Dose audit for patients undergoing two common radiography examinations with digital radiology systems

PURPOSE

We aimed to determine the radiation doses delivered to patients undergoing general examinations using computed or digital radiography systems in Turkey.

MATERIALS AND METHODS

Radiographs of 20 patients undergoing posteroanterior chest X-ray and of 20 patients undergoing anteroposterior kidney-ureter-bladder radiography were evaluated in five X-ray rooms at four local hospitals in the Ankara region. Currently, almost all radiology departments in Turkey have switched from conventional radiography systems to computed radiography or digital radiography systems. Patient dose was measured for both systems. The results were compared with published diagnostic reference levels (DRLs) from the European Union and International Atomic Energy Agency.

RESULTS

The average entrance surface doses (ESDs) for chest examinations exceeded established international DRLs at two of the X-ray rooms in a hospital with computed radiography. All of the other ESD measurements were approximately equal to or below the DRLs for both examinations in all of the remaining hospitals. Improper adjustment of the exposure parameters, uncalibrated automatic exposure control systems, and failure of the technologists to choose exposure parameters properly were problems we noticed during the study.

CONCLUSION

This study is an initial attempt at establishing local DRL values for digital radiography systems, and will provide a benchmark so that the authorities can establish reference dose levels for diagnostic radiology in Turkey.Standard radiology procedures in projection radiography (plain films or digital equipment) account for 48% of all diagnostic radiology examinations and contribute 41% to the collective dose (1). One of the main reasons for introducing the diagnostic reference level (DRL) concept was to investigate situations where patient doses are unusually high. Therefore, DRLs provide a valuable method for dose optimization (2). The as-low-as-reasonably-achievable principle should be considered in such dose-optimization processes. Surveys have shown variation by as much as two magnitudes in the doses to patients undergoing the same X-ray examinations (3). This wide variation in patient dose proves that there is room to optimize the radiography process. There is also considerable evidence that substantial reductions in these medical exposures are possible without detriment to patient care (4).To reduce the radiation dose to the patient, guidelines must be followed for appropriate levels of exposure. The International Commission on Radiological Protection (ICRP) and European Commission have recommended the use of DRLs (3–5). It has been recommended that the 75th percentile or third quartile of the dose distribution in a population of standard-sized patients is an appropriate level for the DRL (5). According to the Commission of European Communities, the purpose of DRLs is to encourage radiology departments to investigate their patient radiation doses and make historical, national, or international comparisons (6). To our knowledge, there are no published Turkish data on patient doses in general radiography with digital X-ray systems. Torres et al. (7) made the following statement: the implementation of these new technologies requires an estimation of the doses that are actually being administered in clinical practice, in order to check that, in cases of both day-to-day practice and optimization protocols, doses are kept within reference values and as low as achievable in relation to the aimed image quality. This statement also holds true for Turkey.In Turkey, many X-ray examinations are performed using new technologies such as computed radiography (CR) and direct digital radiography (DR), although no DRLs for conventional radiography practices published by national authorities have investigated this new equipment, which has the potential to deliver lower patient doses than previous X-ray devices. Council Directive 97/43 of the European Atomic Energy Community defines DRL and expects member states to promote the establishment of DRLs for radiodiagnostic examinations. Therefore, national DRLs should be defined by national authorities, and European levels have already been established.The objectives of this study were to perform a radiation dose audit, to compare the results of the patient dose survey with international DRLs for both examinations, to present the study results to radiologists in Turkey in order to draw attention to the patient doses using digital radiography systems, and to observe improper practices in the clinics studied.     

Assessing the use of digital radiography and a real-time interactive pulmonary nodule analysis system for large population lung cancer screening

Rationale and objectives

To assess the use of chest digital radiograph (DR) assisted with a real-time interactive pulmonary nodule analysis system in large population lung cancer screening.

Materials and methods

346 DR/CR patient studies with corresponding CT images were selected from 12,500 patients screened for lung cancer from year 2007 to 2009. Two expert chest radiologists established CT-confirmed Gold Standard of nodules on DR/CR images with consensus. These cases were read by eight other chest radiologists (participating radiologists) first without using a real-time interactive pulmonary nodule analysis system and then re-read using the system. Performances of participating radiologists and the computer system were analyzed.

Results

The computer system achieved similar performance on DR and CR images, with a detection rate of 76% and an average FPs of 2.0 per image. Before and after using the computer-aided detection system, the nodule detection sensitivities of the participating radiologists were 62.3% and 77.3% respectively, and the A_z values increased from 0.794 to 0.831. Statistical analysis demonstrated statically significant improvement for the participating radiologists after using the computer analysis system with a P-value 0.05.

