Bob Liu

• Ph.D.
• Professor (Associate) at Massachusetts General Hospital

Purpose: We aim to analyze higher-order textural components of digital breast tomosynthesis (DBT) images to quantify differences in the appearance of breast parenchyma produced by different vendors. Approach: We included consecutive women who had normal screening DBT exams in January 2018 from a GE system and in adjacent years from Hologic syste...

Background Radiography is one of the most widely used x‐ray imaging modalities. In National Council on Radiation Protection and Measurements (NCRP) Report No. 147, transmission data for radiographic systems were evaluated on those installed before 2000. For x‐ray systems (except intraoral dental) manufactured on or after June 10, 2006, the U.S. req...

To assess cumulative effective dose (CED) over a 4-year period in patients undergoing multimodality recurrent imaging at a major hospital in the USA. CED from CT, fluoroscopically guided intervention (FGI), and nuclear medicine was analyzed in consecutive exams in a tertiary care center in 2018–2021. Patients with CED ≥ 100 mSv were classified by a...

Background It is challenging to assess the accuracy of volume CT Dose Index (CTDIvol) when the axial scan modes corresponding to a helical scan protocol are not available. An alternative approach was proposed to directly measure CTDIvolH$CTDI_{vol}^H$ using helical acquisitions and relatively small differences (< 20%) from CTDIvol were observed. P...

Purpose: Patient skin dose from interventional fluoroscopy procedures may exceed the threshold of tissue injuries and established guidelines recommend patient follow-up for air kerma at reference point (Ka,r) ≥ 5 Gy for individual procedures. Patients may undergo multiple procedures and skin injuries may be possible by cumulative exposure, even wh...

Background Dose evaluation at longitudinal positions of body computed tomography (CT) scans is useful for CT quality assurance programs and patient organ dose evaluation. Accurate estimates depend on both patient size and scan length. Purpose To propose practical evaluation of the average dose to the transverse slab of an axial image slice for adu...

Background In children exposed to multiple computed tomography (CT) exams, performed with varying z-axis coverage and often with tube current modulation, it is inaccurate to add volume CT dose index (CTDIvol) and size-specific dose estimate (SSDE) to obtain cumulative dose values.Objective To introduce the patient-size-specific z-axis dose profile...

Purpose CTDIvol-to-fetal-dose coefficients from Monte Carlo simulations are useful for fetal dose evaluations, but the available data is limited to the fetus being completely inside the abdominopelvic scan range. Whereas in a chest examination, the fetus is completely outside the scan range. In an abdominal examination, the fetus after 16 gestation...

Motion management is a critical component of image guidance radiotherapy for lung cancer. We previously proposed a scheme using kV scattered x-ray photons for marker-less real-time image guidance in lung cancer radiotherapy. This study reports our recently progress using the photon counting detection technique to demonstrate potential feasibility o...

OBJECTIVE. The purpose of this article was to investigate the medical condition of patients who received substantial cumulative effective dose (CED) in fluoroscopically guided interventional (FGI) procedures. MATERIALS AND METHODS. We examined 25,253 patients (mean age, 58.2 years; 50.6% male) who underwent 46,491 FGI procedures at a tertiary care...

OBJECTIVE. The purpose of this study was to establish procedure-specific air kerma-area product (KAP) and effective dose for a large number of fluoroscopically guided interventional (FGI) procedures. MATERIALS AND METHODS. This retrospective study collected dose data for consecutive adult cases from 12 examination rooms between May 2016 and October...

Purpose Multi‐series CT examination is common in the clinic, but no metric is agreed upon to report the overall dose from such an examination. This work proposes a relevant metric for tracking patient dose from multi‐series examinations and illustrates the evaluation method through explanatory examples. Materials and methods In each acquisition se...

Purpose To analyze the clinical effect of continuous dose monitoring and patient follow-up for fluoroscopically guided vascular interventional procedures over 8 years. Materials and Methods In this retrospective study, an in-house semiautomated system was developed for fluoroscopic dose monitoring. The quarterly number of procedures from January 20...

