Extraoral bite-wing radiographs: A universally accepted paradox

Radiation doses in extraoral bitewing radiography compared with intraoral bitewing and panoramic radiography

OBJECTIVES

We compared the effective dose (E) and thyroid equivalent dose of 2 extraoral bitewing (EOBW) units and compared E with their respective panoramic (PAN) modes and with intraoral bitewing radiography (IOBW).

STUDY DESIGN

Child and adult anthropomorphic phantoms with dosimeters were used to evaluate Orthophos SL, Rayscan α+, and 1 intraoral unit using rectangular and circular collimation. Extraoral bitewing thyroid equivalent dose was assessed without and with thyroid shielding.

RESULTS

Child and adult E values of EOBW were lower with Orthophos (3.6 and 8.6 μSv) than with Rayscan (28.1 and 30.2 μSv). For IOBW, E was lower with rectangular vs circular collimation for child (7.0 vs 11.8 μSv) and adult (4.6 vs 14.2 μSv). E values of EOBW were lower than PAN for Orthophos. The IOBW E was lower than Rayscan EOBW for child (≤11.8 vs 28.1 μSv) and adult (≤14.2 vs 30.2 μSv). Adult E for rectangular IOBW (4.6 μSv) was lower than EOBW with Orthophos (8.6 μSv) and Rayscan (30.2 μSv). Thyroid shielding reduced EOBW thyroid equivalent dose with Rayscan in the adult from 190.7 to 89.0 μSv.

CONCLUSION

Orthophos provides significantly lower EOBW E than Rayscan, thus EOBW recommendations must be unit specific. For children, Orthophos EOBW could be an alternative to IOBW, for which rectangular collimation is recommended. Thyroid shielding reduced adult Rayscan equivalent dose but added imaging artifacts.

"New Normal" Radiology

COVID-19, the most recent and globally impactful zoonotic viral pandemic in the last 20 years, has now entered its third year. As the global dental profession returns to providing as full a range of services as possible, in addition to embedding the new infection-control processes that were developed for this pandemic, it should also take full advantage of digital conventional radiology (intraoral, extraoral, and panoramic radiography) and cone-beam computed tomography. Regardless of vaccinations, new or yet-to-manifest variants, and testing, some dentists may be working in communities where the asymptomatic but potentially infectious patient poses a real risk. This needs to be met with not only the whole COVID-19 panoply the dentist is already too familiar with but also the need to minimise aerosol generation production by dental radiography. A flowchart and a table that compares the attributes of the above modalities are included.