Radiation dose reduction using a CdZnTe‐based computed tomography system: Comparison to flat‐panel detectors

Lê, Huy; Ducote, Justin L.; Molloi, Sabee

doi:10.1118/1.3312435

Cited by 77 publications

(81 citation statements)

References 44 publications

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“…It was found that the contrast-to-noise ratio was increased by 1.35 times, while the dose can be reduced by 52.05%, when compared to flat panel systems. 21 The ability to identify and quantify specific materials adds another dimension to the imaging system. In a single CT scan using the CZT system, one obtains both the standard CT data and the additional information about the amount of material present in a particular image region.…”

Section: Discussionmentioning

confidence: 99%

“…Current CZT detector technology allows for five to eight user-selectable energy bins. 16,18,21,28 Here, our simulated detector could resolve the spectrum into five energy bins. The sinogram for each energy bin is calculated by…”

Section: Iie System Geometry and X-ray Transportmentioning

confidence: 99%

“…20 Some investigators have proposed using energy discriminating detectors for breast CT to improve image quality and reduce patient dose. 17,18,21 An additional advantage of such a system is the ability to decompose relevant materials in the breast. A four-material decomposition technique is useful in the case of contrast-enhanced breast imaging.…”

Section: Introductionmentioning

confidence: 99%

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Least squares parameter estimation methods for material decomposition with energy discriminating detectors

Lê

Molloi

2010

Medical Physics

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Purpose: Energy resolving detectors provide more than one spectral measurement in one image acquisition. The purpose of this study is to investigate, with simulation, the ability to decompose four materials using energy discriminating detectors and least squares minimization techniques. Methods: Three least squares parameter estimation decomposition techniques were investigated for four-material breast imaging tasks in the image domain. The first technique treats the voxel as if it consisted of fractions of all the materials. The second method assumes that a voxel primarily contains one material and divides the decomposition process into segmentation and quantification tasks. The third is similar to the second method but a calibration was used. The simulated computed tomography ͑CT͒ system consisted of an 80 kVp spectrum and a CdZnTe ͑CZT͒ detector that could resolve the x-ray spectrum into five energy bins. A postmortem breast specimen was imaged with flat panel CT to provide a model for the digital phantoms. Hydroxyapatite ͑HA͒ ͑50, 150, 250, 350, 450, and 550 mg/ml͒ and iodine ͑4, 12, 20, 28, 36, and 44 mg/ml͒ contrast elements were embedded into the glandular region of the phantoms. Calibration phantoms consisted of a 30/70 glandular-toadipose tissue ratio with embedded HA ͑100, 200, 300, 400, and 500 mg/ml͒ and iodine ͑5, 15, 25, 35, and 45 mg/ml͒. The x-ray transport process was simulated where the Beer-Lambert law, Poisson process, and CZT absorption efficiency were applied. Qualitative and quantitative evaluations of the decomposition techniques were performed and compared. The effect of breast size was also investigated. Results: The first technique decomposed iodine adequately but failed for other materials. The second method separated the materials but was unable to quantify the materials. With the addition of a calibration, the third technique provided good separation and quantification of hydroxyapatite, iodine, glandular, and adipose tissues. Quantification with this technique was accurate with errors of 9.83% and 6.61% for HA and iodine, respectively. Calibration at one point ͑one breast size͒ showed increased errors as the mismatch in breast diameters between calibration and measurement increased. A four-point calibration successfully decomposed breast diameter spanning the entire range from 8 to 20 cm. For a 14 cm breast, errors were reduced from 5.44% to 1.75% and from 6.17% to 3.27% with the multipoint calibration for HA and iodine, respectively. Conclusions:The results of the simulation study showed that a CT system based on CZT detectors in conjunction with least squares minimization technique can be used to decompose four materials. The calibrated least squares parameter estimation decomposition technique performed the best, separating and accurately quantifying the concentrations of hydroxyapatite and iodine.

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Section: Discussionmentioning

confidence: 99%

Section: Iie System Geometry and X-ray Transportmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Least squares parameter estimation methods for material decomposition with energy discriminating detectors

Lê

Molloi

2010

Medical Physics

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“…Recent advances in solid state semiconductor materials allow photon-counting and energy discriminating imaging detectors to be used in a breast CT system to produce higher quality images. [1][2][3][4][5][6][7][8][9] Cadmium zinc telluride (CZT) single crystal detectors have been investigated and implemented as x-ray detectors in current breast CT systems. These systems use CZT due to its large effective atomic number (49.6), high mass density (5.8 g/cm 3 ), and higher quantum efficiency.…”

Section: Introductionmentioning

confidence: 99%

Tight‐frame based iterative image reconstruction for spectral breast CT

et al. 2013

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Purpose: To investigate tight-frame based iterative reconstruction (TFIR) technique for spectral breast computed tomography (CT) using fewer projections while achieving greater image quality. Methods: The experimental data were acquired with a fan-beam breast CT system based on a cadmium zinc telluride photon-counting detector. The images were reconstructed with a varying number of projections using the TFIR and filtered backprojection (FBP) techniques. The image quality between these two techniques was evaluated. The image's spatial resolution was evaluated using a high-resolution phantom, and the contrast to noise ratio (CNR) was evaluated using a postmortem breast sample. The postmortem breast samples were decomposed into water, lipid, and protein contents based on images reconstructed from TFIR with 204 projections and FBP with 614 projections. The volumetric fractions of water, lipid, and protein from the image-based measurements in both TFIR and FBP were compared to the chemical analysis. Results:The spatial resolution and CNR were comparable for the images reconstructed by TFIR with 204 projections and FBP with 614 projections. Both reconstruction techniques provided accurate quantification of water, lipid, and protein composition of the breast tissue when compared with data from the reference standard chemical analysis. Conclusions: Accurate breast tissue decomposition can be done with three fold fewer projection images by the TFIR technique without any reduction in image spatial resolution and CNR. This can result in a two-third reduction of the patient dose in a multislit and multislice spiral CT system in addition to the reduced scanning time in this system.

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“…However, technical improvements in CT detector design, which are now capable of event by event counting, will markedly reduce the radiation burden, making Coronary CT Angiography more attractive. 2 Given the demand for 'newer' and 'better' by the referring clinicians, it is time to take the plunge, and for Nuclear Physicians to make the case for higher quality patient care, offered by well-established PET/CT technology.…”

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confidence: 99%

Perfusion debate

Strauss

2017

Journal of Nuclear Cardiology

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Radiation dose reduction using a CdZnTe‐based computed tomography system: Comparison to flat‐panel detectors

Cited by 77 publications

References 44 publications

Least squares parameter estimation methods for material decomposition with energy discriminating detectors

Least squares parameter estimation methods for material decomposition with energy discriminating detectors

Tight‐frame based iterative image reconstruction for spectral breast CT

Perfusion debate

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