Digital mammography screening with photon-counting technique: can a high diagnostic performance be realized at low mean glandular dose?

PURPOSE: To assess screening performance of a direct radiography (DR) photon-counting system versus statewide screening units with different digital technologies. MATERIALS AND METHODS: The local ethics board approved retrospective study of prospectively acquired data from the North Rhine-Westphalian mammography screening program (2009-2010). Informed consent was waived. Examinations in 13 312 women with a DR photon-counting system and statewide digital screening examinations in 993 822 women were included (37 computed radiography mammography systems and 55 DR systems). Diagnostic performance was assessed with cancer detection rate, recall rate, and proportion of small invasive cancers and ductal carcinoma in situ (DCIS). Mean glandular dose was calculated for DR photon counting and for a conventional DR subgroup. Differences were tested with χ(2) and t tests (P < .05). RESULTS: The cancer detection rate for subsequent screenings was higher for DR photon counting than statewide rates (0.76% [67 of 8842] vs 0.59% [3108 of 527 194], P = .05) at a higher recall rate (5.4% [475 of 8842] vs 3.3% [17 656 of 527 194], P = .001). Detection of invasive cancers up to 10 mm for DR photon counting was high for initial (40% [14 of 35]) and subsequent (42% [19 of 45]) screenings but not significantly different from statewide rates (initial, 31.6% [942 of 2979], P = .50; subsequent, 32.5% [765 of 2353], P = .25). The DCIS subsequent screening rate was higher for DR photon counting than statewide screening (0.23% [20 of 8842] vs 0.12% [616 of 527 194], P = .01) and the conventional DR subgroup (0.23% [20 of 8842] vs 0.12% [65 of 52 813], P = .025). Mean glandular dose for DR photon counting was significantly lower than that for conventional DR (0.60 mGy ± 0.20 vs 1.67 mGy ± 0.47 [craniocaudal views], 0.64 mGy ± 0.23 vs 1.79 mGy ± 0.53 [mediolateral oblique views], both P = .0001). CONCLUSION: Digital mammography screening with dose-efficient photon counting enables desirable detection rates of small invasive cancers and DCIS. Higher detection rates compared with statewide performance occurred with subsequent screening but had higher recall rates.

Pediatric computed tomography doses in Germany from 2016 to 2018 based on large-scale data collection.

PURPOSE: Accumulating evidence from epidemiological studies that pediatric computed tomography (CT) examinations can be associated with a small but non-zero excess risk for developing leukemia or brain tumor highlights the need to optimize doses of pediatric CT procedures. Mandatory dose reference levels (DRL) can support reduction of collective dose from CT imaging. Regular surveys of applied dose-related parameters are instrumental to decide when technological advances and optimized protocol design allow lower doses without sacrificing image quality. Our aim was to collect dosimetric data to support adapting current DRL to changing clinical practice. METHOD: Dosimetric data and technical scan parameters from common pediatric CT examinations were retrospectively collected directly from Picture Archiving and Communication Systems (PACS), Dose Management Systems (DMS), and Radiological Information Systems (RIS). RESULTS: We collected data from 17 institutions on 7746 CT series from the years 2016 to 2018 from examinations of the head, thorax, abdomen, cervical spine, temporal bone, paranasal sinuses and knee in patients below 18 years of age. Most of the age-stratified parameter distributions were lower than distributions from previously-analyzed data from before 2010. Most of the third quartiles were lower than German DRL at the time of the survey. CONCLUSIONS: Directly interfacing PACS, DMS, and RIS installations allows large-scale data collection but relies on high data-quality at the documentation stage. Data should be validated by expert knowledge or guided questionnaires. Observed clinical practice in pediatric CT imaging suggests lowering some DRL in Germany is reasonable.

Prenatal radiation exposure in diagnostic and interventional radiology. / Pränatale Strahlenexposition in der diagnostischen und interventionellen Radiologie.

