CBCT Field of View (FOV) Selection: How to Choose the Right Size

Why FOV Selection Matters

The field of view (FOV) is one of the most important decisions when acquiring a CBCT scan. It determines how much anatomy is captured, the radiation dose to the patient, the scan resolution, and the resulting file size. Selecting the right FOV means capturing everything needed for diagnosis while minimizing unnecessary radiation exposure — a direct application of the ALARA principle.

FOV Categories

CBCT FOVs are generally classified into four categories:

• Ultra-small (≤5×5 cm): Captures 3-4 teeth. Highest resolution available (voxel sizes as small as 0.075 mm). Ideal for endodontic diagnosis, single implant sites, and periapical pathology assessment.
• Small (5×5 to 8×8 cm): Covers a dental quadrant or anterior segment. Good resolution with manageable file sizes. Suitable for implant planning in a localized area, third molar assessment, and periodontal evaluation.
• Medium (8×8 to 12×10 cm): Captures a full single arch or both arches in the anterior region. Versatile for most general dental applications including multi-site implant planning, full-arch periodontal assessment, and impacted canine localization.
• Large (13×10 cm and above): Captures both dental arches, TMJs, sinuses, and airway. Required for orthodontic treatment planning, orthognathic surgery planning, TMJ bilateral comparison, airway analysis, and full-mouth reconstruction.

FOV Selection by Clinical Indication

Endodontics

Use the smallest FOV available (ultra-small or small). You only need to see the tooth in question and its immediately surrounding structures. A 5×5 cm FOV centered on the affected tooth provides the highest resolution for detecting missed canals, vertical root fractures, and periapical pathology. Smaller FOV also means lower patient dose — particularly important for repeat imaging during treatment monitoring.

Implant Planning (Single Site)

A small FOV (5×5 to 8×5 cm) is typically sufficient for a single implant site. It captures the crestal bone, opposing arch for occlusal clearance assessment, and adjacent teeth. Ensure the FOV extends at least 5 mm beyond the planned implant site in all directions to capture surrounding anatomy.

Implant Planning (Multiple Sites or Full Arch)

Use a medium to large FOV (10×8 to 12×10 cm) to capture all planned implant sites in one scan. This avoids the need for multiple scans and provides a comprehensive view for prosthetic planning. For All-on-4 or All-on-6 cases, ensure the FOV captures both the anterior and posterior regions of the arch.

Orthodontics

Large FOV (15×13 cm or larger) is standard for orthodontic assessment. Orthodontists need to evaluate both arches, skeletal relationships, TMJ morphology, impacted teeth, and airway dimensions in a single scan. This replaces multiple 2D radiographs (panoramic, cephalometric, periapicals).

Third Molar Assessment

A small FOV (5×5 to 8×5 cm) focused on the third molar region is usually sufficient. The key structures to capture are the tooth, surrounding bone, inferior alveolar canal, and adjacent second molar.

TMJ Evaluation

A medium to large FOV that captures both TMJs is recommended for bilateral comparison. A single medium FOV scan can often capture both joints if positioned correctly. For isolated unilateral TMJ assessment, a smaller FOV is acceptable.

Balancing Dose, Resolution, and Diagnostic Need

The relationship between FOV and radiation dose is roughly proportional — doubling the FOV height roughly doubles the dose. Always start by asking: "What is the smallest FOV that will answer the clinical question?" This approach ensures optimal image quality at the lowest possible dose.

When viewing scans in CBCTHub, the viewer automatically adapts to the FOV size — whether it's a focused endodontic scan or a full craniofacial volume, you and your referral network can review the complete dataset through any browser.