interfractional

Full Definition

Interfractional refers to phenomena, variations, or changes that occur between individual radiation therapy treatment sessions (fractions). Common interfractional considerations include patient weight loss, tumor shrinkage, organ filling variations (bladder, rectum), and setup uncertainties that may accumulate over the treatment course. These factors can affect dose distribution accuracy and may necessitate adaptive treatment planning, imaging guidance, or treatment plan modifications to maintain optimal tumor coverage and normal tissue sparing.

Usage

Usage note: Carefully distinguish from 'intrafractional' (within a single fraction).

In Context

• "Interfractional anatomy changes prompted a plan adaptation after 15 fractions." — Treatment modification note
• "The study analyzed interfractional setup variations using daily cone-beam CT." — Research protocol