Single-exposure dual-energy subtraction chest radiography: detection of pulmonary nodules and masses in clinical practice

The purpose of this retrospective study was to evaluate the impact of energy subtraction (ES) chest radiography on the detection of pulmonary nodules and masses in daily routine. Seventy-seven patients and 25 healthy subjects were examined with a single exposure digital radiography system. Five blinded readers evaluated first the non-subtracted PA and lateral chest radiographs alone and then together with the subtracted PA soft tissue images. The size, location and number of lung nodules or masses were registered with the confidence level. CT was used as standard of reference. For the 200 total lesions, a sensitivity of 33.5-52.5% was found at non-subtracted and a sensitivity of 43.5-58.5% at energy-subtracted radiography, corresponding to a significant improvement in four of five readers (p < 0.05). However, in three of five readers the rate of false positives was higher with ES. With ES, sensitivity, but not the area under the alternative free-response receiver operating characteristics (AFROC) curve, showed a good correlation with reader experience (R = 0.90, p = 0.026). In four of five readers, the diagnostic confidence improved with ES (p = 0.0036). We conclude that single-exposure digital ES chest radiography improves detection of most pulmonary nodules and masses, but identification of nodules <1 cm and false-positive findings remain a problem.

Comparative dose measurements by spiral tomography for preimplant diagnosis: the Scanora machine versus the Cranex Tome radiography unit

Objective. The purpose of this study was to determine the dose profile of the Cranex Tome radiography unit and compare it with that of the Scanora machine.Study design. The radiation dose delivered by the Cranex Tome radiography unit during the cross-sectional mode was determined. Single tooth gaps in regions 3 (16) and 30 (46) were simulated. Dosimetry was carried out with 2 phantoms, a head and neck phantom and a full-body phantom loaded with 142 thermoluminescent dosimeters (TLD) and 280 TLD, respectively; all locations corresponded to radiosensitive organs or tissues. The recorded local mean organ doses were compared with those measured in another study evaluating the Scanora machine.Results. Generally, dose values from the Cranex Tome radiography unit reached only 50% to 60% of the values measured for the Scanora machine. The effective dose was calculated as 0.061 mSv and 0.04 mSv for tooth regions 3 (16) and 30 (46), respectively. Corresponding values for the Scanora machine were 0.117 mSv and 0.084 mSv.Conclusion. Cross-sectional imaging in the molar region of the upper and the lower jaw can be performed with the Cranex Tome unit, which delivers only approximately half of the dose that the Scanora machine delivers.

Effects of dose reduction on the detectability of standardized radiolucent lesions in digital panoramic radiography

Dose reduction in digital panoramic radiography was studied. Intentional underexposure was performed with the Orthophos DS while six different human mandibles were radiographed. Exposure settings were 69 kV/15 mA (standard), 64 kV/16 mA, and 60 kV/16 mA. Standardized spherical defects, each either 1 or 1.25 mm in diameter, were simulated in 288 of 432 images, and seven observers decided whether defects were present or not. Areas under the receiver operating characteristics curves were calculated. They showed no significant differences in the detectability of the 1-mm defect at 69, 64, or 60 kV. For the 1.25-mm defect, no difference was found between the 69 and 60 kV images, but a statistically significant different detectability was found for 64 kV images in comparison with both 69 and 60 kV images. A dose reduction of up to 43% was ascertained with a Pedo-RT-Humanoid phantom when panoramic radiography was performed at 60 kV/16 mA. The conclusion is that with the Orthophos DS, it seems possible to reduce the dose rate of x-rays without loss of diagnostic quality in the case of radiolucent changes.

Effective doses from scan projection radiographs of the head: impact of different scanning practices and comparison with conventional radiography

For CT scan planning, scan projection radiographs (SPR) are used. Tube tension and current for head SPR can be reduced to a minimum because of the small head diameter and because only high-contrast structures need to be visualized for planning. The goal of this study was to investigate SPR of the head in respect to effective doses, the influence of dose-reduction measures, and comparison with conventional x-ray.

Comparison of periapical radiography and limited cone-beam tomography in posterior maxillary teeth referred for apical surgery

This study compared periapical (PA) radiography and cone-beam tomography (CBT) for preoperative diagnosis in posterior maxillary teeth of consecutive patients referred for possible apical surgery. Images were concurrently analyzed by an oral radiologist and an endodontist to reach consensus in interpretation of the radiographic findings. The final material included 37 premolars and 37 molars with a total of 156 roots. CBT showed significantly more lesions (34%, p < 0.001) than PA radiography. Detecting lesions with PA radiography alone was most difficult in second molars or in roots in close proximity to the maxillary sinus floor. Additional findings were seen significantly more frequently in CBT compared with PA radiography including expansion of lesions into the maxillary sinus (p < 0.001), sinus membrane thickening (p < 0.001), and missed canals (p < 0.05). The present study highlights the advantages of using CBT for preoperative treatment planning in maxillary posterior teeth with apical pathology.

Displaced premolars in panoramic radiography: fact or fallacy?

OBJECTIVE: To test the null hypothesis that there is no difference between premolar position visualized on panoramic radiographs (PRs) and lateral headfilms (LHs). MATERIALS AND METHODS: The prevalence of differences in the direction of crown angulation between PR and LH was assessed. Furthermore, brass wire markers with different sagittal and transverse angulations were placed in a dry skull. With the markers in place, LHs and PRs were taken. RESULTS: A difference in the direction of crown angulation of unerupted second premolars between PR and LH occurred in 19.5% of patients. The reason for the angulation differences is a buccolingual orientation of the tooth, which appears as a mesiodistal angulation on the PR. CONCLUSION: The null hypothesis was rejected since in one-fifth of the patients premolar projection differs between the panoramic radiograph and the lateral headfilm.

Assessment of vertical facial and dentoalveolar changes using panoramic radiography

The purpose of the study was to analyse longitudinal vertical facial and dentoalveolar changes using panoramic radiographs (PRs) and to compare the results with measurements on lateral cephalometric radiographs (LCRs) in order to determine whether, under certain circumstances, the radiation dose for a patient may be reduced by taking only a PR instead of a PR and a LCR. Pre- and post-treatment PRs and LCRs of 30 (15 females and 15 males) orthodontically treated adolescents (mean age pre-treatment 10.9 years, post-treatment 13.4 years) were analysed using Pearson's correlation coefficients and gender differences using Fisher's z-transformation. The results revealed that most variables exhibited larger absolute values on PRs than on LCRs. Comparison of dentoskeletal morphology between the LCRs and the PRs revealed moderate to high, mostly statistically significant, interrelations both before and after orthodontic treatment. The lowest correlations were found for the maxillary jaw base angle (NL/H; r= 0.35***) and the highest for the gonial angle (ML/RL; r = 0.90***). However, when assessing the combined growth and treatment changes from before to after treatment, only weak to moderate, not statistically significant, interrelations were found between LCRs and PRs. Anterior face height (AFH; r = 0.43***), the mandibular plane angle (ML/H; r = 0.06*), and the distance of the incisal tip of the most extruded mandibular incisor to the ML-line (ii-ML; r = -0.21*) were the only statistically significant parameters. The average group differences for growth and treatment changes, however, were small for most parameters. Analysis of vertical facial and dentoalveolar parameters on PRs delivers a moderate approximation to the situation depicted on LCRs. However, PRs cannot be recommended for the analysis of individual longitudinal changes in vertical facial and dentoalveolar parameters.