Ionizing Radiation in Medicine – Linear Accelerator (Radiotherapy)

Vocabulary flashcards covering key terms and definitions from Lecture 05 on ionizing radiation, radiotherapy, linear accelerators, and nuclear medicine tracers.

Ionizing Radiation

High-energy radiation capable of removing electrons from atoms, creating ions and biological damage.

Non-Ionizing Radiation

Low-energy radiation that cannot ionize atoms; includes microwaves, radio waves, and visible light.

Alpha (α) Radiation

Heavy, positively charged particles emitted from nuclei; low penetration, stopped by paper or skin.

Beta (β) Radiation

High-speed electrons or positrons; moderate penetration, blocked by thin metal like aluminum.

Gamma (γ) Radiation

High-energy electromagnetic waves released from nuclei; deeply penetrating, shielded by lead or concrete.

X-Rays

Electromagnetic waves produced outside the nucleus; used in imaging and therapy.

Neutron Radiation

Neutral particles emitted during nuclear reactions; highly penetrating and biologically damaging.

Cancer

Disease in which abnormal cells divide uncontrollably and invade surrounding tissue due to DNA changes.

Radiation Therapy

Medical use of ionizing radiation to damage cancer cells while sparing healthy tissue.

Linear Accelerator (LINAC)

Device that accelerates charged particles in a straight line to deliver targeted radiation to tumors.

Brachytherapy

Radiation treatment technique placing radioactive sources inside or next to the tumor.

Consultation (Radiotherapy)

Initial meeting with a radiation oncologist to discuss diagnosis, options, and potential side effects.

Simulation (Radiotherapy)

Imaging session creating a 3-D map of the tumor to guide precise treatment planning.

Treatment Planning

Process by oncologist and dosimetrist to set radiation type, dose, and number of fractions.

Marking and Set-Up

Placement of small tattoos or ink marks to ensure consistent patient positioning for each session.

Fractionation

Delivering radiation in multiple small doses to exploit cancer cell division cycles and reduce toxicity.

Three-Dimensional Conformal Radiation Therapy (3D-CRT)

Technique shaping radiation beams to match the 3-D contour of the tumor.

Intensity Modulated Radiation Therapy (IMRT)

Advanced 3D-CRT that varies beam intensity to spare normal tissues more effectively.

Proton Beam Therapy

Radiotherapy using protons whose Bragg peak allows precise dose deposition with minimal exit dose.

Neutron Beam Therapy

Treatment with fast neutrons, useful for certain radio-resistant tumors.

Stereotactic Radiotherapy

High-precision, high-dose radiation delivered in one or few sessions to small targets.

Image-Guided Radiation Therapy (IGRT)

Use of imaging before or during treatment to verify and adjust patient positioning.

Tracer (Nuclear Medicine)

Radioactive substance introduced into the body to visualize organ function via gamma detection.

Technetium-99m

Widely used gamma-emitting tracer with a 6-hour half-life, ideal for diagnostic imaging.

Half-Life (Radiopharmaceutical)

Time required for radioactivity to fall to half its original value; determines imaging window and dose.

Tracer Selection Criteria

Ability to localize in target tissue, short half-life, and emission of detectable gamma rays.

Radiation Oncologist

Physician specializing in prescribing and overseeing radiation therapy.

Medical Physicist

Expert ensuring accurate radiation dose delivery and machine calibration.

Dosimetrist

Professional who calculates the optimal radiation dose distribution for treatment plans.

Radiation Therapist

Technologist who operates the LINAC and delivers daily radiation treatments.

Radiation Oncology Nurse

Nurse providing patient education, care, and management of therapy side effects.

Gamma Camera

Device that detects gamma rays from tracers to create diagnostic images of internal organs.

Bone Scan (MDP)

Imaging technique using 99mTc-MDP to identify bone metabolism and lesions.

Renogram (MAG3)

Functional kidney imaging using 99mTc-MAG3 to assess renal perfusion and excretion.