Clinical Studies

AFP Imaging: The Future of 3D Radiography

“Clinical Application of Cone Beam Digital Volume Tomography in Children with Cleft Lip and Palate”

R Wörtche*¹, S Hassfeld1, CJ Lux², E Müssig, FW Hensley³, R Krempien3, and C Hofele¹

¹ Department of Oral and Maxillofacial Surgery; University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany;
² Department of Orthodontics, University of Heidelberg, Im Neueheimer Feld Feld 400, 69120 Heidelberg, Germany;
³ Department of Radiation Oncology, University of Heidelberg, Im Neueheimer Feld Feld 400, 69120 Heidelberg, Germany

Objectives: The diagnostic advantages of digital volume tomography (DVT) over conventional imaging and computed tomography are demonstrated in terms of the respective radiation exposure. The potential role for three-dimensional imaging in cleft lip and palate patients is illustrated on hte basis of clinical examples.

Methods: The radiation exposure resulting from scans using a cone beam DVT (NewTom QR-DVT 9000, Marburg, Germany) was measured with an Alderson-Rando-Phantom (The Phantom Laboratory, New York, NY) and compared with that resulting from other standard imaging modalities. The patient sample consisted of young children with cleft lip and palate on whom orthodontic and surgical treatment was planned on an interdisciplinary basis at the University Hospital of Heidelberg.

Results: Digital volume tomography allows high-quality three-dimensional imaging of the premaxilla region, with an effective equivalent investigation dose of (110kV, 5.4 mA) 0.342 mSv based on ICRP recommendations. While the effective equivalent investigation dose for DVT is higher than that for standard imaging techniques (for expample digital panoramic radiograph Orthophos Plus DS Ceph (66 kV, 8 mA) 0.016 mSv), it is much lower thatn that for a normal CT scan (e.g. Picker International Inc., Highland Heights, OH) adjusted at (spiral 130 kV, 125mA, and 30 mA, 1.5 s) 2.27 mSv. Digital volume tomography provides extensive data important in clinical decision making.

Conclusions: The clinical examples show the good applicability of DVT with a reduced radiation dose.
Dentomaxillofacial Radiology (2006) 35, 88-94. Doi: 10.1259/dmfr/27536604

Source: Dentomaxillofacial Radiology (2006) 35, 88-94 © 2006 The British Institute of Radiology
http://dmfr.birjournals.org

“Dosimetry of 3 CBCT Devices for Oral and Maxillofacial Radiology: CB Mercurary, NewTom 3G and i-CAT”

JB Ludlow*¹, LE Davies-Ludlow², SL Brooks³, WB Howerton⁴

¹ Department of Diagnostic Sciences and General Dentistry, University of North Carolina School of Dentistry, Chapel Hill, North Carolina, USA; ²University of North Carolina School of Dentistry, Chapel Hill, North Carolina, USA; ³Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry; Ann Arbor, Michigan, USA; ⁴Private practice of Oral and Maxillofacial Radiology, Raleigh, NC, USA

Objectives: Cone Beam computed tomography (CBCT), which provides a lower dose, lower cost alternative to conventional CT, is being used with increasing frequency in the practice of oral and maxillofacial radiology. This study provides comparative measurements of effective dose for three commercially available, large (12") field-of-view (FOV), CBCT units: CB Mercuray, NewTom 3G and i-CAT.

Methods: Thermoluminescent dosemeters (TLDs) were placed at 24 sites throughout the layers of the head and neck of a tissue-equivalent human skull RANDO phantom. Depending on availability, the 12" FOV and smaller FOV scanning modes were used with similar phantom positioning geometry for each CBCT unit. Radiation weighted doses to individual organs were summed using 1990 (E1990) and proposed 2005 (E2005 draft) ICRP tissue weighting factors to calculate two measures of whole-body effective dose. Dose as a multiple of a representative panoramic radiography dose was also calculated.

Results: For repeated runs in dosimetry was generally reproducible within 2.5%. Calculated doses in mSv (E1990, E2005 draft) were NewTom3G (45,59), i-CAT (135, 193) and CB Mercuray (477, 558). These are 4 to 42 times greater than comparable panoramic examination doses (6.3 mSv, 13.3 mSv). Reductions in dose were seen with reduction in field size and mA and kV technique factors.

