Dr. Randolph L. McKinley Profile

KEYWORDS: Breast, 3D acquisition, X-ray computed tomography, Sensors, Signal attenuation, X-rays, Data acquisition, 3D metrology, Reconstruction algorithms, 3D image processing

Read Abstract +

Proceedings Article | 19 March 2014 Paper

Design of a nested SPECT-CT system with fully suspended CT sub-system for dedicated breast imaging

Jainil Shah, Steve Mann, Randolph McKinley, Martin Tornai

Proc. SPIE. 9033, Medical Imaging 2014: Physics of Medical Imaging

KEYWORDS: Breast, SolidWorks, Chest, X-ray computed tomography, Imaging systems, Sensors, X-rays, Computed tomography, Single photon emission computed tomography, 3D image processing

Read Abstract +

Proceedings Article | 14 March 2009 Paper

Initial investigation of novel trajectories to improve chest wall imaging in a dedicated breast computed tomography system

Dominic Crotty, Randolph McKinley, Priti Madhav, Spencer Cutler, Martin Tornai

Proc. SPIE. 7258, Medical Imaging 2009: Physics of Medical Imaging

KEYWORDS: Breast, Chest, Optical spheres, X-ray computed tomography, Visualization, Imaging systems, X-rays, Head, Image quality, Computer aided design

Read Abstract +

Proceedings Article | 28 March 2007 Paper

A contrast-detail comparison of computed mammotomography and digital mammography

Randolph McKinley, Martin Tornai, Carey Floyd, Ehsan Samei

Proc. SPIE. 6510, Medical Imaging 2007: Physics of Medical Imaging

KEYWORDS: Breast, Optical spheres, Tissues, Imaging systems, Sensors, Computing systems, Mammography, X-ray detectors, Rhodium, Digital mammography

Read Abstract +

Proceedings Article | 21 March 2007 Paper

Investigating novel patient bed designs for use in a hybrid dual-modality dedicated 3D breast imaging system

Dominic Crotty, Priti Madhav, Randolph McKinley, Martin Tornai

Proc. SPIE. 6510, Medical Imaging 2007: Physics of Medical Imaging

KEYWORDS: Breast, Chest, X-ray computed tomography, Imaging systems, Sensors, X-rays, Computer aided design, Single photon emission computed tomography, Solid modeling, 3D image processing

Read Abstract +

Proceedings Article | 21 March 2007 Paper

Evaluation of lesion distortion at various CT system tilts in the development of a hybrid system for dedicated mammotomography

Priti Madhav, Dominic Crotty, Randolph McKinley, Martin Tornai

Proc. SPIE. 6510, Medical Imaging 2007: Physics of Medical Imaging

KEYWORDS: Breast, 3D acquisition, Optical spheres, Imaging systems, Distortion, Reconstruction algorithms, Modulation transfer functions, Spherical lenses, Single photon emission computed tomography, 3D image processing

Read Abstract +

A hybrid SPECT-CT system for dedicated 3D breast imaging (mammotomography) is currently under development. Each imaging system will be placed on top of a single rotation stage and moved in unison azimuthally, with the SPECT system additionally capable of polar and radial motions. In this initial prototype, the CT system will initially be positioned at a fixed polar tilt. Using a phantom with three tungsten wires, the MTF of the CT system was measured in 3D for different CT system tilts. A phantom with uniformly arranged 0.5cm diameter acrylic spheres was suspended in air in the CT field of view, and also placed at multiple locations and orientations inside an oil-filled breast phantom to evaluate the effect of CT system tilt on lesion visibility and distortion. Projection images were collected using various simple circular orbits with fixed polar tilts ranging between ±15°, and complex 3D saddle trajectories including combined polar and azimuthal motions at maximum polar tilt angles. Reconstructions were performed using an iterative reconstruction algorithm on 4x4 binned projection images with 0.508mm3 voxels. There was minor variation in the MTF in the imaged volume for the CT system at all trajectories, potentially due to the use of an iterative reconstruction algorithm. Results from the spherical cross phantoms indicated that there was more reconstruction inaccuracy and geometric distortion in the reconstructed slices with simple circular orbits with fixed tilt in contrast to complex 3D trajectories. Line profiles further showed a cupping artifact in planes farther away from the flat plane of the x-ray cone beam placed at different tilts. However, this cupping artifact was not seen for images acquired with complex 3D trajectories. This indicated that cupping artifacts can also be caused by undersampled cone beam data. These findings generally indicate that despite insufficient sampling with the cone beam imaging geometry, it is possible to place the CT system at a stationary polar tilt with the CT tube positioned upward such that a patient can be comfortably placed above the system and allow complete sampling near the top of the pendant, uncompressed breast and chest wall. However, a complex 3D trajectory allows for more complete sampling of the entire image volume.

