Ehsan Samei

Journal article Med Phys · August 2013 Featured Publication PURPOSE: Wireless flat panel detectors are gaining increased usage in portable medical imaging. Two such detectors were evaluated and compared with a conventional flat-panel detector using the formalism of the International Electrotechnical Commission (IEC ... Full text Link to item Cite

The effect of dose heterogeneity on radiation risk in medical imaging.

Journal article Radiat Prot Dosimetry · June 2013 Featured Publication The current estimations of risk associated with medical imaging procedures rely on assessing the organ dose via direct measurements or simulation. The dose to each organ is assumed to be homogeneous. To take into account the differences in radiation sensit ... Full text Link to item Cite

Precision of iodine quantification in hepatic CT: effects of iterative reconstruction with various imaging parameters.

Journal article AJR Am J Roentgenol · May 2013 Featured Publication OBJECTIVE: The objective of this study was to evaluate the feasibility of using iterative reconstructions in hepatic CT to improve the precision of Hounsfield unit quantification, which is the degree to which repeated measurements under unchanged condition ... Full text Link to item Cite

Population of anatomically variable 4D XCAT adult phantoms for imaging research and optimization.

Journal article Med Phys · April 2013 Featured Publication PURPOSE: The authors previously developed the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. The XCAT consisted of highly detailed whole-body models for the standard male and female adult, including the cardiac and respiratory ... Full text Link to item Cite

A methodology for image quality evaluation of advanced CT systems.

Journal article Med Phys · March 2013 Featured Publication PURPOSE: This work involved the development of a phantom-based method to quantify the performance of tube current modulation and iterative reconstruction in modern computed tomography (CT) systems. The quantification included resolution, HU accuracy, noise ... Full text Link to item Cite

Relating noise to image quality indicators in CT examinations with tube current modulation.

Journal article AJR Am J Roentgenol · March 2013 Featured Publication OBJECTIVE: Modern CT systems use surrogates of noise-noise index (NI) and quality reference effective tube current-time product (Q)-to infer the quality of images acquired using tube current modulation. This study aimed to determine the relationship betwee ... Full text Link to item Cite

Evaluation of two objective methods to optimize kVp and personnel exposure using a digital indirect flat panel detector and simulated veterinary patients.

Journal article Vet Radiol Ultrasound · 2013 Featured Publication It is important to optimize digital radiographic technique settings for small animal imaging in order to maximize image quality while minimizing radiation exposure to personnel. The purpose of this study was to evaluate two objective methods for determinin ... Full text Link to item Cite

Effects of protocol and obesity on dose conversion factors in adult body CT.

Journal article Med Phys · November 2012 Featured Publication PURPOSE: In computed tomography (CT), organ dose, effective dose, and risk index can be estimated from volume-weighted CT dose index (CTDI(vol)) or dose-length product (DLP) using conversion coefficients. Studies have investigated how these coefficients va ... Full text Link to item Cite

Automated size-specific CT dose monitoring program: assessing variability in CT dose.

Journal article Med Phys · November 2012 Featured Publication PURPOSE: The potential health risks associated with low levels of ionizing radiation have created a movement in the radiology community to optimize computed tomography (CT) imaging protocols to use the lowest radiation dose possible without compromising th ... Full text Link to item Cite

Quantitative comparison of noise texture across CT scanners from different manufacturers.

Journal article Med Phys · October 2012 Featured Publication PURPOSE: To quantitatively compare noise texture across computed tomography (CT) scanners from different manufacturers using the noise power spectrum (NPS). METHODS: The American College of Radiology CT accreditation phantom (Gammex 464, Gammex, Inc., Midd ... Full text Link to item Cite

The effects of ambient lighting in chest radiology reading rooms.

Journal article J Digit Imaging · August 2012 Featured Publication Under typical dark chest radiography reading room conditions, a radiologist's pupils contract and dilate as their visual focus intermittently shifts between the high luminance monitor and the darker background wall, resulting in increased visual fatigue an ... Full text Link to item Cite

Achieving routine submillisievert CT scanning: report from the summit on management of radiation dose in CT.

Journal article Radiology · August 2012 Featured Publication This Special Report presents the consensus of the Summit on Management of Radiation Dose in Computed Tomography (CT) (held in February 2011), which brought together participants from academia, clinical practice, industry, and regulatory and funding agencie ... Full text Link to item Cite

Towards task-based assessment of CT performance: System and object MTF across different reconstruction algorithms.

Journal article Med Phys · July 2012 Featured Publication PURPOSE: To investigate a measurement method for evaluating the resolution properties of CT imaging systems across reconstruction algorithms, dose, and contrast. METHODS: An algorithm was developed to extract the task-based modulation transfer function (MT ... Full text Link to item Cite

Quantitative CT: technique dependence of volume estimation on pulmonary nodules.

Journal article Phys Med Biol · March 7, 2012 Featured Publication Current estimation of lung nodule size typically relies on uni- or bi-dimensional techniques. While new three-dimensional volume estimation techniques using MDCT have improved size estimation of nodules with irregular shapes, the effect of acquisition and ... Full text Link to item Cite

Point/Counterpoint: The 2014 initiative can have potentially unintended negative consequences for medical physics in diagnostic imaging and nuclear medicine.