BACKGROUND: The exposure of a pregnant woman to X-rays is an event that can cause uncertainty for all concerned. This review provides guidance on how to assess such a situation and how to determine the dose to the unborn child. In general, the use of X-rays in pregnant women in radiology should be avoided. If possible, alternatives should be used, or examinations postponed to a time after the pregnancy. This review gives a summary of the procedure for determining the radiation exposure of a pregnant woman. METHOD: Based on the previous report of 2002 and the literature on prenatal radiation exposure published thereafter, the DGMP/DRG report on the procedure for the assessment of prenatal radiation exposure was adapted to the current state of science and technology. RESULTS: Typically, only relatively low radiation exposures of less than 20 mSv occur for the unborn child in X-ray diagnostics in the vast majority of cases. At these dose level the additional risk of damage to the embryo or fetus caused by the radiation is low and therefore only a rough conservative estimate using tabulated values are made. Only in a few types of examination (CT and interventional radiology) higher doses values might occur in the uterus. Instead of dose estimates (step 1 in the two-step model) in these cases the calculation of dose (step 2) are required and further action by the physician may be necessary. CONCLUSIONS: During the assessment, it is useful to initially use simple conservative estimation procedures to quickly determine whether a case falls into this large group less than 20 mSv, where there is a very low risk to the unborn child. If this is the case, the pregnant woman should be informed immediately by the doctor who performed the examination/treatment. This avoids a psychological burden on the patient. The DGMP/DRG report suggests a relatively simple, clearly structured procedure with advantages for all parties involved (physician, medical physics experts, MTRA and patient). KEY POINTS: · The DGMP/DRG report on prenatal radiation exposure describes the procedure for calculating radiation exposures and the associated risks for the unborn child.. · Using the two-step model, only a simple assessment based on the first step is necessary for most prenatal radiation exposures.. · With the given tables it is possible to estimate individual risks for the unborn child taking into account the radiation exposure.. · Only in the rare case that the first estimate results in a uterine dose larger 20 mSv a more accurate calculation is necessary.. CITATION FORMAT: · Fiebich M, Block A, Borowski M et al. Prenatal radiation exposure in diagnostic and interventional radiology. Fortschr Röntgenstr 2021; 193: 778 - 786.

Evaluation of the New DIN Standard for Quality Assurance of Diagnostic Displays - Technical Review DIN 6868-157.

Acceptance and regular constancy tests are necessary to ensure the quality of diagnostic displays. In November 2014, a new standard (DIN 6868-157) was published which defines the test procedure and limiting values. There are several substantial changes compared with the previous standard DIN V 6868-57, i. e. considering the complete image display system including workstation and application software instead of only the displays. Since its publication, the new standard has raised many questions. This technical review aims to show the strengths and weaknesses of the new standard. Positive aspects are the introduction of a limiting value for the illuminance and the extension of the interval for constancy tests from 3 to 6 six months. The daily constancy test on the other hand, raises several problems and should be replaced by a randomized test. Additionally, the medical relevance is critically questioned and an overview of software for the quality assurance will be given. KEY POINTS: · Acceptance and constancy tests for diagnostic displays are defined in DIN 6868-157.. · The new standards has positive and negative aspects.. · Randomized tests should be introduced.. CITATION FORMAT: · Entz K, Sommer A, Lenzen H. DIN 6868-157: Image Quality Assurance in Diagnostic X-ray Departments - X-ray Ordinance Acceptance and Constancy Test of Image Display Systems in their Environment - Technical Review -. Fortschr Röntgenstr 2018; 190: 51 - 60.

Digital breast tomosynthesis plus synthesised images versus standard full-field digital mammography in population-based screening (TOSYMA): protocol of a randomised controlled trial.

