| 1. |
- Granlund, Christina, et al.
(författare)
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Absorbed organ and effective doses from digital intra-oral and panoramic radiography applying the ICRP 103 recommendations for effective dose estimations
- 2016
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Ingår i: British Journal of Radiology. - : British Institute of Radiology. - 0007-1285 .- 1748-880X. ; 89:1066
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Tidskriftsartikel (refereegranskat)abstract
- Objective: During dental radiography, the salivary and thyroid glands are at radiation risk. In 2007, the International Commission on Radiological Protection (ICRP) updated the methodology for determining the effective dose, and the salivary glands were assigned tissue-specific weighting factors for the first time. The aims of this study were to determine the absorbed dose to the organs and to calculate, applying the ICRP publication 103 tissue-weighting factors, the effective doses delivered during digital intraoral and panoramic radiography. Methods: Thermoluminescent dosemeter measurements were performed on an anthropomorphic head and neck phantom. The organ-absorbed doses were measured at 30 locations, representing different radiosensitive organs in the head and neck, and the effective dose was calculated according to the ICRP recommendations. Results: The salivary glands and the oral mucosa received the highest absorbed doses from both intraoral and panoramic radiography. The effective dose from a fullmouth intraoral examination was 15mSv and for panoramic radiography, the effective dose was in the range of 19-75 mSv, depending on the panoramic equipment used. Conclusion: The effective dose from a full-mouth intraoral examination is lower and that frompanoramic radiography is higher than previously reported. Clinicians should be aware of the higher effective dose delivered during panoramic radiography and the risk-benefit profile of this technique must be assessed for the individual patient.
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| 2. |
- Lofthag-Hansen, Sara, 1956, et al.
(författare)
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Calculating effective dose on a cone beam computed tomography device: 3D Accuitomo and 3D Accuitomo FPD.
- 2008
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Ingår i: Dento maxillo facial radiology. - : British Institute of Radiology. - 0250-832X .- 1476-542X. ; 37:2, s. 72-9
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: This study evaluates two methods for calculating effective dose, CT dose index (CTDI) and dose-area product (DAP) for a cone beam CT (CBCT) device: 3D Accuitomo at field size 30x40 mm and 3D Accuitomo FPD at field sizes 40x40 mm and 60x60 mm. Furthermore, the effective dose of three commonly used examinations in dental radiology was determined. METHODS: CTDI(100) measurements were performed in a CT head dose phantom with a pencil ionization chamber connected to an electrometer. The rotation centre was placed in the centre of the phantom and also, to simulate a patient examination, in the upper left cuspid region. The DAP value was determined with a plane-parallel transmission ionization chamber connected to an electrometer. A conversion factor of 0.08 mSv per Gy cm(2) was used to determine the effective dose from DAP values. Based on data from 90 patient examinations, DAP and effective dose were determined. RESULTS: CTDI(100) measurements showed an asymmetric dose distribution in the phantom when simulating a patient examination. Hence a correct value of CTDI(w) could not be calculated. The DAP value increased with higher tube current and tube voltage values. The DAP value was also proportional to the field size. The effective dose was found to be 11-77 microSv for the specific examinations. CONCLUSIONS: DAP measurement was found to be the best method for determining effective dose for the Accuitomo. Determination of specific conversion factors in dental radiology must, however, be further developed.