Journal article Med Phys · March 2012 Featured Publication Full text Link to item Cite

Biplane correlation imaging: a feasibility study based on phantom and human data.

Journal article J Digit Imaging · February 2012 Featured Publication The objective of this study was to implement and evaluate the performance of a biplane correlation imaging (BCI) technique aimed to reduce the effect of anatomic noise and improve the detection of lung nodules in chest radiographs. Seventy-one low-dose pos ... Full text Link to item Cite

The tenuous state of clinical medical physics in diagnostic imaging.

Journal article Med Phys · December 2011 Featured Publication Full text Link to item Cite

Effect of gadolinium chelate contrast agents on diffusion weighted MR imaging of the liver, spleen, pancreas and kidney at 3 T.

Journal article Eur J Radiol · November 2011 Featured Publication PURPOSE: To retrospectively test the null hypotheses that the qualitative appearance of DWI and the signal intensity values in DWI and corresponding ADC values of the liver, spleen, pancreas and kidneys are identical before and after the administration of ... Full text Link to item Cite

Synthetic positron emission tomography-computed tomography images for use in perceptual studies.

Journal article Semin Nucl Med · November 2011 Featured Publication To better understand fundamental issues, perception studies of the fusion display would best be performed with a panel of lesions of variable location, size, intensity, and background. There are compelling reasons to use synthetic images that contain artif ... Full text Link to item Cite

Dual-energy contrast-enhanced breast tomosynthesis: optimization of beam quality for dose and image quality.

Journal article Phys Med Biol · October 7, 2011 Featured Publication Dual-energy contrast-enhanced breast tomosynthesis is a promising technique to obtain three-dimensional functional information from the breast with high resolution and speed. To optimize this new method, this study searched for the beam quality that maximi ... Full text Link to item Cite

Effective dose efficiency: an application-specific metric of quality and dose for digital radiography.

Journal article Phys Med Biol · August 21, 2011 Featured Publication The detective quantum efficiency (DQE) and the effective DQE (eDQE) are relevant metrics of image quality for digital radiography detectors and systems, respectively. The current study further extends the eDQE methodology to technique optimization using a ... Full text Link to item Cite

Patient-specific radiation dose and cancer risk for pediatric chest CT.

Journal article Radiology · June 2011 Featured Publication PURPOSE: To estimate patient-specific radiation dose and cancer risk for pediatric chest computed tomography (CT) and to evaluate factors affecting dose and risk, including patient size, patient age, and scanning parameters. MATERIALS AND METHODS: The inst ... Full text Link to item Cite

An anthropomorphic breast model for breast imaging simulation and optimization.

Journal article Acad Radiol · May 2011 Featured Publication RATIONALE AND OBJECTIVES: Optimization studies for x-ray-based breast imaging systems using computer simulation can greatly benefit from a phantom capable of modeling varying anatomical variability across different patients. This study aimed to develop a t ... Full text Link to item Cite

Lung nodule detection in pediatric chest CT: quantitative relationship between image quality and radiologist performance.

Journal article Med Phys · May 2011 Featured Publication PURPOSE: To determine the quantitative relationship between image quality and radiologist performance in detecting small lung nodules in pediatric CT. METHODS: The study included clinical chest CT images of 30 pediatric patients (0-16 years) scanned at tub ... Full text Link to item Cite

Comparative performance of multiview stereoscopic and mammographic display modalities for breast lesion detection.

Journal article Med Phys · April 2011 Featured Publication PURPOSE: Mammography is known to be one of the most difficult radiographic exams to interpret. Mammography has important limitations, including the superposition of normal tissue that can obscure a mass, chance alignment of normal tissue to mimic a true le ... Full text Link to item Cite

Patient-specific radiation dose and cancer risk estimation in CT: part II. Application to patients.

Journal article Med Phys · January 2011 Featured Publication PURPOSE: Current methods for estimating and reporting radiation dose from CT examinations are largely patient-generic; the body size and hence dose variation from patient to patient is not reflected. Furthermore, the current protocol designs rely on dose a ... Full text Link to item Cite

Patient-specific radiation dose and cancer risk estimation in CT: part I. development and validation of a Monte Carlo program.

Journal article Med Phys · January 2011 Featured Publication PURPOSE: Radiation-dose awareness and optimization in CT can greatly benefit from a dose-reporting system that provides dose and risk estimates specific to each patient and each CT examination. As the first step toward patient-specific dose and risk estima ... Full text Link to item Cite

Quantitative breast tomosynthesis: from detectability to estimability.

Journal article Med Phys · December 2010 Featured Publication PURPOSE: This work aimed to extend Fourier-based imaging metrics for modeling and predicting quantitative imaging performance. The new methodology was applied to the platform of breast tomosynthesis for investigating the influence of acquisition parameters ... Full text Link to item Cite

Detection of pancreatic tumors, image quality, and radiation dose during the pancreatic parenchymal phase: effect of a low-tube-voltage, high-tube-current CT technique--preliminary results.

Journal article Radiology · August 2010 Featured Publication PURPOSE: To intraindividually compare a low-tube-voltage (80 kVp), high-tube-current (675 mA) computed tomographic (CT) technique with a high-tube-voltage (140 kVp) CT protocol for the detection of pancreatic tumors, image quality, and radiation dose durin ... Full text Link to item Cite

Quantitative imaging in breast tomosynthesis and CT: Comparison of detection and estimation task performance.