Conclusion

The computer system could help radiologists identify more lesions, especially small ones that are more likely to be overlooked on chest DR/CR images, and could help reduce inter-observer diagnostic variations, while its FPs were easy to recognize and dismiss. It is suggested that DR/CR assisted by the real-time interactive pulmonary nodule analysis system may be an effective means to screen large populations for lung cancer.     

To evaluate the efficacy of ultrasonography compared to clinical diagnosis, radiography and histopathological findings in the diagnosis of maxillofacial swellings

Aim

To evaluate the efficacy of Ultrasonography compared to clinical diagnosis, radiography and histopathological findings in the diagnosis of maxillofacial swellings.

Material and methods

The study was conducted on forty-five patients with maxillofacial swellings. The clinical diagnosis, radiographic diagnosis and ultrasonographic diagnosis were made which was compared to the histopathological diagnosis. The maxillofacial swellings included cystic lesions, benign swellings, malignant swellings, lymphadenopathies and abscesses and space infections.

Results

The diagnostic accuracy and contingency coefficient was evaluated considering histopathology as gold standard. The diagnostic accuracy of ultrasound was found to be 92.30% in the diagnosis of cystic lesions, 87.5% in benign tumors, 81.8% in malignant tumors, 100% in lymphadenopathies and 90% in space infections and abscesses. The contingency coefficient of 0.934 was obtained when ultrasonography was compared to the histopathology, which was highly significant. Similar significant results were obtained comparing ultrasonography with clinical diagnosis (0.895) and radiographic diagnosis (0.889).

Conclusion

Ultrasonography provides accurate imaging of the head and neck region and provides information about the nature of the lesion, its extent, and relationship with the surrounding structures. As the conventional and digital radiography enable the diagnosis of the presence of the disease, but do not give any indication of its nature. So, together with clinical and histopathological examinations, real time ultrasound imaging works out as a valuable adjunct in the diagnosis of orofacial swellings.     

Digital versus screen-film mammography: a retrospective comparison in a population-based screening program

Background

Digital radiography has several advantages over screen-film radiography in data storage and retrieval, making it an attractive alternative to screen-film radiography in screening mammography programs, if it performs as well.

Methods

We retrospectively compared screen-film mammography, photon-counting direct radiography, and computed radiography with population-based screening data from the Breast Unit at Helsingborg Hospital, Sweden, collected between January 2000 and February 2005. Outcomes were cancer detection rates, recall rates, and positive predictive values for breast cancer detection in women reappearing for screening.

Results

Data were available for 52,172 two-view mammography examinations of 24,875 women. No initial screening (prevalence) examinations were included. Cancer detection rates based on mammographic findings were 0.31% (81/25,901) for film, 0.49% (48/9841) for photon-counting, and 0.38% (63/16,430) for computed radiography. The recall rate for film was 1.4%, which was significantly higher than that for PC-DR (1.0%; P < 0.001) and computed radiography (1.0%; P < 0.001). The positive predictive value was lower for film (22%) than for photon-counting (47%; P < 0.001) and computed radiography (39%; P < 0.001). In addition, the average glandular dose was 1.1 mGy for film, 0.28 mGy for photon-counting and 0.92 mGy for computed radiography. Thus, photon-counting provided a 75% dose reduction, and computed radiography a 16% dose reduction, over film.

Conclusions

Digital radiography, especially photon-counting, performs as well as or better than screen-film radiography. Given the advantages related to improved data storage and communication, digital radiography seems to be a valid alternative to screen-film radiography.     

Dosisreduktion und ad?quate Bildqualit?t in der digitalen Radiographie: ein Widerspruch?

Clinical/methodical issue

Dose reduction and adequate image quality in digital radiography – a contradiction?

Standard radiological methods

Digital radiography has already replaced traditional screen-film systems.

Methodical innovations

Substantial improvements in both dose efficiency and spatial resolution demonstrate the rapid developments in digital radiography.

Performance

Needle-detector systems have shown up to a 50% dose reduction compared to traditional screen-film systems. There is also a dose reduction capability of up to 50% comparing direct radiography (DR) systems to computed radiography (CR) systems for chest X-rays. However, despite the most recent achievements of CR technology, the dose efficiency of DR systems (caesium iodide flat-panel detector) is unparalleled.

