Investigations of moving-slit radiography

The technique of moving-slit radiography for reduction of scattered radiation was investigated using a prototype moving-slit radiographic apparatus. Slit widths of 1-2 cm, when used in conjuction with an 8: 1 grid, were found to improve radiographic contrast by a factor of 2 in studies employing physical as well as anatomic phantoms. Use of the moving-slit technique at elevated kVp's was found to provide radiographic contrast as good as or better than that obtained in conventional low-kVp full-field techniques, but with a substantial reduction of patient exposure (factor of 2-4). Considerations in the design of an optimal multislit apparatus are discussed. Excessive tube loading is shown not to be a factor in such a system.     

Common errors in panoramic radiography of edentulous patients

PURPOSE: Instructions for patient positioning during panoramic radiography usually describe positioning dentate patients, and errors in patient positioning are commonly identified by distortion of the dentition. The purposes of this study were to identify common errors in panoramic radiography of edentulous patients, describe the image distortions that can be expected with positioning errors in edentulous patients, and review quality assurance methods that improve the diagnostic value of panoramic films. MATERIALS AND METHODS: Panoramic films were randomly selected from the inactive files of 75 edentulous patients seen at the dental school for complete denture construction. The radiographs were numbered and reviewed by a board-certified oral and maxillofacial radiologist trained to identify errors in panoramic radiography. RESULTS: Of the 75 panoramic radiographs examined, only 6 films (8.0%) were free of errors, and 67 films (89.3%) had one or more errors in patient positioning and 33 films (44.0%) had one or more technical errors. The most common positioning errors were positioning the chin too high (32 films, 41.3%) and positioning the patient too far forward (26 films, 34.7%). CONCLUSIONS: Without modification, manufacturer's instructions for positioning dentate patients during panoramic radiography may result in positioning errors on the panoramic radiographs of edentulous patients. Proper training and appropriate attention to detail while exposing and developing panoramic films are required to ensure maximum diagnostic benefits for edentulous patients.     

Digital radiology in dentistry: experience with direct intraoral techniques (radiovideography)

The aim of this paper was to discuss the techniques for intraoral digital radiography (radiovisiography) and to compare their accuracy in dental radiographical diagnosis. Emphasis was given to their potential applications in oral radiology. Radiovisiography was compared with intraoral films and electronic magnifications from digital panoramic radiographs in 38 patients, for a total amount of 36 caries, 27 periapical conditions and 58 metal implants. Moreover, the accuracy of the measurements made with the three techniques was assessed on a specimen of mandibular and maxillary arches containing 28 extracted teeth with endodontic files of known length. Radiovisiography was as effective as intraoral films and more effective than digital panoramic radiographs in the diagnosis of caries and periapical lesions. Nevertheless, it produced a significant magnification and yielded unreliable measurements of root canals and metal implants. Radiovisiography is very easy to use and does not require dark room procedures nor chemicals of any kind. In addition, it reduces patient's X-ray exposure by over 50% with respect to film studies. For these reasons, this technique seems to be worthy of widespread use in dental radiography, with the exception of the conditions requiring an exact measurement of working length.     

Must radiation dose for CT of the maxilla and mandible be higher than that for conventional panoramic radiography?

We evaluated the feasibility of performing preoperative spiral CT of the maxilla and mandible with a radiation dose similar to that used for conventional panoramic radiography. The skin entrance doses of radiation used for spiral CT (collimation, 1 mm; pitch, 2; tube voltage, 80 kV; tube current, 40 mA) and for panoramic radiography (75 kV, 8 mA, 15 seconds) were measured in one patient by using thermoluminescent dosimeter chips. Results were 0.56 +/- 0.06 mGy for CT and 0.59 +/- 0.04 mGy for radiography. Image quality was adequate for preoperative implant planning. Spiral CT of the mandible and maxilla may therefore be feasible with a radiation dose of similar magnitude as that used for conventional panoramic radiography.     