Journal article Med Phys · June 2010 Featured Publication PURPOSE: This work investigates a framework for modeling volumetric breast imaging to compare detection and estimation task performance and optimize quantitative breast imaging. METHODS: Volumetric reconstructions of a breast phantom, which incorporated el ... Full text Link to item Cite

The quantitative potential for breast tomosynthesis imaging.

Journal article Med Phys · March 2010 Featured Publication PURPOSE: Due to its limited angular scan range, breast tomosynthesis has lower resolution in the depth direction, which may limit its accuracy in quantifying tissue density. This study assesses the quantitative potential of breast tomosynthesis using relat ... Full text Link to item Cite

A technique optimization protocol and the potential for dose reduction in digital mammography.

Journal article Med Phys · March 2010 Featured Publication Digital mammography requires revisiting techniques that have been optimized for prior screen/film mammography systems. The objective of the study was to determine optimized radiographic technique for a digital mammography system and demonstrate the potenti ... Full text Link to item Cite

Generalized "satisfaction of search": adverse influences on dual-target search accuracy.

Journal article J Exp Psychol Appl · March 2010 Featured Publication The successful detection of a target in a radiological search can reduce the detectability of a second target, a phenomenon termed satisfaction of search (SOS). Given the potential consequences, here we investigate the generality of SOS with the goal of si ... Full text Link to item Cite

Low-tube-voltage, high-tube-current multidetector abdominal CT: improved image quality and decreased radiation dose with adaptive statistical iterative reconstruction algorithm--initial clinical experience.

Journal article Radiology · January 2010 Featured Publication PURPOSE: To investigate whether an adaptive statistical iterative reconstruction (ASIR) algorithm improves the image quality at low-tube-voltage (80-kVp), high-tube-current (675-mA) multidetector abdominal computed tomography (CT) during the late hepatic a ... Full text Link to item Cite

Optimized image acquisition for breast tomosynthesis in projection and reconstruction space.

Journal article Med Phys · November 2009 Featured Publication Breast tomosynthesis has been an exciting new development in the field of breast imaging. While the diagnostic improvement via tomosynthesis is notable, the full potential of tomosynthesis has not yet been realized. This may be attributed to the dependency ... Full text Link to item Cite

Effective DQE (eDQE) and speed of digital radiographic systems: an experimental methodology.

Journal article Med Phys · August 2009 Featured Publication Prior studies on performance evaluation of digital radiographic systems have primarily focused on the assessment of the detector performance alone. However, the clinical performance of such systems is also substantially impacted by magnification, focal spo ... Full text Link to item Cite

An exposure indicator for digital radiography: AAPM Task Group 116 (executive summary).

Journal article Med Phys · July 2009 Featured Publication Digital radiographic imaging systems, such as those using photostimulable storage phosphor, amorphous selenium, amorphous silicon, CCD, and MOSFET technology, can produce adequate image quality over a much broader range of exposure levels than that of scre ... Full text Link to item Cite

Pediatric MDCT: towards assessing the diagnostic influence of dose reduction on the detection of small lung nodules.

Journal article Acad Radiol · July 2009 Featured Publication RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the effect of reduced tube current (dose) on lung nodule detection in pediatric multidetector array computed tomography (MDCT). MATERIALS AND METHODS: The study included normal clinical ch ... Full text Link to item Cite

Can compression be reduced for breast tomosynthesis? Monte carlo study on mass and microcalcification conspicuity in tomosynthesis.

Journal article Radiology · June 2009 Featured Publication PURPOSE: To assess, in a voxelized anthropomorphic breast phantom, how the conspicuity of breast masses and microcalcifications may be affected by applying reduced breast compression in tomosynthesis. MATERIALS AND METHODS: A breast tomosynthesis system wa ... Full text Link to item Cite

Hypervascular liver tumors: low tube voltage, high tube current multidetector CT during late hepatic arterial phase for detection--initial clinical experience.

Journal article Radiology · June 2009 Featured Publication PURPOSE: To intraindividually compare a low tube voltage (80 kVp), high tube current computed tomographic (CT) technique with a standard CT protocol (140 kVp) in terms of image quality, radiation dose, and detection of malignant hypervascular liver tumors ... Full text Link to item Cite

Three-dimensional simulation of lung nodules for paediatric multidetector array CT.

Journal article Br J Radiol · May 2009 Featured Publication The purpose of this study was to develop and validate a technique for three-dimensional (3D) modelling of small lung nodules on paediatric multidetector array computed tomography (MDCT) images. Clinical images were selected from 21 patients (<18 years old) ... Full text Link to item Cite

Towards optimized acquisition scheme for multiprojection correlation imaging of breast cancer.

Journal article Acad Radiol · April 2009 Featured Publication RATIONALE AND OBJECTIVES: Correlation imaging (CI) is a form of multiprojection imaging in which multiple images of a patient are acquired from slightly different angles. Information from these images is combined to make the final diagnosis. A critical fac ... Full text Link to item Cite

The influence of increased ambient lighting on mass detection in mammograms.

