Technique factors and their relationship to radiation dose in pendant geometry breast CT

Boone, John M.; Kwan, Alexander L. C.; Seibert, J. Anthony; Shah, Nikula; Lindfors, Karen K.; Nelson, Thomas R.

doi:10.1118/1.2128126

Cited by 115 publications

(105 citation statements)

References 13 publications

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“…Since exposure of the complete thorax is avoided, lower kV and mAs settings are possible than in standard CT. There is agreement with respect to the finding that CT imaging at an adequate image quality level can be achieved by such scanners at a dose level which is equivalent to two-view standard mammography [47][48][49]. The major challenge for this FD-CT application is not image quality, but patient positioning to ensure that the breast is imaged completely.…”

Section: Fd-ct For Dedicated Maxillo-facial Scanningmentioning

confidence: 66%

“…Spatial resolution was insufficient at the time, and dose levels were significantly higher than in standard mammography. At present, new efforts are under way using dedicated FD-CT scanner set-ups, which expose the female breast only [47]. The patient is positioned prone on a table with one breast at a time in the field of measurement.…”

Section: Fd-ct For Dedicated Maxillo-facial Scanningmentioning

confidence: 99%

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Flat-detector computed tomography (FD-CT)

2007

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Flat-panel detectors or, synonymously, flat detectors (FDs) have been developed for use in radiography and fluoroscopy with the defined goal to replace standard X-ray film, filmscreen combinations and image intensifiers by an advanced sensor system. FD technology in comparison to X-ray film and image intensifiers offers higher dynamic range, dose reduction, fast digital readout and the possibility for dynamic acquisitions of image series, yet keeping to a compact design. It appeared logical to employ FD designs also for computed tomography (CT) imaging. Respective efforts date back a few years only, but FD-CT has meanwhile become widely accepted for interventional and intraoperative imaging using C-arm systems. FD-CT provides a very efficient way of combining two-dimensional (2D) radiographic or fluoroscopic and 3D CT imaging. In addition, FD technology made its way into a number of dedicated CT scanner developments, such as scanners for the maxillo-facial region or for micro-CT applications. This review focuses on technical and performance issues of FD technology and its full range of applications for CT imaging. A comparison with standard clinical CT is of primary interest. It reveals that FD-CT provides higher spatial resolution, but encompasses a number of disadvantages, such as lower dose efficiency, smaller field of view and lower temporal resolution. FD-CT is not aimed at challenging standard clinical CT as regards to the typical diagnostic examinations; but it has already proven unique for a number of dedicated CT applications, offering distinct practical advantages, above all the availability of immediate CT imaging in the interventional suite or the operating room.

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Section: Fd-ct For Dedicated Maxillo-facial Scanningmentioning

confidence: 66%

Section: Fd-ct For Dedicated Maxillo-facial Scanningmentioning

confidence: 99%

Flat-detector computed tomography (FD-CT)

2007

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“…26,48 In previous studies, the dose for the reference size breast used in this study was reported to be approximately 6 mGy for a dedicated breast CT based on flat-panel detectors at 80 kVp. 48 Therefore, the current study was carefully designed, so that the total dose from both low and high energy scans matches the desired level of approximately 6 mGy. As stated in Sec.…”

Section: -9mentioning

confidence: 99%

Measurement of breast tissue composition with dual energy cone‐beam computed tomography: A postmortem study

2013

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Purpose:To investigate the feasibility of a three-material compositional measurement of water, lipid, and protein content of breast tissue with dual kVp cone-beam computed tomography (CT) for diagnostic purposes. Methods: Simulations were performed on a flat panel-based computed tomography system with a dual kVp technique in order to guide the selection of experimental acquisition parameters. The expected errors induced by using the proposed calibration materials were also estimated by simulation. Twenty pairs of postmortem breast samples were imaged with a flat-panel based dual kVp cone-beam CT system, followed by image-based material decomposition using calibration data obtained from a three-material phantom consisting of water, vegetable oil, and polyoxymethylene plastic. The tissue samples were then chemically decomposed into their respective water, lipid, and protein contents after imaging to allow direct comparison with data from dual energy decomposition. Results: Guided by results from simulation, the beam energies for the dual kVp cone-beam CT system were selected to be 50 and 120 kVp with the mean glandular dose divided equally between each exposure. The simulation also suggested that the use of polyoxymethylene as the calibration material for the measurement of pure protein may introduce an error of −11.0%. However, the tissue decomposition experiments, which employed a calibration phantom made out of water, oil, and polyoxymethylene, exhibited strong correlation with data from the chemical analysis. The average root-mean-square percentage error for water, lipid, and protein contents was 3.58% as compared with chemical analysis. Conclusions:The results of this study suggest that the water, lipid, and protein contents can be accurately measured using dual kVp cone-beam CT. The tissue compositional information may improve the sensitivity and specificity for breast cancer diagnosis.

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“…20 Flux levels were adjusted to match the air kerma that imparts a mean glandular dose that is the same for a standard two view mammography protocol. 32 Energy sampling of the spectrum is in steps of 1 keV and the average energy of the spectrum is 43 keV.…”

Section: Iib Tube Spectrummentioning

confidence: 99%

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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Technique factors and their relationship to radiation dose in pendant geometry breast CT

Cited by 115 publications

References 13 publications

Flat-detector computed tomography (FD-CT)

Flat-detector computed tomography (FD-CT)

Measurement of breast tissue composition with dual energy cone‐beam computed tomography: A postmortem study

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

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