CT Facilities Research Articles

The impact of digital PET on radiation protection requirements in PET\\CT facilities

The impact of digital PET on radiation protection requirements in PET\\CT facilities

A retrospective survey to establish institutional diagnostic reference levels for CT urography examinations based on clinical indications: preliminary results.

Objective. To establish institutional diagnostic reference levels (IDRLs) based on clinical indications (CIs) for three- and four-phase computed tomography urography (CTU).Methods. Volumetric computed tomography dose index (CTDIvol), dose-length product (DLP), patients' demographics, selected CIs like lithiasis, cancer, and other diseases, and protocols' parameters were retrospectively recorded for 198 CTUs conducted on a Toshiba Aquilion Prime 80 scanner. Patients were categorised based on CIs and number of phases. These groups' 75th percentiles of CTDIvoland DLP were proposed as IDRLs. The mean, median and IDRLs were compared with previously published values.Results. For the three-phase protocol, the CTDIvol(mGy) and DLP (mGy.cm) were 22.7/992 for the whole group, 23.4/992 for lithiasis, 22.8/1037 for cancer, and 21.2/981 for other diseases. The corresponding CTDIvol(mGy) and DLP (mGy.cm) values for the four-phase protocol were 28.6/1172, 30.6/1203, 27.3/1077, and 28.7/1252, respectively. A significant difference was found in CTDIvoland DLP between the two protocols, among the phases of three-phase (except cancer) and four-phase protocols (except DLP for other diseases), and in DLP between the second and third phases (except for cancer group). The results are comparable or lower than most studies published in the last decade.Conclusions. The CT technologist must be aware of the critical dose dependence on the scan length and the applied exposure parameters for each phase, according to the patient's clinical background and the corresponding imaging anatomy, which must have been properly targeted by the competent radiologist. When clinically feasible, restricting the number of phases to three instead of four could remarkably reduce the patient's radiation dose. CI-based IDRLs will serve as a baseline for comparison with CTU practice in other hospitals and could contribute to national DRL establishment. The awareness and knowledge of dose levels during CTU will prompt optimisation strategies in CT facilities.

A voxel-by-voxel method for mixing two filaments during a 3D printing process for soft-tissue replication in an anthropomorphic breast phantom

Objective. In this study, a novel voxel-by-voxel mixing method is presented, according to which two filaments of different material are combined during the three dimensional (3D) printing process. Approach. In our approach, two types of filaments were used for the replication of soft-tissues, a polylactic acid (PLA) filament and a polypropylene (PP) filament. A custom-made software was used, while a series of breast patient CT scan images were directly associated to the 3D printing process. Each phantom´s layer was printed twice, once with the PLA filament and a second time with the PP filament. For each material, the filament extrusion rate was controlled voxel-by-voxel and was based on the Hounsfield units (HU) of the imported CT images. The phantom was scanned at clinical CT, breast tomosynthesis and micro CT facilities, as the major processing was performed on data from the CT. A side by side comparison between patient´s and phantom´s CT slices by means of profile and histogram comparison was accomplished. Further, in case of profile comparison, the Pearson´s coefficients were calculated. Main results. The visual assessment of the distribution of the glandular tissue in the CT slices of the printed breast anatomy showed high degree of radiological similarity to the corresponding patient´s glandular distribution. The profile plots´ comparison showed that the HU of the replicated and original patient soft tissues match adequately. In overall, the Pearson´s coefficients were above 0.91, suggesting a close match of the CT images of the phantom with those of the patient. The overall HU were close in terms of HU ranges. The HU mean, median and standard deviation of the original and the phantom CT slices were −149, −167, ±65 and −121, −130, ±91, respectively. Significance. The results suggest that the proposed methodology is appropriate for manufacturing of anthropomorphic soft tissue phantoms for x-ray imaging and dosimetry purposes, since it may offer an accurate replication of these tissues.

