XRay Interpretation

Five Radiographic Densities (in order of increasing brightness)
1. Air (e.g. lung, dark)
2. Fat
3. Fluid and soft tissue (e.g. heart)
4. Bone or calcifications
5. Metal or Contrast Material (very bright)
Differences in radiographic density allows for differentiation of structures on XRay
1. Adjacent objects with similar densities will have indistinct abbutting margins
2. Blurred structural margin suggests an adjacent structure (Silhouette Sign)
Image Geometry
1. Orthogonal views (90 degrees) reduces distortion
2. Objects further from the xray film are distorted
  1. Objects close to XRay film or cassette have sharp edges without significant magnification
  2. Objects further from XRay film or cassette have blurred edges and greater magnification
Penetration
1. Over-penetration: Dark films
2. Under-penetration: White films
Artifacts
1. Mach Bands
  1. Optical Illusion that appears similar to a Fracture line at the interface between radiopaque objects
  2. Two superimposed structures (e.g. bone on bone) have slightly different shades of gray

Read the full imaging report (not just the impression)
Read your own imaging studies early
1. Follow the established review pattern for each imaging study (e.g. ABCD for Chest XRay Interpretation)
2. Do not wait for radiology over-read (delays care, missed findings)
3. Act on serious findings, and alert radiology if needing faster over-read for related findings
Discharging before radiology over-read risks missed patient notification
1. Have a system for abnormal late-result review (e.g. nurse triage pool)
2. Alert the patient to which results are pending and how they can view final results (e.g. Epic MyChart)
3. Facilitate patient follow-up

Unlike fluoroscopy or CT, single modern xray exposure risk is negligible (0.04 mSv)
1. Single Xray exposure is equivalent to 10 days of environmental background Radiation Exposure
Radiation Exposure is reduced even further with distance from XRay source (by inverse of square of distance)
1. Distance 2 feet from XRay Source drops Radiation Exposure to 25% (compared with 1 foot distance)
2. Distance 3 feet from XRay Source drops Radiation Exposure to 11% (compared with 1 foot distance)
3. Distance 4 feet from XRay Source drops Radiation Exposure to 6.3% (compared with 1 foot distance)
4. Distance 5 feet from XRay Source drops Radiation Exposure to 4% (compared with 1 foot distance)

Check Metadata
1. Patient Name and Identifiers
2. Exam Date and Time
3. Technician Notations (e.g. Expiration film)
Patient Position
1. Supine
2. Semiupright
3. Erect
Patient Alignment
1. Rotation
2. Lordosis or kyphosis
Systematic Review in General
1. Prowl the film in systematic fashion (see xray findings below for specific approaches)
2. View images adjusting brightness/contrast presets (e.g. bone window) and different magnification
Systematic Review: Musculoskeletal XRay ABCs
1. Adequacy and Alignment
2. Bones
3. Cartilage and Joints
4. Soft tissue and spacing