INTRODUCTION: Development of digital breast tomosynthesis (DBT) provides a technology that generates three-dimensional data sets, thus reducing the pitfalls of overlapping breast tissue. Observational studies suggest that the combination of two-dimensional (2D) digital mammography and DBT increases diagnostic accuracy. However, because of duplicate exposure, this comes at the cost of an augmented radiation dose. This undesired adverse impact can be avoided by using synthesised 2D images reconstructed from the DBT data (s2D).We designed a diagnostic superiority trial on a high level of evidence with the aim of providing a comparison of screening efficacy parameters resulting from DBT+s2D versus the current screening standard 2D full-field digital mammography (FFDM) in a multicentre and multivendor setting on the basis of the quality-controlled, population-based, biennial mammography screening programme in Germany. METHODS AND ANALYSIS: 80 000 women in the eligible age 50-69 years attending the routine mammography screening programme and willing to participate in the TOSYMA trial will be assigned by 1:1 randomisation to either the intervention arm (DBT+s2D) or the control arm (FFDM) during a 12-month recruitment period in screening units of North Rhine-Westphalia and Lower Saxony. State cancer registries will provide the follow-up of interval cancers.Primary endpoints are the detection rate of invasive breast cancers at screening examination and the cumulative incidence of interval cancers in the 2 years after a negative examination. Secondary endpoints are the detection rate of ductal carcinoma in situ and of tumour size T1, the recall rate for assessment, the positive predictive value of recall and the cumulative 12-month incidence of interval cancers. An adaptive statistical design with one interim analysis provides the option to modify the design. ETHICS AND DISSEMINATION: This protocol has been approved by the local medical ethical committee (2016-132-f-S). Results will be submitted to international peer-reviewed journals. TRIAL REGISTRATION: NCT03377036; Pre-results.

Portable flat-panel detector for low-dose imaging in a pediatric intensive care unit: comparison with an asymmetric film-screen system.

OBJECTIVE: We sought to evaluate the diagnostic performance of a portable indirect flat-panel detector for low-dose imaging as compared with an asymmetric film-screen system in a pediatric intensive care unit. MATERIALS AND METHODS: A total of 120 neonates underwent chest radiographs using a portable flat-panel detector (digital speed 800) and an asymmetric film-screen system (400 speed). Four readers evaluated the detection of 11 anatomic and 5 pathologic landmarks and 4 support devices. Statistical analysis was performed using repeated analysis of variance. The level of statistical significance was P = 0.05. RESULTS: The detection of 4 anatomic/4 pathologic landmarks and 2 support devices was significantly better using the flat-panel detector as compared with the asymmetric film-screen system (P < 0.05). Another 8 anatomic and one pathologic landmarks were detected equally well or slightly better with the flat-panel detector (P > 0.05). CONCLUSIONS: The portable flat-panel detector offers the potential of a 50% dose reduction with equal or significantly better detection of clinically important structures.

Diagnostic performance of a flat-panel detector at low tube voltage in chest radiography: a phantom study.

RATIONALE AND OBJECTIVES: To evaluate a large area, cesium iodide amorphous silicon flat-panel detector (CsI/a-Si) at 3 tube voltages to detect simulated interstitial lung disease, nodules, and catheters. METHODS: Simulated interstitial lung disease, nodules, and catheters were superimposed over a chest phantom. Images were generated at 125 kVp, 90 kVp, and 70 kVp at the same surface dose and reduced effective dose equivalent for 90 kVp and 70 kVp and printed on hard copies. Fifty-four thousand observations were analyzed by receiver operating characteristic (ROC). RESULTS: Detectability of linear, miliary, reticular pattern, and nodules over lucent lung as well as of catheters and nodules over obscured chest areas increased at 90 and/or 70 kVp with higher Az values; however, only it was statistically significant for reticular pattern at 70 kVp and nodules at 90 kVp compared with 125 kVp (P < 0.05). The detection of ground-glass pattern was worse at lower kVp (P > 0.05). CONCLUSION: For most simulated patterns, differences in diagnostic performance at 70 kVp/90 kVp and 125 kVp were not significant, except for reticular pattern and nodules over lucent lung.

Experimental evaluation of a portable indirect flat-panel detector for the pediatric chest: comparison with storage phosphor radiography at different exposures by using a chest phantom.

PURPOSE: To compare the exposure dose requirements and performance of a portable indirect flat-panel detector for pediatric use in the depiction of catheters, simulated pulmonary nodules, and simulated interstitial lung disease with those of storage phosphor radiography. MATERIALS AND METHODS: Catheters and simulated nodules and subtle interstitial lung disease (miliary, reticular, linear, and ground-glass patterns) were superimposed over an anthropomorphic chest phantom. Images were obtained with different exposures corresponding to simulated speeds of 400 and 800 with a portable flat-panel detector and printed on hard copies. These images were compared with those from storage phosphor radiography at a simulated speed of 400, which is typically used in pediatric radiology. Four independent readers recorded 7200 observations per pattern (for a total of 600 statistically independent observations), and these observations were subjected to receiver operating characteristic (ROC) analysis. Differences were considered significant at a P value of .05. RESULTS: Catheters over obscured chest areas, nodules 10 mm or smaller and larger than 10 mm over lucent lung, nodules 10 mm or smaller over obscured chest areas, and miliary and linear patterns over lucent lung showed higher areas under the ROC curve (A(z)) with the flat-panel detector at 400 and 800 digital speed compared with storage phosphor radiography. A(z) values for reticular and ground-glass patterns with the flat-panel detector were equal to or less than those with storage phosphor radiography. These differences, however, were not statistically significant. CONCLUSION: In the detection of catheters, nodules, and almost all interstitial lung disease, A(z) values were higher with the portable flat-panel detector than with storage phosphor radiography at equivalent and reduced speeds. These results suggest that the portable flat-panel detector could be used with reduced exposure dose in pediatric patients.

