Evaluating cone cut in rectangular collimation in intraoral radiography: application of ALADA and radiation stewardship.

OBJECTIVE: Rectangular collimation is a popular method used in intraoral radiography to reduce patient exposure to ionizing radiation. One of the perceived drawbacks of rectangular collimation is the possibility of an increase in cone cut errors ultimately impacting the diagnostic value of the radiographs. Thus, the aim of this study was to explore the frequency of cone cut errors in radiographs taken using a rectangular collimator. MATERIALS AND METHODS: Radiographs taken using PSP plates at Academic Center for Dentistry Amsterdam in the Netherlands by staff and students from January to December 2015 were assessed for cone cut errors. The radiographs were grouped as bitewings, front teeth, inferior premolars and molars, and superior premolars and molars and categorized as no cone cut, cone cut but diagnostically usable, and cone cut but diagnostically not usable. The results were entered into Microsoft Excel and analyzed thereafter. RESULTS: A total of 53,684 radiographs were assessed, 79% had no cone cut errors and consequently 21% had some degree of cone cut. However, the diagnostic value was unaffected in 18% of the radiographs with cone cut. Only 3% of the radiographs were deemed diagnostically unusable due to cone cut. The most common area of cone cut was in the premolar and molar areas while cone cut in the front teeth was least likely to be diagnostically unusable. CONCLUSION: Cone cut from the use of a rectangular collimator does not seem to result in an increase of diagnostically unusable radiographs. Thus, rectangular collimation should be preferred as it decreases the amount of radiation exposure to the patient while producing diagnostically usable radiographs and thus allowing the dental professional to adhere to the ALADA principle and practice radiation stewardship. CLINICAL RELEVANCE: Scientific rationale for the study: rectangular collimation is a method used to reduce patient exposure to ionizing radiation; however, this benefit is negligible if radiographs must be retaken due to cone cut errors that make the radiograph diagnostically unusable. Therefore, the aim of this study was to explore the frequency of cone cut in radiographs taken using a rectangular collimator. PRINCIPAL FINDINGS: cone cut was observed in 21% of the radiographs; however, only 3% of the radiographs were considered diagnostically unusable. PRACTICAL IMPLICATIONS: rectangular collimation does not result in a high number of diagnostically unusable radiographs and should be used to reduce patient exposure to ionizing radiation.

[How to detect opacities in the orofacial soft tissue on a panoramic radiograph: heterotopic ossifications and foreign bodies]. / Herkenning van wekedelenopaciteiten op een panoramische röntgenopname: heterotopische ossificaties en corpora aliena.

Opacities in the orofacial soft tissue rather than the bone are frequently seen on panoramic radiographs. The differential diagnosis of these opacities is diverse and concerns frequently occurring disorders but also rare ones. Due to the diversity of diagnoses, the clinical interpretation of a soft tissue opacity is often difficult. A distinction is made among heterotopic calcifications, heterotopic ossifications, and foreign bodies. Heterotopic calcifications are subdivided into 3 groups, i.e. dystrophic, idiopathic and metastatic calcifications. In this article, stress is placed on the radiographic and clinical characteristics of heterotopic ossifications and foreign bodies, and how they can be recognised on a panoramic radiograph. Besides this, attention will be paid to the need for possible additional imaging techniques and indications regarding treatment option.

[How to detect opacities in the orofacial soft tissue on a panoramic radiograph? Idiopathic calcifications]. / Herkenning van wekedelen­opaciteiten op een panoramische röntgenopname: idiopathische calcificaties.

Opacities not in the bone but in the orofacial soft tissue, are frequently seen on panoramic radiographs. The differential diagnosis of these opacities is diverse and concerns frequently occurring disorders but also rare ones. Due to the diversity of diagnoses, the clinical interpretation of a soft tissue opacity is often difficult. A distinction is made among heterotopic calcifications, heterotopic ossifications, and foreign bodies. Heterotopic calcifications are subdivided into 3 groups, i.e. dystrophic calcifications, idiopathic calcifications, and metastatic calcifications. In this article, stress is placed on the radiographic and clinical characteristics ofidiopathic calcifications and how they can be recognised on a panoramic radiograph. Besides this, attention will be paid to the need for possible additional imaging techniques and indications regarding treatment options. Idiopathic calcification results from deposition of calcium salts in healthy tissue without an apparent cause. Calcium and phosphate levels in the serum are normal in these cases.