Characteristics, Quality, and Safety Issues Identified During Intersocietal Accreditation Commission (IAC) Assessment of Orthopaedic Facilities Utilizing Cone-Beam CT Equipment

Category: Other Introduction/Purpose: The Intersocietal Accreditation Commission (IAC) began accrediting diagnostic CT facilities in 2007. Recently there has been an increase in the number of outpatient orthopaedic facilities that use cone beam CT (CBCT) equipment seeking accreditation. The accreditation process comprehensively evaluates a facility's daily operation, with quality determined by compliance with the IAC Standards and Guidelines for CT Accreditation. The Standards represent the minimum requirements for staff qualifications, instrumentation, quality assurance, physicist safety surveys, scan procedures, radiation dose optimization, interpretative accuracy, reporting, and quality improvement that a facility must meet to earn accreditation. The Standards are based on the published guidelines of 12 sponsoring professional medical societies, representing various specialties. This investigation aimed to discover characteristics of these facilities and to identify common quality and safety issues. Methods: To become accredited, facilities applying for IAC CT accreditation submit facility demographic data, staff qualifications, policies and procedures, sample quality assurance results, physicist survey reports, radiation dose logs, quality improvement data, and representative case studies via an online application process. The materials are evaluated by trained peer reviewers and findings are reported to the IAC CT Board of Directors for final accreditation decision. The IAC accreditation database was used to extract the characteristics and application findings of all orthopaedic facilities using CBCT that applied for accreditation from 2019-2021. Results: Facility Characteristics Currently, 41 orthopaedic facilities have achieved IAC CT accreditation (see map). The facilities perform a median of 378 scans per site annually (range 75-2400). On average, there were 4 physicians (range 1-20) and 2 technologists (range 0-15) per site. Most sites (n = 32) used CurveBeam CBCT equipment followed by Carestream (n=5) and Planmed (n=4). Facility Deficiencies Identified quality issues included poor scan quality (n=4) such as improper patient positioning or excessive motion artifact and inadequate reporting (n=14) such as inaccurate patient identification information, incomplete exam/technique documentation, or non-compliant report finalization/signature. Identified procedural issues included failure to perform/document routine quality control (n=12) such as phantom testing to ensure the safety of CT scanner operation; missing safety policies such as the medical emergency policy or incomplete clinical scan protocols (n=5); and lack of quality improvement activities (n=5).Finally, facility personnel did not meet staff qualification requirements at 11 sites. Conclusion: In summary, the IAC CT accreditation process rigorously evaluates CT facilities to improve quality and safety. Evaluation of the accreditation findings for outpatient orthopaedic facilities utilizing CBCT equipment and seeking IAC accreditation identified deficiencies at many sites. All facilities were required to rectify the deficiencies prior to being awarded IAC accreditation, and they must continue to monitor quality and safety to remain accredited.

Patient dose in CT angiography examinations: An institutional survey

This study aims to evaluate the radiation dose during five computed tomography angiography (CTA) examinations performed with a GE Light Speed 16 (16-slice) and a Toshiba Aquilion Prime 80 (80-slice) CT system and to establish institutional DRLs (IDRLs). The volume computed tomography dose index (CTDIvol), dose length product (DLP) per examination, patients' demographic and anatomical data, and technical data were retrospectively recorded for 240 adult patients. The effective dose (ED) was calculated based on the recorded DLP values and suitable conversion coefficients. The 75th percentiles of the distribution of the CTDIvol and DLP values were proposed as IDRLs. The radiation dose values were compared to corresponding previously published international data. For the GE system, the IDRLs were 15.6 mGy and 1041 mGycm for thoracic aorta, 18.1 mGy and 1691 mGycm for abdomen aorta, and 12.1 mGy and 407 mGycm for pulmonary arteries, in terms of CTDIvol and DLP values, respectively. For the Toshiba system, the IDRLs were 34.9 mGy and 845 mGycm for the brain, 6.5 mGy and 280 mGycm for carotids, 5.3 mGy and 218 mGycm for thoracic aorta, 7.7 mGy and 425 mGycm for abdomen aorta, and 7.2 mGy and 196 mGycm for pulmonary arteries, in terms of CTDIvol and DLP values, respectively. The mean ED values were 12.6 mSv for thoracic aorta, 20.4 mSv for abdomen aorta, and 4.9 mSv for pulmonary arteries, as well as 1.7 mSv for the brain, 2.5 mSv for carotids, 2.6 mSv for thoracic aorta, 5.3 mSv for abdomen aorta, and 2.2 mSv for pulmonary arteries examinations, for the GE and Toshiba systems, respectively. A reduction of 48–64% and 55–79% was reported for the mean CTDIvol and DLP values obtained with the Toshiba compared to the GE system (Mann-Whitney test p < 0.0001), due to the implementation of dose-saving technologies, such as lowered tube voltage and iterative reconstruction algorithm. The Toshiba system's IDRLs and ED values were comparable or lower than those reported in most of the previously published studies. There are significant variations in patient doses during CTA examinations, due to the CT systems' differences, scanning parameters and departmental CTA protocols utilised. Patient dose surveys could highlight the necessity of increasing the awareness and knowledge of the radiation dose levels during CTA examinations, to prompt dose optimisation strategies in CT facilities.