Purpose To determine the radiation dose associated with CT-guided percutaneous liver ablations and identify potential risk factors that result in higher radiation doses. Materials and Methods Between June 2011 and June 2015, 245 consecutive patients underwent 304 CT-guided liver ablation treatments. Patient demographics, tumor characteristics and...

Purpose To present procedure-specific radiation dose metric distributions and define quantitative CT utilization factors for CT-guided interventional procedures. Materials and Methods This single-center, retrospective study collected dictation reports and radiation dose data from 9143 consecutive CT-guided interventional procedures in adult patient...

Purpose: Development of patient organ dose evaluation method in computed tomography (CT) needs to model the correlation between organ dose and patient size, under various conditions of scan length, tube current lineshape, and organ location. To facilitate this task, this work was to perform a comprehensive study of the relationship between the dos...

Purpose: To measure, evaluate, and model the broad beam x-ray transmission of the patient supports from representative modern fluoroscopy-guided interventional systems, for the purpose of patient skin dose calculation. Methods: Broad beam transmission was evaluated by varying incident angle, kVp, added copper (Cu) filter, and x-ray field size fo...

Objectives: To quantify the effect of IV contrast, tube current and slice thickness on skeletal muscle cross-sectional area (CSA) and density (SMD) on routine CT. Methods: CSA and SMD were computed on 216 axial CT images obtained at the L3 level in 72 patients with variations in IV contrast, slice thickness and tube current. Intra-patient mean d...

Purpose: The purpose of this work is to evaluate the performance of dual-energy CT (DECT) for determining proton stopping power ratios (SPRs) in an experimental environment and to demonstrate its potential advantages over conventional single-energy CT (SECT) in clinical conditions. Methods: Water equivalent range (WER) measurements of 12 tissue-...

Purpose: The volume CT dose index (CTDIvol) and the size-specific dose estimate (SSDE) are widely used for monitoring patient dose from CT examinations. Both metrics may represent the average dose over the central scan plane of the CTDI phantom or the patient under constant tube current (mA), but they are not intended for the tube current modulati...

Objective: To assess radiation dose for patients who received abdominal quantitative CT and to compare the midpoint dose [DL(0)] at the center of 1-cm scan length with the volume CT dose index (CTDIvol). Although the size-specific dose estimate (SSDE) proposed in AAPM Report No. 204 is not applicable for short length scans, commercial dose monitor...

Purpose: To present shielding calculations for clinical digital breast tomosynthesis (DBT) rooms with updated workload data from a comprehensive survey and to provide reference shielding data for DBT rooms. Methods: The workload survey was performed from eight clinical DBT (Hologic Selenia Dimensions) rooms at Massachusetts General Hospital (MGH...

Purpose: To accurately measure the beam filter profiles from a variety of CT scanner models and to provide reference data for Monte Carlo simulations of CT scanners. Methods: This study proposed a new method to measure CT beam filter profiles using a linear-array x-ray detector (X-Scan 0.8f3-512; Detection Technology Inc., Espoo, Finland) under...

To determine the effect of patient off-centering on point organ radiation dose measurements in a human cadaver scanned with routine abdominal CT protocol. A human cadaver (88 years, body-mass-index 20 kg/m(2)) was scanned with routine abdominal CT protocol on 128-slice dual source MDCT (Definition Flash, Siemens). A total of 18 scans were performed...

Purpose X-ray micro-computed tomography (μCT) is a widely used imaging modality in preclinical research with applications in many areas including orthopedics, pulmonology, oncology, cardiology, and infectious disease. X-rays are a form of ionizing radiation and, therefore, can potentially induce damage and cause detrimental effects. Previous review...

Purpose:In multidetector CT, the volume CT dose index (CTDI vol) is reported for each scan series and dose conversion factors are used for the size-specific dose estimate (SSDE) and scanner-independent organ dose evaluation. This study aimed at examining the dependencies of conversion factors on scan length, tube voltage, and subject size. The resu...