[How to detect opacities in the orofacial soft tissue on a panoramic radiograph? Dystrophic calcifications]. / Herkenning van wekedelenopaciteiten op een panoramische röntgen­opname: dystrofische calcificaties.

Opacities in the orofacial soft tissue rather than the bone are frequently seen on panoramic radiographs. The differential diagnosis of these opacities is diverse and comprises abnormalities both frequently seen and rare. On account of this diversity, the clinical interpretation of a soft tissue opacity is often difficult. Heterotopic calcifications, heterotopic ossifications, and foreign bodies are distinguished. Heterotopic calcifications are subdivided into 3 groups, i.e. dystrophic calcifications, idiopathic calcifications, and metastatic calcifications. In this article, the emphasis will be on radiological and clinical characteristics of dystrophic calcifications and how to recognize these on panoramic radiographs. In dystrophic calcification, calcium salts are deposited in chronically inflamedor necrotic tissue.

Reducing an already low dental diagnostic X-ray dose: does it make sense? Comparison of three cost-utility analysis methods used to assess two dental dose-reduction measures.

OBJECTIVES: To find a method that is suitable for providing an objective assessment of the cost effectiveness of a dose-reducing measure used for diagnostic dental X-ray exposures. METHODS: Three cost-utility analysis (CUA) methods were evaluated by comparing their assessments of two dose-reduction measures, a rectangular collimator and the combination of two devices that reduce the radiation dose received during orthodontic lateral cephalography. The following CUA methods were used: (1) the alpha value (AV), a monetary valuation of dose reduction used in the nuclear industry; (2) the value of a statistical life for valuation of the reduction in stochastic adverse effects; and (3) the time-for-time method, based on the postulate that risk reduction is effective when the number of years of life gained is more than the years that an average worker must work to earn the costs of the risk-reducing measure. The CUA methods were used to determine the minimum number of uses that was required for the dose-reducing device to be cost effective. The methods were assessed for coherence (are comparable results achieved for comparable countries?) and adaptability (can the method be adjusted for age and gender of specific patient groups?). RESULTS: The performance of the time-for-time method was superior to the other methods. Both types of dose-reduction devices tested were assessed as cost effective after a realistic number of uses with all three methods except low AVs. CONCLUSIONS: CUA for the methods of X-ray dose reduction can be performed to determine if investment in low dose reduction is cost effective. The time-for-time method proved to be a coherent and versatile method for performing CUA.

Effect of head position on cephalometric evaluation of the soft-tissue facial profile.

OBJECTIVES: During a cone beam CT scan, the patient is in an upright or supine position. This position depends on the brand and type of the scanner. The aims of this study are: (1) to investigate if the head position has an effect on cephalometric evaluation of the soft-tissue facial profile, comparing the recordings in natural head position (NHP) and supine head position (SHP) and (2) to investigate if age, gender and body mass index (BMI) are contributing factors to the effect of the head position. METHODS: 90 subjects were photographed in profile both in NHP and in SHP. 12 soft-tissue angular and linear cephalometric values were calculated. Two-way random intraclass correlation coefficients were calculated to determine observer reliability. Paired t-tests and linear regression analyses were performed to investigate the differences between the head positions and the influence of age, gender and BMI. RESULTS: Intraobserver reliability was generally high. Paired t-tests showed significant changes as a result of head positioning (p < 0.0001) in 9 of the 12 measurements. These differences were small and clinically not relevant, except for the "lower face-throat angle". Regression analysis revealed no relevant influence of age, gender and BMI. CONCLUSIONS: Cephalometric soft-tissue evaluation from a recording in SHP is generally reliable, except for the throat-chin area where a clinically relevant difference was found. The contour of the submandibular tissues in SHP causes the chin to appear more prominently. This can cause incorrect orthodontic diagnosis and treatment planning.