Variability of redundant scan coverages along the Z-axis and dose implications for common computed tomography examinations

BackgroundScan length optimization is a method of optimization which ensures that, imaging is performed to cover just the area of interest without unnecessarily exposing structures that would not add value to answer a given clinical question. PurposeThis study assessed the variability and degree of redundant scan coverages along the z-axis of CT examinations of common indications and the associated radiation dose implications in CT facilities in Ghana for optimization measures to be recommended. MethodsOn reconstructed acquired CT images, the study measured extra distances covered above and below anatomical targets for common indications with calibrated calipers across 25 CT facilities. The National Cancer Institute Dosimetry System for CT (NCICT) (Monte Carlo-based-software) was used to simulate the scanning situations and organ dose implications for scans with and without the inclusion of the redundant scan areas. ResultsA total of 1,640 patients’ CT data sets were used in this study. The results demonstrated that CT imaging utilized varying scan lengths (16.45±21.0–45.99±4.3 cm), and 70.6% of the scans exceeded their pre-defined anatomic boundaries by a mean range of 2.86±1.07–5.81±1.66 cm, thereby resulting in extra patient radiation dose. Hence, scanning without the redundant coverages could generate a dose length product (DLP) reduction of 17.5%, 18.8%, 15.5% and 9.0% without degrading image quality for brain lesion, lung lesion, pulmonary embolism and abdominopelvic lesion CT imaging, respectively, whilst ensuring organ dose reduction of0.8%–79.1%. ConclusionThe study strongly recommends that radiographers should avoid the inclusion of redundant areas in CT examinations to reduce organ doses.

U.S. Diagnostic Reference Levels and Achievable Doses for 10 Pediatric CT Examinations.

Background Diagnostic reference levels (DRLs) and achievable doses (ADs) were developed for the 10 most commonly performed pediatric CT examinations in the United States using the American College of Radiology Dose Index Registry. Purpose To develop robust, current, national DRLs and ADs for the 10 most commonly performed pediatric CT examinations as a function of patient age and size. Materials and Methods Data on 10 pediatric (ie, patients aged 18 years and younger) CT examinations performed between 2016 and 2020 at 1625 facilities were analyzed. For head and neck examinations, dose indexes were analyzed based on patient age; for body examinations, dose indexes were analyzed for patient age and effective diameter. Data from 1 543 535 examinations provided medians for AD and 75th percentiles for DRLs for volume CT dose index (CTDIvol), dose-length product (DLP), and size-specific dose estimate (SSDE). Results Of all facilities analyzed, 66% of the facilities (1068 of 1625) were community hospitals, 16% (264 of 1625) were freestanding centers, 9.5% (154 of 1625) were academic facilities, and 3.5% (57 of 1625) were dedicated children's hospitals. Fifty-two percent of the patients (798 577 of 1 543 535) were boys, and 48% (744 958 of 1 543 535) were girls. The median age of patients was 14 years (boys, 13 years; girls, 15 years). The head was the most frequent anatomy examined with CT (876 655 of 1 543 535 examinations [57%]). For head without contrast material CT examinations, the age-based CTDIvol AD ranged from 19 to 46 mGy, and DRL ranged from 23 to 55 mGy, with both AD and DRL increasing with age. For body examinations, DRLs and ADs for size-based CTDIvol, SSDE, and DLP increased consistently with the patient's effective diameter. Conclusion Diagnostic reference levels and achievable doses as a function of patient age and effective diameter were developed for the 10 most commonly performed CT pediatric examinations using American College of Radiology Dose Index Registry data. These benchmarks can guide CT facilities in adjusting pediatric CT protocols and resultant doses for their patients. © RSNA, 2021 An earlier incorrect version appeared online. This article was corrected on October 29, 2021.

