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Introduction: Flat-panel detector C-arms (FCs) are reported to reduce radiation exposure and improve image quality compared with conventional image intensifier C-arms (CCs). The purpose of this study was to compare radiation exposure and image quality between three commonly used FCs. Materials and Methods: A cadaver model was placed in the prone position to simulate percutaneous nephrolithotomy. We compared the following three FCs: OEC Elite CFD from GE HealthCare, Zenition 70 from Philips, and Ziehm Vision RFD from Ziehm Imaging. To measure the radiation dose, optically stimulated luminescence dosimeters (OSLDs) were utilized during five 300-second trials, conducted under three settings: automatic exposure control (AEC), AEC with low dose (LD), and LD with the lowest pulse rate (LDLP). Ten blinded urologists evaluated the image quality. Data were statistically analyzed using the analysis of variance (ANOVA) and Tukey's B post hoc tests. Results: In the AEC setting, the Philips C-arm demonstrated lower ventral OSLD exposure (42,446 mrad) compared with both the GE (51,076 mrad) and Ziehm (83,178 mrad; p  < 0.001) C-arms. Similarly, in the LD setting, the Philips C-arm resulted in less ventral OSLD exposure (25,926 mrad) than both the Ziehm (30,956 mrad) and GE (38,209 mrad; p  < 0.001) C-arms. Meanwhile, in the LDLP setting, the Ziehm C-arm showed less ventral OSLD exposure (4019 mrad) than both the GE (7418 mrad) and Philips (8229 mrad; p  < 0.001) C-arms. All three manufacturers received adequate image quality ratings at the AEC and LD settings. However, at LDLP, the Ziehm C-arm received inadequate ratings in 8% of images, whereas both the GE and Philips C-arms received 100% adequate ratings ( p  = 0.016). Conclusions: Radiation produced by flat-panel C-arms varies dramatically, with the highest exposure (Ziehm) being almost double the lowest (Philips) in AEC. Improved picture quality at the lowest settings may come at the cost of increased radiation dose. Surgeons should carefully select the machine and settings to minimize radiation exposure while still preserving the image quality.

Purpose: Conventional mammography is a decisive tool in detecting breast cancer. Continuous efforts are undertaken in order to further improve the image quality as well as to reduce the applied doses. The purpose of our study was to compare diagnostic image quality of dose reduced computed mammography with a new needle-based detector system to full dose powder imaging plates., Methods: We retrospectively compared 360 randomly chosen mammographies performed on a GE Senographe DMR running the Agfa DX-M needle-based imaging plate system (NIP) with their preliminary examinations which were acquired at standard dose with the same GE mammography device and an Agfa CR85-X powdered storage phosphor imaging plate system (PIP). NIP-based mammographies were about 29.8 % dose-reduced. The preliminary examinations had to be performed not earlier than 2 years before the recent investigations. Exclusion criteria were changes in ACR level and appearance of the scored targets and not optimally positioned and exposed mammographies. The images were blinded and read separately twice by 2 mammography experts according to a 3-point score on diagnostic image quality and the visualization of parenchyma, cysts, fibroadenomas, physiologic lymph nodes, solitary microcalcifications and macrocalcifications., Results: Dose reduced NIPs showed a significantly better visualization of parenchyma at ACR II/III and solitary microcalcifications at ACR I-III mammographies (p < 0.001) whereas the difference in scoring macrocalcifications, cysts, fibroadenomas and physiologic lymph nodes was not significant. The reading showed an excellent intra- (r = 0.97/0.94) and interobserver agreement (r = 0.92)., Conclusion: With computed mammography using the needle-based detector system a significant dose reduction is possible without loss of diagnostic image quality., Competing Interests: Declaration of Competing Interest The authors declare that there are no conflicts of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Data from dental intraoral radiography quality controls was gathered from 1201 units (22% of the licensed X-ray units existing in Portugal), using film and digital image systems, between 2016 and 2018. The median incident air KERMA for standard superior molar tooth was evaluated in 0.9 mGy with the value of 1.3 mGy as the upper quartile. Comparisons with a 1990 published survey from dental exposures in Portugal were made. A 85% reduction for incident air KERMA per exposure was observed (6.0 mGy for the 1990 survey), which can be attributed to technical advances in the X-ray image receptors, as well as the implementation of legal requirements for technical acceptability of radiological units. It was also observed an increase of X-ray exams, which is related to an increase of dental practitioners, available radiological equipment and the level of dental healthcare., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: Image processing plays an important role in optimizing image quality and radiation dose in projection radiography. Unfortunately commercial algorithms are black boxes that are often left at or near vendor default settings rather than being optimized., Objective: We hypothesize that different commercial image-processing systems, when left at or near default settings, create significant differences in image quality. We further hypothesize that image-quality differences can be exploited to produce images of equivalent quality but lower radiation dose., Materials and Methods: We used a portable radiography system to acquire images on a neonatal chest phantom and recorded the entrance surface air kerma (ESAK). We applied two image-processing systems (Optima XR220amx, by GE Healthcare, Waukesha, WI; and MUSICA(2) by Agfa HealthCare, Mortsel, Belgium) to the images. Seven observers (attending pediatric radiologists and radiology residents) independently assessed image quality using two methods: rating and matching. Image-quality ratings were independently assessed by each observer on a 10-point scale. Matching consisted of each observer matching GE-processed images and Agfa-processed images with equivalent image quality. A total of 210 rating tasks and 42 matching tasks were performed and effective dose was estimated., Results: Median Agfa-processed image-quality ratings were higher than GE-processed ratings. Non-diagnostic ratings were seen over a wider range of doses for GE-processed images than for Agfa-processed images. During matching tasks, observers matched image quality between GE-processed images and Agfa-processed images acquired at a lower effective dose (11 ± 9 μSv; P < 0.0001)., Conclusion: Image-processing methods significantly impact perceived image quality. These image-quality differences can be exploited to alter protocols and produce images of equivalent image quality but lower doses. Those purchasing projection radiography systems or third-party image-processing software should be aware that image processing can significantly impact image quality when settings are left near default values.

Background: Many image-intensifier fluoroscopy systems have been replaced by flat-panel detectors in recent years., Objective: To compare the level of contrast, image resolution and radiation dose between an image-intensifier and a newer-generation flat-panel detector system in a pediatric radiology unit., Materials and Methods: We compared two systems — a conventional image intensifier and a newer-generation flat-panel system. We measured image quality and radiation dose using a technical phantom. Additionally, we retrospectively compared age-matched fluoroscopic pediatric voiding cystourethrography (n = 15) and upper gastrointestinal investigations (n = 25)., Results: In phantom studies image contrast was equal while image resolution was higher and mean radiation dose lower using the flat-panel system (P < 0.0001). In pediatric investigations, mean dose area product was significantly reduced on the flat-panel system for upper gastrointestinal investigation (45 ± 38 μGy*m2 vs. 11 ± 9 μGy*m2; P < 0.0001) and for voiding cystourethrography (18 ± 20 μGy*m2 vs. 10 ± 12 μGy*m2; P = 0.04)., Conclusion: The newer flat-panel system performs at lower dose levels with equal to better image quality and therefore seems to be the more suitable technique for pediatric fluoroscopy in comparison to image-intensifier systems.

Recently, for medical imaging, digital radiography systems are widely used in clinical practices. However, a study in the past reported that a patient radiation exposure level by digital radiography is in fact not lower than that by analog radiography system. High level of attention needs to be paid for over-exposure when using the conventional analog radiography with a screen and a film, as it results in high density of the film. However, for digital radiography systems, since the automatic adjusting function of image density is equipped with them, no attention for radiation dose need to be paid. Thus technologists tend to be careless and results in higher chance for over-exposure. Current digital radiography systems are high-performance in the image properties and capable of patient dose reduction. Especially, the image quality of the flat panel detector system is recognized, higher than that of the computed radiography system by imaging plates, in both objective and subjective evaluations. Therefore, we technologists are responsible for optimizing the balance between the image quality of the digital radiogram and the radiation dose required for each case. Moreover, it is also required for us as medical technologists to make effective use of such evaluation result of medical images for patients.