Achievements

The progress in detector technology has contributed to dose reduction and improved image quality, while saving time and providing a higher examination rate.

Practical recommendations

The use of dose indicators and longitudinal dose control are important to avoid substantial accidental dose increase. The dose applied to patients should fall markedly below the defined diagnostic reference levels within the European Union. Regular quality control, as well as continuous education and training of medical and technical personnel, contribute to ensure that the ALARA (as low as reasonably achievable) principle is consistently followed.     

Radiation dose of digital tomosynthesis for sinonasal examination: comparison with multi-detector CT

Objective

Using an anthropomorphic phantom, we have investigated the feasibility of digital tomosynthesis (DT) of flat-panel detector (FPD) radiography to reduce radiation dose for sinonasal examination compared to multi-detector computed tomography (MDCT).

Materials and methods

A female Rando phantom was scanned covering frontal to maxillary sinus using the clinically routine protocol by both 64-detector CT (120 kV, 200 mA s, and 1.375-pitch) and DT radiography (80 kV, 1.0 mA s per projection, 60 projections, 40° sweep, and posterior–anterior projections). Glass dosimeters were used to measure the radiation dose to internal organs including the thyroid gland, brain, submandibular gland, and the surface dose at various sites including the eyes during those scans. We compared the radiation dose to those anatomies between both modalities.

Results

In DT radiography, the doses of the thyroid gland, brain, submandibular gland, skin, and eyes were 230 ± 90 μGy, 1770 ± 560 μGy, 1400 ± 80 μGy, 1160 ± 2100 μGy, and 112 ± 6 μGy, respectively. These doses were reduced to approximately 1/5, 1/8, 1/12, 1/17, and 1/290 of the respective MDCT dose.

Conclusion

For sinonasal examinations, DT radiography enables dramatic reduction in radiation exposure and dose to the head and neck region, particularly to the lens of the eye.     

"Drug mules" as a radiological challenge: sensitivity and specificity in identifying internal cocaine in body packers, body pushers and body stuffers by computed tomography, plain radiography and Lodox

Purpose

The purpose of our study was to retrospectively evaluate the specificity, sensitivity and accuracy of computed tomography (CT), digital radiography (DR) and low-dose linear slit digital radiography (LSDR, Lodox^®) in the detection of internal cocaine containers.

Methods

Institutional review board approval was obtained. The study collectively consisted of 83 patients (76 males, 7 females, 16–45 years) suspected of having incorporated cocaine drug containers. All underwent radiological imaging; a total of 135 exams were performed: nCT = 35, nDR = 70, nLSDR = 30. An overall calculation of all “drug mules” and a specific evaluation of body packers, pushers and stuffers were performed. The gold standard was stool examination in a dedicated holding cell equipped with a drug toilet.

Results

There were 54 drug mules identified in this study. CT of all drug carriers showed the highest diagnostic accuracy 97.1%, sensitivity 100% and specificity 94.1%. DR in all cases was 71.4% accurate, 58.3% sensitive and 85.3% specific. LSDR of all patients with internal cocaine was 60% accurate, 57.9% sensitive and 63.4% specific.

Conclusions

CT was the most accurate test studied. Therefore, the detection of internal cocaine drug packs should be performed by CT, rather than by conventional X-ray, in order to apply the most sensitive exam in the medico-legal investigation of suspected drug carriers. Nevertheless, the higher radiation applied by CT than by DR or LSDR needs to be considered. Future studies should include evaluation of low dose CT protocols in order to address germane issues and to reduce dosage.     

National reference doses for dental cephalometric radiography

Objectives

Diagnostic reference levels (DRLs) are an important tool in the optimisation of clinical radiography. Although national DRLs are provided for many diagnostic procedures including dental intra-oral radiography, there are currently no national DRLs set for cephalometric radiography. In the absence of formal national DRLs, the Health Protection Agency (HPA) has previously published National Reference Doses (NRDs) covering a wide range of diagnostic X-ray examinations. The aim of this study was to determine provisional NRDs for cephalometric radiography.

Methods

Measurements made by the Dental X-ray Protection Service (DXPS) of the HPA, as part of the cephalometric X-ray equipment testing service provided to dentists and dental trade companies throughout the UK, were used to derive provisional NRDs.

Results

Dose–area product measurements were made on 42 X-ray sets. Third quartile dose–area product values for adult and child lateral cephalometric radiography were found to be 41 mGy cm² and 25 mGy cm², respectively, with individual measurements ranging from 3 mGy cm² to 108 mGy cm².