Journal article Acad Radiol · March 2009 Featured Publication RATIONALE AND OBJECTIVES: Recent research has provided evidence that in reading rooms equipped with liquid crystal displays (LCDs), a measured increase of ambient lighting may improve clinicians' detection performance. In agreement with this research, the ... Full text Link to item Cite

Comparison of patient size-based methods for estimating quantum noise in CT images of the lung.

Journal article Med Phys · February 2009 Featured Publication The authors explored four methods for estimating quantum noise in CT images of the lung, each based on a different definition of patient size (water-equivalent diameter) and the relationship between noise and diameter determined in water phantoms. The accu ... Full text Link to item Cite

Mass detection on mammograms: influence of signal shape uncertainty on human and model observers.

Journal article J Opt Soc Am A Opt Image Sci Vis · February 2009 Featured Publication We studied the influence of signal variability on human and model observers for detection tasks with realistic simulated masses superimposed on real patient mammographic backgrounds and synthesized mammographic backgrounds (clustered lumpy backgrounds, CLB ... Full text Link to item Cite

Micro-CT imaging of breast tumors in rodents using a liposomal, nanoparticle contrast agent.

Journal article Int J Nanomedicine · 2009 Featured Publication A long circulating liposomal, nanoscale blood pool agent encapsulating traditional iodinated contrast agent (65 mg I/mL) was used for micro-computed tomography (CT) imaging of rats implanted with R3230AC mammary carcinoma. Three-dimensional vascular archit ... Open Access Link to item Cite

Patient-specific dose estimation for pediatric chest CT.

Journal article Med Phys · December 2008 Featured Publication Current methods for organ and effective dose estimations in pediatric CT are largely patient generic. Physical phantoms and computer models have only been developed for standard/limited patient sizes at discrete ages (e.g., 0, 1, 5, 10, 15 years old) and d ... Full text Link to item Cite

Detector or system? Extending the concept of detective quantum efficiency to characterize the performance of digital radiographic imaging systems.

Journal article Radiology · December 2008 Featured Publication PURPOSE: To develop an experimental method for measuring the effective detective quantum efficiency (eDQE) of digital radiographic imaging systems and evaluate its use in select imaging systems. MATERIALS AND METHODS: A geometric phantom emulating the atte ... Full text Link to item Cite

The effect of breast compression on mass conspicuity in digital mammography.

Journal article Med Phys · October 2008 Featured Publication This study analyzed how the inherent quality of diagnostic information in digital mammography could be affected by breast compression. A digital mammography system was modeled using a Monte Carlo algorithm based on the Penelope program, which has been succ ... Full text Link to item Cite

Automated breast mass detection in 3D reconstructed tomosynthesis volumes: a featureless approach.

Journal article Med Phys · August 2008 Featured Publication The purpose of this study was to propose and implement a computer aided detection (CADe) tool for breast tomosynthesis. This task was accomplished in two stages-a highly sensitive mass detector followed by a false positive (FP) reduction stage. Breast tomo ... Full text Link to item Cite

Introduction to grayscale calibration and related aspects of medical imaging grade liquid crystal displays.

Journal article J Digit Imaging · June 2008 Featured Publication Consistent presentation of digital radiographic images at all locations within a medical center can help ensure a high level of patient care. Currently, liquid crystal displays (LCDs) are the electronic display technology of choice for viewing medical imag ... Full text Link to item Cite

Object detectability at increased ambient lighting conditions.

Journal article Med Phys · June 2008 Featured Publication Under typical dark conditions encountered in diagnostic reading rooms, a reader's pupils will contract and dilate as the visual focus intermittently shifts between the high luminance display and the darker background wall, resulting in increased visual fat ... Full text Link to item Cite

Optimization of exposure parameters in full field digital mammography.

Journal article Med Phys · June 2008 Featured Publication Optimization of exposure parameters (target, filter, and kVp) in digital mammography necessitates maximization of the image signal-to-noise ratio (SNR), while simultaneously minimizing patient dose. The goal of this study is to compare, for each of the maj ... Full text Link to item Cite

A comparative contrast-detail study of five medical displays.

Journal article Med Phys · April 2008 Featured Publication The objective of this study was to compare the contrast-detail performance of five different commercial liquid crystal displays (LCDs) to other LCD and cathode-ray tube (CRT) displays for medical applications. A contrast-detail phantom, supplemented with 5 ... Full text Link to item Cite

A mathematical model platform for optimizing a multiprojection breast imaging system.

Journal article Med Phys · April 2008 Featured Publication Multiprojection imaging is a technique in which a plurality of digital radiographic images of the same patient are acquired within a short interval of time from slightly different angles. Information from each image is combined to determine the final diagn ... Full text Link to item Cite

Hypervascular liver tumors: low tube voltage, high tube current multi-detector row CT for enhanced detection--phantom study.

Journal article Radiology · January 2008 Featured Publication PURPOSE: To prospectively evaluate, for the depiction of simulated hypervascular liver lesions in a phantom, the effect of a low tube voltage, high tube current computed tomographic (CT) technique on image noise, contrast-to-noise ratio (CNR), lesion consp ... Full text Link to item Cite

Does image quality matter? Impact of resolution and noise on mammographic task performance.

Journal article Med Phys · October 2007 Featured Publication The purpose of this study was to examine the effects of different resolution and noise levels on task performance in digital mammography. This study created an image set with images at three different resolution levels, corresponding to three digital displ ... Full text Link to item Cite

Effect of dose reduction on the detection of mammographic lesions: a mathematical observer model analysis.

