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  • 1.
    Ahlqvist, Jan
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Bryndahl, Frerik
    Umeå University, Faculty of Medicine, Department of Odontology.
    Eckerdal, Olof
    Isberg, Annika
    Sources of radiographic distortion in conventional and computed tomography of the temporal bone.1998In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 27, no 6, p. 351-7Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: To identify those bony regions of the glenoid fossa where, due to the inclination, there is an increased risk of radiographic distortion in conventional and computed tomography (CT).

    METHODS: The inclination of the roof and posterior wall of the glenoid fossa was determined relative to established imaging planes. Measurements were performed on 50 corrected coronal MR and 50 axial CT images and 200 sagittal cryosections of 50 temporomandibular joints (TMJs). The location of regions with unfavourable bone wall inclination was identified using the condyle as a reference.

    RESULTS: The inclination of parts of the fossa roof exceeded the limit for reliable depiction in corrected sagittal and coronal planes in 40% and 8% of the joints respectively. The inclination of parts of the posterior wall of the fossa exceeded the limit for reliable depiction in corrected sagittal and in true sagittal planes in 100% and 84% of the joints respectively. In 84% of the joints the inclination exceeded the limit for reliable depiction in the axial plane. For both bone walls the regions with unfavourable inclination were in the medial part of the joint.

    CONCLUSIONS: The angulation of parts of the roof and posterior wall of the glenoid fossa in relation to established imaging planes makes them highly susceptible to distortion. The oblique coronal projection is well suited for depiction of the roof of the fossa and preferable to a sagittal projection. An oblique axial projection is required for the posterior wall.

  • 2. Ahlqvist, Jan
    et al.
    Eliasson, S
    Welander, Ulf
    The cephalometric projection. Part II. Principles of image distortion in cephalography.1983In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 12, no 2, p. 101-8Article in journal (Refereed)
  • 3.
    Ahlqvist, Jan
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Isberg, Annika
    Umeå University, Faculty of Medicine, Department of Odontology.
    Validity of computed tomography in imaging thin walls of the temporal bone1999In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 28, no 1, p. 13-19Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: To evaluate the validity of computed tomography (CT) for reproduction of the bone margins of the temporomandibular joint (TMJ).

    METHODS: Seven TMJ specimens were examined with a CT and then cryosectioned. The bone separating the TMJ from the middle cranial fossa, middle ear and external auditory canal was measured as the full width at half maximum (FWHM). Measurements were compared with the true thickness of the bone wall.

    RESULTS: There was good agreement when the bone walls were thicker than 1 mm: accuracy was influenced only by the angle of the bone wall to the scanning plane. Conversely, bone walls thinner than 1 mm were reproduced with a magnification that increased with decreasing bone thickness. The difference increased further as the inclination of the bone wall became greater.

    CONCLUSION: Measurements performed at FWHM are reliable within +/- 10% for bone walls more than approximately 1 mm thick which form an angle of less than 35 degrees to the perpendicular of the scanning plane. For bone walls thinner than 1 mm and for those thicker than 1 mm with an inclination exceeding approximately 35 degrees, partial volume effects result in a progressively increasing magnification of bone thickness.

  • 4. Ahlqvist, Jan
    et al.
    Legrell, Per Erik
    A technique for the accurate administration of corticosteroids in the temporomandibular joint.1993In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 22, no 4, p. 211-3Article in journal (Refereed)
    Abstract [en]

    A new technique for intra-articular injection of a corticosteroid in the temporomandibular joint (TMJ) is presented. The corticosteroid is mixed with contrast medium and the administration visualized and controlled using fluoroscopy. When superior and inferior joint spaces have been filled and the soft tissues of the joint have been identified in the fluoroscopic image, additional corticosteroid can be administered to selected sites within the TMJ.

  • 5. Bou Serhal, C
    et al.
    Jacobs, R
    Flygare, Lennart
    Quirynen, M
    van Steenberghe, D
    Perioperative validation of localisation of the mental foramen2002In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 31, no 1, p. 39-43Article in journal (Refereed)
    Abstract [en]

    AIM: To assess the accuracy of panoramic radiography and spiral or computed tomography for the localisation of the mental foramen.