Conclusion

This report proposes provisional NRDs of 40 mGy cm² and 25 mGy cm² for adult and child lateral cephalometric radiographs, respectively; these doses could be considered by employers when establishing their local DRLs.Since the introduction of the Ionising Radiation (Medical Exposure) Regulations in 2000 (IR(ME)R 2000) [1], employers responsible for the use of dental and medical X-ray equipment have been required to establish local diagnostic reference levels (DRLs) for each common radiographic procedure undertaken. Reviews of their radiography practices are required if DRLs are consistently exceeded. In effect, a diagnostic reference level can be considered the level of dose expected not to be exceeded for a standard procedure when good and normal practice regarding diagnostic and technical performance is applied. Local DRLs should be established by the employer in consultation with the appointed medical physics expert (MPE).To assist employers to set appropriate local DRLs, the Department of Health adopted national DRLs for many common X-ray examinations [2]. National DRLs are normally set at the third quartile value of the patient dose distribution observed for a particular type of X-ray examination during a widescale survey (i.e. the patient dose value that only 25% of assessed X-ray sets exceed).The national DRLs adopted by the Department of Health were primarily based on the Health Protection Agency’s (HPA) 2000 review of the National Patient Dose Database (NPDD) [3]. However, at the time of the review, dental X-ray examinations were not included in the NPDD. Subsequently, the national DRL for dental intra-oral examinations was based on separate patient dose data published by the HPA in 1999 [4].The NPDD was designed to collate measurements of patient radiation doses from common diagnostic X-ray examinations carried out throughout the UK and to provide a major source of information for the review and adoption of new national DRLs. In July 2007, the HPA published the 2005 review of the NPDD [5]; this time, the review included dose data from dental X-ray examinations and proposed new National Reference Doses (NRDs) for intra-oral and panoramic examinations, which updated those first proposed in 1999 [4]. Although these NRDs for intra-oral and panoramic examinations have not been formally adopted by the Department of Health as national DRLs, the data collected are representative of current practice.When setting a local DRL, national DRLs and NRDs should be considered and it would be expected that the local DRL should not normally exceed the national level. However, just ensuring that patient doses are below the national DRL or NRD does not mean that local practices are being optimised. Dental surgeries using modern equipment and techniques should be able to set a local DRL significantly lower than the national level, based on their local circumstances.A national review of doses arising from dental cephalometric examinations has never been undertaken in the UK and cephalometric doses have not, to date, been included in the NPDD. For many years, however, the Dental X-ray Protection Service (DXPS) of the HPA has carried out the commissioning and routine quality assurance testing of cephalometric equipment installed throughout the UK. As part of the testing procedures, measurements are made of representative patient doses. This report proposes a patient dose measurement method together with rounded third quartile dose values for adult and child lateral cephalometric radiography based on the patient dose measurements made by DXPS.Owing to the specialist applications of cephalometric radiography, there are only a relatively small number of units in use in the UK compared with intra-oral or panoramic equipment; consequently, the sample size considered in this report is fairly small. However, the dose measurements are considered reasonably representative of UK practice so that the third quartile values can be considered as provisional NRDs and provide a useful guide to employers when establishing their local DRLs. Furthermore, it is anticipated that the patient dose data presented in this report and any data subsequently collected on cephalometric radiography doses will be included in the NPDD so that future reviews of the database can propose NRDs for cephalometric radiography.     

National Survey of Radiation Doses of Pediatric Chest Radiography in Korea: Analysis of the Factors Affecting Radiation Doses

Objective

To investigate radiation doses in pediatric chest radiography in a national survey and to analyze the factors that affect radiation doses.

Materials and Methods

The study was based on the results of 149 chest radiography machines in 135 hospitals nationwide. For each machine, a chest radiograph was obtained by using a phantom representing a 5-year-old child (ATOM® dosimetry phantom, model 705-D, CIRS, Norfolk, VA, USA) with each hospital''s own protocol. Five glass dosimeters (M-GD352M, Asahi Techno Glass Corporation, Shizuoka, Japan) were horizontally installed at the center of the phantom to measure the dose. Other factors including machine''s radiography system, presence of dedicated pediatric radiography machine, presence of an attending pediatric radiologist, and the use of automatic exposure control (AEC) were also evaluated.