Dose reduction of cone beam CT scanning for the entire oral and maxillofacial regions with thyroid collars.

OBJECTIVE: The aim of this study was to evaluate the influence of thyroid collars on radiation dose during cone beam CT (CBCT) scanning. METHODS: Average tissue-absorbed dose for a NewTom 9000 CBCT scanner (Quantitative Radiology, Verona, Italy) was measured using thermoluminescent dosemeter chips in a phantom. The scans were carried out with and without thyroid collars. Effective organ dose and total effective dose were derived using International Commission on Radiological Protection 2007 recommendations. RESULTS: The effective organ doses for the thyroid gland and oesophagus were 31.0 µSv and 2.4 µSv, respectively, during CBCT scanning without a collar around the neck. When the thyroid collars were used loosely around the neck, no effective organ dose reduction was observed. When one thyroid collar was used tightly on the front of the neck, the effective organ dose for the thyroid gland and oesophagus were reduced to 15.9 µSv (48.7% reduction) and 1.4 µSv (41.7% reduction), respectively. Similar organ dose reduction (46.5% and 41.7%) was achieved when CBCT scanning was performed with two collars tightly on the front and back of the neck. However, the differences to the total effective dose were not significant among the scans with and without collars around the neck (p = 0.775). CONCLUSIONS: Thyroid collars can effectively reduce the radiation dose to the thyroid and oesophagus if used appropriately.

Reversibility of the anti-FXa activity of idrabiotaparinux (biotinylated idraparinux) by intravenous avidin infusion.

BACKGROUND: Idraparinux is an inhibitor of activated factor X (FXa) with a long half-life allowing once-weekly dosing. Idrabiotaparinux is a biotinylated version of idraparinux; its activity can be reversed with avidin. OBJECTIVE: To investigate the tolerability, safety and pharmacodynamics of avidin in healthy subjects and patients with deep vein thrombosis (DVT) receiving idrabiotaparinux. PATIENTS AND METHODS: In a placebo-controlled, randomized, double-blind Phase I study, 41 healthy males received subcutaneous idrabiotaparinux before being randomized to a 30-min intravenous avidin infusion or placebo. Idrabiotaparinux plus avidin were re-administered 10-14 months later in eight subjects. In addition, in a prospective substudy of the Phase III EQUINOX trial, 55 patients who received weekly idrabiotaparinux for 6 months were randomized to receive either 100 mg avidin (n = 33) or placebo (n = 22). The primary activity outcome was anti-FXa activity calculated immediately before and after avidin infusion. Adverse events were recorded to assess safety and tolerability. RESULTS: Avidin rapidly reversed the anti-FXa activity of idrabiotaparinux, ranging from 66.1 to 90.3% in healthy subjects and from 67 to 97% (mean 78%) in DVT patients. Avidin was well tolerated, with a similar nature and frequency of adverse events to placebo. No venous thromboembolism recurrence occurred in the 3-month post-avidin infusion. CONCLUSION: A 30-min intravenous infusion of avidin 100 mg is well tolerated, safe, and offers immediate and specific reversibility both after single and repeated doses of idrabiotaparinux in healthy subjects, and in DVT patients following a 6-month treatment period.

The pharmacokinetics of idraparinux, a long-acting indirect factor Xa inhibitor: population pharmacokinetic analysis from Phase III clinical trials.