PRACTICAL CHALLENGES WITH IMAGING COVID-19 IN BRAZIL: MITIGATION IN AND BEYOND THE PANDEMIC.

Computed tomography (CT) provides useful information in patients with known or suspected COVID-19 infection. However, there are substantial variations and challenges in scanner technologies and scan practices that have negative effect on the image quality and can increase radiation dose associated with CT. Objective: In this article, we present major issues and challenges with use of CT at five Brazilian CT facilities for imaging patients with known or suspected COVID-19 infection and offer specific mitigating strategies. Methods: Observational, retrospective and prospective study of five CT facilities from different states and regions of Brazil, with approval of research and ethics committees. Results: The most important issues include frequent use of CT, lack of up-to-date and efficient scanner technologies, over-scanning and patient off-centring. Mitigating strategies can include updating scanner technology and improving scan practices.

Investigating centering, scan length, and arm position impact on radiation dose across 4 countries from 4 continents during pandemic: Mitigating key radioprotection issues.

PurposeOptimization of CT scan practices can help achieve and maintain optimal radiation protection. The aim was to assess centering, scan length, and positioning of patients undergoing chest CT for suspected or known COVID-19 pneumonia and to investigate their effect on associated radiation doses.MethodsWith respective approvals from institutional review boards, we compiled CT imaging and radiation dose data from four hospitals belonging to four countries (Brazil, Iran, Italy, and USA) on 400 adult patients who underwent chest CT for suspected or known COVID-19 pneumonia between April 2020 and August 2020. We recorded patient demographics and volume CT dose index (CTDIvol) and dose length product (DLP). From thin-section CT images of each patient, we estimated the scan length and recorded the first and last vertebral bodies at the scan start and end locations. Patient mis-centering and arm position were recorded. Data were analyzed with analysis of variance (ANOVA).ResultsThe extent and frequency of patient mis-centering did not differ across the four CT facilities (>0.09). The frequency of patients scanned with arms by their side (11–40% relative to those with arms up) had greater mis-centering and higher CTDIvol and DLP at 2/4 facilities (p = 0.027–0.05). Despite lack of variations in effective diameters (p = 0.14), there were significantly variations in scan lengths, CTDIvol and DLP across the four facilities (p < 0.001).ConclusionsMis-centering, over-scanning, and arms by the side are frequent issues with use of chest CT in COVID-19 pneumonia and are associated with higher radiation doses.

Lung Cancer Screening by Low-Dose Computed Tomography: Part 2 - Key Elements for Programmatic Implementation of Lung Cancer Screening.

For screening with low-dose CT (LDCT) to be effective, the benefits must outweigh the potential risks. In large lung cancer screening studies, a mortality reduction of approx. 20 % has been reported, which requires several organizational elements to be achieved in practice. The elements to be set up are an effective invitation strategy, uniform and quality-assured assessment criteria, and computer-assisted evaluation tools resulting in a nodule management algorithm to assign each nodule the needed workup intensity. For patients with confirmed lung cancer, immediate counseling and guideline-compliant treatment in tightly integrated regional expert centers with expert skills are required. First, pulmonology contacts as well as CT facilities should be available in the participant's neighborhood. IT infrastructure, linkage to clinical cancer registries, quality management as well as epidemiologic surveillance are also required. An effective organization of screening will result in an articulated structure of both widely distributed pulmonology offices as the participants' primary contacts and CT facilities as well as central expert facilities for supervision of screening activities, individual clarification of suspicious findings, and treatment of proven cancer. In order to ensure that the benefits of screening more than outweigh the potential harms and that it will be accepted by the public, a tightly organized structure is needed to ensure wide availability of pulmonologists as first contacts and CT facilities with expert skills and high-level equipment concentrated in central facilities. · For lung cancer screening, elements must function optimally and be tightly organized.. · Lung cancer screening requires a network of expert centers and collaborating facilities.. · IT infrastructure, QM, epidemiological surveillance, and linkage to cancer registries are essential.. · Delorme S, Kaaks R: Lung Cancer Screening by Low-Dose Computed Tomography: Part 2 - Key Elements for Programmatic Implementation of Lung Cancer Screening. Fortschr Röntgenstr 2021; 193: 644 - 651.