Results

The average protocol for pediatric chest radiography examination in Korea was 94.9 peak kilovoltage and 4.30 milliampere second. The mean entrance surface dose (ESD) during a single examination was 140.4 microgray (µGy). The third quartile, median, minimum and maximum value of ESD were 160.8 µGy, 93.4 µGy, 18.8 µGy, and 2334.6 µGy, respectively. There was no significant dose difference between digital and non-digital radiography systems. The use of AEC significantly reduced radiation doses of pediatric chest radiographs (p < 0.001).

Conclusion

Our nationwide survey shows that the third quartile, median, and mean ESD for pediatric chest radiograph is 160.8 µGy, 93.4 µGy, and 140.4 µGy, respectively. No significant dose difference is noticed between digital and non-digital radiography systems, and the use of AEC helps significantly reduce radiation doses.     

Accuracy of vertical height measurements on direct digital panoramic radiographs using posterior mandibular implants and metal balls as reference objects

Objectives:

Conventional panoramic radiography, a widely used radiographic examination tool in implant treatment planning, allows evaluation of the available bone height before inserting posterior mandibular implants. Image distortion and vertical magnification due to projection geometry is well described for rotational panoramic radiographs. To assess the accuracy of vertical height measurements on direct digital panoramic radiographs, implants and metal balls positioned in the posterior mandible were used as radio-opaque reference objects. The reproducibility of the measuring method was assessed by the inter- and intraobserver agreements.

Methods:

Direct digital panoramic radiographs, performed using a Kodak 8000C (Eastman Kodak Company, Rochester, NY), of 17 partially edentulous patients (10 females, 7 males, mean age 65 years) were selected from an X-ray database gathered during routine clinical evaluation of implant sites. Proprietary software and a mouse-driven calliper were used to measure the radiological length of 25 implants and 18 metal reference balls, positioned in mandibular posterior segments. The distortion ratio (DR) was calculated by dividing the radiological implant length by the implant''s real length and the radiological ball height by the ball''s real height.

Results:

Mean vertical DR was 0.99 for implants and 0.97 for balls, and was unrelated to mandibular sites, side, age, gender or observer. Inter- and intraobserver agreements were acceptable for both reference objects.

Conclusions:

Vertical measurements had acceptable accuracy and reproducibility when a software-based calibrated measurement tool was used, confirming that digital panoramic radiography can be reliably utilized to determine the pre-operative implant length in premolar and molar mandibular segments.     

Accuracy of direct digital radiography for detecting occlusal caries in primary teeth compared with conventional radiography and visual inspection: an in vitro study

Objectives

The diagnosis of caries lesions is still a matter of concern in dentistry. The diagnosis of dental caries by digital radiography has a number of advantages over conventional radiography; however, this method has not been explored fully in the field of paediatric dentistry. This in vitro research evaluated the accuracy of direct digital radiography compared with visual inspection and conventional radiography in the diagnosis of occlusal caries lesions in primary molars.

Methods

50 molars were selected and evaluated under standardized conditions by 2 previously calibrated examiners according to 3 diagnostic methods (visual inspection, conventional radiography and direct digital radiography). Direct digital radiographs were obtained with the Dixi3 system (Planmeca, Helsinki, Finland) and the conventional radiographs with InSight film (Kodak Eastman Co., Rochester, NY). The images were scored and a reference standard was obtained histologically. The interexaminer reliability was calculated using Cohen''s kappa test and the specificity, sensitivity and accuracy of the methods were calculated.

Results

Examiner reliability was good. For lesions limited to the enamel, visual inspection showed significantly higher sensitivity and accuracy than both radiographic methods, but no significant difference was found in specificity. For teeth with dentinal caries, no significant differences were found for any parameter when comparing visual and radiographic evaluation.

Conclusions

Although less accurate than the visual method for detecting caries lesions confined to the enamel, the direct digital radiographic method is as effective as conventional radiographic examination and visual inspection of primary teeth with occlusal caries when the dentine is involved.     

A comparison between the electronic magnification (EM) and true magnification (TM) of breast phantom images using a CDMAM phantom

Purpose

To provide a comparison between the image quality of electronically magnified (EM) and geometric, or true, magnification (TM) mammographic images.

Materials and methods

One Computed Radiography (CR), one Digital Radiography (DR) and two screen–film (S–F) imaging systems were investigated. A Contrast-Detail Mammography (CDMAM) phantom was used as a test object. Three contact images and three sets of TM images with a magnification factor of 1.8 were taken on all systems. Software was used to zoom the contact images by a factor of 1.8 to produce EM images. Two observers evaluated all of the images. An Image Quality Figure and contrast detail curve were used to analyze the observer data and Mann–Whitney U-tests were performed to determine the statistical significance of the results.