Background: The radiation risk of patients undergoing invasive cardiology remains considerable and includes skin injuries and cancer. To date, submillisievert coronary angiography has not been considered feasible., Patients and Methods: In 2011, we compared results from 100 consecutive patients undergoing elective coronary angiography using the latest-generation flat-panel angiography system (FPS) with results from examinations by the same operator using 106 historic controls with a conventional image-intensifier system (IIS) that was new in 2002., Results: The median patient exposure parameters were measured as follows: dose-area product (DAP) associated with radiographic cine acquisitions (DAP(R)) and fluoroscopy (DAP(F)) scenes, radiographic frames and runs, and cumulative exposure times for radiography and fluoroscopy. On the FPS as compared to the traditional IIS, radiographic detector entrance dose levels were reduced from 164 to 80 nGy/frame and pulse rates were lowered from 12.5/s to 7.5/s during radiography and from 25/s to 4/s during fluoroscopy. The cardiologist's performance patterns remained comparable over the years: fluoroscopy time was constant and radiography time even slightly increased. Overall patient DAP decreased from 7.0 to 2.4 Gy × cm(2); DAP(R), from 4.2 to 1.7 Gy × cm(2); and DAP(F), from 2.8 to 0.6 Gy × cm(2). Time-adjusted DAP(R)/s decreased from 436 to 130 mGy × cm(2) and DAP(F)/s, from 21.6 to 4.4 mGy × cm(2). Cumulative patient skin dose with the FPS amounted to 67 mGy, and the median (interquartile range) of effective dose was 0.5 (0.3 … 0.7) mSv., Conclusion: Consistent application of radiation-reducing techniques with the latest-generation flat-panel systems enables submillisievert coronary angiography in invasive cardiology.

Background: Ultrasound-guided central venous puncture and fluoroscopic guidance during central venous catheter (CVC) positioning optimizes technical success and lowers the complication rates in children, and is therefore considered standard practice., Objective: The purpose of this study was to compare the radiation exposure levels recorded during CVC placement in children weighing less than 10 kg in procedures performed using an image intensifier-based angiographic system (IIDS) to those performed in a flat-panel detector-based interventional suite (FPDS)., Materials and Methods: A retrospective review of 96 image-guided CVC placements, between January 2008 and October 2013, in 49 children weighing less than 10 kg was performed. Mean age was 8.2 ± 4.4 months (range: 1-22 months). Mean weight was 7.1 ± 2.7 kg (range: 2.5-9.8 kg). The procedures were classified into two categories: non-tunneled and tunneled CVC placement., Results: Thirty-five procedures were performed with the IIDS (21 non-tunneled CVC, 14 tunneled CVC); 61 procedures were performed with the FPDS (47 non-tunneled CVC, 14 tunneled CVC). For non-tunneled CVC, mean DAP was 113.5 ± 126.7 cGy cm(2) with the IIDS and 15.9 ± 44.6 cGy · cm(2) with the FPDS (P < 0.001). For tunneled CVC, mean DAP was 84.6 ± 81.2 cGy · cm(2) with the IIDS and 37.1 ± 33.5 cGy cm(2) with the FPDS (P = 0.02)., Conclusion: The use of flat-panel angiographic equipment reduces radiation exposure in small children undergoing image-guided CVC placement.

A Monte Carlo model of a novel electronic portal imaging device (EPID) has been developed using Geant4 and its performance for imaging and dosimetry applications in radiotherapy has been characterised. The EPID geometry is based on a physical prototype under ongoing investigation and comprises an array of plastic scintillating fibres in place of the metal plate/phosphor screen in standard EPIDs. Geometrical and optical transport parameters were varied to investigate their impact on imaging and dosimetry performance. Detection efficiency was most sensitive to variations in fibre length, achieving a peak value of 36% at 50 mm using 400 keV x-rays for the lengths considered. Increases in efficiency for longer fibres were partially offset by reductions in sensitivity. Removing the extra-mural absorber surrounding individual fibres severely decreased the modulation transfer function (MTF), highlighting its importance in maximising spatial resolution. Field size response and relative dose profile simulations demonstrated a water-equivalent dose response and thus the prototype's suitability for dosimetry applications. Element-to-element mismatch between scintillating fibres and underlying photodiode pixels resulted in a reduced MTF for high spatial frequencies and quasi-periodic variations in dose profile response. This effect is eliminated when fibres are precisely matched to underlying pixels. Simulations strongly suggest that with further optimisation, this prototype EPID may be capable of simultaneous imaging and dosimetry in radiotherapy.

Objective: The purpose of this study is to compare the diagnostic performance and radiation exposure of flat-panel CT arthrography for cartilage defect detection in the ankle joint to standard MDCT arthrography, using gross anatomy and thermoluminescent dosimetry as reference standards., Materials and Methods: Ten cadaveric ankle specimens were obtained from individuals who had willed their bodies to science. Five milliliters of a mixture of diluted ioxaglate and saline were injected. Specimens were examined consecutively with the use of flat-panel CT and MDCT. Radiation doses of flat-panel CT and MDCT were recorded using thermoluminescent dosimeters. Flat-panel CT and MDCT arthrography examinations were blinded and randomly evaluated by two musculoskeletal radiologists in consensus. In each ankle specimen, eight cartilage areas were assessed separately: medial talar surface, medial talar trochlea, lateral talar trochlea, lateral talar surface, tibial malleolus, medial tibial pla-fond, lateral tibial plafond, and fibular malleolus. Findings at flat-panel CT and MDCT arthrography were compared with macroscopic assessments in 80 cartilage areas., Results: For the detection of cartilage lesions, flat-panel CT showed a sensitivity of 80%, specificity of 98%, and accuracy of 94%, and MDCT arthrography showed a sensitivity of 55%, specificity of 98%, and accuracy of 88%. Flat-panel CT and MDCT arthrography showed almost perfect (κ = 0.83) and substantial (κ = 0.65) agreement, respectively, with anatomic examination. Radiation dose was significantly lower for flat-panel CT (mean, 2.1 mGy; range, 1.1-3.0 mGy) than for MDCT (mean, 47.2 mGy; range, 39.3-53.8 mGy) (p < 0.01)., Conclusion: Flat-panel CT arthrography is accurate for detecting cartilage defects in the ankle joint and is an alternative to MDCT arthrography that may have better diagnostic performance and may permit the use of a lower radiation dose.

Purpose: The purpose of this study was to gain insight into the distribution and application of digital intraoral radiographic techniques within general dental practices and to compare these with film-based systems in terms of patient dose reduction., Materials and Methods: 1100 questionnaires were handed out to general dental practitioners. Data was analyzed with respect to the type of system by using descriptive statistics and nonparametric tests, i.e. Kruskal-Wallis, Mann-Whitney and chi-square test (SPSS 20)., Results: 64% of the questioned dentists still use film-based radiology, 23% utilize storage phosphor plate (SPP) systems and 13% use a charge-coupled device (CCD). A strong correlation between the number of dentists working in a practice and the use of digital dental imaging was observed. Almost 3/4 of the film users work with E- or F-speed film. 45% of them refuse to change to a digital system. The use of lead aprons was popular, while only a minority preferred thyroid shields and rectangular collimators. A fourfold reduction of exposure time from D-speed film to CCD systems was observed. Due to detector size and positioning errors, users of CCD systems take significantly more single-tooth radiographs in total. Considering the number of radiographs per patient, there is only a slight tendency towards more X-rays with CCD systems. Up to image generation, digital systems seem to be as or even more difficult to handle than film-based systems, while their handling was favored after radiographic exposure., Conclusion: Despite a slight increase of radiographs taken with CCD systems, there is a significant dosage reduction. Corresponding to the decrease in exposure time, the patient dose for SPP systems is reduced to one half compared to film. The main issues in CCD technology are positioning errors and the size of the X-ray detectors which are difficult to eliminate. The usage of radiation protection measures still needs to be improved., Key Points: ► Responsible use of digital intraoral radiology results in a significant dose reduction in everyday practice. ► The ALARA principle is only achieved by strict implementation of dose-reducing methods. ► The efforts to use dose-reducing devices must be increased., (© Georg Thieme Verlag KG Stuttgart · New York.)