    MATERIALS AND METHODS: The distance from the alveolar crest to the mental foramen was measured from panoramic radiographs, spiral tomograms and CT scans. The same distance was measured during implant surgery using a specially designed caliper.

    RESULTS: Panoramic radiography showed more deviation (+0.6 mm) from the perioperative measurements than either spiral or computed tomography (+0.4 and -0.3 mm respectively). The difference was significant (P<0.05). In general, distances were overestimated on the panoramic radiographs.

    CONCLUSIONS: Cross-sectional imaging techniques are recommended for the pre-operative planning of implants in the posterior mandible.

  • 6. Brown, J
    et al.
    Jacobs, R
    Levring Jäghagen, Eva
    Umeå University, Faculty of Medicine, Department of Odontology, School of Dentistry.
    Lindh, C
    Baksi, G
    Schulze, D
    Schulze, R
    Basic training requirements for the use of dental CBCT by dentists: a position paper prepared by the European Academy of DentoMaxilloFacial Radiology2014In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 43, no 1, article id 20130291Article in journal (Refereed)
    Abstract [en]

    Cone beam CT (CBCT) is a relatively new imaging modality, which is now widely available to dentists for examining hard tissues in the dental and maxillofacial regions. CBCT gives a three-dimensional depiction of anatomy and pathology, which is similar to medical CT and uses doses generally higher than those used in conventional dental imaging. The European Academy of DentoMaxilloFacial Radiology recognizes that dentists receive training in two-dimensional dental imaging as undergraduates, but most of them have received little or no training in the application and interpretation of cross-sectional three-dimensional imaging. This document identifies the roles of dentists involved in the use of CBCT, examines the training requirements for the justification, acquisition and interpretation of CBCT imaging and makes recommendations for further training of dentists in Europe who intend to be involved in any aspect of CBCT imaging. Two levels of training are recognized. Level 1 is intended to train dentists who prescribe CBCT imaging, such that they may request appropriately and understand the resultant reported images. Level 2 is intended to train to a more advanced level and covers the understanding and skills needed to justify, carry out and interpret a CBCT examination. These recommendations are not intended to create specialists in CBCT imaging but to offer guidance on the training of all dentists to enable the safe use of CBCT in the dentoalveolar region.

  • 7. Eckerdal, Olof
    et al.
    Ahlqvist, Jan
    Alehagen, U
    Wing, K
    Length dimensions and morphologic variations of the external bony auditory canal. A radiographic and histologic investigation.1978In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 7, no 1, p. 43-50Article in journal (Refereed)
  • 8. Eliasson, S
    et al.
    Welander, U
    Ahlqvist, Jan
    The cephalographic projection. Part I: General considerations.1982In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 11, no 2, p. 117-22Article in journal (Refereed)
  • 9. Flygare, Lennart
    et al.
    Öhman, A
    Kull, L
    Letter to the editor concerning Parrott LA, Ng SY. A comparison between bitewing radiographs taken with rectangular and circular collimators in UK military dental practices: a retrospective study published in Dentomaxillofacial Radiology (2001;40:102–109).2011In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 40, no 4, p. 262-263Article in journal (Refereed)
  • 10.
    Garoff, Maria
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Ahlqvist, Jan
    Umeå University, Faculty of Medicine, Department of Odontology.
    Levring Jäghagen, Eva
    Umeå University, Faculty of Medicine, Department of Odontology.
    Johansson, Elias
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine. Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Wester, Per
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine. Department of Clinical Sciences, Karolinska Insititutet, Danderyds hospital, Stockholm.
    Carotid calcification in panoramic radiographs: radiographic appearance and the degree of carotid stenosis2016In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 45, no 6, article id 20160147Article in journal (Refereed)
    Abstract [en]

    Objectives: Approximately 7% of patients examined with panoramic radiographs (PRs) for odontological reasons, and with incidental findings of carotid artery calcification (CAC), have significant (≥50%) carotid stenosis (SCS). The aim of this study was to determine if the radiographic appearance of CACs in PRs could be categorized such that we could improve the positive-predictive value (PPV) for SCS detection.