Results

No significant differences were found between soft copy and hard copy for any imaging modality. No significant difference in contrast detail detectability (CDD) was seen between EM images from the two digital systems and TM images on S–F systems. The results for the DR EM images and S–F TM images also showed no differences. The CDD of DR TM images was significantly better than both EM and S–F TM images.

Conclusion

Digitally zoomed images offer the same level of CDD as S–F TM images, and so may be viably used in their place. DR systems offer greater CDD than conventional S–F images, when comparing the TM images. This implies that doses can be greatly reduced for TM views using DR systems, while maintaining acceptable image quality.     

Quantitative assessment of the influence of anatomic noise on the detection of subtle lung nodule in digital chest radiography using fractal-feature distance

Purpose

To confirm whether or not the influence of anatomic noise on the detection of nodules in digital chest radiography can be evaluated by the fractal-feature distance.

Materials and methods

We used the square images with and without a simulated nodule which were generated in our previous observer performance study; the simulated nodule was located on the upper margin of a rib, the inside of a rib, the lower margin of a rib, or the central region between two adjoining ribs. For the square chest images, fractal analysis was conducted using the virtual volume method. The fractal-feature distances between the considered and the reference images were calculated using the pseudo-fractal dimension and complexity, and the square images without the simulated nodule were employed as the reference images. We compared the fractal-feature distances with the observer's confidence level regarding the presence of a nodule in plain chest radiograph.

Results

For all square chest images, the relationships between the length of the square boxes and the mean of the virtual volumes were linear on a log–log scale. For all types of the simulated nodules, the fractal-feature distance was the highest for the simulated nodules located on the central region between two adjoining ribs and was the lowest for those located in the inside of a rib. The fractal-feature distance showed a linear relation to an observer's confidence level.

Conclusion

The fractal-feature distance would be useful for evaluating the influence of anatomic noise on the detection of nodules in digital chest radiography.     

Technical and clinical breast cancer screening performance indicators for computed radiography versus direct digital radiography

Objectives

To compare technical and clinical screening performance parameters between computed radiography (CR) and direct digital radiography (DR) systems.

Methods

The number of women screened with CR was 73,008 and with DR 116,945. Technical and patient dose survey data of 25 CR and 37 DR systems were available. Technical performance was expressed by threshold thickness values at the mean glandular dose (MGD) level of routine practice. Clinical indicators included recall rate (RR), cancer detection rate (CDR), percentage of ductal carcinoma in situ (DCIS), percentage of cancers with T-scores smaller than 1 cm and positive predictive value (PPV).

Results

Contrast threshold values for the 0.1-mm gold disk were 1.44 μm (SD 0.13 μm) for CR and 1.20 μm (SD 0.13 μm for DR). MGD was 2.16 mGy (SD 0.36 mGy) and 1.35 mGy (SD 0.32 mGy) for CR and DR respectively. We obtained for CR, respectively DR, the following results: RR in the first round of 5.48 % versus 5.61 %; RR in subsequent rounds of 2.52 % versus 2.65 %; CDR of 0.52 % versus 0.53 %; DCIS of 0.08 % versus 0.11 %; a rate of cancers with T-scores smaller than 1 cm of 0.11 % versus 0.11 %; PPV of 18.45 % versus 18.64 %; none of them was significantly different.

Conclusion

Our screening indicators are reassuring for the use of CR and DR, with CR operating at 60 % higher MGD.

Key Points

? Breast cancer screening can employ both computed (CR) and direct digital radiography (DR). ? Screening performance parameters for CR and DR technology are not significantly different. ? Screening parameters are in accordance with European Guidelines. ? Radiation doses employed for CR are generally 60 % greater than for DR.     

Diagnostic quality of 50 and 100 μm computed radiography compared with screen-film mammography in operative breast specimens

Objective

To compare reader ratings of the clinical diagnostic quality of 50 and 100 μm computed radiography (CR) systems with screen–film mammography (SFM) in operative specimens.

Methods

Mammograms of 57 fresh operative breast specimens were analysed by 10 readers. Exposures were made with identical position and compression with three mammographic systems (Fuji 100CR, 50CR and SFM). Images were anonymised and readers blinded to the CR system used. A five-point comparative scoring system (−2 to +2) was used to assess seven quality criteria and overall diagnostic value. Statistical analysis was subsequently performed of reader ratings (n=16 925).