BACKGROUND: Idraparinux, a long-acting synthetic pentasaccharide, is a specific antithrombin-dependent inhibitor of activated factor X that has been investigated in the treatment and prevention of thromboembolic events. OBJECTIVES: To characterize the population pharmacokinetic profile of idraparinux in patients enrolled in van Gogh and Amadeus Phase III clinical trials. PATIENTS AND METHODS: Idraparinux was administered once-weekly subcutaneously at a dose of 2.5 mg, or 2.5 mg (first dose) and then 1.5 mg for patients with severe renal insufficiency (creatinine clearance<30 mL min(-1)). A population pharmacokinetic model was developed using data from 704 patients with acute deep-vein thrombosis or pulmonary embolism, 1310 patients suffering from atrial fibrillation, and 40 healthy subjects. Potential covariates analyzed included demographics (age, sex, weight and ethnicity), and serum creatinine and creatinine clearance determinations. RESULTS: A three-compartment model best described idraparinux pharmacokinetics, with interindividual variability on clearance, central volume of distribution, and absorption rate constant; residual variability was low. Typical clearance, central volume of distribution, absorption rate constant and volume of distribution at steady-state were 0.0255 L h(-1), 3.36 L, 1.37 h and 30.8 L, respectively. Peak concentration was reached at 2.5 h. The terminal half-life was 66.3 days and time to steady-state was 35 weeks. At steady-state, exposures were similar for patients without and with severe renal impairment receiving adjusted-dose. Creatinine clearance was the most important covariate affecting idraparinux clearance. The particular characteristics of idraparinux--rapid onset of action and long-acting anticoagulant effect--offer interesting clinical perspectives currently under investigation with idrabiotaparinux, the reversible biotinylated form of idraparinux.

Comparing the performance of storage phosphor plate and Insight film images for the detection of proximal caries depth.

OBJECTIVES: To compare proximal caries depth between conventional film images, unenhanced and enhanced storage phosphor plate images. METHOD: Bitewing radiographs were taken on 100 patients presenting for Conservative and Periodontal treatment. Only one bitewing was taken on a patient either the right or left hand side of the patient A DenOptics storage phosphor plate and size 3 Kodak Insight film were simultaneously placed into a Rinn bitewing holder. The Insight film was placed behind the phosphor plate. Both were simultaneously exposed to radiation. The unenhanced phosphor plate images were copied four times. Contrast and brightness were either increased or decreased on the copied images. A five point scale was chosen for proximal caries depth: 0--sound, 1--caries in enamel, 2--caries reaching dentino-enamel junction, 3--caries into dentine, 4--caries in a restored area. The bitewing images were evaluated by 4 clinicians. Images with technical errors were excluded from the study. RESULTS: Altogether 1848 tooth surfaces were evaluated of which 136 surfaces were excluded due to technical errors. The results show that for the detection of proximal caries there is no significant difference in accuracy between unenhanced storage phosphor plate and Kodak Insight film images (p > 0.001). When decreasing both contrast and brightness there was no significant difference in diagnostic accuracy (p > 0.001) between unenhanced and enhanced storage phosphor plate images. More surfaces were analyzed for caries into the dentine on the enhanced images when both contrast and brightness were increased. CONCLUSION: Although contrast-enhanced and brightness-enhanced images retween conventional film, unenhanced and enhanced images.

Comparison between effective radiation dose of CBCT and MSCT scanners for dentomaxillofacial applications.

OBJECTIVES: To compare the effective dose levels of cone beam computed tomography (CBCT) for maxillofacial applications with those of multi-slice computed tomography (MSCT). STUDY DESIGN: The effective doses of 3 CBCT scanners were estimated (Accuitomo 3D, i-CAT, and NewTom 3G) and compared to the dose levels for corresponding image acquisition protocols for 3 MSCT scanners (Somatom VolumeZoom 4, Somatom Sensation 16 and Mx8000 IDT). The effective dose was calculated using thermoluminescent dosimeters (TLDs), placed in a Rando Alderson phantom, and expressed according to the ICRP 103 (2007) guidelines (including a separate tissue weighting factor for the salivary glands, as opposed to former ICRP guidelines). RESULTS: Effective dose values ranged from 13 to 82 microSv for CBCT and from 474 to 1160 microSv for MSCT. CBCT dose levels were the lowest for the Accuitomo 3D, and highest for the i-CAT. CONCLUSIONS: Dose levels for CBCT imaging remained far below those of clinical MSCT protocols, even when a mandibular protocol was applied for the latter, resulting in a smaller field of view compared to various CBCT protocols. Considering this wide dose span, it is of outmost importance to justify the selection of each of the aforementioned techniques, and to optimise the radiation dose while achieving a sufficient image quality. When comparing these results to previous dosimetric studies, a conversion needs to be made using the latest ICRP recommendations.