Introduction: Radiation exposure is recognized as having long term consequences, resulting in increased risks over the lifetime. Children, in particular, have a projected lifetime risk of cancer, which should be reduced if within our capacity. The objective of this study is to quantify the amount of ionizing radiation in care for children being tr...

Importance There is no consensus as to the timing of videofluoroscopic swallow studies (VFSSs) in determining resolving aspiration after laryngeal cleft repair. There is a growing literature on the effect of radiation exposure in children. Objective To modify a previously published best-practice algorithm based on a literature review and our clinic...

Purpose:To evaluate the clinical performance of dual-energy CT (DECT) in determining proton stopping power ratios (SPR) and demonstrate advantages over conventional single-energy CT (SECT). Methods:SECT and DECT scans of tissue-equivalent plastics as well as animal meat samples are performed with a Siemens SOMATOM Definition Flash. The methods of S...

Purpose:To accurately measure the scatter radiation from a Hologic digital breast tomosynthesis (DBT) system and to provide updated scatter distribution to guide radiation shielding calculation for DBT rooms. Methods:A high sensitivity GOS-based linear detector was used to measure the angular distribution of scatter radiation from a Hologic Selenia...

Purpose:To compare size-specific dose estimate (SSDE) in abdominal fat quantitative CT with another dose estimate Dsize,L that also takes into account scan length. Methods:This study complied with the requirements of the Health Insurance Portability and Accountability Act. At our institution, abdominal fat CT is performed with scan length = 1 cm an...

Purpose:Spatial resolution in digital breast tomosynthesis (DBT) is affected by inherent/binned detector resolution, oblique entry of x-rays, and focal spot size/motion; the limited angular range further limits spatial resolution in the depth-direction. While DBT is being widely adopted clinically, imaging performance metrics and quality control pr...

Purpose:To investigate how longitudinal dose profile DL(z) in 30 cm-diameter water cylinder change with tube current (mA) distribution and scan length. Methods:A constant and four variable mA distributions from two previous papers [Dixon et al., Med. Phys. 40, 111920 (14pp.) (2013); Zhang et al., Med. Phys. 41, 091911 (9pp.) (2014)] were adopted in...

Purpose:To accurately measure CT bow-tie profiles from various manufacturers and to provide non-proprietary information for CT system modeling. Methods:A GOS-based linear detector (0.8 mm per pixel and 51.2 cm in length) with a fast data sampling speed (0.24 ms/sample) was used to measure the relative profiles of bow-tie filters from a collection o...

Purpose: To measure the scattered radiation intensity around a clinical digital breast tomosynthesis (DBT) unit and to provide updated data for radiation shielding design for DBT systems with tungsten-anode x-ray tubes.

Objective: Extremity cone-beam CT (CBCT) scanners have become available for clinical use in the United States. The purpose of this study was to review an initial clinical experience with CBCT of the foot and ankle in pediatric patients. Materials and methods: A retrospective review was conducted of all foot or ankle CBCT examinations performed o...

Rationale and objectives: The aim of this study was to compare the directly measured and the estimated computed tomography (CT) organ doses obtained from commercial radiation dose-tracking (RDT) software for CT performed with modulated tube current or automatic exposure control (AEC) technique and fixed tube current (mAs). Materials and methods:...

Purpose: To present a noninvasive technique for directly measuring the CT bow-tie filter attenuation with a linear array x-ray detector. Methods: A scintillator based x-ray detector of 384 pixels, 307 mm active length, and fast data acquisition (model X-Scan 0.8c4-307, Detection Technology, FI-91100 Ii, Finland) was used to simultaneously detect...

The Monte Carlo radiation transport community faces a number of challenges associated with peta- and exa-scale computing systems that rely increasingly on heterogeneous architectures involving hardware accelerators such as GPUs and Xeon Phi coprocessors. Existing Monte Carlo codes and methods must be strategically upgraded to meet emerging hardware...

This paper describes the development and testing of VirtualDose-a software for reporting organ doses for adult and pediatric patients who undergo x-ray computed tomography (CT) examinations. The software is based on a comprehensive database of organ doses derived from Monte Carlo (MC) simulations involving a library of 25 anatomically realistic pha...

