tilt source–detector configuration demonstrates minimally distorted patient images.

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Section: Introductionmentioning

confidence: 99%

Evaluation of tilted cone-beam CT orbits in the development of a dedicated hybrid mammotomograph

McKinley³

et al. 2009

Phys. Med. Biol.

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“…Preliminary studies with the imaging system components indicated that there was decreased emission contamination into the emission [7] and transmission images [19] and transmission contamination into the emission image [20], but this needs to be fully assessed with this fully assembled prototype bed.…”

Section: Discussionmentioning

confidence: 99%

“…Further studies [9,10] will build on previous results [19,20] and investigate the effect of emission and transmission source contamination on the ability to visualize lesions under different conditions in the SPECT and CT images.…”

Section: Discussionmentioning

confidence: 99%

“…A radio-opaque bed should minimize primary and scattered out-of-field emission activity in the emission image [7] and minimize both transmission contamination in emission images [20] and scattered x-ray dose to the patient. Emission contamination of the transmission image [19] and has been initially measured and results pertaining to bed design are reproduced here.…”

Section: Image Cross Contaminationmentioning

confidence: 99%

See 1 more Smart Citation

Patient Bed Design for an Integrated SPECT-CT Dedicated Mammotomography System

2006 IEEE Nuclear Science Symposium Conference Record

McKinley

et al. 2006

This study investigates the significant challenges and tradeoffs associated with designing a patient positioning system for a novel, compact SPECT-CT system dedicated to 3D breast and chest wall imaging. The primary challenge is to maintain patient comfort while optimally positioning the patient for maximal chest wall imaging, given the physical and geometric dimensions of the dual-modality system. The dedicated breast SPECT system comprises a 16x20cm 2 CZT-based gamma camera attached to a versatile gantry, capable of varying polar tilt, radial distance and azimuth. The dedicated breast cone beam CT system, initially designed here without dynamic polar tilt, includes a tungsten target x-ray source and a 20x25cm 2 CsI(Tl) detector laterally offset from the central ray, separated by a 60cm SID. The integrated imaging system with a common fieldof-view is positioned below the custom-designed, 3-dimensionally flexible bed positioning system. An additional consideration of the bed is that it is radio-opaque, which minimizes both emission contamination from the patient's body into the transmission CT system, while simultaneously minimizing any x-ray scatter onto the patient's body. This preliminary implementation and investigation indicates the need for novel camera trajectories to satisfy both chest wall proximity imaging and patient comfort. The effects of breast volume imaged within the common FOV and table angles, which are assumed to correspond to patient comfort, are examined. A manufactured galvanized steel prototype demonstrates the practicability of the bed.

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Initial Development of a Dual-Modality SPECT-CT System for Dedicated Mammotomography

2006 IEEE Nuclear Science Symposium Conference Record

McKinley

et al. 2006