    Methods: This cross-sectional study included 278 patients with CACs identified by PRs, 127 with SCS and 151 without SCS. CACs were categorized based on the following appearances: (1) single, (2) scattered or (3) vessel-outlining. Correlates were derived for each category according to positivity or not for SCS in the corresponding neck sides. For a representative adult population (in dentistry) presenting with CACs in PRs, PPVs for SCS prediction were then calculated for three subgroups based on different combinations of appearances (2) and/or (3).

    Results: Vessel-outlining CACs corresponded to 65% of neck sides with SCS vs 47% without SCS (p < 0.001). Single CACs corresponded to 15% of neck sides with SCS vs 27% without SCS (p = 0.006). Scattered CACs corresponded to 20% of neck sides with SCS vs 26% without SCS (p  = 0.127). In the representative population, the PPVs for SCS detection were comparable (7.2–7.8%) for all three subgroups and when the presence of a CAC is the sole criterion (7.4%).

    Conclusions: Stratifying the radiographic appearance of CACs in PRs does not improve the PPV for SCS detection. Whether different radiographic appearances are associated with future risk of stroke, or other cardiovascular events, remains unknown.

  • 11. Horner, K
    et al.
    Islam, M
    Flygare, Lennart
    Tsiklakis, K
    Whaites, E
    Basic principles for use of dental cone beam computed tomography: consensus guidelines of the European Academy of Dental and Maxillofacial Radiology2009In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 38, no 4, p. 187-195Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: To develop "basic principles" on the use of dental cone beam CT by consensus of the membership of the European Academy of Dental and Maxillofacial Radiology.

    METHODS: A guideline development panel was formed to develop a set of draft statements using existing European directives and guidelines on radiation protection. These statements were revised after an open debate of attendees at a European Academy of Dental and Maxillofacial Radiology (EADMFR) Congress in June 2008. A modified Delphi procedure was used to present the revised statements to the EADMFR membership, utilising an online survey in October/November 2008.

    RESULTS: Of the 339 EADMFR members, 282 had valid e-mail addresses and could be alerted to the online survey. A response rate of 71.3% of those contacted by e-mail was achieved. Consensus of EADMFR members, indicated by high level of agreement for all statements, was achieved without a need for further rounds of the Delphi process.

    CONCLUSIONS: A set of 20 basic principles on the use of dental cone beam CT has been devised. They will act as core standards for EADMFR and, it is hoped, will be of value in national standard-setting within Europe.

  • 12. Legrell, P E
    et al.
    Nyström, Elisabeth
    Umeå University, Faculty of Medicine, Odontology, Oral and Maxillofacial Surgery.
    Radiographic study of structural changes in the temporomandibular joint after oblique sliding osteotomy: comparison between the extra-oral and intra-oral approaches.1990In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 19, no 4, p. 145-148Article in journal (Refereed)
    Abstract [en]

    Oblique sliding osteotomy of the mandibular rami was performed on 41 patients by either an intra-oral (21 patients) or extra-oral (20 patients) approach. The temporomandibular joints were radiographed preoperatively and then immediately and 18 months postoperatively. Signs of structural changes were recorded so as to compare the two approaches to osteotomy. The most common findings following the operation were signs of sclerosis and bone remodelling in 85% and 73% respectively of the two groups but these differences were not statistically significant.