A newly developed Digital Radiography (DR) detector has smaller pixel size and higher fill factor than earlier detector models. These technical advantages should theoretically lead to higher sensitivity and higher spatial resolution, thus making dose reduction possible without scarifying image quality compared to previous DR detector versions. To examine whether the newly developed Canon CXDI-70C DR detector provides an improved image quality and/or allows for dose reductions in hand and pelvic bone examinations as well as premature chest examinations, compared to the previous (CXDI-55C) DR detector version. A total of 450 images of a technical Contrast-Detail phantom were imaged on a DR system employing various kVp and mAs settings, providing an objective image quality assessment. In addition, 450 images of anthropomorphic phantoms were taken and analyzed by three specialized radiologists using Visual Grading Analysis (VGA). The results from the technical phantom studies showed that the image quality expressed as IQFINV values was on average approximately 45 % higher with the CXDI-70C detector compared to the CXDI-55C detector. Consistently, the VGA results from the anatomical phantom studies indicated that by using the CXDI-70C detector, diagnostic image quality could be maintained at a dose reduction of in average 30 %, depending on anatomy and kVp level. This indicates that the CXDI-70C detector is significantly more sensitive than the previous model, and supports a better clinical image quality. By using the newly developed DR detector a significant dose reduction is possible while maintaining image quality.

Rationale and Objectives: The recent increasing utilization of imaging has increased the population exposure to ionizing radiation. With increasing knowledge of the potential harm of radiation exposure, efforts should be made to minimize patient radiation whenever possible, especially in young children. The purpose of this study was to use the exposure index (EI) standard to assess the potential for reducing radiation dose to babies by removing a soft comfort pad, often placed underneath the baby. The pad is located between the baby and the image detector plate. As such it absorbs x-rays that have already passed through the baby but have not yet reached the imaging detector plate., Materials and Methods: Using a thoracic infant phantom and fixed exposure factors, we measured the percentage of the radiation exiting a neonatal chest phantom that was absorbed/attenuated by the comfort pad, before it hit the detector to create the image. We studied comfort pads of 4 different thicknesses, ranging from 0.5″ to 8″., Results: Radiation beam attenuation, ranging from 12% to 72.1%, was found with all comfort pads, with increased x-ray beam attenuation occurring with increasing pad thickness., Conclusions: The study shows that comfort pads cause a high attenuation of the radiation beam, after it exits the chest phantom. As such, removal of the pads prior to radiographic exposure of babies is a method of potentially reducing patient radiation exposure in the newborn nursery., (Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.)

Purpose: To compare image quality of standard-dose computed radiography and dose reduced needle-technology CR for supine CXR in a clinical setting., Materials and Methods: We prospectively evaluated 128 radiographs of 32 immunocompromised patients. For each patient four clinical CXR were performed within one week, two with powder image plates (PIP; Fuji ST-V) and two with needle image plates (NIP; Agfa DXS) at standard and half dose, respectively. One experienced radiologist and two residents blinded to dose level and kind of imaging system rated different anatomical structures, image noise, tubes/lines and abnormalities on a image quality scale from 1 to 10 (1=poor, 10=excellent). The rating scores were tested for statistical differences using analysis of variance with repeated measures., Results: A statistical difference (p<0.05) was found for the two systems as well as for the two dose levels. Overall rating scores were 6.5 for PIP with full dose, 6.2 for PIP with half dose, 7.6 for NIP with full dose and 7.4 for NIP with half dose. There was a significant difference in favour of the NIP system at the same dose level. Also the NIP images obtained at half dose were ranked significantly better compared to the PIP images at standard dose. The differences in ranking of anatomical structures and abnormalities were more pronounced in low absorption areas (pulmonary vessels, parenchyma) than in high absorption areas (mediastinum, spine)., Conclusion: For supine chest radiograms the NIP technology allows for a dose reduction of 50% while providing higher image quality., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To establish local diagnostic reference levels (DRL) for typical radiographic examinations in a fully digital imaging institution., Methods: The initial survey included 6 standard radiographic projections performed in 19 computed radiography (CR) and digital radiography (DR) rooms. Because of the expected difference in the performance, the local reference levels were analysed separately for those 2 modalities. Data of 226 average size adult patients were included in the analysis. Entrance surface dose (ESD) was calculated from the recorded radiographic techniques and tube radiation output measurements. After observing wide variations in the results of the patient survey, the examinations were repeated by using anthropomorphic phantoms. Initial efforts to understand the reasons for dose variations were focused on CR chest, abdomen, pelvis, and lumbar spine examinations., Results: The average size patient doses for similar examinations were lower in the DR rooms than in the CR rooms by factors that ranged from 1.2 to 3, with the exception of the chest examination. Standardization of the CR exposure index value allowed us to decrease ESD by 21%-30%. Detector sensitivity had an insignificant effect (2%) on ESD; proper collimation lowered the dose by 17%. However, the major effect, up to 46% difference, was found because of antiscatter grids cutoff., Conclusion: Modality specific local diagnostic reference levels for standard examinations have been established in a large digital imaging department with hybrid modalities. Typically the local reference values were lower than those recommended in Safety Code 35, except for CR chests. Factors that affect the dose variations have been investigated and determined., (Copyright © 2012 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.)

Purpose: To assess and compare the radiation dose of DynaCT in phantoms to that of MSCT., Methods and Materials: A male Anderson Radiation Therapy 200 phantom with embedded thermoluminescence dosimeters (TLDs) was scanned with DynaCT (Axiom Artis dTA, Siemens Healthcare, Forchheim, Germany) and MSCTs (MSCT1: Lightspeed VCT, GE, Milwaukee, USA; MSCT2: Sensation Cardiac 64, Siemens Healthcare, Erlangen, Germany), respectively. For DynaCT, radiation exposure data with automatic exposure control were obtained from scanning of head, chest and abdomen. For MSCT, scanning protocols for head, chest, and abdomen were examined under conventional exposure conditions. Effective doses were calculated from LiF-TLD measurements according to ICRP103. A Catphan phantom (Phantom Lab, USA) was used to evaluate the spatial resolution and low contrast detectability of DynaCT and MSCT., Results: The effective doses for DynaCT from head, chest and abdomen scanning were 1.18, 7.32, 7.48 mSv (20 s scan) and 0.85, 6.01, 7.04 mSv (8 s scan); the effective doses for MSCT from head, chest and abdomen scanning were 3.33, 7.62 and 8.42 mSv (MSCT1), and 1.89, 7.52, 8.23 mSv (MSCT2). Significant difference between the organ doses from DynaCT and from MSCT (p<.05) was shown. The spatial resolution of 12 lp/cm was achieved and it was able to recognize a 3mm low contrast object at 0.5% contrast level in DynaCT, which was on the same level as in the MSCT images., Conclusion: The phantom study indicates that DynaCT applies significantly less dose to patient and achieves similar spatial resolution and low contrast detectability to standard diagnostic MSCT., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Purpose: The aim of the present study was the evaluation and optimization of radiation dose to the ovaries (D) in hysterosalpingography (HSG)., Methods: The study included a phantom study and a clinical one. In the phantom study, we evaluated imaging results for different geometrical setups and irradiation conditions. In the clinical study, 34 women were assigned into three different fluoroscopy modes and D was estimated with direct cervical TLD measurements., Results: In the phantom study, we used a source-to-image-distance (SID) of 110 cm and a field diagonal of 48 cm, and thus decreased air KERMA rate (KR) by 19% and 70%, respectively, for beam filtration: 4 mm Al and 0.9 mm Cu (Low dose). The least radiation exposure was accomplished by using the 3.75 pps fluoroscopy mode in conjunction with beam filtration: Low dose. In the clinical study, D normalized to 50 s of fluoroscopy time with a 3.75 pps fluoroscopy mode reached a value of 0.45 ± 0.04 mGy. Observers' evaluation of diagnostic image quality did not significantly differ for the three different modes of acquisition that were compared., Conclusions: Digital spot radiographs could be omitted in modern flat panel systems during HSG. Fluoroscopy image acquisitions in a modern flat panel unit at 3.75 pps and a beam filtration of 4 mm Al and 0.9 mm Cu demonstrate acceptable image quality with an average D equal to 0.45 mGy. This value is lower compared to the studied literature. For these reasons, the proposed method may be recommended for routine HSG examination in order to limit radiation exposure to the ovaries.

