Covers the principle of X-ray diagnostics, explaining how differential absorption in tissues produces images and how X-rays arise in a tube through bremsstrahlung and characteristic radiation, with lead shielding. It then describes radiography, fluoroscopy and computed tomography with their typical uses, followed by external beam therapy and brachytherapy, and closes with justification, ALARA, protection of pregnant women, children and workers, and the risks of overexposure.
Topic 41 of 42 in the MU Sofia syllabus for Physics (Medicine, Year 1). The free AceMed note covers it in 5 sections, about 345 words (2 min of reading), with 8 flashcards.
In this note
X-ray Diagnostics
Principle of X-ray Diagnostics
X-ray Diagnostic Methods
Therapeutic Applications of X-rays
Considerations and Safety
Principle of X-ray Diagnostics
Fundamental Principle:
X-rays are a form of electromagnetic radiation with high energy and short wavelength.
They penetrate tissues with varying absorption depending on density, atomic number, and thickness.
Dense tissues (e.g., bone) absorb more X-rays → appear white on film.
Soft tissues absorb less → appear darker.
X-ray Production:
Produced in an X-ray tube by accelerating electrons toward a metal target (e.g., tungsten).
X-rays arise via:
Bremsstrahlung radiation (braking radiation).
Characteristic radiation (electron transitions in the target atom).
Lead Shielding:
Used to protect patients and healthcare workers from unnecessary exposure.
Lead is effective due to its high density and high atomic number.
X-ray Diagnostic Methods
1. Radiography
Produces static 2D images.
X-rays pass through the body → differential absorption captured on film or digital detector.