  • 13.
    Levring Jäghagen, Eva
    et al.
    Umeå University, Faculty of Medicine, Odontology, Oral and Maxillofacial Radiology.
    Franklin, KA
    Umeå University, Faculty of Medicine, Public Health and Clinical Medicine.
    Isberg, A
    Umeå University, Faculty of Medicine, Odontology, Oral and Maxillofacial Radiology.
    Snoring, sleep apnoea and swallowing dysfunction: a videoradiographic study2003In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 32, no 5, p. 311-316Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: Snoring is associated with subclinical pharyngeal swallowing dysfunction, probably owing to vibration trauma to the pharyngeal tissues caused by snoring. Negative intrathoracic pressure during apnoea causes stretching of the velum and pharynx. The aim of this study was to investigate whether patients with severe sleep apnoea have an increased frequency of videoradiographically diagnosed subclinical pharyngeal swallowing dysfunction compared with snoring patients with or without mild sleep apnoea as well as with non-snoring controls. METHODS: Eighty consecutive patients referred for sleep apnoea recordings because of snoring were examined. Fourteen of these patients were excluded because they suffered from dysphagia. Fifteen non-snoring, non-dysphagic volunteers served as controls. Videoradiography was performed to examine the oral and pharyngeal swallowing function in patients and controls. Overnight sleep apnoea recordings were used to evaluate the apnoea-hypopnoea index (AHI). RESULTS: Pharyngeal swallowing dysfunction was observed in 34/66 (52%) of the snoring patients and in 1/15 (7%) of the non-snoring controls. Pharyngeal swallowing dysfunction was observed in 50% of patients with an AHI of >or=30, in 61% of patients with an AHI of 5-29 and in 43% of patients with an AHI of <5. There was no significant difference in the frequency of pharyngeal swallowing dysfunction between snoring patients with different AHIs. CONCLUSION: Snoring patients run an increased risk of developing subclinical pharyngeal swallowing dysfunction independent of concomitant sleep apnoea.

  • 14. Mota de Almeida, F. J.
    et al.
    Knutsson, K.
    Flygare, Lennart
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    The effect of cone beam CT (CBCT) on therapeutic decision-making in endodontics2014In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 43, no 4, article id 20130137Article in journal (Refereed)
    Abstract [en]

    Objectives: The aim was to assess to what extent cone beam CT (CBCT) used in accordance with current European Commission guidelines in a normal clinical setting has an impact on therapeutic decisions in a population referred for endodontic problems.

    Methods: The study includes data of consecutively examined patients collected from October 2011 to December 2012. From 2 different endodontic specialist clinics, 57 patients were referred for a CBCT examination using criteria in accordance with current European guidelines. The CBCT examinations were performed using similar equipment and standardized among clinics. After a thorough clinical examination, but before CBCT, the examiner made a preliminary therapy plan which was recorded. After the CBCT examination, the same examiner made a new therapy plan. Therapy plans both before and after the CBCT examination were plotted for 53 patients and 81 teeth. As four patients had incomplete protocols, they were not included in the final analysis.

    Results: 4% of the patients referred to endodontic clinics during the study period were examined with CBCT. The most frequent reason for referral to CBCT examination was to differentiate pathology from normal anatomy, this was the case in 24 patients (45% of the cases). The primary outcome was therapy plan changes that could be attributed to CBCT examination. There were changes in 28 patients (53%).

    Conclusions: CBCT has a significant impact on therapeutic decision efficacy in endodontics when used in concordance with the current European Commission guidelines.

  • 15.
    Nilsson, Tore
    et al.
    Umeå University, Faculty of Medicine, Odontology, Oral and Maxillofacial Radiology.
    Ahlqvist, Jan
    Johansson, Magnus
    Isberg, Annika
    Virtual reality for simulation of radiographic projections: validation of projection geometry2004In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 33, no 1, p. 44-50Article in journal (Refereed)
    Abstract [en]

    Objective: To develop a software for virtual reality (VR) simulation of X-ray images based on perspective projections through a patient model derived from data from a CT examination and to evaluate the accuracy in the projection geometry obtained by the software.

    Methods: A VR software was developed on a personal computer, with models of a patient, an X-ray machine and a detector. The model of the patient was derived from data from a CT examination of a dry skull. Simulated radiographic images of the patient model could be rendered as perspective projections based on the relative positions between the models. The projection geometry of the software was validated by developing an artificial CT data set containing high attenuation points as objects to be imaged. The accuracy in projection geometry was evaluated in a systematic way. The distances between two dots, representing the projected test points in the simulated radiographic images, were measured. They were compared with theoretical calculations of the corresponding distances using traditional mathematical tools.

    Results: The difference between the simulated and calculated projected distances never exceeded 0.5 mm. The error in simulated projected distances was in most cases within 1%. No systematic errors were revealed.