Radiographic modalities for diagnosis and treatment planning in implant dentistry

Early in the development of implant technology it became apparent that conventional dental imaging techniques were limited for evaluating patients for implant surgery. During the treatment planning phase, the recipient bed is routinely assessed by visual examination and palpation, as well as by periapical and panoramic radiology. These two imaging modalities provide a two-dimensional image of mesial-distal and occlusal-apical dimensions of the edentulous regions where implants might be placed. When adequate occlusal-apical bone height is available for endosteal implants, the buccal-lingual width and angulation of the available bone are the most important criteria for implant selection and success. However, neither buccal-lingual width nor angulation can be visualized on most traditional radiographs. Although clinical examination and traditional radiographs may be adequate for patients with wide residual ridges that exhibit sufficient bone crestal to the mandibular nerve and maxillary sinus, these methods do not allow for precise measurement of the buccolingual dimension of the bone or assessment of the location of unanticipated undercuts. For these concerns, it is necessary to view the recipient site in a plane perpendicular to a curved plane through the arch of the maxilla or mandible in the region of the proposed implants. Implant dentists soon recognized that, for optimum placement of implants, cross-sectional views of the maxilla and mandible were the ideal means of providing necessary pre-operative information. Today, the two most often employed and most applicable radiographic studies for implant treatment planning are the panoramic radiograph and tomography. Although distortion can be a major problem with panoramic radiographs, when performed properly they can provide valuable information, and are both readily accessible and cost efficient. To help localize potential implant sites and assist in obtaining accurate measurements, it is recommended that surgical stents be used with panoramic radiographs. In simple cases, where a limited number of implants are to be placed, panoramic radiography and/or tomography may be used to obtain a view of the arch of the jaw in the area of interest. For complex, cases, where multiple implants are required, the CT scan imaging procedure is recommended. Because of its ability to reconstruct a fully three dimensional model of the maxilla and mandible, CT provides a highly sophisticated format for precisely defining the jaw structure and locating critical anatomic structures. The use of CT scans in conjunction with software that renders immediate "treatment plans" using the most real and accurate information provides the most effective radiographic modality currently available for the evaluation of patients for oral implants. To follow patients after implant surgery, DSR can be helpful by addressing the limitations of other radiographic modalities in detecting postoperative changes. By eliminating unchanged information, DSR allows the clinician's eye to focus on actual changes that have occurred between the recordings of two images.     

Cat owners'' risk of acquiring a Helicobacter pylori infection

OBJECTIVES/STUDY DESIGN: A random survey of equal proportions of urban and rural North Carolina general dentists was conducted to assess their knowledge and adoption of radiographic quality assurance guidelines of the American Dental Association. RESULTS: A total of 159 surveys were returned representing a response rate of 51%. A majority of respondents answered "don't know" to questions dealing with intraoral and panoramic radiography units and darkroom monitoring. Higher levels of knowledge (58% to 77%) and adoption (63% to 86%) of guidelines were seen with film-processing activities. Linear regression demonstrated substantial positive association between knowledge and adoption of guidelines (R = 0.50). Stepwise multiple regression revealed positive associations of the demographic variables of years in practice, urban location, and age with greater knowledge of guidelines (R2 = 0.33, p < 0.05). Urban location was associated with increased likelihood of adoption of guidelines (R2 = 0.09, p < 0.05).     

Intensive care for patients with the human immunodeficiency virus]

RATIONALE AND OBJECTIVES: The authors evaluate a new flat-panel x-ray detector (FD) with respect to foreign body detection and reduction of radiation dose compared with screen-film radiography. METHODS: Flat-panel x-ray detector is based on amorphous silicon technology and uses a 1 k x 1 k photo-detector matrix with a pixel size of 143 x 143 microns and 12-bit digital output. A thallium-dotted cesium iodide scintillation layer converts x-rays into light. An ex vivo experimental model was used to determine the detectability of foreign bodies. Foreign bodies with varying sizes were examined: glass with and without addition of lead, bone, aluminium, iron, copper, gravel fragments, and graphite. Four hundred observation fields were examined using conventional radiography (speed, 400; system dose: 2.5 microGy) as well as FD with a simulated speed of 400, 800, 1200, and 1600, corresponding to a detector dose of 2.5 microGy, 1.25 microGy, 0.87 microGy, and 0.625 microGy, respectively. Four independent radiologists performed receiver operating characteristic analysis of 8000 observations. RESULTS: Flat-panel x-ray detector with a simulated speed of 400 was significantly superior (P = 0.012) to screen-film radiography (speed, 400). At a simulated speed of 800 and 1200 FD yielded results equivalent to screen-film radiography. Flat-panel x-ray detector was significantly inferior to screen-film radiography at a simulated speed of 1600 (P = 0.012). CONCLUSIONS: Flat-panel x-ray detector technology allows significant reduction in radiation dose compared with screen-film radiography without loss of diagnostic accuracy.     