Detection of in vitro proximal caries in storage phosphor plate radiographs scanned with different resolutions.

OBJECTIVES: To investigate the effect of the scanning resolution of storage phosphor plate (SPP) radiographs on the detection of proximal caries lesions. METHODS: 10 dentists evaluated 72 proximal surfaces of premolars with respect to caries from SPP radiographs scanned with theoretical spatial resolutions of: (1) the Digora FMX at 7.8 lp mm(-1); (2) the Digora Optime at both 7.8 lp mm(-1) and 12.5 lp mm(-1); and (3) the Dürr VistaScan at 10 lp mm(-1) and 20 lp mm(-1), respectively. The lesions were validated by histological examination. Receiver operating characteristic (ROC) analysis was employed. RESULTS: The A(z) value for the radiographs scanned with the Dürr VistaScan at 10 lp mm(-1) is significantly lower than those for the other series of radiographs (P = 0.000). CONCLUSIONS: For SPP radiographs, an increased theoretical spatial resolution per se is not related to an improved detection of proximal caries.

Evaluation of web-based instruction for anatomical interpretation in maxillofacial cone beam computed tomography.

OBJECTIVES: To evaluate the effectiveness of a web-based instruction in the interpretation of anatomy in images acquired with maxillofacial cone beam CT (CBCT). METHODS: An interactive web-based education course for the interpretation of craniofacial CBCT images was recently developed at our institution. Self-evaluation modules on correlative anatomical features were also included to support the learning process. Three e-learner groups were selected to evaluate the effectiveness of the educational modules. The three groups were (1) oral health specialists (OHSs) (comprising periodontologists, prosthodontists, orthodontists and maxillofacial surgeons); (2) third grade (DS3) and (3) first grade (DS1) undergraduate dental students. The assessment modules that were part of the interactive web-course content were administered after delivery of the course material. In addition, each group received a computer affinity questionnaire to quantify the extent of knowledge about computers and a perception questionnaire to assess their attitudes toward the web-course. RESULTS: The OHS group yielded significantly better scoring results in the post-course test than the pre-course test. However, no statistically significant differences in test scores were found for both undergraduate student groups (DS1 and DS3). All groups presented a highly positive attitude towards the web-course, as was demonstrated by the post-course perception questionnaire. CONCLUSIONS: The present CBCT educational course is an effective didactic method for teaching OHSs the anatomical interpretation of CBCT multiplanar reformatted images and, for undergraduate students, it was found to be as effective as conventional educational methods in dentistry. The efficacy of a web-based educational course requires further evaluation.

Detection of proximal caries with high-resolution and standard resolution digital radiographic systems.

AIMS: The aim of this study was to: (1) compare the diagnostic accuracy of the high-resolution and standard resolution settings of four digital imaging systems for caries diagnosis and (2) compare the effect on the diagnostic accuracy of reducing the high-resolution image sizes to the standard resolution dimensions, and vice versa. MATERIALS AND METHODS: 90 extracted human premolars were mounted in groups of 5 in plaster blocks, containing 4 test teeth and 1 non-test tooth. Two blocks at a time were placed in a jig to simulate a bitewing radiograph. Radiographs were taken using four digital systems (Planmeca Dixi 2; Gendex Visualix HDI; Dürr Vistascan; Digora Optime), each at two resolution settings. Next, the teeth were sectioned and a total of 65 surfaces were incorporated in the study. Additionally, the bicubic interpolation method was applied to reduce the high-resolution original images and to enlarge the standard resolution images. The original, reduced and enlarged images were randomly shown to five observers in two random sessions. The observers were asked to assess caries depth on a 4-point scale. The observers' scores were compared with the results from a histological examination. Data were analysed using the statistical theory for multivariate discrete data. Cohen's kappa was used to determine the agreement with the gold standard. RESULTS: None of the comparisons between the spatial resolution settings, or the comparisons between increased or reduced image size and the original image sizes, showed significant differences in the probability of caries detection (chi2=26.59, df=26, P approximately 0.50). The four digital systems used in this study differ significantly in the probability of caries detection (chi2=41.55, df=24, P<0.02). Compared with the gold standard, the Gendex Visualix HDI CCD sensor has the highest measure of agreement (kappa=0.31). CONCLUSION: Caries diagnosis does not improve when using high-resolution settings compared with the standard settings. The use of bicubic convolution interpolation for zooming has no detectable effect on caries diagnosis and therefore is recommended to use when enlarging or reducing radiographs. The probability of caries detection, however, was different for the sensor systems of the different manufacturers.