Conclusions: CBCT dose varies substantially depending on the device, FOV and selected technique factors. Effective dose detriment is several to many times higher than conventional panoramic imaging and an order of magnitude or more less than reported doses for conventional CT. Dentomaxillofacial Radiology (2006) 35, 219-226. Doi: 10.1259/dmfr/14340323

Source: Dentomaxillofacial Radiology (2006) 35, 219-226 © 2006 The British Institute of Radiology
http://dmfr.birjournals.org

“Geometric accuracy of the NewTom 9000 Cone Beam CT,”

R Marmulla, R Wörtche, J Mühling and S Hassfeld, Department of Cranio-Maxillofacial Surgery, University of Heidelberg, Heidelberg, Germany;

Objectives: To determine the geometric accuracy of digital volume tomograms to assess their usability for implant planning.
Methods: A measuring object with 216 measuring points, whose geometry is exactly known, is X-rayed with a NewTom 9000 cone beam scanner: thereafter the geometry of the volume tomogram of the object is compared to the original body.
Results: Considering all three coordinate axes, geometric mean deviation of 0.13 ±0.09 mm with a maximum deviation of 0.3 mm were determined. These geometric deviations are below the resolution power of the volume tomography.
Conclusion: The digital volume tomographies of NewTom 9000 present images which are geometrically correct and, from a geometrical point of view, suitable for three-dimensional implant planning

Source: Dentomaxillofacial Radiology (2005) 34, 28-31, ©2005 The British Institute of Radiology, http://dmfr.birjournals.org

“Diagnostic criteria for the detection of mandibular osteomyelitis using cone-beam computed tomography,”

D Schulze1, M Blessmann2, P Pohlenz2, KW Wagner1 and M Heiland

¹ Department of Oral Radiology, Department of Oral and Maxillofacial Surgery, University Hospital Freiburg, Freiburg Germany
² Department of Oral and Maxillofacial Surgery, University Medical Centre Hamburg-Eppendorf, Hamburg Germany

Objectives: To investigate the usefulness of cone-beam computed tomography (CBCT) in cases of suspected osteomyelitis (OM) of the mandible

Methods: 13 patients with clinical suspected OM of the mandible underwent cone-beam computed tomography with the NewTom QR-DVT 9000. After CBCT revealed signs confirming the diagnosis of OM, biopsies were performed. Only cases in which histology confirmed the OM were included in this study.

Results: CBCT sufficiently depicts OM-typical lesions like osteolyic and osteosclerotic areas as well as periosteal reaction, ill-defined cortical borders and sequestra.

Conclusions: Because of the local extension of the disease and its relationship to anatomic structures can be sufficiently detected by CBCT, we see an important additional indication for the usage of CBCT. With regard to distinct cases CBCT combined with scinitgraphy seems to be a sufficient diagnostic strategy concerning suspected OM.

Source: Dentomaxillofacial Radiology (2006) 35, 232-235, ©2006 The British Institute of Radiology, http://dmfr.birjournals.org

"Density conversion factor determined using a cone-beam computed tomography unit NewTom QR-DVT 9000"

MO Lagrave`re*,1, Y Fang2, J Carey2, RW Toogood2, GV Packota3 and PW Major1

1Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada; 2Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada; 3Division of Oral Radiology, College of Dentistry, University of Saskatchewan, Canada

Objective: The purpose of this study was to determine a conversion coefficient for Hounsfield Units (HU) to material density (g cm23) obtained from cone-beam computed tomography (CBCT-NewTom QR-DVT 9000) data.

Methods: Six cylindrical models of materials with different densities were made and scanned using the NewTom QR-DVT 9000 Volume Scanner. The raw data were converted into DICOM format and analysed using Merge eFilm and AMIRA to determine the HU of different areas of the models.

Results: There was no significant difference (P ¼ 0.846) between the HU given by each piece of software. A linear regression was performed using the density, r (g cm23), as the dependent variable in terms of the HU (H). The regression equation obtained was r ¼ 0.002H 2 0.381 with an R2 value of 0.986. The standard error of the estimation is 27.104 HU in the case of the Hounsfield Units and 0.064 g cm23 in the case of density.

Conclusion: CBCT provides an effective option for determination of material density expressed as Hounsfield Units.