Localized and diffuse ovarian cancer: is it the same entity?

Scintigraphic methods used in intraoral and extraoral implantology allow the evaluation of bone metabolism in the peri-implant zones, providing anatomic images and functional dynamics information on the osteointegration process. Twenty-five patients who underwent implantation operations for the application of intra- and extraoral prostheses were studied using technetium 99 m single photon emission computed tomographic (SPECT) procedures to evaluate osteointegration dynamics at 3 weeks, and 3, 6, 12, and 24 months. The study demonstrates that radiation emission peaks 3 weeks after surgery with the maximal bone remodeling activity and 6 months after surgery after the functional loading of the implants only in intraoral fixtures. High uptake past the eighth month after surgery has never been detected and must be considered abnormal. SPECT offers the possibility of obtaining a three-dimensional reconstruction of the photon emission of selected structures. The use of these nuclear medicine methods in addition to traditional-type radiological procedures introduces new possibilities, although still in the clinical experimentation phase, for early diagnosis and inserted implant prognosis.     

Assessing the quality of radiographs accompanying biopsy specimens

According to a long-established protocol, biopsy specimens of bony lesions sent to the University of Washington Histopathology Service are accompanied by relevant radiographs. In this study, the authors evaluated the quality of 114 radiographs, both intraoral and panoramic, from 89 consecutive cases. The radiographs were judged on their clinical usefulness, rather than on criteria for technically ideal images, and on the severity, rather than the number, of errors. Only 33 percent of the panoramic radiographs were of acceptable quality, while the quality of the intraoral radiographs was markedly better. The most striking feature was the lack of three-dimensional radiographic coverage of the site of surgical exploration.     

Low-dose radiography of scoliosis in children. A comparison of methods

STUDY DESIGN: Records of 1,582 conventional and computed radiographic examinations performed to evaluate scoliosis were reviewed and compared to determine differences in total radiation burden. OBJECTIVE: This study evaluated the impact of computed radiographic imaging (CRI) on radiation exposure in children undergoing serial spinal radiographs for scoliosis assessment and compared exposure from CRI with that of low-dose film-screen combinations. SUMMARY OF BACKGROUND DATA: CRI permits diagnostic radiographic studies to be performed with a dose reduction of 80%-95% compared to conventional film-screen systems. High speed film-screen systems also permit a significantly lower exposure. Each approach has unique advantages and disadvantages. METHODS: Over 6 years, we performed 1,582 spinal examinations in children 4-14 years old using reduced dosage techniques with computed radiography. The images were obtained with Fuji FCR 101 and Philips PCR/SP systems. The adequacy of diagnostic image quality in the serial evaluation of scoliosis at different exposure levels was evaluated and compared with regular and film-screen systems with speeds ranging from 250 to 1,200. RESULTS: Diagnostic-quality images for evaluating scoliosis can be obtained with doses of 5% or less than required with conventional film-screen systems. Computed radiography provides image quality and dose reduction comparable to a 1,200-speed film-screen system. CONCLUSION: CRI gives satisfactory images at 5% reduction of the standard film-screen dose. Based on comparison with a 1,200 speed film-screen system, CRI provides equal or better image quality at a similar radiation dose. The cost of CRI is higher than for film-screen radiography, but wide latitude and the ability to tailor dose with requirements for image quality are significant advantages for CRI.     

Quantitative digital subtraction radiography for the determination of small changes in bone thickness: an in vitro study