Journal article Med Phys · August 2007 Featured Publication The effect of reduction in dose levels normally used in mammographic screening procedures on the detection of breast lesions were analyzed. Four types of breast lesions were simulated and inserted into clinically-acquired digital mammograms. Dose reduction ... Full text Link to item Cite

Assessment of detective quantum efficiency: intercomparison of a recently introduced international standard with prior methods.

Journal article Radiology · June 2007 Featured Publication PURPOSE: To prospectively evaluate the recently introduced international standard method for measurement of the detective quantum efficiency (DQE) of digital radiography systems, in comparison with representative prior methods. MATERIALS AND METHODS: A rec ... Full text Link to item Cite

Digital mammography: comparative performance of color LCD and monochrome CRT displays.

Journal article Acad Radiol · May 2007 Featured Publication RATIONALE AND OBJECTIVES: To evaluate the comparative performance of high-fidelity liquid crystal display (LCD) and cathode ray tube (CRT) devices for mammography applications, and to assess the impact of LCD viewing angle on detection accuracy. MATERIALS ... Full text Link to item Cite

Digital mammography: effects of reduced radiation dose on diagnostic performance.

Journal article Radiology · May 2007 Featured Publication PURPOSE: To experimentally determine the relationship between radiation dose and observer accuracy in the detection and discrimination of simulated lesions for digital mammography. MATERIALS AND METHODS: This HIPAA-compliant study received institutional re ... Full text Link to item Cite

Multiprojection correlation imaging for improved detection of pulmonary nodules.

Journal article AJR Am J Roentgenol · May 2007 Featured Publication OBJECTIVE: The purpose of this study was the development and preliminary evaluation of multiprojection correlation imaging with 3D computer-aided detection (CAD) on chest radiographs for cost- and dose-effective improvement of early detection of pulmonary ... Full text Link to item Cite

Tomographic digital subtraction angiography for lung perfusion estimation in rodents.

Journal article Med Phys · May 2007 Featured Publication In vivo measurements of perfusion present a challenge to existing small animal imaging techniques such as magnetic resonance microscopy, micro computed tomography, micro positron emission tomography, and microSPECT, due to combined requirements for high sp ... Full text Link to item Cite

Dose dependence of mass and microcalcification detection in digital mammography: free response human observer studies.

Journal article Med Phys · February 2007 Featured Publication The purpose of this study was to evaluate the effect of dose reduction in digital mammography on the detection of two lesion types-malignant masses and clusters of microcalcifications. Two free-response observer studies were performed-one for each lesion t ... Full text Link to item Cite

Ambient illumination revisited: a new adaptation-based approach for optimizing medical imaging reading environments.

Journal article Med Phys · January 2007 Featured Publication Ambient lighting in soft-copy reading rooms is currently kept at low values to preserve contrast rendition in the dark regions of a medical image. Low illuminance levels, however, create inadequate viewing conditions and may also cause eye strain. This eye ... Full text Link to item Cite

Improving mammographic decision accuracy by incorporating observer ratings with interpretation time.

Journal article Br J Radiol · December 2006 Featured Publication Mammography is currently the most established technique for the early detection of breast cancer. However, mammography would benefit from further improvements as it does produce some errors, such as not finding all early-stage cancers. The objectives of th ... Full text Link to item Cite

Recent advances in chest radiography.

Journal article Radiology · December 2006 Featured Publication There have been many remarkable advances in conventional thoracic imaging over the past decade. Perhaps the most remarkable is the rapid conversion from film-based to digital radiographic systems. Computed radiography is now the preferred imaging modality ... Full text Link to item Cite

Optimized radiographic spectra for small animal digital subtraction angiography.

Journal article Med Phys · November 2006 Featured Publication The increasing use of small animals in basic research has spurred interest in new imaging methodologies. Digital subtraction angiography (DSA) offers a particularly appealing approach to functional imaging in the small animal. This study examines the optim ... Full text Link to item Cite

Comparison of LCD and CRT displays based on efficacy for digital mammography.

Journal article Acad Radiol · November 2006 Featured Publication RATIONALE AND OBJECTIVES: To compare two display technologies, cathode ray tube (CRT) and liquid crystal display (LCD), in terms of diagnostic accuracy for several common clinical tasks in digital mammography. MATERIALS AND METHODS: Simulated masses and mi ... Full text Link to item Cite

Visual assessment of angular response in medical liquid crystal displays.

Journal article J Digit Imaging · September 2006 Featured Publication In spite of having non-Lambertian emission, displays based on liquid crystal technology are becoming popular for medical diagnostic work stations. For all liquid crystal displays (LCDs), the contrast performance varies with viewing direction. Accurate meas ... Full text Link to item Cite

Digital mammography image quality: image display.

Journal article J Am Coll Radiol · August 2006 Featured Publication This paper on digital mammography image display is 1 of 3 papers written as part of an intersociety effort to establish image quality standards for digital mammography. The information included in this paper is intended to support the development of an Ame ... Full text Link to item Cite

Simulation of mammographic lesions.