Purpose: To evaluate operator radiation exposure during percutaneous interventions on hemodialysis arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs)., Materials and Methods: Seventy-seven procedures were performed in 57 patients while the interventional radiologist wore two ring dosimeters, two thermoluminescent dosimeters at the lower legs, and a thermoluminescent dosimeter on the forehead. Dose-area product, fluoroscopy time, total procedure time, and radiation exposures to eye lens, hands, and legs were recorded. Variables were procedure type, access site side, and angiography equipment. Statistical analysis was performed with the signed-rank and Mann-Whitney U tests., Results: Mean operator radiation doses for the left hand, right hand, eye lens, left leg, and right leg were 0.28, 0.28, 0.03, 0.11, and 0.12 mSv, respectively. Radiation exposure to the hands was significantly higher compared with that to the legs (P<.0001). In recanalization procedures, fluoroscopy time, total procedure time, and mean number of angiographic runs were higher (all P<.001) than those for percutaneous transluminal angioplasty (PTA), as were radiation exposures to the hands and left leg (all P<.05). Left-sided access interventions resulted in higher doses to the right hand and leg (both P<.05). For right-sided access interventions, doses to the left hand and leg were higher (P<.0001). Eye lens radiation dose was significantly higher for procedures with the flat-panel detector system (P=.002)., Conclusion: Operator radiation exposure to the hands, legs, and eyes during percutaneous interventional procedures performed on hemodialysis AVFs and AVGs is relatively low. Radiation exposure to the hands was higher than that to the legs, and the hand and leg closest to the AVF or AVG received a higher dose. Recanalization procedures resulted in higher doses to the hands and left leg than did PTA. Eye lens radiation dose may be higher with a flat-panel detector system., (© RSNA, 2012.)

Purpose: To develop a protocol for the optimization of diagnostic chest radiography examination, the effect of radiographic exposure reduction on image quality is investigated., Procedure: Fourty-eight adult patients presenting for posterior-anterior (PA) chest radiography in a tertiary health care centre were categorized into 3 groups to assess the effects of exposure (tube current/time mAs) reduction on clinical image quality using in film screen (FS) chest radiography. Images were obtained at existing departmental exposure protocol (T1) while a record of the exposure factors was made. Test exposures obtained by reducing average mAs values by 20% (T2) and 50% (T3) were used to obtain radiographic images of patients following normal ethically based clinical practice. To make up for the reduction in mAs, a 4% increase in the T1 kVp was used. The quality of images obtained with each exposure protocol was studied by two consultant radiologists, using the image quality criteria of the Commission of European Communities (CEC). Assessors used the method of ranked scoring and worked independently., Results: Results showed no change in image quality following the 20% exposure (mAs) reduction. However, there was a significant change in image quality at 50% reduction of mAs values (P < 0.05) with higher image quality scores suggesting improved perceptibility of all assessed criteria among the observers., Conclusion: Improving radiation protection of the patient while maintaining diagnostic quality of the radiographic image at reduced exposures is a clinically desirable development. This study will find application in current efforts at optimization of radiography procedures in the area of study.

Radiographic inspection is one of the most widely employed techniques for medical testing methods. Because of poor contrast and high un-sharpness of radiographic image quality in films, converting radiographs to a digital format and using further digital image processing is the best method of enhancing the image quality and assisting the interpreter in their evaluation. In this research work, radiographic films of 70 infant chest images with different sizes of defects were selected. To digitise the chest images and employ image processing the two algorithms (i) spatial domain and (ii) frequency domain techniques were used. The MATLAB environment was selected for processing in the digital format. Our results showed that by using these two techniques, the defects with small dimensions are detectable. Therefore, these suggested techniques may help medical specialists to diagnose the defects in the primary stages and help to prevent more repeat X-ray examination of paediatric patients.

Philips DigitalDiagnost, a digital radiographic system mounting flat panel detector (FPD), can display dose area data (DiDi dose) calculated by examination parameters. We evaluated its fundamental characteristics and compared the values of DiDi dose andactual measured data obtained by the area dose product meter (PD-4100L). Tendency of varied values of mAs, X-ray tube values and exposure area from both the area dose product meter and the DiDi dose were coincided. Further, in clinical images of chest PA 100 cases, chest lateral 50 cases and abdomen stand 25 cases, the determination coefficient was overly high as R(2)=0.99. Based on these results, it is clear that the DiDi dose can be treated the same as the area dose product meter. Under increasing of patient X-ray exposure dose is a concern in digital general radiography, this research indicates that maximum values of histogram obtained by DiDi dose contributes dose awareness for radiographer.

Angiographic equipment has tended toward using flat-panel detector (FPD). However, the radiation dose varies depending on the size of field of view (FOV) in the FPD. Although we were using 7 inch FOV in cardiac procedures, we examined a way to reduce the patients' radiation dose by using 8 inch FOV utilizing a digital zoom processing. We measured the absorbed dose rates at an interventional reference point (IRP) with 20 cm acrylic board to compare 8 inch FOV using a digital zoom processing with 7 inch FOV. Additionally we visually evaluated these phantom images. Result of comparison of absorbed dose rates at IRP, 8 inch FOV using a digital zoom processing was reduced more than 7 inch FOV (fluoroscopic 29.0% and digital cine 37.5%). These phantom images were of equivalent quality. The method to use 8 inch FOV utilizing a digital zoom processing technique in cardiac procedures is one of the effective radiation exposure reduction methods.

Reducing radiation dose while maintaining adequate image quality on conventional and digital radiographs requires optimal use of the unit. Additional filtration avoids unnecessary tissue exposure and improves photon transmission. Automatic exposure control may reduce exposure and dose. The volume of tissue imaged must be limited by the use of diaphragms and shutters or compression. Sensitive detectors with increased photon detection also contribute to reduce dose. Radiographic films combined to rare-earth screens also afford a good photon-conversion efficiency. Large area flat panel amorphous silicon x-ray sensors may also reduce dose up to 50% compared to films. Finally, calculation of the Kerma-area product independent of the source distance constitutes an important indicator of radiation dose.

Objectives: The aim of the study was to clarify the change in image quality upon X-ray dose reduction and to re-analyse the possibility of X-ray dose reduction in photostimulable phosphor luminescence (PSPL) X-ray imaging systems. In addition, the study attempted to verify the usefulness of multiobjective frequency processing (MFP) and flexible noise control (FNC) for X-ray dose reduction., Methods: Three PSPL X-ray imaging systems were used in this study. Modulation transfer function (MTF), noise equivalent number of quanta (NEQ) and detective quantum efficiency (DQE) were evaluated to compare the basic physical performance of each system. Subjective visual evaluation of diagnostic ability for normal anatomical structures was performed. The NEQ, DQE and diagnostic ability were evaluated at base X-ray dose, and 1/3, 1/10 and 1/20 of the base X-ray dose., Results: The MTF of the systems did not differ significantly. The NEQ and DQE did not necessarily depend on the pixel size of the system. The images from all three systems had a higher diagnostic utility compared with conventional film images at the base and 1/3 X-ray doses. The subjective image quality was better at the base X-ray dose than at 1/3 of the base dose in all systems. The MFP and FNC-processed images had a higher diagnostic utility than the images without MFP and FNC., Conclusions: The use of PSPL imaging systems may allow a reduction in the X-ray dose to one-third of that required for conventional film. It is suggested that MFP and FNC are useful for radiation dose reduction.