OBJECTIVE: The objective of this study was to determine the ability of quantitative digital subtraction radiography to detect small changes in bone thickness adjacent to tooth roots. STUDY DESIGN: A series of cortical or cancellous bone slices with a 50 microm-stepwise increasing thickness were attached to 4 porcine mandible sections covering buccal and interproximal "defect" regions. Standardized radiographs were quantitatively evaluated for radiographic density changes with the use of digital subtraction radiography. Furthermore, all radiographs were conventionally evaluated by 10 clinicians. The Wilcoxon signed-rank test and the Mann-Whitney U test were used for statistical analysis (alpha = 0.05). RESULTS: A high linear correlation was found between the actual thickness of bone slices and radiographic density changes (cortical bone: r2 = 0.89 to 0.99; cancellous bone r2 = 0.61 to 0.86, p < or = 0.001). A certain increase in bone thickness caused a 3 times higher increase in radiographic density for cortical bone than for cancellous bone (p < or = 0.05). The detection limits of digital subtraction radiography were 200 microm for cortical and 500 microm for cancellous bone, whereas the detection limits of conventional radiography were 600 microm and 2850 microm, respectively. CONCLUSIONS: This in vitro study demonstrated a very high correlation between the objective, quantitative assessment of subtle changes in alveolar bone by digital subtraction radiography and the true changes in bone thickness.     

Image distortion in rotational panoramic radiography. VI. Distortion effects in sliding systems

A mathematical model for calculating the form distortion in rotational panoramic radiographic systems with a sliding beam path and an elliptical form of the sharply depicted plane was developed. The distortion of a spherical model object was calculated for two different systems exemplifying properties of commercially available equipment. The spherical object was distorted toward an ovoid shape in the image. No marked deviations were found between this ovoid distortion and the ellipsoid distortion previously calculated for a theoretical system having a constant effective projection radius and a cylindrical form of the sharply depicted plane. Except for extremely displaced objects in the anterior region the form reproduction in sliding rotational panoramic systems seems to be satisfactory for clinical purposes.     

Usefulness of panoramic radiography in the diagnosis of postmenopausal osteoporosis in women. Width and morphology of inferior cortex of the mandible

OBJECTIVES: To evaluate the usefulness of width and morphology of the inferior cortex of the mandible on panoramic radiographs in the diagnosis of postmenopausal osteoporosis. METHODS: The width and morphology of the mandibular inferior cortex on panoramic radiographs were compared with trabecular bone mineral density (TBMD) of the 3rd lumbar vertebrae (L3) measured by dual energy quantitative computed tomography in 29 premenopausal and 95 postmenopausal women. RESULTS: There was a significant negative correlation between the width (Kendall's tau = -0.36, p < 0.001) and morphology (Kendall's tau = -0.49, p < 0.001) of the mandibular inferior cortex and the L3 TBMD. Regression analysis showed that significant linear relationships were observed between the L3 TBMD and age (p < 0.001), cortical width (p < 0.05), morphology (p < 0.05), controlling body mass index, number of teeth present and menopausal status (R2 = 0.42). CONCLUSION: Our results suggest that panoramic radiography could be reliable in screening for osteoporosis.     

Guidelines for the selective ordering of admission chest radiography in adult obstructive airway disease

STUDY OBJECTIVE: To validate previously developed guidelines for the selective use of chest radiography in adults admitted for exacerbation of obstructive airway disease. DESIGN: Prospective, observational cohort study using criteria developed in a previous retrospective study. PARTICIPANTS: Unselected convenience sample of 128 adults with obstructive airway disease who did not respond to standard emergency department treatment and required admission. SETTING: Municipal hospital ED and inpatient medical service. INTERVENTIONS: Patients were categorized as "complicated" or "uncomplicated" according to previously developed criteria. Management was recorded as altered if the patient's physician answered the question, "Did the chest radiography alter your management of this patient?" affirmatively. RESULTS: Of 27 patients whose management was altered by the chest radiography, 26 were classified as complicated, for a sensitivity of 96% (95% confidence interval [CI], 81, 100). One of 44 admissions classified as uncomplicated had management altered by the chest radiography (negative predictive value, 98%, 95% CI, 88, 100). This chest radiography was later reread as normal. Classification as an uncomplicated patient with obstructive airway disease was strongly associated with either a normal chest radiography or a radiographic finding that was clinically unimportant (P = .0002). CONCLUSION: Patients with acute exacerbation of obstructive airway disease who are otherwise uncomplicated do not benefit from routine admission chest radiography. The use of this simple clinical strategy would safely reduce the number of chest radiographs by about one-third in this and similar patient populations, decreasing both health care costs and exposure to ionizing radiation.     

