Chapter 1 – Introduction to Imaging and Radiologic Sciences

Vocabulary flashcards summarizing fundamental terms from the history of x-rays, electromagnetic spectrum, and modern imaging modalities presented in Chapter 1.

Wilhelm Conrad Roentgen

German physicist who discovered x-rays on November 8, 1895 and received the 1901 Nobel Prize in Physics.

X-ray (Roentgen ray)

Human-made form of electromagnetic energy produced when high-speed electrons are suddenly stopped; capable of ionizing matter.

Radiograph

Recorded image of internal body structures produced by the passage of x-rays or gamma rays through the body.

Crookes Tube

Early vacuum tube used by Roentgen; accelerated electrons from cathode to anode, leading to the accidental discovery of x-rays.

Bremsstrahlung

‘Braking radiation’ produced when high-speed electrons are decelerated by the atomic nucleus, generating x-rays.

Cathode

Negative electrode in an x-ray tube that emits electrons when heated (thermionic emission).

Anode

Positive electrode in an x-ray tube that attracts electrons; modern tubes use a rotating, beveled anode to dissipate heat.

Thermionic Emission

Release of electrons from a heated filament (cathode) in an x-ray tube.

Fluoroscope

Device, originally hand-held by Thomas Edison, that allows real-time viewing of x-ray images.

Barium Platinocyanide

Fluorescent chemical that glowed during Roentgen’s experiments, revealing x-ray exposure.

Ionization

Process in which a neutral atom gains or loses electrons, acquiring a net electrical charge.

Ionizing Radiation

High-energy electromagnetic waves (gamma, x-ray, some ultraviolet) capable of removing electrons from atoms.

Electromagnetic Spectrum (EMS)

Range of all electromagnetic radiation types, from radio waves (longest wavelength) to gamma rays (shortest).

Gamma Ray

Highest-energy, shortest-wavelength electromagnetic radiation; strongly ionizing.

Ultraviolet Radiation

Electromagnetic waves shorter than visible light but longer than x-rays; partially ionizing.

Wavelength

Distance between successive crests of a wave; shorter wavelength equals higher energy and frequency.

Frequency

Number of wave cycles passing a point per second, measured in hertz (Hz).

Crest

Top (maximum point) of a wave.

Trough

Bottom (minimum point) of a wave.

Atmospheric Window

Range of electromagnetic wavelengths that can pass through Earth’s atmosphere without being absorbed.

Medical Radiation Sciences

Field that studies the use of radiation and related energies in medicine to create images or treat disease.

Imaging Sciences

Preferred term for disciplines that employ non-ionizing energies (e.g., MRI, sonography) to produce medical images.

Radiography

Imaging modality that uses x-ray energy to create static images of the body.

Computed Tomography (CT)

Imaging technique using x-ray energy and computer processing to produce cross-sectional body images.

Magnetic Resonance Imaging (MRI)

Modality that employs strong magnetic fields and radio waves to generate detailed body images without ionizing radiation.

Medical Sonography

Imaging method that uses high-frequency sound waves to visualize internal structures; non-ionizing.

Thermography

Imaging technique that records natural heat emitted by the body to produce thermal maps.

Electrocardiography (ECG)

Recording of the heart’s electrical activity for diagnostic purposes.

Nuclear Medicine

Imaging and therapeutic discipline using radioactive isotopes that emit gamma radiation inside the body.

Cardiovascular Interventional Imaging

Use of x-rays and contrast material via catheter to visualize and treat blood vessels and heart anatomy.

Radiation Therapy

Medical specialty that employs high-energy ionizing radiation to treat malignant tumors.

Antiseptic Embalming (Ancient Egypt)

Early use of chemicals to prevent decay, marking one of the first recorded medical antiseptic practices.

Hippocrates

Ancient Greek ‘father of Western medicine’ who emphasized disease prevention and ethical practice.

Antonie van Leeuwenhoek

17th-century scientist who invented the microscope, opening the study of microorganisms.

Edward Jenner

18th-century physician who developed the first successful smallpox vaccine.

Electromagnetic Energy

Form of energy transmitted through space or matter as electric and magnetic fields moving as waves at light speed.