The purpose of the present work was to describe a method of using an imaging plate from a computed radiography system to determine the computed tomography (CT) dose profile (the tritium method) and to compare this method with point-dose measurements using a solid-state detector (CT Dose Profiler; RTI Electronics, Mölndal, Sweden) and the indirect method of comparing the air kerma-length product (P(KL)) at different beam collimations. The three methods were used to determine the full width at half maximum (FWHM) of the dose profile of a multi-slice CT at different nominal beam collimations. For all beam collimations, the obtained deviation between the tritium method and the CT Dose Profiler was smaller than 0.1 mm. The maximum relative error was 2 %. For the P(KL) method, the deviation from the CT Dose Profiler was between 0.2 and 0.4 mm, resulting in a relative error larger than 10 % for the smallest beam collimation even after normalisation to a known FWHM. In conclusion, the proposed method of using an imaging plate to determine the FWHM of the CT dose profile has a high accuracy and shows good agreement with the more advanced method of point-dose measurements using a solid-state detector.

The aim of this study was to evaluate and compare organ doses delivered to patients in wrist and petrous bone examinations using a multislice spiral computed tomography (CT) and a C-arm cone-beam CT equipped with a flat-panel detector (XperCT). For this purpose, doses to the target organ, i.e. wrist or petrous bone, together with those to the most radiosensitive nearby organs, i.e. thyroid and eye lens, were measured and compared. Furthermore, image quality was compared for both imaging systems and different acquisition modes using a Catphan phantom. Results show that both systems guarantee adequate accuracy for diagnostic purposes for wrist and petrous bone examinations. Compared with the CT scanner, the XperCT system slightly reduces the dose to target organs and shortens the overall duration of the wrist examination. In addition, using the XperCT enables a reduction of the dose to the eye lens during head scans (skull base and ear examinations).

Field junctions between megavoltage photon beams are important in modern radiotherapy for treatments such as head and neck and breast cancer. An electronic portal imaging device (EPID) may be used to study junction dose between two megavoltage X-ray fields. In this study, the junction dose was used to determine machine characteristics such as jaw positions and their reproducibility, collimator rotation and the effect of gantry rotation. All measurements were done on Varian linear accelerators with EPID (Varian, Palo Alto, CA). The results show reproducibility in jaw positions of approximately 0.3 mm for repeated jaw placement while EPID readings were reproducible within a standard deviation of 0.4% for fixed jaw positions. Junction dose also allowed collimator rotation error of 0.1 degrees to be observed. Dependence of junction dose on gantry rotation due to gravity was observed; the gravity effect being maximum at 180 degrees gantry angle (beam pointing up). EPIDs were found to be reliable tools for checking field junctions, which in turn may be used to check jaw reproducibility and collimator rotation of linacs.

Purpose: The aim of this study was to introduce a prototype cone-beam computed tomography system equipped with a flat panel detector (FPD-CT system) and measure its radiation dose and spatial and lowcontrast resolution., Materials and Methods: A patient was rotated in a sitting position, and cone beam data were acquired with the flat panel detector from a fixed X-ray tube. Absorbed dose, spatial and low-contrast resolution, and variation in the CT attenuation value were assessed quantitatively in the acrylic phantom. The visibility of normal blood vessels in clinical images of seven patients was analyzed qualitatively by five board-certified radiologists. These quantitative and qualitative data were compared between the FPD-CT system and multidetector row CT (MDCT)., Results: Minimal low-contrast sensitivity and a moderate spatial resolution were demonstrated in images of central lung fields acquired by FPD-CT. The absorbed dose in the FPD-CT system decreased to approximately 2.5% of the dose in the MDCT system., Conclusion: Considering crossover structures in normal blood vessels and bronchi in the central areas of lung fields, this result implies that fairly acceptable spatial resolution can be realized with FPD-CT for detection and frequent follow-up of pulmonary abnormalities in the central lung fields.

Purpose: To measure the entrance surface dose (ESD) during three-dimensional (3D) imaging of a phantom and evaluate a method to estimate ESD with use of dose-area product (DAP) values., Materials and Methods: The present study used an angiographic unit with a digital flat-panel system for 3D imaging. DAP values and ESDs were evaluated on square phantoms with thicknesses of 12.0, 15.0, 18.0, 21.0, and 25.0 cm with use of 5-second acquisitions. ESDs were measured on the lateral and posterior surfaces of the square phantom. DAP values and ESDs were also evaluated on a human-shaped phantom with various table heights, with ESDs measured on the phantom surfaces on the posterior centerline, right middle axillary line, and their midpoint., Results: The posterior ESDs were 7.3 mGy, 12.1 mGy, 18.8 mGy, 26.9 mGy, and 38.5 mGy for the square phantoms with thicknesses of 12 cm, 15 cm, 18 cm, 21 cm, and 25 cm, respectively. The DAP and the posterior ESDs were correlated (r = 0.998, P < .0001). The regression equation was D = DAP x 0.0014, where D was the posterior ESD (mGy). For the human-shaped phantom, the posterolateral ESD tended to be slightly larger than the posteromedial ESD, with the differences less than 10%. The estimated doses based on this relationship were almost equal to the actual posterolateral doses for each table height., Conclusions: The ESD of a single 3D imaging study was considerably lower than the thresholds for radiation skin injuries. The DAP values are useful to estimate the maximum patient ESD during 3D imaging.

Background: In 2007, the International Commission on Radiological Protection (ICRP) revised estimates of the radiosensitivity of tissues including those in the maxillofacial region. The authors conducted a study to reassess patients' risk related to common dental radiographic exposures using the 2007 ICRP recommendations., Methods: The authors used a tissue-equivalent head phantom to measure dose. They calculated effective doses by using both 1990 and revised 2007 ICRP recommendations. Effective dose is a calculation that takes into consideration the different sensitivities of organs to long-term effects from ionizing radiation. It is the preferred method for comparing doses between different types of exposures., Results: Effective doses (per the 2007 ICRP) in microsieverts were as follows: full-mouth radiographs (FMX) with photo-stimulable phosphor (PSP) storage or F-speed film with rectangular collimation, 34.9 microSv; four-image posterior bitewings with PSP or F-speed film with rectangular collimation, 5.0 microSv; FMX using PSP or F-speed film with round collimation, 170.7 microSv; FMX with D-speed film and round collimation, 388 microSv; panoramic Orthophos XG (Sirona Group, Bensheim, Germany) with charge-coupled device (CCD), 14.2 microSv; panoramic ProMax (Planmeca, Helsinki, Finland) with CCD, 24.3 microSv; posteroanterior cephalogram with PSP, 5.1 microSv; and lateral cephalogram with PSP, 5.6 microSv. These values are 32 to 422 percent higher than those determined according to the 1990 ICRP guidelines., Conclusions: Although radiographs are an indispensable diagnostic tool, the increased effective doses of common intraoral and extraoral imaging techniques are high enough to warrant reconsideration of means to reduce patients' exposure., Clinical Implications: Clinicians can reduce patients' dose substantively by using digital receptors or F-speed film instead of D-speed film, rectangular collimation instead of round collimation and radiographic selection criteria.