Results

For most quality criteria, both CR systems were rated as equivalent to or better than SFM. The CR systems were significantly better at demonstrating skin edge and background tissue (p<1×10⁻⁵). Microcalcification was best demonstrated on the CR50 system (p<1×10⁻⁵). The overall diagnostic value of both CR systems was rated as being as good as or better than SFM (p<1×10⁻⁵).

Conclusion

In this clinical setting, the overall diagnostic performance of both CR systems was as good as or better than SFM, with the CR50 system performing better than the CR100.There are currently three technologies widely available for diagnostic mammography: screen–film mammography (SFM) and two forms of large-field digital mammography [1]. The use of the term full-field digital mammography (FFDM) varies in the published literature and has been applied to both computed radiography (CR) and direct digital radiography (DR). Small-field digital mammography (SFDM) is mainly used for imaging during stereotactic biopsy [2].The advantages of digital mammography over SFM include: improved sensitivity in dense breast tissue, reduced radiation dose, the ability to manipulate images for review, and digital storage and retrieval methods [3]. CR was the earliest digital system in use. Imaging cassettes contain a re-useable photostimulable phosphor, replacing the traditional screen–film cassettes, and are then transferred to a laser reader. DR has an in-built detector and reader. Digital mammography has a lower spatial resolution than SFM, but has a very high contrast resolution. This allows the overall resolution of digital mammography to be at least equivalent to SFM [4-8], even when viewing calcification smaller than the pixel size [9]. Some CR systems have not met the quality standards of a number of governing bodies for mammography, including the European Network of Reference Assessment Centres (EUREF) and the NHS Breast Screening Programme (NHSBSP) [10,11]. This is related to the resolution achievable with 100 µm cassettes [12]. It is now known that CR systems using 50 µm cassettes can provide improved resolution, at an acceptable mean glandular dose, and have been approved for screening by the NHSBSP [13-15].Phantom studies indicate that the resolution and performance of DR are greater than those of CR [16,17], but have limitations. Although there are many clinical studies comparing the performance of DR and SFM [4-7,9,18-26], there are fewer that compare CR with SFM or DR [8,25,27-32]. We sought a method to compare the clinical diagnostic quality of two types of CR technology with that of SFM. We chose to study surgical specimens of breast tissue, which, although not absolutely comparable to in vivo mammography, allows realistic testing of image quality. In addition, multiple exposures can be obtained in reproducible conditions without irradiating the patient.     

Organ doses and lifetime attributable risk evaluations for scoliosis examinations of adolescent patients with the EOS imaging system

Purpose

The goal of this work is to evaluate organ doses and lifetime attributable risk of cancer incidence and mortality in scoliosis examinations of adolescent patients performed with EOS imaging system, in order to optimize patient dose and protocols.

Methods

An anthropomorphic phantom of a normal patient, with thermoluminescent dosimeters in correspondence with the main organs at risk, was imaged with both EOS and computed radiography (CR). For each modality, effective dose was calculated from the measured organ doses. Lifetime attributable risk was computed accordingly to the Committee on the Biological Effects of Ionizing Radiation (BEIR VII) and Public Health England (HPA) publications.

Results

Except for testes and eyes, which were excluded from the scan in CR protocol, for all the other organs the doses delivered with CR examination were higher than these delivered by EOS system. The effective dose in EOS examination (0.43 ± 0.04 mSv) is about two times less than the dose in computed radiography with anti-scatter grid examination (0.87 ± 0.09 mSv), and, consequently, also the cancer probability is lower (5.4 vs 9.7 number of any cancers induction cases per 100,000 person examined, for a 20-year-old male patient).

Conclusions

The EOS system is efficient in limiting patient dose. The shielding of testes and the exclusion of eyes from the scan could allow to further reduce the dose.

     

Systematic review of flexion/extension radiography of the cervical spine in trauma patients

Introduction

The aim of this review was to investigate whether Flexion/Extension (F/E) radiography adds diagnostic value to CT or MRI in the detection of cervical spine ligamentous injury and/or clinically significant cervical spine instability of blunt trauma patients.

Methods

A systematic search of literature was done in Pubmed, Embase and Cochrane Library databases. Primary outcome was sensitivity and specificity of F/E radiography. Secondary outcomes were the positive predicting value (PPV) and negative predicting value (NPV) (with CT or MRI as reference tests due to the heterogeneity of the included studies) of each modality and the quality of F/E radiography.

