Human Anatomy, Physiology and Pathology Relevant to Imaging
Human Anatomy, Physiology and Pathology Relevant to Imaging
This domain tests normal anatomy, radiographic densities, and common pathology visible on images. Expect chest, abdominal, skeletal and soft-tissue appearances.
Core rules
- Radiographic densities: air is black, fat dark grey, soft tissue grey, bone white, metal bright white.
- Anatomical position: patient upright, facing observer, palms forward. Use right and left from the patient's perspective.
- Chest: assess lung zones, hila, heart border, costophrenic angles, diaphragm and mediastinum. A PA erect film reduces magnification.
- Abdomen: liver right, spleen left, kidneys retroperitoneal, bladder central. Bowel gas is normal; air-fluid levels may indicate obstruction.
- Pathology: consolidation gives opacity with air bronchograms; pneumothorax gives hyperlucency with absent lung markings; effusion blunts the costophrenic angle; fracture shows a lucent line.
Worked example
A right lower-zone opacity obscures the right hemidiaphragm and contains air bronchograms. The silhouette sign localises it to the right lower lobe, and air bronchograms suggest alveolar consolidation rather than pleural fluid. Pleural fluid would blunt the angle and shift the meniscus.
Traps
- Calling the image left when it is the patient's right.
- Describing air as white; air is black on radiographs.
- Treating every opacity as pneumonia.
- Forgetting that positioning and inspiration change apparent heart size.