X-rays from CT scans can increase cancer risk to patients. Lifetime Attributable Risk of Cancer Incidence for adult patients has been investigated and shown to decrease as patient age. However, a new risk model shows an increasing risk trend for several radiosensitive organs for middle age patients. This study investigates the feasibility of a gene...

To simulate off-center chest CT scans on adult phantoms and to determine the impact on organ dose. A GPU-based fast Monte Carlo code ARCHER was used for simulation of chest CT scan on RPI-adult female (RPI-AF) and RPI-adult male (RPI-AM) phantoms. A CT scanner model of GE LightSpeed Pro 16 previously developed was simulated with a fixed 200 mAs per...

Purpose: ICRU Report No. 87 Committee and AAPM Task Group 200 designed a three-sectional polyethylene phantom of 30 cm in diameter and 60 cm in length for evaluating the midpoint dose DL (0) and its rise-to-the-equilibrium curve H(L) = DL (0)/D eq from computed tomography (CT) scanning, where D eq is the equilibrium dose. To aid the use of the pha...

Protocol review plays a critical role in CT quality assurance, but large numbers of protocols and inconsistent protocol names on scanners and in exam records make thorough protocol review formidable. In this investigation, we report on a data-driven cataloging process that can be used to assist in the reviewing and management of CT protocols. We co...

Purpose The approach to equilibrium function has been used previously to calculate the radiation dose to a shift‐invariant medium undergoing CT scans with constant tube current [Li, Zhang, and Liu, Med. Phys. 39, 5347–5352 (2012)]. The authors have adapted this method to CT scans with tube current modulation (TCM). Methods For a scan with variable...

Purpose: The knowledge of longitudinal dose distribution provides the most direct view of the accumulated dose in computed tomography (CT) scanning. The purpose of this work was to perform a comprehensive study of dose distribution width and energy absorption with a wide range of subject sizes and beam irradiated lengths. Methods: Cumulative dos...

Purpose: To present a study of radiation dose measurements with a human cadaver scanned on a clinical CT scanner. Methods: Multiple point dose measurements were obtained with high-accuracy Thimble ionization chambers placed inside the stomach, liver, paravertebral gutter, ascending colon, left kidney, and urinary bladder of a human cadaver (183...

Purpose: For CT scanning in the stationary-table modes, AAPM Task Group 111 proposed to measure the midpoint dose on the central and peripheral axes of sufficiently long phantoms. Currently, a long cylindrical phantom is usually not available in many clinical facilities. The use of a long phantom is also challenging because of the heavy weight. In...

Objective: Use of mobile digital specimen radiography systems expedites intraoperative verification of excised breast specimens. The purpose of this study was to evaluate the performance of a such a system for verifying targets. Materials and methods: A retrospective review included 100 consecutive pairs of breast specimen radiographs. Specimens...

Purpose: To evaluate a sterile, disposable lead-free drape for reducing scatter radiation exposure during fluoroscopy-guided procedures. Materials and methods: Computer-aided design software was used to model a procedure room with a thoracic anthropomorphic phantom on the angiography table. Using this model, measurements of scatter radiation wer...

The Monte Carlo radiation transport community faces a number of challenges associated with peta- and exa-scale computing systems that rely increasingly on heterogeneous architectures involving hardware accelerators such as GPUs and Xeon Phi coprocessors. Existing Monte Carlo codes and methods must be strategically upgraded to meet emerging hardware...

Several novel modalities have been or are on the verge of being introduced into the breast imaging clinic. These include tomosynthesis imaging, dedicated breast CT, contrast‐enhanced digital mammography, and automated breast ultrasound, all of which are covered in this course. Tomosynthesis and dedicated breast CT address the problem of tissue supe...