We investigated X-ray energy distribution in an X-ray microbeam produced by a polycapillary X-ray lens in combination with a sealed-type X-ray tube. This polycapillary X-ray lens has an output focal distance (OFD) of approximately 15 mm. The size of the X-ray microbeam and its OFD were estimated by using a wire scanning method. In our case, the sizes of the X-ray microbeams at the output focal distance were 49 microm for Mo L(alpha), 36 microm for W L(alpha), and 28 microm for Mo K(alpha). The spot sizes depend on the energy of the X-ray fluorescence. The reason for the energy dependence is that X-ray capillary optics is based on the principle of propagation through glass capillaries by means of X-ray total external reflection. The evaluated OFD values of Mo L(alpha) and Mo K(alpha) were slightly changed in 17 microm. However, a deviation of 100 microm from the OFD caused only a 3% increase of the focal spot size. Therefore, we concluded that the OFD showed no significant dependence on X-ray energy.

For the dose study, a semi-automated method of data collection is used in this study. The participating centres were asked to fill out a spreadsheet with all necessary data and return it. For direct digital (DR) systems, the relevant data available in the DICOM header were used. All data is automatically added to a database and processed. The data were used to calculate the mean glandular dose for every image and for different thicknesses of polymethyl methacrylate phantoms using available conversion factors. Second-degree polynomials were fitted to the patient dose data and a reference dose curve was constructed for a range of thicknesses instead of a dose reference level at a single point. The dose reference curve rises from 1.57 mGy for a thickness of 30 mm to 2.50 mGy for 55 mm and 3.83 mGy for 75 mm. The results show centres that exceed this curve lie only in the lower or higher range of thicknesses and would remain undetected using a dose reference value in a single point. This gives better information to radiographers on where there is room for improvement of the dose levels in their system.

The correlation of image quality with the exposure index (EI) and the processing protocol was investigated in a Kodak computed radiography (CR) system using clinical radiographs and a water phantom containing an aluminium and a copper step-wedge. The phantom was exposed to different dose levels and the acquired images were processed using four clinical protocols. The quality of these images was evaluated in terms of image brightness, contrast and noise. In clinical radiographs, there was no straightforward correlation of image quality with EI. In phantom images, higher EI values improved contrast and reduced noise but after a point this improvement does not justify the implied increase in patient dose. Image brightness, contrast and noise were also strongly dependent on the processing protocol. To obtain the images of satisfactory quality with the Kodak CR system, a dose slightly higher than those used in 400 relative speed screen-film systems and a processing protocol designated for the specific radiographic examination are required.

Since 1965, medical radiation exposure in the population of Romania has been evaluated by the Network of Radiation Hygiene Laboratories of the Ministry of Public Health, including 23 laboratories throughout the whole country; the network is co-ordinated by the Institute of Public Health Bucharest. In Romania, for a population of 22.5 million inhabitants, 465 X-ray examinations were reported during the last survey, the most frequent being chest examination. There was no specific reference to digital radiology. Digital radiology has been introduced only recently in Romania, and only some rough data on the situation can be presented. Siemens AG is now present in Romania with 23 installations, type SIEREGRAPH CF and AXIOM ICONOS. A digital image intensifier technique is used only for fluoroscopy, and radiography is performed using a conventional film/screen combination. The company Philips has nine installations for angiography, model INTEGRIS, and uses a computed radiography technique. Several direct digital radiography MULTISYSTEM SWISSRAY installations (about 40 units) are also available for adult and paediatric examinations. The Council Directive 97/43/EURATOM on health protection of individuals against dangers of ionising radiation in relation to medical exposure was fully transformed into Romanian legislation in 2002.

The purpose of this investigation was to measure the patient and staff dose during routine interventional cardiology procedures for an image intensifier-based and a flat detector system using a water phantom. The Integris BH3000 image intensifier-based (Philips) and the Axiom Artis flat detector-based (Siemens) angiography units were used in this study. The accuracy of tubes potential and irradiation timers and also internal dosimeters were verified and confirmed. A water phantom with a thickness of 18 cm was used for patient and staff dose measurements. For the Philips system, phantom entrance dose rates were 2.77 and 38.97 microGym(2) s(-1) during fluoroscopy and cineangiography. The respective dose rates for the Siemens were 1.98 and 13.46 microGym(2) s(-1). Phantom entrance dose rate was 28.5 and 65% higher for the Philips system during fluoroscopy and cineangiography, respectively. Comparing the scattered dose rates at the operator location showed that the flat detector-based Siemens system delivers five times lower dose to the operator in comparison with the image intensifier-based Philips unit. The results suggest that the decrease in received dose of the patient and staff is achievable using the flat detector system. In addition, application of lead curtain and glass is recommended to lower the cardiologist dose especially for the image intensifier-based Philips system.

Objectives: The aim of the present study was to determine (1) the absorbed and the exit radiation doses for cephalometric exposures on a phantom head with various exposure settings and image receivers, and (2) the diagnostic image quality for various modalities assessed on cephalometric radiographs of patients., Methods: The dose measurements for lateral cephalometric radiographs were performed with a semiconductor detector, and also with thermoluminescent detectors and an Alderson phantom. Both the integral and the effective doses were determined. Two radiographs of each patient (n=119) were taken at two different times, one at a low tube potential setting, 75+/-5 kV, and one with a decreased dose. Film-screen systems with speed class 400 and one storage phosphor plate were used. Five observers assessed the radiographs for the visualization of six cephalometric reference points on a three-point scale with -1, 0 and 1. Twenty-seven image pairs were rescored to determine inter- and intrarater reliability. The statistical analysis was done using analysis of variance and Tukey's HSD (honestly significant difference) post hoc test., Results: Increasing the tube potential setting led to an average dose reduction to 83% (integral dose) or to 87% (effective dose). Instead of taking the radiograph at a low tube potential setting (75 kV), a dose reduction of about 15% was feasible at a high tube potential setting (90 kV). A significant difference in reference point visibility existed between film radiographs at low tube potential settings (mean score 0.984) and at high tube potential settings (90 kV, mean score 0.958). For the storage phosphor plates, there was no significant difference to the film-screen combinations at low tube potential and halved milliampere seconds settings. In the second assessment, there was a high degree of agreement (96.6%) compared with the first assessment (unadjusted for random agreement)., Conclusions: As there is only minimal dose reduction at increased tube potential settings, for a dose reduction, it seems to be more useful to use storage phosphor plates at unchanged tube potential and halved milliampere seconds settings compared with the film-screen combination.

The surface doses to patients during chest, abdomen and pelvis radiography were measured over a period of 3 years, during which time computed radiography (CR) and digital radiography (DR) systems were introduced to replace film-screen systems. For film-screen and CR the surface doses were measured with thermoluminescent dosimeters. For DR the surface doses were calculated from the dose-area product (DAP) meter readings. Measurements were made for each type of examination and detector type on 10 average-size patients. Measurements were made immediately after the new systems were introduced, and subsequently as adjustments were made to optimize dose and image quality. Published diagnostic reference levels were used as target values in this optimization. Initially, CR doses were the same as or higher than for film-screen, and the doses were lower for DR compared to film-screen. Subsequent clinical experience with the systems led to changes in the technique used for chest examinations both for CR and for DR. For CR, it was possible to change the algorithm and decrease the dose to one quarter of the initial value with acceptable image quality. For DR, it was decided to reduce noise by increasing the dose by a factor of two. No changes were made to abdomen or pelvic imaging techniques for either CR or DR. The final patient surface doses using CR were similar to published diagnostic reference doses; for DR, all patient doses were less than published reference levels.

