Final Review: Radiographic Techniques
Mastery & Troubleshooting for the RHS Exam
You have covered individual techniques—from PAs to CBCT. This final review synthesizes that knowledge into a Clinical Decision Matrix. Use this to double-check your logic before taking the unit exam.
1. Selecting the Right Image
The exam will describe a patient’s need. You must select the most appropriate survey:
| Patient Presentation | Correct Choice |
|---|---|
| Suspicion of interproximal decay (standard). | Horizontal Bitewings |
| Generalized bone loss / Periodontal disease. | Vertical Bitewings |
| Suspected apical abscess (infection at root). | Periapical (PA) |
| Large lesion, impacted wisdom teeth, or jaw fracture. | Panoramic |
| Measuring bone volume for a dental implant. | CBCT (3D) |
2. The “Fix-It” Guide (Troubleshooting)
If an image is non-diagnostic, you must identify the technical cause. This table is high-yield for the exam:
- ❌ Problem: Overlapped contacts.
✅ Solution: Correct Horizontal angulation. - ❌ Problem: Elongated or Foreshortened images.
✅ Solution: Correct Vertical angulation. - ❌ Problem: Cone-cut (clear unexposed area).
✅ Solution: Center the PID over the sensor/film. - ❌ Problem: Blurred image.
✅ Solution: Instruct patient to remain still (eliminate movement).
3. Geometry of the Beam
Recall the rules for shadow casting to minimize distortion:
- The sensor should be parallel to the tooth.
- The beam should be perpendicular to the sensor.
- The focal spot (inside the tubehead) should be as small as possible.
- A longer PID (16″ vs 8″) reduces magnification and increases image sharpness.
✅ Ready for the Unit Exam?
If you can differentiate between Vertical and Horizontal errors and know which sensor sizes belong to which technique (Size 2 for adult PAs/BWs, Size 4 for Occlusal), you are ready to move forward.