Utility of thyroid collars in cephalometric radiography

Area of Science:

• Dentistry
• Radiology
• Orthodontics

Background:

• Cephalometric radiography is crucial in orthodontics and oral surgery.
• Thyroid collars (TCs) are used to shield patients from radiation during radiography.
• Concerns exist regarding the impact of TCs on image quality.

Purpose of the Study:

• To evaluate whether thyroid collars (TCs) negatively affect the diagnostic quality of lateral cephalograms.
• To determine if TCs obscure specific anatomical landmarks used in cephalometric analysis.

Main Methods:

• A randomized, observer-blinded study compared lateral cephalograms taken with and without TCs.
• Two blinded observers identified 15 predefined landmarks on 100 digital cephalograms (50 with TC, 50 without).
• Interobserver reliability was assessed.

Main Results:

• 12 out of 15 landmarks were consistently identified in both groups.
• The hyoid bone, second cervical vertebra, and third cervical vertebra were not identifiable when TCs were used.
• No significant difference was found in interobserver landmark identification variability.

Conclusions:

• Thyroid collars can obscure specific landmarks on lateral cephalograms, notably those essential for skeletal maturity index (SMI) assessment.
• Lead TCs provide effective thyroid protection during cephalometric radiography.
• TC use is advisable in routine cephalometric radiography when SMI analysis is not a primary objective.