Objective: The objective of our study was to evaluate the exposure doses to patients and radiologists during transcatheter arterial embolization (TAE) for hepatocellular carcinoma (HCC) using a new angiographic unit with a digital flat-panel system., Subjects and Methods: Doses were assessed for 24 procedures: 12 using a new unit with a digital flat-panel system and 12 using a conventional unit. Doses to patients' skin were evaluated with thermoluminescent dosimeters behind the left, middle, and right portions of the liver. The doses to the radiologists were measured by an electronic personal dosimeter placed on the chest outside a lead protector. The maximal skin doses to the patients and the dose equivalents, Hp(0.07), to the radiologists were compared between the two procedure groups with each angiographic unit., Results: For procedures with the new unit, the mean maximal skin dose to the patients was 284 +/- 127 (SD) mGy (range, 130-467 mGy), and Hp(0.07) to the radiologists was 62.8 +/- 17.4 muSv. For procedures with the conventional unit, the maximal skin dose to the patients was 1,068 +/- 439 mGy (range, 510-1,882 mGy), and Hp(0.07) to the radiologists was 68.4 +/- 25.7 muSv. The maximal skin dose to the patients was significantly lower with the new unit than with the conventional unit (p < 0.0005). There was no significant difference in the Hp(0.07) to the radiologists between the two procedure groups., Conclusion: The new digital flat-panel system for angiographic imaging can reduce the radiation dose to patients' skin during TAE for HCC as compared with the conventional system.

Purpose: To compare radiation doses given to patients undergoing IVU (intravenous urography) before and after digitalization of our X-ray department., Material and Methods: IVU examinations were monitored with dose area product meters before and after the X-ray department changed to digital techniques. The first step was a change from film-screen to storage phosphor plates, while the second step involved changing to a flat panel detector. Forty-two patients were included for the film-screen situation, 69 when using the storage phosphor plates, and 70 using the flat panel detector., Results: A dose reduction from 41.8 Gycm2 to 31.5 Gycm2 was achieved with the first step when the film-screen system was replaced with storage phosphor plates. A further reduction to 12.1 Gycm2 was achieved using the flat panel detector., Conclusion: The introduction of the flat panel detectors made a considerable dose reduction possible.

Purpose: To analyze the effects of an optimized fluoroscopy time on patient radiation exposure in the course of coronary angiography (CA) and percutaneous coronary interventions (PTCA), in comparison to those with consistent collimation to the region of interest (ROI). Furthermore, to analyze efforts concerning reduction of radiographic frames as well as concerning adequate instead of best possible image quality., Material and Methods: For 3,115 elective CAs and 1,713 PTCA performed by one interventionist since 1997, we documented the radiographic dose-area products (DAP (R)) and fluoroscopic dose-area products (DAP (F)), the number of radiographic frames and the fluoroscopy times during selected 2-month intervals. Under conditions of constant image intensifier entrance dose, levels of DAP (R)/frame and DAP (F)/s represent valid parameters for consistent collimation., Results: In 1997, the mean baseline values of DAP for elective CA and PTCA amounted to 37.1 and 31.6 Gy x cm (2), respectively. A reduction of mean fluoroscopy times from 264 to 126 seconds for CA and from 630 to 449 seconds for PCI, both resulted in an overall DAP-reduction of merely 20 %. Optimization of mean radiographic frames from 543 to 98 for CA and from 245 to 142 for PTCA enabled reductions of 53 and 13 %, respectively. By restriction to adequate instead of best-possible image quality for coronary angiography in clinical routine, we achieved an optimized radiographic DAP/frame of 30.3 to 13.3 mGy x cm (2), which enabled a 45 % reduction of overall DAP. Most efficient however was a consistent collimation to the ROI, which resulted in a remarkable radiation reduction by 46 % for CA and by 65 % for PTCA., Conclusions: Radiation-reducing educational efforts in the clinical routine of invasive cardiology should -- against widely held opinion -- focus less exclusively toward a reduction of fluoroscopy time but more efficiently toward consistent collimation to the region of interest, reduction of radiographic frames and restriction to an adequate instead of best-possible image quality.

Purpose: We sought to evaluate the performance of dual-readout and single-readout computed radiography compared with direct radiography for detecting subtle lung abnormalities with a standard and a low-dose technique., Materials and Methods: Posteroanterior radiographs of an anthropomorphic chest phantom were obtained with a single-readout storage phosphor radiography system (CRS, pixel size 200 microm), a dual-readout storage phosphor radiography system (CRD, pixel size 100 microm), and a direct detector (DR, pixel size 143 microm) at dose levels of 400 and 800 speed. Ten templates were superimposed to project 4 types of lesions over low- and high-attenuation areas, simulating nodules, micronodules, lines, and patchy opacities. Six radiologists evaluated 60 hard-copy images for the presence or absence of lesions. Statistical significance of differences was evaluated using receiver operating characteristic analysis and analysis of variance., Results: For both low- and high-attenuation areas, CRD (Az = 0.85 and 0.66) was superior to CRS (Az = 0.75 and 0.58) for overall performance and all lesion subtypes (P < 0.05). DR (Az = 0.87 and 0.67) performed slightly better than CRD, being significant only for the detection of micronodules. Acquisition dose significantly affected only the detection of lines and micronodules, whereas the detection of nodules and patchy opacities was not significantly different with reduced exposure, regardless of the system used., Conclusion: The dual-readout CR system significantly outperformed the single-readout CR and almost equaled the performance of DR. Dose reduction was more critical for small-sized lesions (micronodules, lines) than for nodular or patchy opacifications and affected mainly the lesions in high attenuation areas.

After the installation of computed radiography (CR) systems in three hospitals in Luxembourg a patient dose survey was carried out for three radiographic examinations, thorax, pelvis and lumbar spine. It was found that the patient doses had changed in comparison with the patient doses measured for conventional radiography in the same three hospitals. A close collaboration between the manufacturers of the X-ray installations, the CR imaging systems and the medical physicists led to the discovery that the speed class with which each radiographic examination was to be performed, had been ignored, during installation of the digital imaging systems. A number of procedures were carried out in order to calibrate and program the X-ray installations in conjunction with the CR systems. Following this optimisation procedure, a new patient dose survey was carried out for the three radiographic examinations. It was found that patient doses for the three hospitals were reduced.

This paper describes a method for automatic optimisation of parameters (AOP) in digital mammography systems. Using a model of the image chain, contrast to noise ratio (CNR) and average glandular dose (AGD) are computed for possible X-ray parameters and breast types. The optimisation process consists of the determination of the operating points providing the lowest possible AGD for each CNR level and breast type. The proposed metric for the dose used in the design of an AOP mode is the resulting dose to the population, computed by averaging the AGD values over the distribution of breast types in the population. This method has been applied to the automatic exposure control of new digital mammography equipment. Breast thickness and composition are estimated from a low dose pre-exposure and used to index tables containing sets of optimised operating points. The resulting average dose to the population ranges from a level comparable to state-of-the-art screen/film mammography to a reduction by a factor of two. Using this method, both CNR and dose are kept under control for all breast types, taking into consideration both individual and collective risk.

In diagnostic radiology, radiation exposure measures the amount of radiation at a given location in an x-ray beam, dose measures the energy deposited in a specified absorber, and equivalent dose quantifies the biological harm expected from this deposited energy. The effective dose attempts to account for the energy deposited in all irradiated organs as well as their relative radiosensitivity, and is the best available descriptor of the stochastic patient risk. Effective doses can be estimated from measures of the radiation beam incident on the patient as either entrance skin dose or dose-area product in conjunction with appropriate conversion coefficients. These effective dose-conversion coefficients are influenced by the patient size, exposed body region, x-ray beam quality, and x-ray beam area. We present values of skin dose, dose-area product, and effective dose for common examinations in pediatric patients whose size ranges from the newborn to adolescents. In screen-film radiography, the system speed defines the amount of radiation required to generate a satisfactory radiographic film density. Changing the screen thickness normally modifies the speed of screen-film systems, which affects the system resolution but not the level of image noise (mottle). By contrast, digital systems have a fixed resolution but can operate satisfactorily over a wide range of receptor dose, with the amount of noise in the resultant image being inversely related to the amount of radiation used. To ensure that patient doses are kept as low as reasonably achievable (ALARA), it is essential that digital receptor doses be monitored to ensure they stay constant. It is also important that protocols in digital radiography are specific for the imaging task to be performed, and use no more radiation than needed to achieve a satisfactory diagnosis.