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| 3. |
- Lofthag-Hansen, Sara, 1956
(författare)
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Cone Beam Computed Tomography - radiation dose and image quality assessments
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diagnostic radiology has undergone profound changes in the last 30 years. New technologies are available to the dental field, cone beam computed tomography (CBCT) as one of the most important. CBCT is a catch-all term for a technology comprising a variety of machines differing in many respects: patient positioning, volume size (FOV), radiation quality, image capturing and reconstruction, image resolution and radiation dose. When new technology is introduced one must make sure that diagnostic accuracy is better or at least as good as the one it can be expected to replace. The CBCT brand tested was two versions of Accuitomo (Morita, Japan): 3D Accuitomo with an image intensifier as detector, FOV 3 cm x 4 cm and 3D Accuitomo FPD with a flat panel detector, FOVs 4 cm x 4 cm and 6 cm x 6 cm. The 3D Accuitomo was compared with intra-oral radiography for endodontic diagnosis in 35 patients with 46 teeth analyzed, of which 41 were endodontically treated. Three observers assessed the images by consensus. The result showed that CBCT imaging was superior with a higher number of teeth diagnosed with periapical lesions (42 vs 32 teeth). When evaluating 3D Accuitomo examinations in the posterior mandible in 30 patients, visibility of marginal bone crest and mandibular canal, important anatomic structures for implant planning, was high with good observer agreement among seven observers. Radiographic techniques have to be evaluated concerning radiation dose, which requires well-defined and easy-to-use methods. Two methods: CT dose index (CTDI), prevailing method for CT units, and dose-area product (DAP) were evaluated for calculating effective dose (E) for both units. An asymmetric dose distribution was revealed when a clinical situation was simulated. Hence, the CTDI method was not applicable for these units with small FOVs. Based on DAP values from 90 patient examinations effective dose was estimated for three diagnostic tasks: implant planning in posterior mandible and examinations of impacted lower third molars and retained upper cuspids. It varied between 11-77 μSv. Radiation dose should be evaluated together with image quality. Images of a skull phantom were obtained with both units varying tube voltage, tube current, degree of rotation and FOVs. Seven observers assessed subjective image quality using a six-point rating scale for two diagnostic tasks: periapical diagnosis and implant planning in the posterior part of the jaws. Intra-observer agreement was good and inter-observer agreement moderate. Periapical diagnosis was found to, regardless of jaw, require higher exposure parameters compared to implant planning. Implant planning in the lower jaw required higher exposure parameters compared to upper jaw. Substantial dose reduction could be made without loss of diagnostic information by using a rotation of 180°, in particular implant planning in upper jaw. CBCT with small FOVs was found to be well-suited for periapical diagnosis and implant planning. The CTDI method is not applicable estimating effective dose for these units. Based on DAP values effective dose varied between 11-77 μSv (ICRP 60, 1991) in a retrospectively selected patient material. Adaptation of exposure parameters to diagnostic task can give substantial dose reduction.
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| 4. |
- Lofthag-Hansen, Sara, 1956, et al.
(författare)
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Cone-beam CT for preoperative implant planning in the posterior mandible: visibility of anatomic landmarks.
- 2009
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Ingår i: Clinical implant dentistry and related research. - : Wiley. - 1708-8208 .- 1523-0899. ; 11:3, s. 246-55
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The technical development has given a new type of modality, cone-beam computed tomography (CBCT). This technique has a high potential to solve different diagnostic problems among which is preoperative planning for implants in the posterior mandible. PURPOSE: The aim of this retrospective study was to evaluate the visibility of the mandibular canal and the marginal bone crest and the agreement between observers in images from one CBCT technique. MATERIALS AND METHODS: Thirty consecutive patients were examined with 3D Accuitomo (J. Morita Mfg. Corp., Kyoto, Japan) in one side of the mandible, where the second premolar and molars were lost. The examined volume was 30 by 40 mm. Seven observers evaluated the visibility and the location of the mandibular canal and the marginal crest by visually deciding if the structures were clearly visible, probably visible, or invisible in one cross-sectional image, approximately 1 cm posterior to the mental foramen. In a later session, the observers also marked the two anatomic structures. If the decision was not "clearly visible" or if the anatomic structures were difficult to identify, the observers had to use other cross-sectional, axial, and/or sagittal images in the volume. RESULTS: The confidence among the observers evaluating the marginal bone crest was high. Two observers never used any other images, and the rest took help in two to seven cases. When marking the mandibular canal, the observers, in general, used more images. In five cases (17%), all the observers only used the single cross-sectional image. The agreement on the position of the canal was also high. CONCLUSION: With this CBCT modality (3D Accuitomo), the visibility of the mandibular canal and the marginal crest, as well as the observer agreement of the location of these structures, was high. Hence, the 3D Accuitomo can be recommended for implant planning in the posterior mandible.
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| 5. |
- Lofthag-Hansen, Sara, 1956, et al.
(författare)
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Evaluation of subjective image quality in relation to diagnostic task for cone beam computed tomography with different fields of view.