Results

F/E radiography was overall regarded to be inferior to CT or MRI in the detection of ligamentous injury. This was reflected by the high specificity and NPV for CT with F/E as reference test (ranging from 97 to 100% and 99 to 100% respectively) and the ambiguous results for F/E radiography with MRI as its reference test (0–98% and 0–83% for specificity and NPV respectively). Image quality of F/E radiography was reported to have 31 to 70% adequacy, except in two studies which reported an adequacy of respectively 4 and 97%.

Conclusion

This systematic review of the literature shows that F/E radiography adds little diagnostic value to the evaluation of blunt trauma patients compared to CT and MRI, especially in those cases where CT or MRI show no indication of ligamentous injury.     

Radiation dose in digital chest radiography: comparison among three technologies

PURPOSE: To compare the Entrance Surface Dose (ESD) for a normal patient, measured on three types of dedicated digital equipment for chest radiography: an amorphous selenium system, a CR (Computed Radiography) system, and a system for direct radiography (DR) based on an amorphous silicon active matrix (a-Si) connected to a CsI(T1) detector. MATERIALS AND METHODS: The ESD values were measured with different dosimeters placed in the air parallel to the detector plane, and at a distance equal to the thickness of a normal-build patient. The measurements were taken with the radiological parameters (Posterior-Anterior projection (PA) and Lateral projection (L)) used in diagnostic practice to obtain high-quality diagnostic radiographic images. The measurements taken with the DR equipment were repeated after the manufacturer added a 0.2 mm-thick Cu filter. The ESD values obtained by this series of measurements were reported as mean and standard deviation values (M+/-SD). RESULTS: With the PA projection, the doses measured for the different devices were the following: amorphous selenium system 0.12+/-0.06 mGy, CR system 0.3+/-0.05 mGy, DR system 0.05+/-0.02 mGy. With the L projection: amorphous selenium system 0.40+/-0.13 mGy, CR system 0.9+/-0.17 mGy, and DR system 0.21+/-0.15 mGy. CONCLUSIONS: The use of digital systems allows a significant reduction of the patient dose. In particularly the Direct Radiography system, based on a CsI/a-Si detector, administers the lowest patient dose.     

Optimum patient orientation for pelvic and hip radiography: A randomised trial

PurposeTo investigate the effect of patient orientation on the radiation dose and image quality (IQ) for digital (DR) and computed radiography (CR) examinations of the pelvis.MethodsA randomised study was conducted using DR and CR X-ray equipment. The standard patient orientation of head towards (HT) the two outer Automatic Exposure Device (AED) chambers was compared with a group of patients with their head away (HA) from the two outer AED chambers. Collection of mAs, source-to-skin distance and kVp data facilitated the calculation of entrance surface dose (ESD) and effective dose (ED) which were compared between groups. Each image was graded independently by three observers. IQ data were analysed for inter-observer variability and statistical differences.ResultsFor DR pelvis examinations switching orientation (HT to HA) reduced the mean ESD and ED by 31% (P < 0.001), respectively. For CR examinations the dose reduction was greater between the two orientations (38%; P = 0.009). Examinations of the hips allowed dose reductions of around 50% when switching between orientations. For DR examinations minor reductions in IQ were seen and favoured the HT orientation (P = 0.03). For CR examinations there were no statistical differences in IQ between orientations.ConclusionSwitching patient orientation relative to the AED chambers can help optimise radiation dose. In order to facilitate this chamber position should be clearly marked on all equipment and patient orientation should be a consideration when tailoring individual examinations. For DR minor changes in IQ are a consequence of changing orientation and should be factored into the decision making.     

数字X线成像系统图像质量影响因素的实验研究

目的 比较非晶体硒平板探测器DR系统和CR系统的图像噪声、空间分辨率和入射体表剂量（ESD），研究数字X线图像质量影响因素的相关性。方法 采用相同管电压（125kVp）和不同mAs对仿真胸部体模用分辨率测试卡进行DR和CR曝光成像，测量ESD、空间分辨率，计算均方根（RMS）值，分析mA8、ESD、RMS及空间分辨率之间的变化关系。结果 两种系统的RMS随mAs的增加而降低，ESD随mAs的增加而增加。两种系统成像相同ESD时，DR的RMS略高于CR。ESD增加至一定量时，空间分辨率达到极限值（CR为3．1lp／mm，DR为3．4lp／mm）。结论 数字系统放射线剂量的改变会导致噪声、分辨率变化。适度的噪声水平对空间分辨率影响不明显。