Radiation Oncology Glossary
100 terms total — 24 showing — Last updated 15 Sep 2026
couch kick
A non-coplanar beam angle achieved by rotating the treatment couch away from zero degrees.
acute toxicity
Side effects from radiation therapy that occur during or shortly after treatment completion.
adaptive radiation therapy
Treatment approach that modifies radiation plans during treatment course based on anatomical or biological changes.
alpha/beta ratio
Radiobiological parameter describing tissue sensitivity to fraction size changes in radiation therapy.
arc therapy
A radiation delivery technique where the treatment beam rotates around the patient during dose delivery.
beam hardening
The preferential filtering of low-energy photons from a radiation beam as it passes through tissue, resulting in a highe...
beam modulation
The process of varying radiation beam intensity across the treatment field to achieve desired dose distribution.
Beam Spoiler
Material placed in the electron beam path to degrade beam energy and modify dose distribution characteristics.
beam's eye view
A visualization perspective showing the treatment volume and anatomy as seen from the radiation source along the beam di...
biologically effective dose
Mathematical model comparing different fractionation schemes based on their biological effects on tissues.
bolus
A tissue-equivalent material placed on the patient's skin surface to modify the dose distribution and bring the maximum...
brachytherapy
Internal radiation therapy where radioactive sources are placed directly inside or next to the tumor.
build-up region
The shallow depth region where radiation dose gradually increases from the surface to reach maximum value in tissue for...
clinical target volume
The anatomical volume that contains the gross tumor and areas at risk for microscopic disease spread.
Collimator
A beam-shaping device that defines the shape and size of the radiation beam before it reaches the patient.
commissioning
Comprehensive testing and validation process for new radiation therapy equipment before clinical use.
cone-beam computed tomography
On-treatment imaging technique using a cone-shaped X-ray beam to verify patient positioning and anatomical changes.
conformity index
Quantitative measure of how well the prescription dose distribution conforms to the target volume.
coplanar
Treatment fields or beam arrangements that lie within the same geometric plane, typically the transverse plane through t...
couch kick
A non-coplanar beam angle achieved by rotating the treatment couch away from zero degrees.
CTCAE
Common Terminology Criteria for Adverse Events, the standardized classification system for grading treatment-related tox...
CyberKnife
A robotic radiosurgery system that delivers highly precise radiation beams while tracking tumor motion in real-time.
DICOM-RT
Digital Imaging and Communications in Medicine standard for radiation therapy data exchange.
Dose Escalation Study
Clinical trial design that systematically increases radiation doses to determine maximum tolerated dose and optimal trea...
DVH
Graphical representation showing the percentage of organ volume receiving specific radiation doses.