Screening for early lung cancer with low-dose spiral CT: prevalence in 817 asymptomatic smokers.

PURPOSE: To present prevalence screening data from a nonrandomized screening trial by using low-dose computed tomography (CT) and a simple algorithm based on the size and attenuation of detected nodules to guide diagnostic work-up. MATERIALS AND METHODS: Eight hundred seventeen asymptomatic volunteers (age range, 40-78 years; median age, 53 years; median tobacco consumption, 45 pack-years) underwent spiral low-dose CT of the chest without contrast material enhancement. We regarded all noncalcified pulmonary nodules greater than 10 mm in diameter as potentially malignant and recommended histologic examination or follow-up after 3, 6, 12, and 24 months to exclude growth. For noncalcified pulmonary nodules of 10 mm or smaller, repeat low-dose CT was recommended to exclude growth. RESULTS: In 43% (350 of 817) of individuals, 858 noncalcified pulmonary nodules were found. Thirty-two nodules in 29 subjects were larger than 10 mm. Biopsy of 15 lesions revealed lung cancer in 12 lesions in 11 subjects (prevalence for all ages, 1.3% [11 of 817 subjects]; >50 years of age, 2.1% [11 of 519 subjects]; >60 years of age, 3.9% [eight of 206 subjects]), with a high proportion of early tumor stages (seven tumors, stage I; two, stage II; and three, stage III); three lesions were benign. In 17 nodules larger than 10 mm, follow-up with low-dose CT for a minimum of 24 months did not demonstrate growth. CONCLUSION: Lung cancer screening with low-dose CT demonstrated a prevalence of asymptomatic cancers in 1.3% of a smoking population, including a high proportion of early tumor stages and a 20% (three of 15) rate of invasive procedures for benign lesions.

Detection of subtle undisplaced rib fractures in a porcine model: radiation dose requirement--digital flat-panel versus screen-film and storage-phosphor systems.

PURPOSE: To compare a large-area direct read-out flat-panel detector radiography system with screen-film and storage-phosphor systems with regard to detection of subtle undisplaced rib fractures and to assess the diagnostic performance of the flat-panel system with decreasing exposure level. MATERIALS AND METHODS: Subtle fractures were created artificially in 100 of 200 porcine rib specimens. Specimens were enclosed in containers of water to generate absorption and scatter radiation conditions similar to those of a human chest wall. Imaging was performed with flat-panel, screen-film, and storage-phosphor systems with conditions that were exactly matched. Different exposure levels equivalent to speed classes (S) of 400, 800, 1,600, and 6,400 were used. All images were independently assessed for the presence of fracture by three radiologists with a five-level confidence scale. Receiver operating characteristic (ROC) analysis was performed for a total of 4,200 observations (600 for each imaging system and exposure level). Diagnostic performance was estimated with area under the ROC curve (Az). Significance of differences in diagnostic performance was tested with analysis of variance. RESULTS: ROC analysis yielded mean Az values for the flat-panel system of 0.879 (S = 400), 0.833 (S = 800), 0.765 (S = 1,600), and 0.576 (S = 6,400). Az values were 0.834 (S = 400) for the screen-film system and 0.789 (S = 400) and 0.729 (S = 800) for the storage-phosphor system. Analysis of variance revealed significant differences in diagnostic performance between various combinations of imaging system and exposure levels (P <.05). CONCLUSION: The flat-panel system is superior to the screen-film and storage-phosphor systems for detection of subtle undisplaced rib fractures at clinical exposure settings (eg, S = 400). With the flat-panel system, radiation dose can be reduced by 50% to achieve diagnostic performance comparable to that of a speed class 400 screen-film system.

