Quality of film-based and digital panoramic radiography

OBJECTIVES: To compare the image quality of panoramic radiographs obtained with storage phosphor plate and screen-film systems. METHODS: Panoramic radiographs were taken in 60 patients both with film and with a storage phosphor plate system (30 with DenOptix (Dentsply/Gendex) and 30 with Digora PCT). The images were obtained with either the Cranex Tome or the Scanora multimodal X-ray unit. The screen-film combination was Lanex medium/Curix Ortho HT-G. The digital images were displayed as 8-bit images with a 300 dpi resolution on a 19" monitor and the film images were placed on a light box adjacent to the screen. Ten observers evaluated diagnostic image quality by means of visual grading analysis of different anatomical structures. The structures were scored as being visualized much better (5), better (4), equal (3), worse (2) or much worse (1) in the digital images than in the film images. The mean number of patients receiving the different scores was calculated. Statistical methods used were Wilcoxon sign rank test and Mann-Whitney test. RESULTS: On average, visualization was equal in 19 of the 30 patients imaged using Digora PCT; in 10 it was worse. The corresponding values for DenOptix were 20 and 9. The difference between the film-based and the digital images was small but statistically significant (P<0.0001). The difference between the two image plate systems was not statistically significant (P>/=0.17). CONCLUSIONS: It was concluded that digital panoramic radiographs are equivalent to film-based images for most purposes.     

Cross-sectional tomograms obtained with four panoramic radiographic units in the assessment of implant site measurements

OBJECTIVES: The aim of this study was to evaluate the ability of four panoramic X-ray units to produce cross-sectional images and to assess the effect of interexaminer and intraexaminer variations on the results. METHODS: Cross-sectional tomograms of a human cadaver mandible were taken from two edentulous and one dentate area using four different X-ray units: OP-100 Ortho Trans (Instrumentarium Imaging Co, Tuusula, Finland), Proscan (Planmeca Co, Helsinki, Finland), Cranex-Tome and Scanora (Soredex, Orion Co, Espoo, Finland). Four different linear distances were measured from each radiograph. The mandible was then cut into 4 mm thick slices at three marked places. These slices were microradiographed and used as the gold standard for measurements made from each cross-sectional tomogram. RESULTS: Of all measurements only the thickness of the mandible in the radiographs taken with the OP-100 differed significantly (P < 0.021) from the gold standard. In the interexaminer variation, the agreement was 85% and Kappa index 0.68. In the intraexaminer reproducibility, the agreement was 76.7% and Kappa indices 0.52 and 0.50. CONCLUSIONS: The X-ray units studied were found to be similar in terms of image performance and the produced images were acceptable for dental implant placement planning. Interexaminer and intraexaminer variations can be large and the main source of error can be the interpreter him or herself.     

A comparison of two different T-grain films in rare-earth screens with a standard film-screen combination for intravenous pyelography and bone examinations

T-grain film is claimed to give significantly improved image quality, allowing the use of faster screens without loss of quality and thus reducing radiation dose. We tested this claim for two systems. In each case comparison was made with our usual screen-film combination, Agfa Curix RP1 film with Kodak Xomatic Regular screens (a nominally 200 speed system). The systems tested were Kodak TMatG in Kodak Lanex Medium screens (300 speed) and Agfa STG in Kodak Lanex Regular screens (400 speed). The Agfa STG-Lanex Regular system performed less well than the standard system for intravenous pyelograms (IVPs), bones and soft-tissue detail. Its speed advantage was not apparent below 70 kV. The Kodak TMatG-Lanex Medium system was better than the standard system for IVPs but not as good for bones. It gave virtually no speed advantage below 90 kV. Kodak T-grain film in a medium-speed, rare-earth screen was found to be better than the standard system for IVPs. Agfa T-grain film in a fast rare-earth screen was unsatisfactory for IVPs. Neither combination was as good as the standard system for bones.     