    Conclusion: The software, developed for personal computers, can produce simulated X-ray images with high geometric accuracy based on perspective projections through a CT data set. The software can be used for simulation of radiographic examinations.

  • 16.
    Nilsson, Tore
    et al.
    Umeå University, Faculty of Medicine, Odontology.
    Hedman, Leif
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Ahlqvist, Jan
    Umeå University, Faculty of Medicine, Odontology, Oral and Maxillofacial Radiology. Oral diagnostisk radiologi.
    Visual-spatial ability and interpretation of three-dimensional information in radiographs2007In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 36, p. 86-91Article in journal (Refereed)
    Abstract [en]

    Objectives: To investigate whether skill in the interpretation of three-dimensional (3D) information in radiographs utilizing the parallax phenomenon is associated with visual-spatial ability and whether development of this skill is related to visual-spatial ability.

    Methods: Eighty-six individuals with a median age of 25 years participated in the study. It was organized into three parts: (1) assessment before training, (2) training in object depth localization utilizing parallax and (3) assessment after training. Before training, visual-spatial ability was assessed with a mental rotation test, MRT-A; skill in interpreting 3D information was assessed with two specifically designed proficiency tests: a radiography test, which assessed the ability to interpret 3D information in radiographs utilizing motion parallax and a principle test which assessed understanding of the principles of motion parallax. After training, skill in interpreting 3D information was reassessed. Improvement was defined as the difference between test scores after training and before training. Multiple linear regression was used to analyse the effect of student and training characteristics on proficiency test results and improvement.

    Results: Radiography test results after training and improvement of radiography test results were significantly associated with MRT-A scores (P<0.001 and P=0.020, respectively). Principle test results were high before training and did not improve after training. The test results were associated with MRT-A both before (P=0.009) and after training (P=0.003).

    Conclusions: Understanding of the parallax phenomenon is associated with visual-spatial ability. Development of the skill to interpret 3D information in radiographs utilizing parallax is facilitated for individuals with high visual-spatial ability.

  • 17. Ohman, A
    et al.
    Kivijärvi, K
    Blombäck, U
    Flygare, Lennart
    Department of Radiology, Sunderby Hospital, SE-971 80, Luleå, Sweden.
    Pre-operative radiographic evaluation of lower third molars with computed tomography2006In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 35, no 1, p. 30-35Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: To report radiographic findings of examinations with computed tomography (CT) of impacted lower third molars with an intimate relation to the mandibular canal and to investigate how findings of a dark band across the roots of the lower third molar on panoramic views correspond to the CT findings.

    METHODS: CT images of 90 lower third molars (64 patients, mean age 34.6 years) in which plain radiography was insufficient to allow determination of the precise anatomical relations were reviewed retrospectively. Panoramic views of 88 teeth existed; these images were interpreted independent of the CT examinations with respect to presence of a dark band across the roots.

    RESULTS: In 31% of the CT images, the course of the mandibular canal was buccal, in 33% lingual, in 26% inferior, and in 10% inter-radicular. The tooth was in contact with the mandibular canal in 94% and with the lingual cortex in 86%. In 23%, grooving of the root by the canal was judged to be present. In 63% of the cases where a dark band across the roots was observed on panoramic radiographs, CT revealed grooving of the root.

    CONCLUSIONS: Pre-operative CT of lower third molars is motivated in selected cases when plain radiography is inconclusive. The finding of a dark band across the roots on panoramic radiographs is an indicator of grooving of the tooth by the canal and justifies a pre-operative CT examination. The absence of dark bands on panoramic views does not exclude grooving of the roots.

  • 18.
    Rottke, Dennis
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology. Digital Diagnostic Center, Freiburg im Breisgau, Germany.
    Dreger, Julia
    Sawada, Kunihiko
    Honda, Kazuya
    Schulze, Dirk
    Comparison of manual and dose reduction modes of a MORITA R100 CBCT2019In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 48, no 2, article id 20180009Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE:: To compare effective dose differences when acquiring (1) dose reduction mode and (2) manual mode in a MORITA R100 CBCT.

