Dose reduction of cone beam CT scanning for the entire oral and maxillofacial regions with thyroid collars.

OBJECTIVE The aim of this study was to evaluate the influence of thyroid collars on radiation dose during cone beam CT (CBCT) scanning. METHODS Average tissue-absorbed dose for a NewTom 9000 CBCT scanner (Quantitative Radiology, Verona, Italy) was measured using thermoluminescent dosemeter chips in a phantom. The scans were carried out with and without thyroid collars. Effective organ dose and total effective dose were derived using International Commission on Radiological Protection 2007 recommendations. RESULTS The effective organ doses for the thyroid gland and oesophagus were 31.0 µSv and 2.4 µSv, respectively, during CBCT scanning without a collar around the neck. When the thyroid collars were used loosely around the neck, no effective organ dose reduction was observed. When one thyroid collar was used tightly on the front of the neck, the effective organ dose for the thyroid gland and oesophagus were reduced to 15.9 µSv (48.7% reduction) and 1.4 µSv (41.7% reduction), respectively. Similar organ dose reduction (46.5% and 41.7%) was achieved when CBCT scanning was performed with two collars tightly on the front and back of the neck. However, the differences to the total effective dose were not significant among the scans with and without collars around the neck (p = 0.775). CONCLUSIONS Thyroid collars can effectively reduce the radiation dose to the thyroid and oesophagus if used appropriately.

[1]  R Jacobs,et al.  Comparison between effective radiation dose of CBCT and MSCT scanners for dentomaxillofacial applications. , 2009, European journal of radiology.

[2]  Dose reduction in multislice CT by means of bismuth shields: results of in vivo measurements and computed evaluation , 2010, La radiologia medica.

[3]  J. Ludlow,et al.  Effective radiation dose of ProMax 3D cone-beam computerized tomography scanner with different dental protocols. , 2010, Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics.

[4]  P. Mozzo,et al.  A new volumetric CT machine for dental imaging based on the cone-beam technique: preliminary results , 1998, European Radiology.

[5]  R. Nicholson,et al.  Would thyroid and breast shielding be beneficial in CT of the head? , 1998, European Radiology.

[6]  M. Ivanovic,et al.  Comparative dosimetry of dental CBCT devices and 64-slice CT for oral and maxillofacial radiology. , 2008, Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics.

[7]  Icrp.  Preface, Executive Summary and Glossary , 2007 .

[8]  Reyes Enciso,et al.  Evaluation of 3D airway imaging of obstructive sleep apnea with cone-beam computed tomography. , 2005, Studies in health technology and informatics.

[9]  Wonho Lee,et al.  Dose reduction in CT using bismuth shielding: measurements and Monte Carlo simulations. , 2010, Radiation protection dosimetry.

[10]  B. Mealey,et al.  Comparison of clinical, periapical radiograph, and cone-beam volume tomography measurement techniques for assessing bone level changes following regenerative periodontal therapy. , 2009, Journal of periodontology.

[11]  N. Drage,et al.  Effective dose from cone beam CT examinations in dentistry. , 2009, The British journal of radiology.

[12]  Kostas Tsiklakis,et al.  Dose reduction in maxillofacial imaging using low dose Cone Beam CT. , 2005, European journal of radiology.

[13]  D. Fladeland,et al.  Thyroid shields versus z-axis automatic tube current modulation for dose reduction at neck CT. , 2008, Radiology.

[14]  M. Hans,et al.  Influence of CBCT exposure conditions on radiation dose. , 2008, Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics.

[15]  S. Brooks,et al.  Dosimetry of 3 CBCT devices for oral and maxillofacial radiology: CB Mercuray, NewTom 3G and i-CAT. , 2006, Dento maxillo facial radiology.

[16]  Jack Valentin,et al.  The 2007 Recommendations of the International Commission on Radiological Protection. ICRP publication 103. , 2007, Annals of the ICRP.

[17]  C. Hildebolt,et al.  American Academy of Oral and Maxillofacial Radiology executive opinion statement on performing and interpreting diagnostic cone beam computed tomography. , 2008, Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics.

[18]  Jonathan Davies,et al.  Accuracy of measuring the cortical bone thickness adjacent to dental implants using cone beam computed tomography. , 2010, Clinical oral implants research.

[19]  Akira Mishima,et al.  Application of Limited Cone Beam Computed Tomography to Clinical Assessment of Alveolar Bone Grafting: A Preliminary Report , 2005, The Cleft palate-craniofacial journal : official publication of the American Cleft Palate-Craniofacial Association.

[20]  R. Sievert,et al.  Book Reviews : Recommendations of the International Commission on Radiological Protection (as amended 1959 and revised 1962). I.C.R.P. Publication 6. 70 pp. PERGAMON PRESS. Oxford, London and New York, 1964. £1 5s. 0d. [TB/54] , 1964 .

[21]  Bassam Hassan,et al.  Detection of vertical root fractures in endodontically treated teeth by a cone beam computed tomography scan. , 2009, Journal of endodontics.

[22]  S. Merrett,et al.  Cone Beam Computed Tomography: A Useful Tool in Orthodontic Diagnosis and Treatment Planning , 2009, Journal of orthodontics.