Proceedings Article | 2 March 2006 Paper

A novel method to characterize the MTF in 3D for computed mammotomography

Priti Madhav, Randolph McKinley, Ehsan Samei, James Bowsher, Martin Tornai

Proc. SPIE. 6142, Medical Imaging 2006: Physics of Medical Imaging

KEYWORDS: Breast, Imaging systems, Sensors, Tungsten, Image resolution, 3D metrology, Computed tomography, Reconstruction algorithms, Modulation transfer functions, 3D image processing

Read Abstract +

Proceedings Article | 2 March 2006 Paper

Investigation of emission contamination in the transmission image of a dual modality computed mammotomography system

Dominic Crotty, Caryl Brzymialkewicz, Randolph McKinley, Martin Tornai

Proc. SPIE. 6142, Medical Imaging 2006: Physics of Medical Imaging

KEYWORDS: Signal to noise ratio, Breast, Contamination, Imaging systems, Sensors, Photons, X-rays, Image transmission, X-ray imaging, X-ray detectors

Read Abstract +

A dual modality SPECT/CT computed mammotomography (CmT) system for dedicated functional/structural breast imaging is under development. In simultaneous, dual-modality imaging, contamination of the transmission (x-ray) image by emission photons from the uncompressed, pendant breast and torso is an important consideration in the design of hybrid imaging hardware. The lack of a collimator on the transmission image detector implies increased geometric efficiency of primary and scattered emission photons from the breast and neighboring torso region that potentially increase transmission image noise. This study investigates the nature and extent of this cross contamination. Projection and tomographic x-ray images are obtained with and without emission activity in a realistic anthropomorphic torso and various breast phantoms, and also with and without lead shielding on the torso for a variety of x-ray exposure times. Results for emission-source contamination of transmission images are quantified in terms of a mean and standard deviation of regions of interest. There was an observed trend of increased contamination with increasing emission radioactivity in the projection images when the x-ray detector was located immediately beneath the torso phantom, but no discernible effect when the detector was lateral to (and beneath) the torso. Torso shielding mitigated this contamination somewhat. Indeed, in reconstructed CmT data, there was both a decrease in SNR and concomitant decrease in mean attenuation coefficient with increasing emission radioactivity contamination. These results are consistent with the expected increased noise due to a uniform emission irradiation of the detector and hence the resulting apparent increase in detected x-ray transmission events (which yield a lower reconstructed attenuation coefficient value). Despite the emission contamination in both projection and reconstructed images, the contamination is uncorrelated, and indeed no reconstruction artifacts were observed under the various measured conditions. This indicates that a simple contamination correction may be possible to the projection data prior to reconstruction.

Proceedings Article | 2 March 2006 Paper

Preliminary investigation of dose for a dedicated mammotomography system

Randolph McKinley, Martin Tornai

Proc. SPIE. 6142, Medical Imaging 2006: Physics of Medical Imaging

KEYWORDS: Signal to noise ratio, Breast, Tissues, Imaging systems, X-rays, Computing systems, Image resolution, Image quality, Mammography, X-ray imaging