    METHODS:: 24 exposure protocols with different technique factors were performed in both the dose reduction mode and the manual mode in a Veraviewepocs 3D R100 cone beam CT device. 48 TLD were placed in a RANDO head phantom at 24 different sites. Effective doses were calculated according to the formalism published in the 103rd ICRP report.

    RESULTS:: Effective doses for the dose reduction mode protocols ranged from 14 to 156 µSv [mean = 57 µSv, standard deviation (SD) = 37 µSv], whereas effective doses for the manual mode protocols ranged from 22 to 267 µSv (mean = 94 µSv, SD = 65 µSv). Thus, across all protocols, the dose reduction mode leads to a drop of the effective dose by 38 % (SD = 6 %).

    CONCLUSIONS:: The estimated effective doses are significantly lower if dose reduction protocols are acquired.

  • 19.
    Rottke, Dennis
    et al.
    Department of Craniomaxillofacial Surgery, Plastic Surgery, Faculty of Health, University Witten/Herdecke, Hospital Dortmund, Witten/Herdecke, Germany; Digital Diagnostic Center Ltd, Freiburg im Breisgau, Germany.
    Gohlke, Lisa
    Schrödel, Robert
    Hassfeld, Stefan
    Schulze, Dirk
    Operator safety during the acquisition of intraoral images with a handheld and portable X-ray device2018In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 47, no 3, article id 20160410Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: The present study aims at investigating different radiation protection issues and dose values while acquiring intraoral images with a handheld X-ray device.

    METHODS: An Aribex NOMAD Pro 2™, a RANDO® male head phantom, a consistency testing body, a PTW NOMEX® Multimeter, and a PTW Farmer® Ionization Chamber Type 30,010 were used to investigate: (1) dose area products; (2) the expansion of the control area (CA); (3) the scattering pattern and (4) the potential risk for operators of the X-ray device.

    RESULTS: Dose area products at different exposure times were distributed linearly with a high correlation factor (>0.9). At 4000 simulated exposures, the greatest extent of the CA was 42 cm (mean = 16.7 cm, SD = 10.8 cm). The highest occurrence of scattering radiation resulted between the RANDO® phantom and the X-ray device. No scattered radiation was measured at the dorsal part of the phantom or on the operator site of a virtual vertical plane through the focal spot of the X-ray.

    CONCLUSIONS: Through this study, we could demonstrate that the application of an Aribex NOMAD Pro 2 device for intraoral imaging does not increase the risk for the operator if the device is controlled according to the manufacturer's specifications. Furthermore, we were able to show that the CA was significantly smaller than specified by European and other international radiation protection standards.

  • 20. Öhman, A
    et al.
    Kull, Love
    Andersson, Jonas
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Flygare, L
    Radiation doses in examination of lower third molars with computed tomography and conventional radiography.2008In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 37, no 8, p. 445-452Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: To measure organ doses and calculate effective doses for pre-operative radiographic examination of lower third molars with CT and conventional radiography (CR).

    METHODS: Measurements of organ doses were made on an anthropomorphic head phantom with lithium fluoride thermoluminescent dosemeters. The dosemeters were placed in regions corresponding to parotid and submandibular glands, mandibular bone, thyroid gland, skin, eye lenses and brain. The organ doses were used for the calculation of effective doses according to proposed International Commission on Radiological Protection 2005 guidelines. For the CT examination, a Siemens Somatom Plus 4 Volume Zoom was used and exposure factors were set to 120 kV and 100 mAs. For conventional radiographs, a Scanora unit was used and panoramic, posteroanterior, stereographic (scanogram) and conventional spiral tomographic views were exposed.

    RESULTS: The effective doses were 0.25 mSv, 0.060 mSv and 0.093 mSv for CT, CR without conventional tomography and CR with conventional spiral tomography, respectively.

    CONCLUSIONS: The effective dose is low when CT examination with exposure factors optimized for the examination of bone structures is performed. However, the dose is still about four times as high as for CR without tomography. CT should therefore not be a standard method for the examination of lower third molars. In cases where there is a close relationship between the tooth and the inferior alveolar nerve the advantages of true sectional imaging, such as CT, outweighs the higher effective dose and is recommended. Further reduction in the dose is feasible with further optimization of examination protocols and the development of newer techniques.

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