Shielding assessment in two computed tomography facilities in South-South Nigeria: How safe are the personnel and general public from ionizing radiation?

Objective: The aims of this study were to estimate the instantaneous dose rate(IDR) and annual dose rate (ADR) to radiation staff and the general public withinthe controlled and supervised areas, respectively, to determine the shieldingdesign goals (P) of the 2 CT facilities and to determine the average annual dose(AD) to radiographer/operator in the control console during CT scans. Materials and Methods: The equipment used in this study consisted of twonewly installed General Electric (GE) Revolution ACTs CT machines. Technicalparameters used were a thoracic/dorsal spine scan, which was rarely done in both facilities. A calibrated Inspector USB (S.E. International, Inc.) survey meter was positioned &lt; 50 cm from each barrier at various points to determine the average shielded air kerma Results: The average background radiation in the 2 facilities was 0.11 ?Sv/hr. The average ADR to the controlled and supervised areas in CT1 was 0.563±0.25 and 0.369±0.11 mSv/yr, respectively. Also, the average ADR to the controlled and supervised areas in CT2 were 0.410±0.28 and 0.354±0.04 mSv/yr, respectively. The average shielding design goal to the controlled and supervised areas for CT1 was 0.00898±0.0041 and 0.0059±0.0028 mSv/Week, respectively. Similarly, the average shielding design goal for the controlled and supervised areas for CT2 was 0.0066±0.0044 and 0.0057±0.0019 mSv/Week respectively. The estimated average AD to the operator in CT1 and CT2 was 2.5 and 1.3 ?Sv, respectively. Conclusion: The average ADR and shielding design goals in the controlled and supervised areas from both CTs were within acceptable limits for radiation staff and the public.

Shielding assessment in two computed tomography facilities in South-South Nigeria: How safe are the personnel and general public from ionizing radiation?

Objective: The aims of this study were to estimate the instantaneous dose rate(IDR) and annual dose rate (ADR) to radiation staff and the general public withinthe controlled and supervised areas, respectively, to determine the shieldingdesign goals (P) of the 2 CT facilities and to determine the average annual dose(AD) to radiographer/operator in the control console during CT scans. Materials and Methods: The equipment used in this study consisted of twonewly installed General Electric (GE) Revolution ACTs CT machines. Technicalparameters used were a thoracic/dorsal spine scan, which was rarely done in both facilities. A calibrated Inspector USB (S.E. International, Inc.) survey meter was positioned &lt; 50 cm from each barrier at various points to determine the average shielded air kerma Results: The average background radiation in the 2 facilities was 0.11 ?Sv/hr. The average ADR to the controlled and supervised areas in CT1 was 0.563±0.25 and 0.369±0.11 mSv/yr, respectively. Also, the average ADR to the controlled and supervised areas in CT2 were 0.410±0.28 and 0.354±0.04 mSv/yr, respectively. The average shielding design goal to the controlled and supervised areas for CT1 was 0.00898±0.0041 and 0.0059±0.0028 mSv/Week, respectively. Similarly, the average shielding design goal for the controlled and supervised areas for CT2 was 0.0066±0.0044 and 0.0057±0.0019 mSv/Week respectively. The estimated average AD to the operator in CT1 and CT2 was 2.5 and 1.3 ?Sv, respectively. Conclusion: The average ADR and shielding design goals in the controlled and supervised areas from both CTs were within acceptable limits for radiation staff and the public.

Development of a low-cost imaging performance evaluation phantom for a generic multi-detector CT scanner

For quality assurance, an evaluation phantom is an important tool used to assess the imaging performance of a multi-detector CT (MDCT) scanner. In doing so, this would help to prevent the production of low-quality images that may lead to misdiagnosis and repeats of x-ray exposure. However, imaging performance test phantoms available commercially are too costly for resource-limited CT facilities to procure. This study aims to design an imaging performance evaluation phantom, fabricate a low-cost prototype of the design, and assess the suitability of use of the fabricated phantom under existing performance testing protocols. The phantom was designed according to recommended specifications from IAEA and AAPM and the prototype of the design was manufactured using engineering plastics and industrial metals through computer numerical controlled (CNC) machining and stereolithography (SLA) 3D printing. The fabricated phantom prototype was then tested with United Imaging 80-slice MDCT scanner and its usability was compared to Gammex ACR 464 phantom following the ACR QC assessment methods. This research was able to produce a three-module solid plastic phantom with a performance at par with the commercial phantom. Furthermore, the overall manufacturing cost for the fabrication of the phantom was 87% cheaper than the cost of acquiring a commercial phantom. Thus, local development of a quality assurance phantom for CT is a cost-effective solution for resource-limited facilities.