Reproducibility of mandibular third molar assessment comparing two cone beam CT units in a matched pairs design

The aim of this study was to evaluate the reproducibility of the third molar assessment, comparing five observers and two cone beam CT (CBCT) units. 28 patients, each with two impacted mandibular third molars, were included. Each patient was randomly examined with a Scanora^® 3D (Soredex, Helsinki, Finland) CBCT unit in one mandibular third molar region and with a Cranex^® 3D (Soredex) CBCT unit in the other region. Five observers with varying CBCT experience assessed all third molars and recorded the following variables: number and morphology of the roots, relation to the mandibular canal in two directions, shape of the canal and whether there was a direct contact between the roots of the molar and the mandibular canal. The radiographic assessments were compared pairwise among all observers for all variables. Wilcoxon''s signed-rank test was used to test the differences in observer accordance percentages among the recorded variables in the images from the two units, and kappa statistics expressed interobserver reproducibility. The mean percentages for observer accordance ranged from 65.4 to 92.9 for Scanora 3D and 60.3 to 94.8 for Cranex 3D. There was no significant difference between the observer accordance in the two CBCT units (p > 0.05), except for assessing root flex in the mesiodistal direction, for which the observer accordance was higher for Scanora 3D (p < 0.05). Kappa values ranged from 0.1 to 1.0 for Scanora 3D and from 0.2 to 0.9 for Cranex 3D. For the variable “direct contact”, the interobserver reproducibility was excellent for the two trained radiologists. The two units had almost similar interobserver reproducibility for mandibular third molar assessment. Observer variation existed, and experienced radiologists demonstrated the highest interobserver reproducibility for canal-related variables.     

Proximal caries detection accuracy using intraoral bitewing radiography, extraoral bitewing radiography and panoramic radiography

Objective

To compare proximal caries detection using intraoral bitewing, extraoral bitewing and panoramic radiography.

Methods

80 extracted human premolar and molar teeth with and without proximal caries were used. Intraoral radiographs were taken with Kodak Insight film (Eastman Kodak Co., Rochester, NY) using the bitewing technique. Extraoral bitewing and panoramic images were obtained using a Planmeca Promax Digital Panoramic X-ray unit (Planmeca Inc., Helsinki, Finland). Images were evaluated by three observers twice. In total, 160 proximal surfaces were assessed. Intra- and interobserver kappa coefficients were calculated. Scores obtained from the three techniques were compared with the histological gold standard using receiver operating characteristic analysis. Az values for each image type, observer and reading were compared using z-tests, with a significance level of α = 0.05.

Results

Kappa coefficients ranged from 0.883 to 0.963 for the intraoral bitewing, from 0.715 to 0.893 for the extraoral bitewing, and from 0.659 to 0.884 for the panoramic radiography. Interobserver agreements for the first and second readings for the intraoral bitewing images were between 0.717 and 0.780, the extraoral bitewing readings were between 0.569 and 0.707, and the panoramic images were between 0.477 and 0.740. The Az values for both readings of all three observers were highest for the intraoral bitewing. Az values for the extraoral bitewing images were higher than those of the panoramic images without statistical significance (p > 0.05).

Conclusion

Intraoral bitewing radiography was superior to extraoral bitewing and panoramic radiography in diagnosing proximal caries of premolar and molar teeth ex vivo. Similar intra- and interobserver coefficients were calculated for extraoral bitewing and panoramic radiography.     

Paediatric absorbed doses from rotational panoramic radiography

OBJECTIVES: To determine the paediatric doses in rotational panoramic radiography with film/screen and photostimulable phosphor receptors. STUDY DESIGN: A paediatric anthropomorphic head and neck phantom was used. Absorbed doses were measured for two panoramic systems, the Orthophos (Sirona Dental Systems, Bensheim, Germany) and the PM 2002 CC (Planmeca Oy, Helsinki, Finland), with and without programmable child settings, using both screen/film and photostimulable phosphor receptors. RESULTS: Absorbed doses to the eye ranged from 5 to 24 micro Gy. Doses to the dental arches with the Orthophos unit ranged from 50 to 555 micro Gy with the adult and from 27 to 436 micro Gy with the child program; using the PM 2002 CC unit, doses ranged from 56 to 1040 micro Gy using the adult settings, and from 60 to 890 micro Gy with the paediatric settings. The paediatric exposure settings reduced doses at most locations for both panoramic systems. The highest doses were measured near the rotational axes of the X-ray beam. Paediatric settings with the Orthophos P10 resulted in the dose reduction more than 50% to the thyroid but not with the PM 2002 CC. When lower kVcp or mA settings were used, absorbed doses were effectively reduced for all combinations of machines, programs and detectors. CONCLUSIONS: Specific program settings for children reduced the absorbed doses from panoramic radiography irrespective of the machine or receptor used.     