Hazardous situation in the MR bore: induction in ECG leads causes fire.

There is a potential hazard during examinations of patients with attached or implanted long conductors, e.g. ECG leads: an MR exam of the lumbar spine of a patient was performed in a 1.5-T scanner under ECG monitoring using equipment marked as MR compatible. Standard cabling of 370-cm length was guided without loops from the electrodes through the caudal opening of the magnet bore. During a sagittal T1-weighted turbo-spin-echo scan suddenly a flame of approximately 3 cm arose from the patient's shirt, close to the position of the electrodes. The supervising anaesthesiologist extinguished the flames with his hands. A subsequent physical examination revealed second- to third-degree burns. The analysis of the incident revealed that high voltages can be induced in straight conductors without loops as ECG cables by coupling with the electric component of the HF field. Local heating or sparking can cause an open flame at the position of the electrodes. This danger exists even with ECG equipment that is specifically marked as MR compatible.

Screening for early lung cancer with low-dose spiral computed tomography: results of annual follow-up examinations in asymptomatic smokers.

The aim of this study was analysis of incidence results in a prospective one-arm feasibility study of lung cancer screening with low-radiation-dose spiral computed tomography in heavy smokers. Eight hundred seventeen smokers (> or =40 years, > or =20 pack years of smoking history) underwent baseline low-dose CT. Biopsy was recommended in nodules >10 mm with CT morphology suggesting malignancy. In all other lesions follow-up with low-dose CT was recommended. Annual repeat CT was offered to all study participants. Six hundred sixty-eight (81.8%) of the 817 subjects underwent annual repeat CT with a total of 1735 follow-up years. Follow-up of non-calcified nodules present at baseline CT demonstrated growth in 11 of 792 subjects. Biopsy was performed in 8 of 11 growing nodules 7 of which represented lung cancer. Of 174 new nodules, 3 represented lung cancer. The 10 screen-detected lung cancers were all non-small cell cancer (6 stage IA, 1 stage IB, 1 stage IIIA, 2 stage IV). Five symptom-diagnosed cancers (2 small cell lung cancer: 1 limited disease, 1 extensive disease, 3 central/endobronchial non-small cell lung cancer, 2 stage IIIA, 1 stage IIIB) were diagnosed because of symptoms in the 12-month interval between two annual CT scans. Incidence of lung cancer was lower than prevalence, screen-detected cancers were smaller, and stage I was found in 70% (7 of 10) of screen-detected tumors. Only 27% (4 of 15) of invasive procedures was performed for benign lesions; however, 33% (5 of 15) of all cancers diagnosed in the population were symptom-diagnosed cancers (3 central NSCLC, all stage III, 2 SCLC) demonstrating the limitations of CT screening.

Performance of a flat-panel detector in the detection of artificial erosive changes: comparison with conventional screen-film and storage-phosphor radiography.

The purpose of this study was to compare a large-area, direct-readout, flat-panel detector system with a conventional screen-film system, a storage-phosphor system, and a mammography screen-film system with regard to the detection of artificial bone erosions simulating rheumatoid disease, and to assess its diagnostic performance with decreasing exposure dose. Six hundred forty regions were defined in 160 metacarpophalangeal and proximal interphalangeal joint specimens from 20 monkey paws (4 regions per joint). Artificial bone erosions were created in 320 of these 640 regions. Specimens were enclosed in containers filled with water to obtain absorption and scatter radiation conditions similar to those of a human hand. Imaging was performed using a flat-panel system, a speed class 200 screen-film system, a mammography screen-film system, and a storage-phosphor system under exactly matched conditions. Different exposure doses equivalent to speed classes of S=100, 200, 400, 800, 1600, and 3200 were used. In all images the presence or absence of a lesion was assessed by three radiologists using a five-level confidence scale. Receiver operating characteristic (ROC) analysis was performed for a total of 21,120 observations (1920 for each imaging modality and exposure level) and diagnostic performance estimated by the area under the ROC curve (A(z)). The significance of differences in diagnostic performance was tested with analysis of variance. The ROC analysis showed A(z) values of 0.809 (S=200), 0.768 (S=400), 0.737 (S=800), 0.710 (S=1600), and 0.685 (S=3200) for the flat-panel system, 0.770 for the speed class 200 screen-film system, 0.781 (S=200), 0.739 (S=400), 0.724 (S=800), 0.680 (S=1600) for the storage-phosphor system, and 0.798 for the mammography screen-film system. Analysis of variance showed significant differences between different combinations of imaging modalities and exposure doses ( p<0.05). The diagnostic performance of the flat-panel detector system is superior to that of a screen-film system and a storage-phosphor system for the detection of erosive lesions at clinical exposure settings (S=200). Using the flat-panel system the exposure dose can be reduced by 50% to obtain a diagnostic performance comparable to a speed class 200 screen-film system.