Journal article Acad Radiol · July 2006 Featured Publication RATIONALE AND OBJECTIVES: This study presents a method for generating breast masses and microcalcifications in mammography via simulation. This simulation method allows for the creation of large image datasets with particular lesions, which may serve as a ... Full text Link to item Cite

Contrast-detail analysis of three flat panel detectors for digital radiography.

Journal article Med Phys · June 2006 Featured Publication In this paper we performed a contrast detail analysis of three commercially available flat panel detectors, two based on the indirect detection mechanism (GE Revolution XQ/i, system A, and Trixell/Philips Pixium 4600, system B) and one based on the direct ... Full text Link to item Cite

Intercomparison of methods for image quality characterization. II. Noise power spectrum.

Journal article Med Phys · May 2006 Featured Publication Second in a two-part series comparing measurement techniques for the assessment of basic image quality metrics in digital radiography, in this paper we focus on the measurement of the image noise power spectrum (NPS). Three methods were considered: (1) a m ... Full text Link to item Cite

Intercomparison of methods for image quality characterization. I. Modulation transfer function.

Journal article Med Phys · May 2006 Featured Publication The modulation transfer function (MTF) and the noise power spectrum (NPS) are widely recognized as the most relevant metrics of resolution and noise performance in radiographic imaging. These quantities have commonly been measured using various techniques, ... Full text Link to item Cite

Imaging properties of digital magnification radiography.

Journal article Med Phys · April 2006 Featured Publication Flat panel detectors exhibit improved signal-to-noise ratio (SNR) and display capabilities compared to film. This improvement necessitates a new evaluation of optimal geometry for conventional projection imaging applications such as digital projection mamm ... Full text Link to item Cite

Viewing angle performance of medical liquid crystal displays.

Journal article Med Phys · March 2006 Featured Publication Cathode-ray tube (CRT) and liquid crystal display (LCD) are currently two main technologies for displaying medical images. LCDs possess a number of advantages, but their performance varies as a function of viewing angle. Our purpose in this study was to ch ... Full text Link to item Cite

Simulation of liver lesions for pediatric CT.

Journal article Radiology · February 2006 Featured Publication PURPOSE: To develop and validate a technique based on characteristics of real lesions for simulating realistic small liver lesions on pediatric computed tomographic (CT) images. MATERIALS AND METHODS: The institutional review board provided exempt status f ... Full text Link to item Cite

Resolution and noise measurements of five CRT and LCD medical displays.

Journal article Med Phys · February 2006 Featured Publication The performance of soft-copy displays plays a significant role in the overall image quality of a digital radiographic system. In this work, we discuss methods to characterize the resolution and noise of both cathode ray tube (CRT) and liquid crystal displa ... Full text Link to item Cite

Analysis of a novel offset cone-beam computed mammotomography system geometry for accomodating various breast sizes.

Journal article Phys Med · 2006 Featured Publication We evaluate a newly developed dedicated cone-beam transmission computed mammotomography (CmT) system configuration using an optimized quasi-monochromatic cone beam technique for attenuation correction of SPECT in a planned dual-modality emission and transm ... Full text Link to item Cite

Comparison of edge analysis techniques for the determination of the MTF of digital radiographic systems.

Journal article Phys Med Biol · August 7, 2005 Featured Publication The modulation transfer function (MTF) is well established as a metric to characterize the resolution performance of a digital radiographic system. Implemented by various laboratories, the edge technique is currently the most widespread approach to measure ... Full text Link to item Cite

Measurement of the detective quantum efficiency in digital detectors consistent with the IEC 62220-1 standard: Practical considerations regarding the choice of filter material.

Journal article Med Phys · July 2005 Featured Publication As part of a larger evaluation we attempted to measure the detective quantum efficiency (DQE) of an amorphous silicon flat-panel detector using the method described in the International Electrotechnical Commission standard 62220-1 published in October 2003 ... Full text Link to item Cite

Comparative scatter and dose performance of slot-scan and full-field digital chest radiography systems.

Journal article Radiology · June 2005 Featured Publication PURPOSE: To evaluate the scatter, dose, and effective detective quantum efficiency (DQE) performance of a slot-scan digital chest radiography system compared with that of a full-field digital radiography system. MATERIALS AND METHODS: Scatter fraction of a ... Full text Link to item Cite

Assessment of display performance for medical imaging systems: executive summary of AAPM TG18 report.

Journal article Med Phys · April 2005 Featured Publication Digital imaging provides an effective means to electronically acquire, archive, distribute, and view medical images. Medical imaging display stations are an integral part of these operations. Therefore, it is vitally important to assure that electronic dis ... Full text Link to item Cite

Physical characterization of a prototype selenium-based full field digital mammography detector.

Journal article Med Phys · February 2005 Featured Publication The purpose of this study was to measure experimentally the physical performance of a prototype mammographic imager based on a direct detection, flat-panel array design employing an amorphous selenium converter with 70 microm pixels. The system was charact ... Full text Link to item Cite

AAPM/RSNA physics tutorial for residents: technological and psychophysical considerations for digital mammographic displays.

Journal article Radiographics · 2005 Featured Publication Digital mammography is gradually replacing screen-film analog mammography, a transition driven by a desire to improve the efficiency and possibly the quality of the interpretation of mammograms. Digital mammography involves the use of electronic display de ... Full text Link to item Cite

A framework for optimising the radiographic technique in digital X-ray imaging.