Detection of proximal caries in vitro using standard and task-specific enhanced images from a storage phosphor plate system.

Eight dentists evaluated 72 proximal surfaces of premolars with respect to all caries lesions and to lesions into dentine in digital images from a storage phosphor plate system. The images were processed in four different ways: (1) the default algorithm of the standard imaging system (DF); (2) an algorithm correcting for attenuation and visual response (AV), and two proprietary caries-specific enhancement algorithms (3) K1, and (4) K2, respectively. The lesions were validated by histological examination. There were no significant differences in the areas under the receiver operating characteristic curves between differently processed radiographs for the categories of all caries lesions and caries into dentine.

Marginal bone levels measured in film and digital radiographs corrected for attenuation and visual response: an in vivo study.

OBJECTIVE: To compare the accuracy and precision of measurements on marginal bone levels in differently processed digital radiographs and in film-based radiographs. METHODS: Twenty-one patients with a diagnosis of chronic periodontitis were included in this study. Periapical radiographs were exposed with the Dixi digital intraoral radiographic system (Planmeca Oy, Helsinki, Finland) and the F-speed Film (Insight, Eastman-Kodak Co., Rochester, NY), respectively. Digital radiographs were subsequently processed into two sets: (a) correction for attenuation and visual response and (b) the same correction but with an additional shift in grey levels. Patients had periodontal surgery immediately after the radiographs were exposed. The vertical distance from cementoenamel junction to the most apical part of the marginal bone was assessed. The measurements were then employed as reference standard and subtracted by the vertical distance from radiographs accordingly. Altogether, 47 sites were evaluated. Seven observers were employed for evaluation under the same viewing conditions. ANOVA was employed for statistical analysis. RESULTS: No significant differences were found between the absolute differences of the vertical distance obtained from radiographs to their corresponding reference standards when comparing differently processed digital radiographs, but the absolute differences were significantly smaller in digital radiographs than in films. Interobserver variances were not significant. CONCLUSION: Digital radiographs have a favourable measurement accuracy compared with film radiographs when assessing marginal bone levels.

Dosimetry of digital panoramic imaging. Part I: Patient exposure.

OBJECTIVES: To measure patient radiation dose during panoramic exposure with various panoramic units for digital panoramic imaging. METHODS: An anthropomorphic phantom was filled with thermoluminescent dosemeters (TLD 100) and exposed with five different digital panoramic units during ten consecutive exposures. Four machines were equipped with a direct digital CCD (charge coupled device) system, whereas one of the units used storage phosphor plates (indirect digital technique). The exposure settings recommended by the different manufacturers for the particular image and patient size were used: tube potential settings ranged between 64 kV and 74 kV, exposure times between 8.2 s and 19.0 s, at fuse current values between 4 mA and 7 mA. The effective radiation dose was calculated with inclusion of the salivary glands. RESULTS: Effective radiation doses ranged between 4.7 microSv and 14.9 microSv for one exposure. Salivary glands absorbed the most radiation for all panoramic units. When indirect and direct digital panoramic systems were compared, the effective dose of the indirect digital unit (8.1 microSv) could be found within the range of the effective doses for the direct digital units (4.7-14.9 microSv). CONCLUSIONS: A rather wide range of patient radiation doses can be found for digital panoramic units. There is a tendency for lower effective doses for digital compared with analogue panoramic units, reported in previous studies.

Dosimetry of digital panoramic imaging. Part II: Occupational exposure.