Threshold perception performance with computed and screen-film radiography: implications for chest radiography.

Images of a phantom obtained with computed radiography and standard screen-film imaging were compared to evaluate observer threshold perception performance with a modified contrast-detail technique. Optimum exposure necessary for performance with the imaging plate technique to match that with screen-film techniques was determined, as was comparative performance with variation in kilovoltages, plate type, spatial enhancement, and hard-copy interpolation method. It was found that computed radiography necessitates about 75%-100% more exposure than screen-film radiography to optimally match performance with Ortho-C film with Lanex regular or medium screens (Eastman Kodak, Rochester, NY) for detection of objects 0.05-2.0 cm in diameter. However, only minimal loss of detection performance (approximately 10% overall) was experienced if standard screen-film exposures were used with computed radiography. Little change in observer performance was found with variation in plate type, spatial enhancement, or method of hard-copy interpolation. However, perception performance with computed radiographic images was better at lower kilovoltages.     

Exposure factors and screen-film combinations in temporomandibular joint radiography

Exposure factors and screen-film combinations providing optimal quality are identified for transcranial and transpharyngeal temporomandibular joint views, using conventional intra-oral radiographic equipment without grids. Standardized transcranial and transpharyngeal views, using a fixed whole cadaver head, were performed. Ten readily available screen-film combinations, ranging in nominal speed 20-600, were exposed over 40-100 kV. Films were blindly and independently order ranked by three observers on the basis of sharpness and contrast of cortical outline, trabecular detail, and visualization of adjacent bony structures. Preferred screen-film combinations as a function of kV, preferred kV levels for each screen-film combination, and overall ranking irrespective of kV or screen-film combination, were established. Accepting the use of the lowest radiation dose possible for diagnostically useful radiographs but imposing arbitrarily an upper limit of 20 mGy, it was found that exposures between 50 kV and 70 kV gave the optimal result for both techniques. The amount of scattered radiation in the emergent beam differs greatly between the two techniques. The most favoured combinations for the transpharyngeal technique used screens of fine resolution. Min-r/ortho M screen and film with nominal speed 40 at 60 kV gave 8.0 mGy skin dosage at 0.8 seconds exposure; the same combination at 50 kV was the most favoured, but with skin dosage calculated at 16.7 mGy for 3.0 seconds exposure. For the transcranial technique, medium speed screens providing better differentiation of scattered radiation beams and increased speeds were preferred. Most favoured for image quality was the Lanex Fine/T-Mat G combination at 60 kV giving 17.5 mGy skin radiation dose at 1.75 seconds exposure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of two detail screen-film systems using a rheumatoid erosion model

Two detail screen-film systems, Lanex Fine/Ortho M and Lanex Fine/Ortho G, were evaluated using a radiographic model for rheumatoid erosions. Radiographs of hand bones with cortical defects using both screen-film systems were obtained. Seven observers analyzed 48 sites on each of 22 films for the presence of these cortical defects. Using analysis of variance techniques and receiver operating characteristic curves, no significant difference was found between the two systems for the detection of these subtle cortical defects. The authors conclude that although the Lanex Fine/Ortho M system provides better definition of laboratory test objects than Lanex Fine/Ortho G, the two systems do not differ when used for detection of cortical lesions.     

