aspectos básicos da radiografia rx do trauma

1. Radiographic Basics
Rui Domingues, MD
Lincoln Mental and Medical Center
September 2008

2. What causes the blacks, whites
and grays of an x-ray image?
 X-ray beams contains x-ray photons of
differing energies
 As these photons pass through a
patient…

Some are absorbed completely

Some penetrated directly to the plain film

Some are absorbed partially, and

While others are deflected (Scatter)

3. Tissue Density
 A product of the type of tissue and the
thickness of that tissue
 Results in differential absorption

4. Differential Absorption
 Penetration of the x-ray beam is dependent
on tissue density
 Denser object = less penetration
 Less beam striking the film (more absorption)
= WHITER
 More beam striking the film = BLACKER

5. Glass
Test
Tube
Air
Fat
Water
Bone
+
Water
Metal

6. Differential Absorption
Black Air (Lungs / Trachea / Outside the body)
↓ Fat (Perirenal fat / Fascial plane)
↓ Water (Muscle / Organs)
↓ Bone (Bone / Atherosclerotic plaquing)
White Metal (Fillings / Markers / Ortho devices)

7. Radiographic Image
 Adjacent structures of similar densities
are not visualized
 Kidney (water density) against liver
(water density)

8. Radiographic Image
 Adjacent structures of different
densities are visualized
 Liver (water density) next to Bowel (air
density)

10. References
 Felson’s Principles of Chest Roentgenology: A
Programmed Test, 2nd
Edition. Goodman, Lawrence R.;
W.B. Saunders Co., 1999.
 Pocket Atlas of Radiographic Anatomy. Moller, TB et al.;
Thieme Medical Publishers, 1993
 Clinical Imaging with Skeletal, Chest and Abdomen Pattern
Differentials, Dennis Marchiori, ed. (WN 180 M317c)