II. Background
- Five Radiographic Densities (in order of increasing brightness)
- Air (e.g. lung, dark)
- Fat
- Fluid and soft tissue (e.g. heart)
- Bone or calcifications
- Metal or Contrast Material (very bright)
- Differences in radiographic density allows for differentiation of structures on XRay
- Adjacent objects with similar densities will have indistinct abbutting margins
- Blurred structural margin suggests an adjacent structure (Silhouette Sign)
- Image Geometry
- Orthogonal views (90 degrees) reduces distortion
- Objects further from the xray film are distorted
- Objects close to XRay film or cassette have sharp edges without significant magnification
- Objects further from XRay film or cassette have blurred edges and greater magnification
III. Approach: Check Written Information
- Patient Name
- Exam Date and Time
- Technician Notations (e.g. Expiration film)
IV. Approach: Patient Position
- Supine
- Semiupright
- Erect
V. Approach: Patient Alignment
- Rotation
- Lordosis or kyphosis
VI. Approach: Penetration
- Over-penetration: Dark films
- Consider using "bright-light" to see details
- Under-penetration: White films
VII. Approach: Systematic Review
- Prowl the film
- View film from different angles and distances
- Establish strong, even illumination
- Turn off surrounding light panels
- Dim room lights