Purpose To compare the CT doses derived from the experiments and GPU‐based Monte Carlo (MC) simulations, using a human cadaver and ATOM phantom. Methods The cadaver of an 88‐year old male and the ATOM phantom were scanned by a GE LightSpeed Pro 16 MDCT. For the cadaver study, the Thimble chambers (Model 10×5−0.6CT and 10×6−0.6CT) were used to meas...

We are developing and testing a new generation of parallel MC code called ARCHER-CT to accurately and rapidly calculate radiation dose from X-ray Computed Tomography (CT) scans on the modern multi-core CPU and on two types of hardware accelerators: Nvidia Graphics Processing Unit (GPU) and Intel coprocessor. While benchmark tests against MCNPX have...

PURPOSE Recent research suggest that long-term low-dose radiation exposure in the interventional (angiographic) suite may lead to greater stochastic effects than previously believed. Sufficient shielding from scatter radiation during fluoroscopy still remains a formidable challenge. We designed and tested the utility of a disposable, sterile lead c...

CONCLUSION Direct dose measurements inside the Abd/Pelvis region of an anthropomorphic phantom provided realistic dose distributions, and demonstrated the significant difference between scans with fixed mA and with mA modulation. BACKGROUND Helical CT scans with automatic tube current modulation are widely utilized clinically. However, in the regi...

BACKGROUND With recent technical advances, dual energy CT (DE-CT) became widely available in clinical practice. However, the radiation dose is one of the major concerns for the application of DE-CT in clinical practice. CT dose index (CTDIvol) is a conventional radiation metric reported by a scanner, and is based on uniform cylindrical phantoms. To...

Purpose To present a parameterization method based on singular value decomposition (SVD), and to provide analytical parameterization of the mean glandular dose (MGD) conversion factors from eight references for evaluating breast tomosynthesis dose in the Mammography Quality Standards Act (MQSA) protocol and in the UK, European, and IAEA dosimetry p...

Size-specific dose estimate (SSDE), which corrects CT dose index (CTDI) for body diameter and is a better measure of organ dose than is CTDI, has not yet been validated in vivo. The purpose was to determine the correlation between SSDE and measured breast entrance skin dose (ESD) for pediatric chest CT angiography across a variety of techniques, sc...

Purpose: AAPM Task Group 111 proposed to measure the equilibrium dose-pitch product Deq for scan modes involving table translation and the midpoint dose DL(0) for stationary-table modes on the central and peripheral axes of sufficiently long (e.g., at least 40 cm) phantoms. This paper presents an alternative approach to calculate both metrics usin...

Purpose: To present the design and procedure of an experimental method for acquiring densely sampled organ dose map for CT applications, based on optically stimulated luminescence (OSL) dosimeters "nanoDots" and standard ATOM anthropomorphic phantoms; and to provide the results of applying the method--a dose data set with good statistics for the c...

Purpose: Digital breast tomosynthesis (DBT) differs from conventional mammography in target/filter, kVp range, and imaging geometry. The aim of this study was to assess the breast input exposure of a DBT system by completing a workload survey of DBT installations, and to determine the parameters α, β, and γ in the Archer equation for the primary r...

Purpose: To update the development and clinical testing of a new Software as a Service (SaaS) - VirtualDose for tracking and reporting CT doses. Methods: Incorporating SaaS technology and the comprehensive original dose data derived from Monte Carlo simulations on a family of adult and pediatric computational phantoms, covering 50th-percentile a...

Purpose: To establish the method of organ dose calculation through Monte Carlo simulations for patients taking CT scans with tube current modulation (TCM), and to give the dose results as well as the preliminary comparison of the dose with TCM and the dose without TCM. Methods: The MCNPX Monte Carlo code was used to simulate an armless adult mal...

The influence of large x-ray scatter components in projection images remains a problem for digital breast tomosynthesis, especially when anti-scatter grids may not be used because of dose limitation and possible source/detector geometric limitations. Monte-Carlo simulation of scatter fits better in this situation, but the heavy computational cost h...

Purpose: In multidetector CT, the dose integral DIL of single scan dose profile over the integration interval (-L/2, L/2) can predict the accumulated dose DL(0) at the center of the scan range (-L/2, L/2) for a helical scan of pitch = 1. Both DIL and DL(0) increase with L until the limiting levels (DI∞ and Deq) are reached. The DL(0) equilibration...