Evaluation of radiographs developed by a new ultrarapid film processing system

The image quality of radiographs developed by a new ultrarapid processor was evaluated to determine if faster processing causes degradation in the image. The processor used was the Konica Super-Rapid SRX-501 model. Two films designed for this processor (Konica MGH-SR and MGL-SR) were processed in 45 sec and were compared with standard rapid processing in 90 sec of corresponding conventional films (Kodak TMG and OC). Rare-earth screens (Kodak Lanex Regular and Lanex Medium) used with the new and conventional films interleaved during angiographic studies or for phantom images were assessed for image quality. The basic imaging properties of the screen-film systems were examined by measuring (1) Hurter and Driffield curves, (2) modulation transfer functions by using the slit method, and (3) noise Wiener spectra. Subjective clinical assessment showed that the images obtained with ultrarapid processing were acceptable, with increased contrast and graininess. Hurter and Driffield curve measurements confirmed higher gradients. Modulation transfer function measurements were the same as for the conventional films. Noise Wiener spectrum measurements showed a 10% increase in noise for MGH-SR vs TMG film and a 30% increase for MGL-SR vs OC film. We conclude that acceptable image quality can be obtained using ultrarapid processing, with processing time approximately 60% that of conventional rapid processing. Potential applications include all areas in which rapid availability of the radiograph for interpretation is important. Although the processor studied was the first of its kind available, our evaluation indicates that the technology is available for a new class of ultrarapid processors.     

The effect of dose reduction on the detection of anatomical structures on panoramic radiographs

OBJECTIVES: The aim was to evaluate the effect of dose reduction on diagnostic accuracy using different screen-film combinations and digital techniques for panoramic radiography. METHODS: Five observers assessed 201 pairs of panoramic radiographs (a total of 402 panoramic radiographs) taken with the Orthophos Plus (Sirona, Bensheim, Germany), for visualization of 11 anatomical structures on each side, using a 3-point scale -1, 0 and 1. Two radiographs of each patient were taken at two different times (conventional setting and setting with decreased dose, done by increasing tube potential settings or halving tube current). To compare the dose at different tube potential settings dose-length product was measured at the secondary collimator. Films with medium and regular intensifying screens (high and low tube potential settings) and storage phosphor plates (low tube potential setting, tube current setting equivalent to regular intensifying screen and halved) were compared. The five observers made 27 610 assessments. Intrarater agreement was expressed by Cohen's kappa coefficient. RESULTS: The results demonstrated an equivalence of regular screens (low tube potential setting) and medium screens (high and low tube potential settings). A significant difference existed between medium screens (low tube potential setting, mean score 0.92) and the group of regular film-screen combinations at high tube potential settings (mean score 0.89) and between all film-screen combinations and the digital system irrespective of exposure (mean score below 0.82). There were no significant differences between medium and regular screens (mean score 0.88 to 0.92) for assessment of the periodontal ligament space, but there was a significant difference compared with the digital system (mean score below 0.76). The kappa coefficient for intrarater agreement was moderate (0.55). CONCLUSIONS: New regular intensifying screens can replace medium screens at low tube potential settings. Digital panoramic radiographs should be taken at low tube potential levels with an exposure equivalent at least to a regular intensifying screen.     

An investigation of lumbar spine magnetic resonance referrals in two Irish university teaching centres: Radiology clinical judgement versus iRefer guideline compliance

IntroductionWith the annual increase in medical imaging demand, the appropriateness of the lumbar spine magnetic resonance imaging LSMRI referrals is worldwide gaining attention. This study aims to determine the appropriateness of LSMRI referrals and compare radiology clinical decisions to iRefer compliance based solely on referral text content.MethodsReferral text was extracted from 1021 LSMRI referrals. Two review panels were recruited: three expert radiologists and three MRI radiographers. Radiologists classified cases as indicated or not indicated for scanning based on their clinical judgement. The radiographers classified based solely on iRefer guidelines. Majority voting for each case was applied to both review panels and reviewer agreement was tested using Kappa analysis. Logistic regression models were developed to identify medical disciplines associated with high rates of indicated referrals.Results21.7% and 11.9% of the cases were found not indicated for MRI for radiologists and radiographers, respectively. Radiology review identified 18% of the GPs referrals as not indicated and 17% in the radiographers’ review. Panel agreement was fair: Kappa values of 0.23 and0.26 for the radiologists and radiographers respectively. Neurosurgery was associated with the highest rate of indicated referrals across both review panels: oncology referrals raised the highest number of open comments.ConclusionThe study identified a lower number of not indicated referrals compared to previous research. Findings indicate the importance of both guidelines compliance and clinical judgement to optimise practice.Implications for practiceFindings in this study found that even when strict instructions were given to the MR radiographers to vet referrals using the iRefer guidelines, ambiguity within the guidelines resulted in variations in decision-making. This suggests that detailed protocols are required to support radiographers in the vetting process to ensure a standardised approach.     

