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Specialization 08

RADIOLOGY

Before we can fix the biological machine, we must see inside it. By weaponizing the electromagnetic spectrum and acoustic physics, we turn the human body into glass.

Standard X-Ray Energy
30-150 keV
Clinical MRI Magnet
1.5 - 3.0 Tesla
Concept Zero: Choosing the Right Tool
The Modality Matrix

Radiography (X-Ray)

Physics: Electromagnetic Attenuation

Shoots high-energy photons through the body. Dense materials (like calcium in bones) absorb the photons, casting a bright white "shadow" on the film behind the patient.

  • Best for: Fractures, lung pneumonia, dental cavities.
  • Drawback: Uses ionizing radiation. Poor soft-tissue contrast.

The Lexicon of Density

X-Ray & CT (Density)

Radiopaque (Hyperdense)

Blocks X-rays. Appears White. Examples: Bone, Metal implants, Barium contrast.

Radiolucent (Hypodense)

X-rays pass right through. Appears Black. Examples: Air in lungs, bowel gas.

MRI (Signal Intensity)

Hyperintense

Returns a strong radio signal. Appears White/Bright. Example: Fat (on T1), Water/Edema (on T2).

Hypointense

Returns weak/no signal. Appears Black/Dark. Example: Cortical bone (has no mobile water), flowing blood.

The Larmor Equation (MRI Core Physics)

The frequency at which a proton spins (precesses) is directly proportional to the strength of the magnetic field it is inside.

ω=γB0\omega = \gamma B_0