We investigated the relationship between average glandular tissue dose and imaging properties such as image density, contrast, and visual image quality, varying the tube voltage and subject parameters (glandular fraction and breast thickness) The wax inserts of 156 phantom and disk of polymethyl methacrylate (PMMA) were arranged between the BR-12 breast-equivalent phantoms. These phantoms were radiographed using automatic exposure control (AEC) for the various combinations of tube voltage and subject parameters. In addition, exposures were measured at the same time. The results showed that the average glandular tissue dose increased when the high glandular fraction and/or thick phantom were being radiographed with the low tube voltage. We found that the criteria of the Japanese Mammography Screening Accreditation Program for image quality were not satisfied when breast thickness was greater than 6 cm.

In the paediatric cardiac catheterization laboratory the reduction of the radiation dose of diagnostic and interventional procedures is of high priority. Therefore, we performed an experimental study for optimizing the automatic exposure control (AEC) for cardiac angiography. With a Philips Integris BH 5000 system, six AEC programs were configured to acquire X-ray images of 8 cm to 18.5 cm thick PMMA phantoms at tube voltages between 50 kV and 90 kV, with 0.2 mm or 0.4 mm Cu filters and with or without an anti-scatter grid. At constant detector dose, entrance dose (ED) and image quality were evaluated as functions of the voltage. Changes in image quality were determined by the differential signal-to-noise ratio measured within regions of low (SNRb) and high (SNRd) attenuation. At equal voltages, ED saving was approximately 29% with the 0.4 mm Cu beam filtering as compared with 0.2 mm Cu, largely independent of object thickness. SNRb and SNRd were only dependent on the voltage. While SNRb was high at low voltages, SNRd showed a maximum at approximately 79 kV. Using a grid, ED increased with increasing object thickness by a factor of 1.9 to 3.5. At equal voltages, the grid led to significant image improvements, with SNRb and SNRd increasing by 27% and 11%, respectively. SNRb and SNRd are useful descriptors of the image quality in cardiac angiography. Highest image quality was found with tube voltages between 55 kV and 77 kV, independently of object thickness. To minimize dose, the thickness of the copper filter should be chosen to be as large as possible provided the tube's power limit allows keeping the voltage below the upper limit. In view of the substantial image improvement, the use of a grid is recommended for all patients, even for newborns.

Purpose: To investigate the effect of a new device for predialing the number of cinegraphic frames before each coronary angiogaphy, with the objective of reducing the patient dose area product (DAP) from coronary angiography, which typically requires 1000 to 2350 cinegraphic frames. That DAP is high and stated to be between 15.6 to 106.3 Gy x cm (2). Applying the accepted DAP-to-ED conversion factors, for the thoracic region of approximately 0.20 mSv/Gy x cm (2), this corresponds to a mean effective dose (ED) in the range of 3.1 to 21.3 mSv., Material and Methods: For patients undergoing elective coronary angiography, we compared various parameters of radiation exposure obtained with judicious radiation reducing standard techniques (n = 106) and with an additional new rotary switch for predialing the number of cinegraphic frames (n = 106)., Results: The patient radiation dose was significantly lower with the new device, with the mean DAP reduced to 5.5 from 9.1 Gy x cm (2). The corresponding reducation of the mean DAP for left ventriculography and coronary angiography was 1.3 from 1.7, and 4.2 from 7.4 Gy x cm (2), respectively. The number of cinegraphic frames was 98 vs. 184, whereas the number of cinegraphic runs and the fluoroscopy time were comparable., Conclusion: Predialing the cinegraphic frame number before each cinegraphic run enables a reduction of the patients effective dose from coronary angiography to 0.8 mSv, i. e. to 57 % of the baseline value and far below typically reported values.

Since the 1990s, computer-assisted methods have been well-established in the field of orthopedics and traumatology. In addition to the proven improvement in the field of surgical precisioncompared with conventional techniques, the decrease in the amount of emitted ionizing radiation inside of the operating room was cited to constitute an additional major advantage of computer-based navigation. The goal of this study was to quantify X-ray dose values exposed during both conventional methods and computer-assisted procedures, the latter being performed using a C-arm device SIREMOBIL Iso-C3D (Siemens Medical Solutions). The clinical measurements were supplemented by laboratory experiments using a pinpoint ionization chamber placed inside a standard lucite phantom. The clinical part of the study investigated the application of new, i.e. computer assisted, techniques in comparison with conventional procedures on in total 42 patients experiencing surgery either on their lower extremities (n = 14) or on the spine (n = 28). The techniques applied were: (1) conventional surgical procedure, (2) CT-based navigation, (3) C-arm navigation, and (4) Iso-C3D-navigation. The main focus of the clinical evaluation was the determination of radiation dose values by means of thermoluminescence dose meters, accompanied by the registration of the operation times of the X-ray tube during a surgical intervention. The conclusions from the clinical studies are in agreement with the results from the laboratory measurements. Computer-assisted techniques led to a significant reduction in X-ray dose exposure and drastically shortened irradiation times. The most pronounced decrease in the emission of ionizing radiation was achieved in case of the Iso-C3D-navigation, which has only recently been introduced into clinical practice, i.e. during runtime of this study.

Purpose: To compare a large-area amorphous silicon flat-panel detector with an asymmetric screen-film system for the depiction of simulated patterns of interstitial lung disease, nodules, and catheters, as well as for evaluation of dose reduction., Materials and Methods: Ground-glass, linear, miliary, and reticular patterns; nodules; and catheters were superimposed over an anthropomorphic chest phantom. Hard copies were generated at different dose levels (speeds: 400, 800, and 1,600) with a flat-panel detector and were compared with copies generated with an asymmetric screen-film system (speed, 400). Detection performance of eight radiologists was compared with a receiver operating characteristic analysis of 19,200 observations per pattern. A difference was significant with a P value of.05., Results: There was no statistically significant difference between the flat-panel detector and the asymmetric screen-film system at the same speed (P >.05) and between the flat-panel detector at a speed of 800 and the asymmetric screen-film system at a speed of 400 (P >.05). The visibility of linear, miliary, and reticular patterns over lucent lung and of nodules smaller than 10 mm and catheters over obscured chest regions on copies generated at a speed of 1,600 with the flat-panel detector decreased, compared with the visibility of these features on copies generated with the asymmetric screen-film system (P <.05)., Conclusion: The diagnostic performance of the flat-panel detector is comparable to that of the asymmetric screen-film system for depiction of all simulated patterns of interstitial lung diseases, nodules, and catheters at the same speed and offers the potential of dose reduction to a speed of 800.

Purpose: Comparison of the imaging capabilities of storage phosphor (computed) radiography and flat plate radiography with conventional film-screen radiography to find new strategies for quality and dose management, i. e., optimizing imaging quality and dose depending on the imaging method and clinical situation., Materials and Methods: Images of a CDRAD-phantom, hand-phantom, abdomen-phantom and chest-phantom obtained with different exposure voltages (50 kV, 73 kV, 109 kV) and different speeds (200, 400, 800, 1600) were processed with various digital systems (flat plate detector: Digital Diagnost [Philips]; storage phosphors: ADC-70 [Agfa], ADC-Solo [Agfa], FCR XG 1 [Fuji]) and a conventional film-screen system (HT100G/ Ortho Regular [Agfa])., Results: The evaluation of CDRAD images found the flat plate detector system to have the highest contrast detectability for all dose levels, followed by the FCR XG 1, ADC-Solo and ADC-70 systems. Comparison of the organ-phantom images found the flat plate detector system to be equal to film-screen radiography and especially to storage phosphor systems even for low exposure doses., Conclusions: Flat plate radiography systems demonstrate the highest potential for high image quality when reducing the exposure dose. Depending on the system generation, the storage phosphor systems also show an improved image quality, but the possibility of a dose reduction is limited in comparison with the flat plate detector system.