Journal article Radiat Prot Dosimetry · 2005 Featured Publication The transition to digital radiology has provided new opportunities for improved image quality, made possible by the superior detective quantum efficiency and post-processing capabilities of new imaging systems, and advanced imaging applications, made possi ... Full text Link to item Cite

Toward clinically relevant standardization of image quality.

Journal article J Digit Imaging · December 2004 Featured Publication In recent years, notable progress has been made on standardization of medical image presentations in the definition and implementation of the Digital Imaging and Communications in Medicine (DICOM) Grayscale Standard Display Function (GSDF). In parallel, th ... Full text Link to item Cite

Luminance and contrast performance of liquid crystal displays for mammographic applications.

Journal article Technol Cancer Res Treat · October 2004 Featured Publication Liquid crystal displays (LCDs) are gradually replacing cathode-ray tubes (CRTs) as the primary means of electronic display of digital radiographs. The transition from CRT to LCD is fueled by advantages of the LCD technology such as enhanced maximum luminan ... Full text Link to item Cite

Fundamental imaging characteristics of a slot-scan digital chest radiographic system.

Journal article Med Phys · September 2004 Featured Publication Our purpose in this study was to evaluate the fundamental image quality characteristics of a new slot-scan digital chest radiography system (ThoraScan, Delft Imaging Systems/Nucletron, Veenendaal, The Netherlands). The linearity of the system was measured ... Full text Link to item Cite

Determination of the detective quantum efficiency of a digital x-ray detector: comparison of three evaluations using a common image data set.

Journal article Med Phys · August 2004 Featured Publication The detective quantum efficiency (DQE) of an x-ray digital imaging detector was determined independently by the three participants of this study, using the same data set consisting of edge and flat field images. The aim was to assess the possible variation ... Full text Link to item Cite

Assessment of flat panel LCD primary class display performance based on AAPM TG 18 acceptance protocol.

Journal article Med Phys · July 2004 Featured Publication The image display is an important component of the Picture Archiving and Communication System (PACS) and of digital imaging in general. In this paper, we assess the display performance of 32 different flat panel LCD devices, in terms of their reflection, l ... Full text Link to item Cite

Impact of resolution and noise characteristics of digital radiographic detectors on the detectability of lung nodules.

Journal article Med Phys · June 2004 Featured Publication One of the unanswered questions in digital radiography is the connection between physical image quality metrics and clinical detection performance. In this paper, we examine the impact of two physical metrics, resolution and noise, on the detectability of ... Full text Link to item Cite

Simulation study of a quasi-monochromatic beam for x-ray computed mammotomography.

Journal article Med Phys · April 2004 Featured Publication The purpose of this simulation study was to evaluate the feasibility, benefits, and potential operating parameters of a quasi-monochromatic beam from a tungsten-target x-ray source yielding projection images. The application is intended for newly developed ... Full text Link to item Cite

AAPM/RSNA tutorial on equipment selection: PACS equipment overview: general guidelines for purchasing and acceptance testing of PACS equipment.

Journal article Radiographics · 2004 Featured Publication A picture archiving and communication system (PACS) is a comprehensive computer system that is responsible for the electronic storage and distribution of medical images in the medical enterprise. The system is highly integrated with digital acquisition and ... Full text Link to item Cite

Sonography of fetal choroid plexus cysts: detection depends on cyst size and gestational age.

Journal article J Ultrasound Med · November 2003 Featured Publication OBJECTIVE: To establish diagnostic criteria for the diagnosis of fetal choroid plexus cysts across gestation. METHODS: Prenatal sonographic images of 166 fetuses without choroid plexus cysts were prospectively collected from 13 weeks to term. Texture chara ... Full text Link to item Cite

A method for modifying the image quality parameters of digital radiographic images.

Journal article Med Phys · November 2003 Featured Publication A new computer simulation approach is presented that is capable of modeling several varieties of digital radiographic systems by their image quality characteristics. In this approach, the resolution and noise characteristics of ideal supersampled input ima ... Full text Link to item Cite

Subtle lung nodules: influence of local anatomic variations on detection.

Journal article Radiology · July 2003 Featured Publication PURPOSE: To assess the influence of local anatomic noise on the detection of subtle lung nodules depicted on chest radiographs. MATERIALS AND METHODS: Six 8 x 8-cm lung regions were extracted from digital chest radiographs obtained in healthy subjects. Sim ... Full text Link to item Cite

Image quality in two phosphor-based flat panel digital radiographic detectors.

Journal article Med Phys · July 2003 Featured Publication Two general types of phosphor screens are currently used in indirect digital radiographic systems: structured phosphor screens and turbid phosphor screens. The purpose of the study was to experimentally compare the image quality characteristics of two flat ... Full text Link to item Cite

An experimental comparison of detector performance for direct and indirect digital radiography systems.

Journal article Med Phys · April 2003 Featured Publication Current flat-panel detectors either directly convert x-ray energy to electronic charge or use indirect conversion with an intermediate optical process. The purpose of this work was to compare direct and indirect detectors in terms of their modulation trans ... Full text Link to item Cite

Evaluation of a flat panel digital radiographic system for low-dose portable imaging of neonates.