MRI reporting by radiographers: Findings of an accredited postgraduate programme

AimTo analyse the objective structured examination (OSE) results of the first three cohorts of radiographers (n = 39) who completed an accredited postgraduate certificate (PgC) programme in reporting of general magnetic resonance imaging (MRI) investigations and to compare the agreement rates with those demonstrated for a small group of consultant radiologists.MethodForty MRI investigations were used in the OSE which included the following anatomical areas and abnormal appearances: knee; meniscal/ligament injuries, bone bruises, effusions and osteochondral defects; lumbar spine: intervertebral disc morphology, vertebral collapse, tumours (bone and soft tissue), spinal stenosis and/or nerve root involvement; internal auditory meati (IAM): acoustic neuroma. Incidental findings included maxillary polyp, arachnoid cyst, renal cyst, hydroureter, pleural effusion and metastases (adrenal, lung, perirenal and/or thoracic spine). Sensitivity, specificity and total percentage agreement rates were calculated for all radiographers (n = 39) using all reports (n = 1560). A small representative subgroup of reports (n = 27) was compared to the three consultant radiologists' reports which were produced when constructing the OSE. Kappa values were estimated to measure agreement in four groups: consultant radiologists only; radiographers and each of the consultant radiologists independently.ResultsThe sensitivity, specificity and agreement rates for the three cohorts (combined) of radiographers were 99.0%, 99.0% and 89.2%, respectively. For the majority (5/9) of anatomical areas and/or pathological categories no significant differences (p < 0.05) were found between the mean Kappa scores (K = 0.47–0.76) for different groups of observers, whether radiographers were included in the group analysis or not. Where differences were apparent, this was in cases (4/9) where the variation was either not greater than found between radiologists and/or of no clinical significance. These results suggest therefore that in an academic setting, these groups of radiographers have the ability to correctly identify normal investigations and are able to provide a report on the abnormal appearances to a high standard. Further work is required to confirm the clinical application of these findings.     

Agreement between expert thoracic radiologists and the chest radiograph reports provided by consultant radiologists and reporting radiographers in clinical practice: Review of a single clinical site

IntroductionTo compare the clinical chest radiograph (CXR) reports provided by consultant radiologists and reporting radiographers with expert thoracic radiologists.MethodsAdult CXRs (n = 193) from a single site were included; 83% randomly selected from CXRs performed over one year, and 17% selected from the discrepancy meeting. Chest radiographs were independently interpreted by two expert thoracic radiologists (CTR1/2).Clinical history, previous and follow-up imaging was available, but not the original clinical report. Two arbiters compared expert and clinical reports independently. Kappa (Ƙ), Chi Square (χ²) and McNemar tests were performed to determine inter-observer agreement.ResultsCTR1 interpreted 187 (97%) and CTR2 186 (96%) CXRs, with 180 CXRs interpreted by both experts. Radiologists and radiographers provided 93 and 87 of the original clinical reports respectively. Consensus between both expert thoracic radiologists and the radiographer clinical report was 70 (CTR1; Ƙ = 0.59) and 70 (CTR2; Ƙ = 0.62), and comparable to agreement between expert thoracic radiologists and the radiologist clinical report (CTR1 = 76, Ƙ = 0.60; CTR2 = 75, Ƙ = 0.62). Expert thoracic radiologists agreed in 131 cases (Ƙ = 0.48). There was no difference in agreement between either expert thoracic radiologist, when the clinical report was provided by radiographers or radiologists (CTR1 χ = 0.056, p = 0.813; CTR2 χ = 0.014, p = 0.906), or when stratified by inter-expert agreement; radiographer McNemar p = 0.629 and radiologist p = 0.701.ConclusionEven when weighted with chest radiographs reviewed at discrepancy meetings, content of CXR reports from trained radiographers were indistinguishable from content of reports issued by radiologists and expert thoracic radiologists.     

