Dosimetry of a cone-beam computed tomography machine compared with a digital x-ray machine in orthodontic imaging

doi:10.1016/j.ajodo.2011.10.024

American Journal of Orthodontics and Dentofacial Orthopedics

Volume 141, Issue 4, April 2012, Pages 436-443

https://doi.org/10.1016/j.ajodo.2011.10.024 Get rights and content

Introduction

Cone-beam computed tomography (CBCT) has become a routine imaging modality for many orthodontic clinics. However, questions remain about the amount of radiation patients are exposed to during the scans. This study determined the amounts of radiation potentially absorbed by a patient during orthodontic imaging with a CBCT machine with various scan settings compared with a conventional 2-dimensional digital x-ray machine.

Methods

The radiation exposures delivered by a next generation i-CAT CBCT machine (Imaging Sciences International, Hatfield, Pa) at various scan settings and orthopantomograph OP100/OC100 digital x-ray machine (Instrumentarium Dental, Tuusula, Finland) during panoramic and cephalometric radiography were recorded using thermoluminescent dosimeters placed inside a head and neck phantom. The manufacturer-recommended settings for an average adult male were used for both types of machines. Effective doses were calculated using the tissue-weighting factors recommended by the 2007 International Commission on Radiological Protection.

Results

The effective doses at various voxel sizes and field of view settings ranged from 64.7 to 69.2 μSv for standard resolution CBCT scans (scan time 8.9 s) and 127.3 to 131.3 μSv for high resolution full field of view scans (scan time 17.8 s), and measured 134.2 μSv for a high-resolution landscape scan with a voxel size as would be used for SureSmile (OraMetrix, Richardson, Tex) therapy (scan time 26.9 s). The effective doses for digital panoramic and lateral cephalometric radiographs measured 21.5 and 4.5 μSv, respectively.

Conclusions

CBCT, although providing additional diagnostic and therapeutic benefits, also exposes patients to higher levels of radiation than conventional digital radiography.

Section snippets

Material and methods

Doses of the following units were investigated: a next generation i-CAT CBCT machine (Imaging Sciences International, Hatfield, Pa) and an orthopantomograph OP100/OC100 digital x-ray machine (Instrumentarium Dental, Tuusula, Finland). Both units were used at various scan settings representing those used for orthodontic imaging (Table I).

The absorbed radiation dose was recorded with precalibrated thermoluminescent lithium fluoride dosimeter chips (TLD-100, supplied and analyzed by Landauer,

Results

A high level of reproducibility was achieved between the 0.3 voxel portrait CBCT scans performed on 2 separate occasions as documented by a variation between effective doses of only 0.66%. However, the 0.3 and 0.4 voxel portrait CBCT scans as well as the 0.3 and 0.4 voxel high-resolution portrait CBCT scans studied use the same fields of view and exposure factors, and thus are good measures of reproducibility, too. Effective doses calculated for these scans varied by 6.72% and 3.09%,

Discussion

The present study determined the amount of radiation a patient is exposed to during various scan protocols with a next generation i-CAT CBCT and an orthopantomograph OP100/OC100 digital x-ray machine. The principal finding was that the CBCT scan protocols typically used for orthodontic imaging exposed all tissues studied to significantly more radiation than those of a digital 2D x-ray machine. In general, salivary gland tissues received the highest amount of radiation. This finding agrees with

Conclusions

CBCT, while providing proven diagnostic and therapeutic benefits, also exposes patients to higher levels of radiation than conventional 2D digital radiography. It is the responsibility and professional obligation of a conscientious practitioner to weigh the proven and perceived benefits of diagnosis and therapy against the risks to which the patient is exposed.

References (34)

D.C. Hatcher
Operational principles for cone-beam computed tomography
J Am Dent Assoc
(2010)
A.G. Farman et al.
The basics of maxillofacial cone beam computed tomography
Semin Orthod
(2009)
E. Haney et al.
Comparative analysis of traditional radiographs and cone-beam computed tomography volumetric images in the diagnosis and treatment planning of maxillary impacted canines
Am J Orthod Dentofacial Orthop
(2010)
J. Mah et al.
Computer-assisted orthodontic treatment: the SureSmile process
Am J Orthod Dentofacial Orthop
(2001)
J.B. Ludlow et al.
Patient risk related to common dental radiographic examinations: the impact of 2007 International Commission on Radiological Protection recommendations regarding dose calculation
J Am Dent Assoc
(2008)
S.L. Brooks
CBCT dosimetry: orthodontic considerations
Semin Orthod
(2009)
J.B. Ludlow et al.
Comparative dosimetry of dental CBCT devices and 64-slice CT for oral and maxillofacial radiology
Oral Surg Oral Med Oral Pathol Oral Radiol Endod
(2008)
K. Tsiklakis et al.
Dose reduction in maxillofacial imaging using low dose cone beam CT
Eur J Radiol
(2005)
A.C.M. Chau et al.
Comparison of radiation dose for implant imaging using conventional spiral tomography, computed tomography, and cone-beam computed tomography
Oral Surg Oral Med Oral Pathol Oral Radiol Endod
(2009)
M. Loubele et al.
Comparison between effective radiation dose of CBCT and MSCT scanners for dentomaxillofacial applications
Eur J Radiol
(2009)

J.K. Mah et al.