Journal article Med Phys · April 2003 Featured Publication The purpose of this study was to evaluate the clinical utility of an investigational flat-panel digital radiography system for low-dose portable neonatal imaging. Thirty image-pairs from neonatal intensive care unit patients were acquired with a commercial ... Full text Link to item Cite

Chest radiography: optimization of X-ray spectrum for cesium iodide-amorphous silicon flat-panel detector.

Journal article Radiology · January 2003 Featured Publication PURPOSE: To ascertain the optimum x-ray spectrum for chest radiography with a cesium iodide-amorphous silicon flat-panel detector. MATERIALS AND METHODS: End points for optimization included the ratio of tissue contrast to bone contrast and a figure of mer ... Full text Link to item Cite

An experimental comparison of detector performance for computed radiography systems.

Journal article Med Phys · April 2002 Featured Publication The intrinsic resolution, noise, and signal-to-noise transfer characteristics of five commercial digital computed radiography (CR) systems were compared using identical experimental methods. The reader/screen combinations evaluated were Agfa ADC-Compact/MD ... Full text Link to item Cite

Performance evaluation of computed radiography systems.

Journal article Med Phys · March 2001 Featured Publication Recommended methods to test the performance of computed radiography (CR) digital radiographic systems have been recently developed by the AAPM Task Group No. 10. Included are tests for dark noise, uniformity, exposure response, laser beam function, spatial ... Full text Link to item Cite

Evaluation of a quality control phantom for digital chest radiography.

Journal article J Appl Clin Med Phys · 2001 Featured Publication RATIONALE AND OBJECTIVES: To examine the effectiveness and suitability of a quality control (QC) phantom for a routine QC program in digital radiography. MATERIALS AND METHODS: The chest phantom consists of copper and aluminum cutouts arranged to resemble ... Full text Link to item Cite

Health physics consequences of out-patient treatment of non-Hodgkin's lymphoma with 131I-radiolabeled anti-B1 antibody.

Journal article Health Phys · November 2000 Featured Publication The Medical University of South Carolina is currently participating in clinical trials of 131I radiolabeled Anti-B1 antibody for treatment of Non-Hodgkin's lymphoma. Under current South Carolina Department of Health and Environmental Control regulatory gui ... Full text Link to item Cite

Numerical simulation of a TLD pulsed laser-heating scheme for determination of shallow dose and deep dose in low-LET radiation fields.

Journal article Appl Radiat Isot · June 2000 Featured Publication A new method is described to determine the depth-dose distribution in low-LET radiation fields using a thick thermoluminescent dosimeter (TLD) with a pulsed laser-heating scheme to obtain TL glow output. The computational simulation entails heat conduction ... Full text Link to item Cite

Detection of subtle lung nodules: relative influence of quantum and anatomic noise on chest radiographs.

Journal article Radiology · December 1999 Featured Publication PURPOSE: To assess the relative influence of quantum mottle and structured lung patterns (anatomic noise) on the detection of subtle lung nodules on chest radiographs. MATERIALS AND METHODS: Sixty 8 x 8-cm lung pattern images were extracted from digital ch ... Full text Link to item Cite

Experimental comparison of noise and resolution for 2k and 4k storage phosphor radiography systems.

Journal article Med Phys · August 1999 Featured Publication The purpose of this study was to compare the image quality for a digital storage phosphor system using 1760 x 2140 (2k) and 3520 x 4280 (4k) image arrays. Measurements were made on a chest radiography system (Fuji FCR-9501) with special provisions to be op ... Full text Link to item Cite

Chest radiographic image quality: comparison of asymmetric screen-film, digital storage phosphor, and digital selenium drum systems--preliminary study.

Journal article Radiographics · 1998 Featured Publication Conventional screen-film radiography does not display all regions of the thorax satisfactorily. Three chest radiographic techniques display both the lung and the mediastinum with good contrast. These techniques are asymmetric screen-film (ASF), digital sto ... Full text Link to item Cite

A method for measuring the presampled MTF of digital radiographic systems using an edge test device.

Journal article Med Phys · January 1998 Featured Publication The modulation transfer function (MTF) of radiographic systems is frequently evaluated by measuring the system's line spread function (LSF) using narrow slits. The slit method requires precise fabrication and alignment of a slit and high radiation exposure ... Full text Link to item Cite

Simulation of subtle lung nodules in projection chest radiography.

Journal article Radiology · January 1997 Featured Publication PURPOSE: To measure the radiologic characteristics of subtle lung nodules and develop nodule phantoms that simulate these characteristics. MATERIALS AND METHODS: From a database of chest radiographs, 16 radiographs that showed confirmed subtle lung nodules ... Full text Link to item Cite

A limited bibliography of the Federal Government-funded human radiation experiments.

Journal article Health Phys · December 1995 Featured Publication From the early 1940's thousands of U.S. citizens have been the subjects of federally supported scientific experiments that involved the administration of ionizing radiation or radioactive substances. Recently, many questions have been raised regarding the ... Full text Link to item Cite

Sensitivity of a mixed field dosimetry algorithm to uncertainties in thermoluminescent element readings.

Journal article Health Phys · March 1995 Featured Publication An error analysis of the effects of the algorithms used to resolve the deep and shallow dose components for mixed fields from multi-element thermoluminescent (TLD) badge systems was undertaken for a commonly used system. Errors were introduced independentl ... Full text Link to item Cite