Can radiographers read screening mammograms?

AIM: To evaluate the ability of radiographers to read screening mammograms in the National Health Service Breast Screening Programme (NHSBSP). MATERIALS AND METHODS: Two radiographers read a test set of 1000 screening mammograms previously reported by a consultant radiologist. Three radiographers then acted as a second reader for 54,000 screening mammograms, their recall results are presented. Four consultant radiologists and three film reading radiographers were timed while reading 2500 mammograms each. RESULTS: When reading the test mammograms the two radiographers recalled all the cancers previously detected by the radiologist at the original screen read. They also recalled 32/90 women who subsequently presented with interval cancers. As a second reader the radiographers had similar recall and cancer detection rates to the radiologists (P>0.05). Double reading detected 9% more cancers. The radiographers take the same length of time to film read as radiologists (P>0.05). CONCLUSION: Radiographers are able to read screening mammograms at least as well as radiologists and do not take longer to do so.     

Follow up of total hip prothesis: storage phosphor versus screen-film radiography

PURPOSE: Digital radiography may lead to interpretation difficulties in patients with hip prosthesis, especially when initial evaluation was performed using screen film radiography. The purpose of this study was to evaluate inter-observer and inter-technique reproducibility comparing digital and screen-film radiography. MATERIAL AND METHODS: Twenty-eight patients with unilateral (n=24) or bilateral (n=4) hip prosthesis (total=32 prostheses) underwent screen-film and digital (storage phosphor) radiography. The bone-cement and metal-cement interfaces were evaluated for the presence of a lucent line in 14 different sectors reclassified into 3 regions. This evaluation was performed by two independent readers. Inter-observer and inter-technique reproducibility were calculated using kappa values. RESULTS: The inter-observer reproducibility was negligible, poor or average with Kappa values ranging from 0.07 to 0.47. The degree of agreement between the two methods was poor, average or good for both observers with Kappa values ranging from 0.10 to 0.66. CONCLUSION: Although inter-technique agreement is not high, it is better than inter-observer agreement. Therefore, storage phosphor technique should not be rejected for total hip prosthesis follow-up, even though previous films were screen-film radiographs.     

Comparison of patient dose from imaging protocols for dental implant planning using conventional radiography and computed tomography

OBJECTIVES: To compare the radiation doses from imaging protocols for dental implant planning either using conventional radiography only (dental panoramic radiography (DPR), cephalometry and linear cross-sectional tomography) or involving computed tomography (CT). METHODS: Organ absorbed doses were measured using a female Rando anthropomorphic phantom loaded with lithium fluoride thermoluminescent dosemeters (TLD). Standard mandibular protocols for dental implant planning were followed using either a conventional dental radiographic unit (PM 2002 CC Planmeca, Helsinki, Finland) or CT scanner (Excel Twin Elscint, Haifa, Israel). Organ absorbed and effective doses were calculated. Effective dose was calculated using two approaches, one based on the ICRP method which excludes the salivary tissue from the remainder organs (designated E(exc)), and the other with its inclusion (E(inc)). RESULTS: The greatest individual organ doses for any examination were measured in the salivary tissue. E(exc) for panoramic, cephalometric and cross-sectional tomography using DPR was 0.004 mSv, 0.002 mSv and 0.002 mSv, respectively, whereas with CT it was 0.314 mSv. The value of E(inc) calculated using these data was between two and five times E(exc). CONCLUSIONS: E(inc) greatly increases the apparent radiation burden, especially with high dose procedures. CT techniques can provide excellent images, but at the cost of increased radiation detriment. DPR with a cross-sectional tomography facility may give adequate clinical information at a greatly reduced dose.