Purpose: To quantify patient outcome and predicted cancer risk from body computed tomography (CT) in young adults and identify common indications for the imaging examination. Materials and methods: This retrospective multicenter study was HIPAA compliant and approved by the institutional review boards of three institutions, with waiver of inform...

Purpose: To demonstrate a limitation of lifetime radiation-induced cancer risk metrics in the setting of testicular cancer surveillance-in particular, their failure to capture the delayed timing of radiation-induced cancers over the course of a patient's lifetime. Materials and methods: Institutional review board approval was obtained for the us...

To investigate the radiation dose to the fetus using retrospective tube current modulation (TCM) data selected from archived clinical records. This paper describes the calculation of fetal doses using retrospective TCM data and Monte Carlo (MC) simulations. Three TCM schemes were adopted for use with three pregnant patient phantoms. MC simulations...

PURPOSE To update the progress in the development and testing of VirtualDose™- a new software system for tracking and reporting patient CT doses. METHOD AND MATERIALS VirtualDose™ is designed to be an accurate and easy-to-use dose reporting software to meet the increasing need in managing CT exposures. Compared to most existing packages, VirtualDo...

LEARNING OBJECTIVES View learning objectives under main course title.

Radiation dose from CT examination depends on the position relative to the irradiated region in the longitudinal direction. The objective of this work is to present a mechanism for calculating dose at any point on a line parallel to the axis of rotation. In a medium that is uniform in the z direction, the cumulative dose at the midpoint D(L)(0) of...

To provide transmission data for broad 25-39 kVp (kilovolt peak) W/Rh and 25-49 kVp W/Al (target/filter, W-tungsten, Rh-rhodium, and Al-aluminum) x-ray beams through common shielding materials, such as lead, concrete, gypsum wallboard, wood, steel, and plate glass. The unfiltered W-target x-ray spectra measured on a Selenia Dimensions system (Holog...

This paper presents new spectral measurements of a tungsten-target digital breast tomosynthesis (DBT) system, including spectra of 43-49 kVp. Raw x-ray spectra of 20-49 kVp were directly measured from the tube port of a Selenia Dimensions DBT system using a CdTe based spectrometer. Two configurations of collimation were employed: one with two tungs...

Purpose: To report recent progress toward developing and testing the VirtualDose software under the 'Software as a Service (SaaS)' platform for tracking and reporting patient CT doses. Methods: Many of existing tools for reporting CT dose are based on data derived from phantoms that are anatomically crude and ignore pediatric, obese and pregnant pa...

Objective: The purpose of this article is to review fetal radiation doses and associated risks resulting from CT performed during pregnancy. The scanning parameters that influence dose and the techniques for estimating and reducing dose are explained. Conclusion: Fetal radiation doses for CT examinations in which the fetus is not directly imaged...

The aim of this study was to examine the variations of CT dose index (CTDI) efficiencies, ε(CTDI(100))=CTDI(100)/CTDI(∞), with bowtie filters and CT scanner types. This was an extension of our previous study [Li, Zhang, and Liu, Phys. Med. Biol. 56, 5789-5803 (2011)]. A validated Monte Carlo program was used to calculate ε(CTDI(100)) on a Siemens S...

Since the introduction of ASiR, its potential in noise reduction has been reported in various clinical applications. However, the influence of different scan and reconstruction parameters on the trade off between ASiR's blurring effect and noise reduction in low contrast imaging has not been fully studied. Simple measurements on low contrast images...

Complications of pregnancy, whether they occur during gestation or postpartum, often pose complex challenges because they affect two patients (mother and fetus or infant) and because both short- and long-term outcomes must be considered in management decision making. Interventional radiologists play a critical role in treating complications such as...

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PURPOSE As breast tissue is often directly irradiated during abdominal CT, the aim of this study was to quantify the breast radiation dose reduction possible by using a simple method to displace the breasts above the directly exposed region of abdominal CT. METHOD AND MATERIALS 20 female patients undergoing abdominal CT consented to have OSL dosim...