Differences in Epstein-Barr virus expression between primary and secondary cutaneous angiocentric lymphomas. French Study Group of Cutaneous Lymphomas

OBJECTIVE: The aim of this investigation was to report on the radiographic interpretation of the hard palate and nasal fossa floor in panoramic radiographs by studying different skulls, x-ray machines, and head positions in relationship to the Frankfort plane before and after ostectomy. STUDY DESIGN: Twenty dry human skulls were radiographed with three different panoramic x-ray machines in three different positions. Three of the skulls were submitted to different ostectomies. RESULTS: Multiple images of the hard palate and nasal fossa floor were present in 96.12% of the radiographs. Single images (3.88%) occurred only in the "chin up" position. CONCLUSIONS: The lower image represents the nasal fossa floor, especially its lateral and anterior limits. The upper images are double real images mainly formed by the junction of the nasal septum with the nasal fossa floor and possibly by posterior parts of the hard palate and nasal fossa floor. All images overlap in the "chin up" position becoming a single image. The most common shape of the anatomic landmark was wide angle "W" (58.33%). Other shapes present in positions "chin up" and "chin down" indicate patient positioning errors. The x-ray machines did not influence the results.     

Pediatric radiography. The nurses' role]

After a brief review of advanced radiographic diagnostic techniques, how to utilize them in the most cost-effective manner and minimize their risks, the authors examine the role of the nurse in using exploratory radiography in children. Patient opposition, immobilization and protection are some of the possible problems that one might encounter when working in this setting.     

A comparison of upper gastrointestinal endoscopy and radiography

One hundred symptomatic patients were evaluated independently with upper gastrointestinal radiography and fiberoptic endoscopy, and the results were compared. Of the two endoscopists sequentially examining the same patient, one was informed of available clinical and radiographic details and the other was not. Knowledge of the x-ray examination by the informed endoscopist did not improve his accuracy. Each endoscopist made four errors of interpretation. The endoscopic and x-ray findings agreed in 46 of the 100 patients, most often (68%) in esophagus, least often (29%) in the stomach and half the time (45%) in the duodenum. Ulcer craters seen endoscopically were detected radiographically in 36% of patients. We conclude that: 1) knowledge of results of prior upper gastrointestinal radiography did not alter endoscopic results; 2) experienced endoscopists are accurate but make mistakes; and 3) endoscopic findings would have been unaltered had radiography not been performed.     

Measurement of scatter fractions in erect posteroanterior and lateral chest radiography

Scatter fractions (SFs) measured in patients undergoing erect posteroanterior (PA) and lateral chest radiography with a 12:1 antiscatter grid are reported. Modifications to the posterior beam-stop (PBS) technique allowed measurement of scatter in these patients, without altering the diagnostic image and without additional radiation exposure. The SF measurements are reported by anatomic location on 42 clinical chest images. Average SF values ranged from 0.27 to 0.90 on lateral radiographs and from 0.27 to 0.68 on PA radiographs. Scatter measurements with the 12:1 grid were found to be greater than estimates from previous PA chest phantom experiments. To the authors' knowledge, they were the first to measure radiation scatter with the PBS technique in patients undergoing PA and lateral chest radiography with the antiscatter grid.     

Use of computed radiography in the study of an historic painting

The authors demonstrate the use of radiography in the investigation of an historic painting and describe the potential benefits of computed radiography compared with conventional screen-film radiography. The subject for the comparison was a 16 x 19-foot oil-on-canvas painting, Scipio Africanus Freeing Massiva, by Giovanni Battista Tiepolo. Radiographs of the painting were obtained by using a portable, industrial radiographic unit and both conventional screen-film and photostimulable phosphor plate cassettes. For this investigation, computed radiography had a number of advantages over screen-film radiography, largely due to its wider dynamic range and its capabilities for enhancing the digital images with image processing tools such as magnification, edge enhancement, colorization, and airbrushing. The ability to electronically combine images from the large painting into a single composite image file was extremely valuable, as this technique was much less cumbersome and resulted in much higher quality composite images than could be achieved with conventional radiography. An additional advantage of computed radiography includes the capability to easily archive and transmit these images in a digital format for subsequent review.     

Examination of skin moles

The extraoral and intraoral examination should be part of the clinician's examination process. During the extraoral portion, it is necessary to assess skin moles that may be present in the head/neck region or on other accessible skin areas. This review paper is a discussion of melanoma and provides information on evaluation of moles to determine need for referral.