Radiation Oncology Flashcards
Apoptosis
Cell death
Ionizing radiation (IR)
Type of radiation used in radiation oncology (e.g. X-rays)
Differentiated cancer cells
Typically less aggressive, low grade, spread slowly
Undifferentiated cancer cells
Typically more aggressive, grow faster
X-rays/Photons
Type of radiation called electromagnetic waves (X-Rays = Photons)
Proton therapy
Type of radiation that uses protons rather than x-rays to treat cancer. Uses high energy beams and may have fewer side effects than traditional radiation.
Simulation (Sim)
OAR
Organs at risk
Linear Accelerator (LINAC)
Most common device used for external beam radiation therapy (EBRT). Customizes high energy x-rays or electrons to conform to a tumor’s shape and destroy cancer cells while sparing surrounding healthy tissue.
External beam radiation (EBRT)
Comes from a machine (most often LINAC) that aims radiation at cancer/tumor. It’s a local treatment and may use photons, protons or electrons.
Intensity Modulated Radiotherapy (IMRT)
Advanced mode of high-precision radiotherapy (RT) that uses LINACs to safely deliver precise radiation to a tumor while minimizing dose to surrounding normal tissue
Stereotactic body radiation (SBRT)
Type of EBRT that uses special equipment to position patient and precisely deliver radiation to a tumor. The total dose of radiation is divided into several smaller doses given over several days.
Image guided radiotherapy (IGRT)
The use of imaging during radiation to improve precision and accuracy of treatment delivery
Bragg Peak
Pronounced peak on the Bragg curve which plots the energy loss of ionizing radiation (IR) during its travel through matter. For protons, x-rays and other ion rays, the peak occurs immediately before the particles come to rest. This is call the Bragg Peak (after William Henry Bragg who discovered it in 1903)
Brachytherapy
Form of radiotherapy where radioactive material sealed inside a seed, pellet, wire or capsule is implanted in the body using a needle or catheter. The radiation given off by this source damages the DNA of nearby cancer cells.
High Dose Rate (HDR)
Brachytherapy delivered in high dose over a few minutes
Low Dose Rate (LDR)
Brachytherapy delivered in low dose over an extended period of time
Dosimetry
Measurement of the amount or dosage of radiation absorbed by a substance or living organism by means of a dosimeter
Definitive treatment
Treatment for cure
Palliative treatment
Treatment to mitigate pain
Gray (Gy)
Derived unit of ionizing radiation dose in the International System of Units (SI), defined as the absorption of one joule of radiation energy per kilogram of matter. Used as a unit of the radiation quantity absorbed dose that measures the energy deposited by ionizing radiation in a unit mass of matter being irradiated. Used for measuring the delivered dose of ionizing radiation.
Fractionation
Dividing a dose of radiation into multiple “fractions” to maximize destruction of malignant cells while minimizing damage to healthy tissue.
Hypofractionation
Radiation is divided into large doses and treatments are given once a day or less often. Given over a shorter period of time (fewer days or weeks) than standard therapy.
Radiosensitivity
Response of a tumor to irradiation that can be measured by the extent of regression, rapidity of response and response durability.
Radioresistance
When radiation of a tumor does not result in reduced volume or when recurrence occurs after a possible regression
Contouring
Treatment planning
Gross tumor volume (GTV)
Includes all gross disease on physican exam with endoscopy and imaging. All suspicious lymph nodes should also be contoured as GTV.
Planned target volume (PTV)
Used in treatment planning, it is defined to select appropriate beam sizes and arrangements to ensure that the prescribed dose is actually delivered to the CTV.
Clinical target volume (CTV)
Tissue volume that contains the gross tumor volume (GTV) and subclinical microscopic malignant lesions.
Dose-volume histogram (DVH)
Histogram relating radiation dose to tissue volume in RT planning. Most commonly used as a plan evaluation tool and to compare doses from different plans or to structures.
Isodose
Delivering equal doses of radiation to part of the body