PURPOSE The increasing radiation dose in dual-energy CT colonography (DE-CTC) scanning due to the double exposures at 80 kVp and 140 kVp is a major concern in the application of DE-CTC in routine colon screening. The purpose of this study was to develop and evaluate a denoising method for noise reduction in non-cathartic low-dose DE-CTC, for the ob...

The CT scanner-displayed radiation dose information is based on CT dose index (CTDI) over an integration length of 100 mm (CTDI(100)), which is lower than the CTDI over an infinite integration length (CTDI(∞)). In an adult or a pediatric body CT scan, the limiting equilibrium dose can be established near the central scan plane, and CTDI(∞) more clo...

To determine factors influencing the number of acquired scan series and subsequently the radiation dose and time during computed tomography (CT)-guided lung biopsies. This Health Insurance Portability and Accountability Act-compliant, institutional review board-approved, retrospective study reviewed 50 consecutive procedures. Each procedure was sep...

The aims of this study were to define the magnitude of frequent body CT scanning of young adults and to determine associated patient diagnoses, examination indications, short-term outcomes, and estimated radiation-induced cancer risk. Patients aged 18 to 35 years who underwent chest or abdominopelvic CT between 2003 and 2007 at any of 3 hospitals w...

Purpose: To demonstrate a method to estimate organ doses from tube current modulated (TCM) CT examinations using angular organ dose weighting. Method and Materials: An extensive set of Monte Carlo dose calcualtions has become available in recent years using realistic models of human anatomy. Dose to individual organs are documented for particular C...

Objective: The purpose of this article is to describe the development of an automated tool for retrieving texts from CT dose report images. Conclusion: Optical character recognition was adopted to perform text recognitions of CT dose report images. The developed tool is able to automate the process of analyzing multiple CT examinations, includin...

The objective of our study was to analyze body CT utilization trends, indications, fetal radiation doses, and scanning parameters associated with high fetal radiation doses (defined as > 30 mGy). A retrospective review of all chest and abdominopelvic CT examinations performed between 1998 and 2005 of patients known to be pregnant was conducted. Dem...

To objectively characterize the performance of the gemstone spectral imaging (GSI) mode of GE CT750 HD scanner from a user's perspective. A regular scan protocol that approximates the adult abdomen scan protocol frequently used in the authors' institute was selected as the baseline, and a GSI protocol (preset 11) that is similar to the regular prot...

To study the sensitivity of a geometric calibration method using projection matrices for digital tomosynthesis systems. A generic geometric calibration method for tomographic imaging systems has been presented in our previous work. The method involves a scan of a calibration phantom with multiple markers. Their locations in projection images are de...

Objective: This article describes a semiautomated system for the capture and reporting of fluoroscopic dose data in a large radiology department. By use of a novel Web-based interface, dose data are entered by technologists at the time of examination, and radiology reports are populated automatically. Conclusion: Dose data were successfully capt...

Purpose To present a generic geometric calibration method for tomographic imaging systems with flat‐panel detectors in a very detailed manner, in the aim to provide a useful tool to the public domain. Methods The method is based on a projection matrix which represents a mapping from 3D object coordinate system to 2D projection image plane. The pro...

Purpose: To demonstrate CT fetal dose reduction with the use of tube current modulation (TCM) on pregnant patients using retrospective data. Method and Materials:Monte Carlo(MC) simulation techniques are used to model CT scanners the TCM schemes and the pregnant patients. Two MDCT scanners GE LightSpeed Pro 16 and GE LightSpeed? 16 were modeled in...

Purpose: To present an initial performance evaluation of GE Discovery CT 750HD scanner in four imaging modes: Regular, Adaptive Statistical Iterative Reconstruction (ASIR), High Resolution (Hi?Res), and Gemstone Spectral Imaging (GSI) mode, in an effort to better understand the potential advantages of the scanner, including improved spatial resolut...