OBJECTIVES: To measure occupational radiation dose during panoramic exposure from five digital panoramic X-ray units. METHODS: Exposures were made with five different digital panoramic units, of which four were equipped with a direct digital CCD (charge coupled device, "direct digital" technique), and one used storage phosphor plates ("indirect digital" technique). An anthropomorphic phantom served as the patient. An ionization chamber recorded the scattered radiation at 1 m from the phantom at five different locations around the panoramic units, both at the level of the thyroid gland and the level of the gonads, and effective organ doses were calculated. Exposure parameters were set as recommended by the manufacturers for the particular image and patient size: tube potential settings ranged between 64 kV and 74 kV, exposure times between 8.2 s and 19.0 s, tube current values between 4 mA and 7 mA. RESULTS: The maximum organ equivalent dose at 1 m from the panoramic unit was 0.60 microGy, the maximum organ effective dose was 0.10 microSv. Organ equivalent doses varied between 0.18 microGy and 0.30 microGy and organ effective doses between 0.01 microSv and 0.05 microSv for the different positions around the units (average for the different panoramic units). The variations in organ doses for the various machines were 0.04-0.53 microGy organ equivalent dose and 0.01-0.08 microSv organ effective dose. CONCLUSIONS: Assuming that 500 panoramic radiographs per year are taken by a dental practitioner at 1 m distance from the panoramic unit, he or she will receive an annual additional organ effective dose between 5 microSv and 15 microSv for the thyroid gland and between 5 microSv and 40 microSv for the gonads, depending on the type of digital panoramic unit.

Radiation doses of indirect and direct digital cephalometric radiography.

AIM: The aim of this study was to measure organ doses and calculate the effective dose for indirect and direct digital cephalometric exposures. MATERIAL AND METHODS: Indirect digital cephalometric exposures were made of a Rando phantom head using a Cranex Tome multipurpose unit with storage phosphor plates from Agfa and the direct digital (Charge Coupled Device, CCD) exposures were made with a Proline Ceph CM unit. Exposure settings were 70 kV and 4 mAs for indirect digital exposures. Direct digital exposures were made with 70 kV, 10 mA and a total scanning time of 23 s. TLD700 dosemeters were used to measure organ doses, and the effective doses were calculated with (effective dose(sal)) and without inclusion of the salivary glands. A pilot study was carried out to compare diagnostic image quality of both imaging modalities. RESULTS: Effective doses were 1.7 microSv for direct digital and 1.6 microSv for indirect digital cephalometric imaging. When salivary glands were included in the calculation, effective doses(sal) were 3.4 microSv and 2.2 microSv respectively. Organ doses were higher for direct digital imaging, except for the thyroid gland, where the organ doses were comparable. Diagnostic image quality of indirect and direct digital cephalometric images seemed comparable. CONCLUSION: Effective dose and effective dose(sal) were higher for direct digital cephalometric exposure compared with indirect digital exposure. Organ doses were higher for direct digital cephalography. From preliminary data, it may be presumed that diagnostic image quality of indirect and direct digital cephalometric images are comparable.

Appearance of the mandibular incisive canal on panoramic radiographs.

Panoramic radiographs are routinely used in the dental office for various diagnostic purposes. This study aimed to evaluate the visibility of neurovascular structures in the mandibular interforaminal region on such radiographs. Panoramic radiographs were obtained with a Cranex Tome (Soredex) from 545 consecutive patients using a standard exposure and positioning protocol. For visibility scoring of neurovascular structures, a four-point rating scale was used. The mandibular canal and the mental foramen could be observed in the majority of the cases with good visibility. The lingual foramen was visualized in 71% of the cases, with good visibility in 12%. An incisive canal was identified in 15% of the images, with good visibility in only 1%. An anatomical variation to be considered is the anterior looping of the mental nerve (in 11% of images). Panoramic radiographs can be used for visualization of the mental foramen and a potential anterior looping but not for locating the mandibular incisive canal. To verify its existence for preoperative planning purposes, cross-sectional imaging modalities (HR-CT or spiral tomography) should be preferred.