- 2011
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Ingår i: European journal of radiology. - : Elsevier BV. - 1872-7727 .- 0720-048X. ; 80:2, s. 483-488
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To evaluate subjective image quality for two diagnostic tasks, periapical diagnosis and implant planning, for cone beam computed tomography (CBCT) using different exposure parameters and fields of view (FOVs). MATERIALS AND METHODS: Examinations were performed in posterior part of the jaws on a skull phantom with 3D Accuitomo (FOV 3cm×4cm) and 3D Accuitomo FPD (FOVs 4cm×4cm and 6cm×6cm). All combinations of 60, 65, 70, 75, 80kV and 2, 4, 6, 8, 10mA with a rotation of 180° and 360° were used. Dose-area product (DAP) value was determined for each combination. The images were presented, displaying the object in axial, cross-sectional and sagittal views, without scanning data in a random order for each FOV and jaw. Seven observers assessed image quality on a six-point rating scale. RESULTS: Intra-observer agreement was good (κ(w)=0.76) and inter-observer agreement moderate (κ(w)=0.52). Stepwise logistic regression showed kV, mA and diagnostic task to be the most important variables. Periapical diagnosis, regardless jaw, required higher exposure parameters compared to implant planning. Implant planning in the lower jaw required higher exposure parameters compared to upper jaw. Overall ranking of FOVs gave 4cm×4cm, 6cm×6cm followed by 3cm×4cm. CONCLUSIONS: This study has shown that exposure parameters should be adjusted according to diagnostic task. For this particular CBCT brand a rotation of 180° gave good subjective image quality, hence a substantial dose reduction can be achieved without loss of diagnostic information.
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| 6. |
- Lofthag-Hansen, Sara, 1956, et al.
(författare)
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Limited cone-beam CT and intraoral radiography for the diagnosis of periapical pathology
- 2007
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Ingår i: Oral Surg Oral Med Oral Pathol Oral Radiol Endod. ; 103:1, s. 114-119
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Tidskriftsartikel (refereegranskat)abstract
- Objective To compare intraoral periapical radiography with 3D images for the diagnosis of periapical pathology. Study design Maxillary molars and premolars and mandibular molars with endodontic problems and examined with periapical radiographs and a 3D technique (3D Accuitomo) were retrospectively selected and evaluated by 3 oral radiologists. Numbers of roots and root canals, presence and location of periapical lesions, and their relation to neighboring structures were studied. Results Among 46 teeth, both techniques demonstrated lesions in 32 teeth, and an additional 10 teeth were found in the Accuitomo images. As regards individual roots, 53 lesions were found in both techniques, and 33 more roots were found to have lesions in Accuitomo images. Artefacts were sometimes a problem in Accuitomo images. In 32 of the 46 cases, all observers agreed that additional clinically relevant information was obtained with Accuitomo images. Conclusions A high-resolution 3D technique can be of value for diagnosis of periapical problems.
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| 7. |
- Lofthag-Hansen, Sara, et al.
(författare)
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Radiographic assessment of the marginal bone level after implant treatment : a comparison of periapical and Scanora detailed narrow beam radiography
- 2003
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Ingår i: Dento-Maxillo-Facial Radiology. - : British Institute of Radiology. - 0250-832X .- 1476-542X. ; 32:2, s. 97-103
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Objectives: To compare assessments of the marginal bone level around dental implants in the mandible using periapical radiography and Scanora detailed narrow beam (DNB) radiography. METHODS: Forty patients treated with Brånemark dental implants in the lower jaw were examined with periapical and Scanora DNB radiography. Ten implants were selected from each of the four dental regions (molar, incisor, canine, premolar), and no more than one implant was selected from the same patient. Seven observers assessed the level of the marginal bone on the mesial and distal surfaces of the implants. Three of the observers made all the assessments twice. RESULTS: Agreement between the methods was 61 %. The highest agreement was found in the molar region. In DNB radiography the marginal bone level was observed to be situated more “coronally” in 17 % and more “apically” in 22 % compared with periapical radiography. The kappa value for interobserver agreement for all observers was 0.33 for periapical radiography and 0.27 for DNB radiography. The weighted kappa value for intraobserver agreement ranged from 0.75 to 0.99 for DNB radiography and from 0.94 to 0.98 for periapical radiography. CONCLUSIONS: Scanora multimodal radiography simplifies examination of implants in the mandible, and observer variation is comparable with that in intraoral periapical radiography.
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| 8. |
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