A Geospatial Analysis of Factors Affecting Access to CT Facilities: Implications for Lung Cancer Screening

ObjectiveThe association between access to CT facilities for lung cancer screening and population characteristics is understudied. We aimed to determine the relationship between census tract–level socioeconomic characteristics (SEC) and driving distance to an ACR-accredited CT facility. MethodsCensus tract–level SEC were determined from the US Census Bureau. Distance to nearest ACR-accredited CT facility was derived at the census tract level. Census tract–level multivariable regression modeling was used to determine the relationship between driving distance to a CT facility and census tract SEC, including population density (a marker of rural versus urban), gender, race, insurance status or type, and education level. ResultsIn an adjusted multivariable model, census tract–level population density was the greatest relative determinant of distance to a CT facility. Namely, rural census tracts had relatively longer distances to CT facilities than urban census tracts (P < .001). Census tracts with higher uninsured, Medicaid, undereducated (less <high school degree) populations had relatively greater distances to CT facilities (p<0.001), whereas those with higher non-White, female, and Medicare populations had shorter distances (p<0.001). DiscussionRural populations have relatively less geographic access to CT facilities. Furthermore, other vulnerable populations, such as the uninsured, those on Medicaid, and the undereducated, may also have relatively less access to CT imaging facilities. These variations in access to CT may affect the uptake and utilization of lung cancer screening.

Geographic Access to CT for Lung Cancer Screening: A Census Tract-Level Analysis of Cigarette Smoking in the United States and Driving Distance to a CT Facility

PurposeSpatial access to health care resources is a requisite for utilization. Our purpose was to determine, at a census tract level, the geographic distribution of US smokers and their driving distance to an ACR-accredited CT facility. MethodsThe number of smokers per US census tract was determined from US Census Bureau data (American Community Survey, 2011-2015) and census tract smoking prevalence estimates. Driving distance, from the centroid of each census tract to the nearest CT facility, was determined using a geographic information system. Distance variations were assessed, and relationships with tract population density were examined with regression models. ResultsMost US smokers (81.8%) were within 15 miles of a CT facility; however, there was considerable inter- and intrastate variability. For census tracts containing ≥500 smokers, median distance to a CT was 4.3 miles. At the state level, median distance ranged from 1.4 (Washington DC) to 29.1 miles (Wyoming). Within each state, this variation was higher, with Washington, DC, exhibiting the lowest range (range, 4.3; 0.2-4.5 miles) and Maine exhibiting the highest range (range, 244.8; 0.2-245.0 miles). Distance to a CT facility was inversely associated with census tract population density. ConclusionsGeographic variability in CT facility access has implications for lung cancer screening (LCS) implementation. Individuals in densely populated areas have relatively greater spatial access to CT facilities than those in sparsely populated tracts. Further work is needed to identify access disparities to LCS to optimize LCS for all eligible populations.

Improving patient care and outcomes: Standardisation of resuscitation training and equipment provision for health care providers

Background: The Resuscitation Council UK recommends standardisation of equipment used for CPR, throughout an entire organisation. It is recognised that NHS collaboration with the private health care sector occurs more frequently in the UK in this current health care environment. This audit aimed to assess the provision of current resuscitation equipment of privately owned static and mobile medical imaging MRI, PET and CT facilities provided by Alliance healthcare to NHS patients.

DIAGNOSTIC REFERENCE LEVELS FOR CARDIAC CT ANGIOGRAPHY IN AUSTRALIA.

