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Friday, April 06, 2012
Dosimetry of a cone-beam computed tomography machine compared with a digital x-ray machine in orthodontic imaging
Always use the lowest dosage possible to achieve the necessary imaging. MJ
American Journal of Orthodontics & Dentofacial Orthopedics Volume 141, Issue 4 , Pages 436-443, April 2012
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.
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.
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.
although providing additional diagnostic and therapeutic benefits, also
exposes patients to higher levels of radiation than conventional