Read Abstract +

We use a previously reported, optimized quasi-monochromatic beam technique together with unique complex acquisition trajectories made possible with a novel, dedicated cone-beam transmission computed mammotomography (CmT) system to investigate effects of low dose imaging of pendant, uncompressed breasts. Investigators have used a guideline of dose for CmT type applications as that used for dual-view mammography (4-6 mGy for average breast size). This dose is somewhat arbitrary, and it may be possible to reduce this significantly without sacrificing image quality using our quasi-monochromatic x-ray beam, 3D complex acquisition orbits, and iterative reconstruction techniques. A low-scatter acrylic resolution phantom in various media, a breast phantom with sponge and oil-filled lesions, and a cadaver breast are used to evaluate the effect of lowered dose on resolution and image artifacts. Complex saddle acquisition trajectories (necessary to overcome cone-beam distortion) are carried out for total exposures of 96, 300, and 600 mAs over 240 projections. These exposures relate approximately to 1/10^th, 1/3^rd, and 2/3^rd of the standard dual view mammography dose for an average sized 50% adipose/glandular breast. Iterative reconstruction uses an OSTR algorithm with 0.125 mm³ voxels. Image artifacts increased as dose was reduced but did not appear to greatly degrade image quality except at the lowest contrast tested (1% absolute contrast). As expected, noise increased as dose was reduced. However, this did not appear to affect resolution for rods in air (high contrast), nor rods in oil (20% absolute contrast). Resolution was reduced for rods in water (1% absolute contrast) due to increased prevalence of image artifacts as well as increased noise. Breast phantom imaging of soft lesions in a highly glandular breast (6% absolute contrast) clearly yielded the 60uL and all larger volume lesions. Preliminary biological breast tissue results illustrate excellent subjective image quality at all dose levels tested. Results indicate that our quasi-monochromatic beam together with complex orbit capability and iterative reconstruction has the potential to provide sufficient image quality for practical 3D mammotomography of uncompressed breasts at significantly lower dose than dual view mammography. This is nominally a 2-fold improvement over other approaches using circular orbits and broader spectral x-ray beams. While simple image filtering (post-reconstruction smoothing) could improve noise quality, improvements in image artifact correction and scatter correction are required to more accurately determine the lower limits on dose. A contrast-detail study is also warranted with a greater variety of lesion sizes and contrasts.

Proceedings Article | 2 March 2006 Paper

Experimental spectral measurements of heavy K-edge filtered beams for x-ray computed mammotomography

Dominic Crotty, Randolph McKinley, Martin Tornai

Proc. SPIE. 6142, Medical Imaging 2006: Physics of Medical Imaging

KEYWORDS: Breast, Optical filters, Tissues, Imaging systems, Sensors, Signal attenuation, X-rays, Mammography, Optical simulations, Cerium

Read Abstract +

Proceedings Article | 20 April 2005 Paper

Investigation of cone-beam acquisitions implemented using a novel dedicated mammotomography system with unique arbitrary orbit capability

Randolph McKinley, Caryl Bryzmialkiewicz, Priti Madhav, Martin Tornai

Proc. SPIE. 5745, Medical Imaging 2005: Physics of Medical Imaging

KEYWORDS: Breast, Chest, 3D acquisition, 3D image reconstruction, Imaging systems, Sensors, Computing systems, Distortion, 3D image processing, Breast imaging

Read Abstract +

Proceedings Article | 20 April 2005 Paper

Design and development of a fully 3D dedicated x-ray computed mammotomography system

Martin Tornai, Randolph McKinley, Caryl Bryzmialkiewicz, Priti Madhav, Spencer Cutler, Dominic Crotty, James Bowsher, Ehsan Samei, Carey Floyd

Proc. SPIE. 5745, Medical Imaging 2005: Physics of Medical Imaging

KEYWORDS: Breast, Imaging systems, Sensors, X-rays, Computing systems, Distortion, Reconstruction algorithms, X-ray imaging, X-ray detectors, Prototyping

Read Abstract +

Proceedings Article | 14 April 2005 Paper

Anthropomorphic breast phantoms for preclinical imaging evaluation with transmission or emission imaging

Martin Tornai, Randolph McKinley, Caryl Bryzmialkiewicz, Spencer Cutler, Dominic Crotty

Proc. SPIE. 5746, Medical Imaging 2005: Physiology, Function, and Structure from Medical Images

KEYWORDS: Breast, Minerals, Chest, Image compression, Tissues, Imaging systems, Signal attenuation, X-rays, Radiography, Photography

Read Abstract +

Proceedings Article | 6 May 2004 Paper

Measurements of an optimized beam for x-ray computed mammotomography

Randolph McKinley, Ehsan Samei, Caryl Brzymialkiewicz, Martin Tornai, Carey Floyd

Proc. SPIE. 5368, Medical Imaging 2004: Physics of Medical Imaging

KEYWORDS: Signal to noise ratio, Breast, Imaging systems, Sensors, X-rays, Tomography, Image quality, Mammography, Cerium, Lead

Read Abstract +

Proceedings Article | 5 June 2003 Paper

Optimizing beam quality for x-ray computed mammotomography

Randolph McKinley, Martin Tornai, Ehsan Samei, Marques Bradshaw

Proc. SPIE. 5030, Medical Imaging 2003: Physics of Medical Imaging

KEYWORDS: Signal to noise ratio, Breast, Optical filters, Tissues, Sensors, Signal attenuation, X-rays, Image quality, X-ray imaging, Cerium

Read Abstract +

Showing 5 of 17 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years