Radiation absorbed in maxillofacial imaging with a new dental computed tomography device

Oral Surg Oral Med Oral Pathol Oral Radiol Endod

(2003)

S.C. White et al.

Patient image selection criteria for cone beam computed tomography imaging

Semin Orthod

(2009)

R.P. Scholz

The radiology decision

Semin Orthod

(2011)

W. De Vos et al.

Cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial region: a systematic review of the literature

Int J Oral Maxillofac Surg

(2009)

W.C. Scarfe et al.

Clinical applications of cone-beam computed tomography in dental practice

J Can Dent Assoc

(2006)

P.C.M. Benington et al.

An overview of three-dimensional imaging in dentistry

Dent Update

(2010)

G. Kaeppler

Applications of cone beam computed tomography in dental and oral medicine

Int J Comput Dent

(2010)

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Considering the absence of radiation-induced heritable effects in humans and the negligible dose to the gonads and fetus from dentomaxillofacial imaging, the committee recommends discontinuing shielding of the gonads, pelvic structures, and fetuses during all dentomaxillofacial radiographic imaging procedures. On the basis of radiation doses from contemporaneous maxillofacial imaging, the committee considered that the risks from thyroid cancer are negligible and recommends that thyroid shielding not be used during intraoral, panoramic, cephalometric, and cone-beam computed tomographic imaging.
This position statement informs and educates the reader on evolving radiation protection practices and provides simple, unequivocal guidance to dental personnel to implement these guidelines. State and local authorities should be contacted to update regulations to reflect these recommendations.
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The higher filtration of Veraview X800 obviously did not fully compensate for this. Generally, all studied tissues were exposed to considerably more radiation in CBCT examinations compared with panoramic examinations, and this finding is consistent with the literature.20,28,29 In the various protocols used in this study, the bone surface and salivary glands received the highest absorbed doses, and this finding also is in agreement with reports from previous studies.13,14,20,30
The aim of this study was to map and compare the distributions of absorbed doses with Gafchromic film for panoramic radiography and cone beam computed tomography (CBCT) examinations of the temporomandibular joint (TMJ) by using adult and child phantoms.
Gafchromic films were placed at 5 selected levels of anthropomorphic head phantoms of an adult and a child. Clinical protocols for panoramic and CBCT imaging of the TMJ were used for three 2-dimensional or 3-dimensional dental x-ray units. Mean absorbed doses in a set of radiosensitive tissues within the oral and maxillofacial regions were estimated.
The absorbed doses varied considerably among and within radiosensitive tissues. The bone surface and the salivary glands received the highest absorbed doses compared with other tissues, in both panoramic and CBCT examinations of the TMJ. The radiation burden to the adult phantom was generally higher than that to the child phantom. Small right and left fields of view were associated with lower amounts of radiation, in contrast to a single larger field of view.
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Linear distance measurements are made using CBCT in endodontic treatment; implant planning; and evaluation of distances between alveolar ridge edges and the mandibular canal, alveolar ridge edges and the maxillary sinus, and the nasal cavity and incisive canal.1,2 In addition, we sought to determine whether there was any difference between physical and CBCT measurements of linear distances at different voxels, because patients are exposed to less radiation in CBCT at 0.4 than at 0.25 voxels.7,20 Because whole gutta-percha cannot be seen on section images, we used only panoramic images to determine the accuracy of linear measurements.
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We found that linear distance measurements on panoramic image of CBCT were slightly lower than physical measurements. A significant difference was not found for the gutta-percha linear distances and cortical VD measurements at different voxel sizes (P ≥ 0.05). The correlation between measurements of VD at different voxels in cortical bone was greater than 0.85 (P = 0.000).
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: The authors report no commercial, proprietary, or financial interest in the products or companies described in this article.

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Original articleDosimetry of a cone-beam computed tomography machine compared with a digital x-ray machine in orthodontic imaging

Introduction

Methods

Results

Conclusions

Section snippets

Material and methods

Results

Discussion

Conclusions

J Am Dent Assoc

Semin Orthod

Am J Orthod Dentofacial Orthop

Am J Orthod Dentofacial Orthop

J Am Dent Assoc

Semin Orthod

Oral Surg Oral Med Oral Pathol Oral Radiol Endod

Eur J Radiol

Oral Surg Oral Med Oral Pathol Oral Radiol Endod

Eur J Radiol

Oral Surg Oral Med Oral Pathol Oral Radiol Endod

Semin Orthod

Semin Orthod

Int J Oral Maxillofac Surg

Clinical applications of cone-beam computed tomography in dental practice

J Can Dent Assoc

An overview of three-dimensional imaging in dentistry

Dent Update

Applications of cone beam computed tomography in dental and oral medicine

Int J Comput Dent

Original article
Dosimetry of a cone-beam computed tomography machine compared with a digital x-ray machine in orthodontic imaging