Dentomaxillofacial Radiology (2006) 35, 407-409. doi: 10.1259/dmfr/55276404

"Cone beam CT and conventional tomography for the detection of morphological temporomandibular joint changes"

H Hintze*,1, M Wiese1,2 and A Wenzel1

1 Department of Oral Radiology, School of Dentistry, University of Aarhus, Aarhus, Denmark; 2 Department of Radiology, School of Dentistry, University of Copenhagen, Copenhagen, Denmark

*Correspondence to: Hanne Hintze, Department of Oral Radiology, School of Dentistry, Faculty of Health Sciences, University of Aarhus, Vennelyst Boulevard 9, DK-8000 Aarhus C, Denmark; Email: hhintze@odont.au.dk

Received 9 February 2006; revised 30 June 2006; accepted 3 July 2006


Objective: To compare the diagnostic accuracy of cone beam CT images with conventional tomographic images for the detection of morphological temporomandibular joint (TMJ) changes.

Methods: 80 dry human skulls were scanned using a NewTom® 3G scanner and lateral and frontal reconstructions of the right and the left TMJs were performed. In addition, lateral and frontal cross-sectional tomograms of the skulls' TMJs were obtained in a Cranex Tome unit with Digora storage phosphor plates. Naked-eye inspection of the TMJs performed by three observers served as the gold standard for the true presence of morphological changes. The mandibular fossae were excluded from the study due to few changes in this joint component. The NewTom® and the conventional tomographic images were examined by three independent observers using a binary scale for the presence of morphological changes in the condyle (flattening, defects and osteophytes) and the articular tubercle (flattening and defects). The accuracy for the different types of changes in relation to the condyles and the articular tubercles was expressed as sensitivity and specificity values, whereas the diagnostic accuracy for a general assessment including all changes in both joint components was expressed by the sum of cases where the gold standard and the radiographic scores were not identical (absolute difference). Differences between the two radiographic modalities were tested by paired t-test.

Results: Detection of the various types of morphological changes in relation to the condyle and the articular tubercle assessed separately resulted in no significant differences between the two radiographic modalities, with the exception of bone defects in the articular tubercle examined on frontal views alone where the specificity with tomography was significantly higher than with cone beam CT. Detection of all morphological changes in relation to both the condyle and the articular tubercle showed a significantly higher accuracy with tomography than with cone beam CT using lateral views alone, but there was no significant difference between the two modalities using frontal views alone and lateral and frontal views in combination.

Conclusion: In general, no significant differences in diagnostic accuracy for the detection of bone changes in the condyle and in the articular tubercle were found between cone beam CT images and conventional tomograms.

Source: Dentomaxillofacial Radiology (2007) 36, 192-197
© 2007 British Institute of Radiology   doi: 10.1259/dmfr/25523853

"Three-dimensional evaluations of supernumerary teeth using cone-beam computed tomography for 487 cases"

Deng-gao Liu SMD(a), Corresponding Author, Corresponding Author, Wan-lin Zhang DDS(a), Zu-yan Zhang DDS, PhD(b), Yun-tang Wu DDS(b) and Xu-chen Ma DDS, PhD(c)

(a) Associate Professor, Department of Oral Radiology, Peking University School and Hospital of Stomatology, Beijing, China.
(b) Professor, Department of Oral Radiology, Peking University School and Hospital of Stomatology, Beijing, China.
(c) Professor and Chairman, Department of Oral Radiology and Center for TMD, Peking University School and Hospital of Stomatology, Beijing, China.

Received 23 December 2005; revised 24 March 2006; accepted 28 March 2006. Available online 4 August 2006.

Purpose: The purpose of this article is to introduce the use of cone-beam computed tomography (CBCT) for evaluation of supernumerary teeth.

Methods: The study group comprised 487 patients with a total of 626 supernumerary teeth who were examined by CBCT. Patient characteristics were recorded, and the number, location, shape, and 3-dimensional position of the supernumeraries were analyzed. The ability of CBCT to visualize dental and skeletal structures relative to supernumerary teeth was also evaluated.

Results:  Males were affected more than females in a ratio of 2.64:1. Seventy-two percent of the patients had 1 supernumerary tooth, 27.3% had 2, and 0.6% had 3 supernumeraries. Supernumerary teeth were most frequently located in the anterior maxilla (92%), and their sagittal location relative to the neighboring teeth could be used for classification purposes. Supernumeraries were most commonly conical in shape (83.5%). CBCT yielded accurate 3-dimensional pictures of the dental and bony structures. The sagittal positions of the 578 supernumerary teeth in the anterior maxilla were divided into 6 types, of which types I and III were most commonly associated with local malocclusions. Moreover, 43.4% of the premaxillary supernumeraries were inverted and 21.1% were transversely oriented.

Conclusions:  CBCT imaging yields accurate 3-dimensional pictures of local dental and bony structures, which is helpful for pretreatment evaluation of supernumerary teeth.