This study aims to assess patient radiation dose from cardiac computed tomography angiography (CCTA) with the aim of proposing a national diagnostic reference levels (NDRLs) for CCTA procedures in Australia. A questionnaire was used to retrospectively gather baseline information related to CCTA scanning and patient parameters in CT centres across the country. The 75th percentile of both volumetric CT dose index (CTDIvol) and dose length-product (DLP) was used as DRL values for CCTA. A DRL for CT calcium scoring test was also determined. NDRLs were compared with international published data. Data sets of 338 patients from nine CT centres were used for analysis. The CCTA DRL for the CTDIvol and the DLP were 22 mGy and 268 mGy cm, respectively. The CT calcium scoring test DRL for DLP was 137 mGy cm. The DRL values for CCTA in Australia have been recommended for the first time. DRLs are lower than those in most published studies due to the implementation of dose-saving technologies such as prospective ECG-gated mode and iterative reconstruction algorithms. Considerable variations remain in patient doses between hospitals for the most frequently used CCTA protocols, indicating the potential for DRLs to prompt dose optimisation strategies in CT facilities.

Current CT practice in Germany: Results and implications of a nationwide survey

PurposeTo assess patient doses and relative frequencies of standard CT examinations performed in Germany in 2013/14 as well as the effect of modern CT technology on patient exposure. MethodsAll known CT facilities in Germany were requested to complete a questionnaire on the frequency of 34 examinations and the respective parameter settings used. Taking into account type-specific properties of each scanner, effective doses were estimated for each reported examination. The mean and the percentiles of the CT dose index, scan length, dose length product, and effective dose were determined for each type of examination. ResultsAccording to the data provided for about 11% of all medical CT scanners operated in 2013/14, the effective dose was 4.6/5.9mSv per scan/examination. The effective dose was significantly reduced by about 15% compared to the CT practice before 2010. Modern CT technology, such as tube current modulation and iterative image reconstruction reduced the effective dose significantly by 6% and 13%, respectively. The mean effective dose applied at scanners produced by different manufacturers differed by 25%, at maximum. ConclusionPatient exposure was reduced substantially in recent years. There is, however, still a considerable potential for further dose reduction by adapting scan protocols to the medical purpose and by a consequent exploitation of modern CT technologies.

Lung Cancer Screening Practices in North Carolina CT Facilities

BackgroundThe burden of lung cancer in the United States is staggering, with more Americans dying from lung cancer than the next four most common cancers combined. With endorsement of lung cancer screening by the United States Preventive Services Task Force and reimbursement by CMS, the number screened for lung cancer with low-dose CT (LDCT) is anticipated to rise in the near future. MethodsIn 2015, we conducted a cross-sectional study of mailed surveys to 112 ACR CT facilities across North Carolina to examine recommended guidelines for lung cancer screening, referral patterns, and patient tracking methods. We describe the survey results and compare findings with surveys of academic medical centers. ResultsAmong 48 respondents (response rate = 42.9%), 54.2% offer lung cancer screening with LDCT (93.1% community and 6.9% academic settings); of these, 70.8% use ACR/CMS guidelines. In lung cancer screening facilities, reported patient volumes are low (average eight patients screened per month, range: 0-30) and patient tracking occurs in 72% of facilities. ConclusionsAmong our predominately community-based sample of facilities, we found variation in lung cancer screening guideline usage, number of patients screened, and tracking methods.

Poster — Thur Eve — 02: Measurement of CT radiation profile width using Fuji CR imaging plate raw data

Measuring the CT collimation width and assessing the shape of the overall profile is a relatively straightforward quality control (QC) measure that impacts both image quality and patient dose, and is often required at acceptance and routine testing. Most CT facilities have access to computed radiography (CR) systems, so performing CT collimation profile assessments using CR plates requires no additional equipment. Previous studies have shown how to effectively use CR plates to measure the radiation profile width. However, a major limitation of the previous work is that the full dynamic range of CR detector plates are not used, since the CR processing technology reduces the dynamic range of the DICOM output to 210, requiring the sensitivity and latitude settings of CR reader to be adjusted to prevent clipping of the CT profile data. Such adjustments to CR readers unnecessarily complicate the QC procedure. These clipping artefacts hinder the ability to accurately assess CT collimation width because the full‐width at half maximum value of the penumbras are not properly determined if the maximum dose of the profile is not available. Furthermore, any inconsistencies in the radiation profile shape are lost if the profile plateau is clipped off. In this work we developed an opensource Matlab script for straightforward CT profile width measurements using raw CR data that also allows assessment of the profile shape without clipping, and applied this approach during CT QC.