Performance of a flat-panel detector in detecting artificial bone lesions: comparison with conventional screen-film and storage-phosphor radiography.

PURPOSE: To compare a large-area direct-readout flat-panel detector system with a conventional screen-film system and a storage-phosphor system in detecting small artificial osseous lesions simulating osteolytic disease and to assess diagnostic performance with decreasing exposure dose. MATERIALS AND METHODS: Artificial lesions (0.5-3.0 mm) were created in 100 of 200 predefined regions in 20 porcine femoral specimens. Specimens were enclosed in containers filled with water to create absorption and scatter radiation conditions comparable with those in a human extremity. Imaging was performed with a flat-panel detector system, a conventional screen-film system, and a storage-phosphor system. Levels of exposure equivalent to speed classes 400, 800, 1600, and 3200 were used. In all images, the presence or absence of a lesion was assessed by three radiologists using a five-point confidence scale. Receiver operating characteristic (ROC) analysis was performed for 4,800 observations (600 for each imaging modality and exposure level) and diagnostic performance estimated with the area under the ROC curve (A(z)). The significance of differences in diagnostic performance was tested with analysis of variance. RESULTS: ROC analysis showed A(z) values of 0.820 (speed class 400), 0.780 (class 800), 0.758 (class 1600), and 0.676 (class 3200) for the flat-panel detector; 0.761 (class 400), 0.725 (class 800), and 0.662 (class 1600) for the storage-phosphor system; and 0.788 (class 400) for the conventional screen-film system. The A(z) value for the flat-panel detector at speed class 400 was significantly higher than that for all other systems (P <.05). A(z) values for the speed class 400 screen-film system and flat-panel detector system at speed class 800 were not significantly different. CONCLUSION: The flat-panel detector has diagnostic performance superior to that of conventional screen-film and storage-phosphor radiography for detecting small artificial osseous lesions at clinical exposure settings. With the flat-panel detector, exposure dose can be reduced by 50% to obtain diagnostic performance comparable with that of a conventional speed class 400 screen-film system.

Low-voltage digital selenium radiography: detection of simulated interstitial lung disease, nodules, and catheters--a phantom study.

PURPOSE: To compare three tube voltages in digital selenium radiography for the detection of simulated interstitial lung disease, nodules, and catheters. MATERIALS AND METHODS: Simulated catheters, nodules, and ground-glass, linear, miliary, and reticular patterns were superimposed over an anthropomorphic chest phantom. Digital selenium radiography was performed with different tube voltages (70, 90, and 150 kVp). Hard-copy images were generated. Detection performance of five radiologists was compared by using receiver operating characteristic (ROC) analysis involving 54,000 observations. RESULTS: The detection of ground-glass, linear, miliary, and reticular patterns over lucent lung and of nodules equal to, smaller than, and larger than 10 mm increased when 70 kVp and/or 90 kVp was used. However, only the reticular pattern was significantly better detected at lower peak voltage (P <.05). Simulated catheters and nodules over the mediastinum showed smaller areas under the ROC curve at lower peak voltage. These results were not statistically significant (P >.05). CONCLUSION: The diagnostic performance of digital selenium radiography at lower peak voltage is at least as good as that at higher peak voltage for interstitial lung disease over lucent lung. Performance is equivalent for nodules and catheters over obscured chest regions at lower peak voltages compared with that at 150 kVp. Our results implicate that the use of high-voltage technique in digital selenium radiography should be reassessed.