Source: Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology
Volume 103, Issue 3, March 2007, Pages 403-411

"Comparison of conventional and cone beam CT synthesized cephalograms"

V Kumar*,1, JB Ludlow2, A Mol2 and L Cevidanes3

1 Oral and Maxillofacial Radiology Program, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
2 Department of Diagnostic Sciences and General Dentistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
3 Department of Orthodontics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA

*Correspondence to: Dr Vandana Kumar, 121 Dental Office Building, UNC School of Dentistry, Chapel Hill, NC 27599-7450, USA; Email: kumarv@dentistry.unc.edu

Received 7 July 2006; revised 2 October 2006; accepted 22 October 2006

Objectives: To compare cephalometric measurements from synthesized cone beam CT (CBCT) lateral cephalograms using orthogonal and perspective projections with those from conventional cephalometric radiographs and dry skulls.

Methods: Ten skulls were imaged using CBCT and conventional cephalometry. CBCT volume data were exported in DICOM format and imported in Dolphin 3D (pre-release version). Orthogonal and perspective lateral cephalometric radiographs were created from 3D virtual models. Nine linear and five angular measurements were made in Dolphin at three different times. Three calliper measures of midsagittal landmarks were made directly onto skulls. Perspective and conventional image measurements were corrected for known magnification. Reproducibility of measurements was assessed using multivariate analysis of variance (MANOVA). Linear and angular measurements were compared between image modalities by measurement using a repeated measures MANOVA model. Differences and absolute value of differences between image measurements and skull measurements were assessed using analysis of variance (ANOVA).

Results: Measurements were not different between the imaging modalities (P>0.05), except for the mandibular unit length (P=0.01). Linear midsagittal measurements were significantly greater than skull measurements for perspective CBCT and significantly less than skull measurements for conventional images (P=0.003). Precision of orthogonal CBCT midsagittal linear measurements was significantly better than the other modalities (P=0.007). Orthogonal CBCT projections provided more accurate midsagittal skull measurements than perspective CBCT or conventional cephalometric radiographs.

Conclusions: CBCT can reproduce conventional cephalometric geometry with similar precision and accuracy. Orthogonal CBCT projections provided greater accuracy of measurement for midsagittal plane dimensions than perspective CBCT or conventional cephalometric images.

Source:  Dentomaxillofacial Radiology (2007) 36, 263-269
© 2007 British Institute of Radiology
doi: 10.1259/dmfr/98032356

"Three-dimensional cone-beam computed tomography for assessment of mandibular changes after orthognathic surgery"

Lucia H. S. Cevidanes,a L'Tanya J. Bailery,b Scott F. Tucker,c Martin A. Styner,d Andre Mol,e Ceib L. Phillips,f William R. Proffit,g and Timothy Turveyh Chapel Hill, NC

Introduction: The purpose of this study was to assess alterations in the 3-dimensional (3D) position of the mandibular rami and condyles in patients receiving either maxillary advancement and mandibular setback or maxillary surgery only.

Methods: High resolution cone-beam computed tomography scans were taken of 21 patients before and after orthognathic surgery. Ten patients with various malocclusions underwent maxillary surgery only, and 11 Class III patients received maxillary advancement and mandibular setback. Presurgery and postsurgery 3D models were registered on the surface of the cranial base. A new tool was used for graphical overlay and 3D display with color maps to visually assess the locations and to quantify positional changes in the posterior border of the mandibular rami and condyles between superimposed models.

Results: The average displacements in condylar position were small-0.77 mm (SD, 0.12 mm) and 0.70 mm (SD, 0.08 mm)-for 2-jaw and 1-jaw surgeries, respectively not significant, P>.05). All 2-jaw surgery patients and backward rotational displacements of the mandibular rami (mean, 1.98 mm; SD, 1.03 mm), with a maximum surface distance change of ≥2 mm in 8 of 11 subjects. For the 1-jaw surgery, all subjects had small backward rotational displacements of the mandibular rami (mean, 0.78 mm; SD, 0.25 mm), with only 1 subject having a maximum surface distance change ≥2 mm. The difference in mean backward rotational displacement was statistically significant (P ,.01).

Conclusions: The visualization of 3D model superimposition clearly identified the location, magnitude and direction of mandibular displacement. The 3D imaging allowed quantification of vertical, transverse, and anteroposterior ramus displacement that accompanied mandibular, but not maxillary only, surgery. (Am J Orthod Dentofacial Orthop 2007;131:44-50)