Intensity-modulated radiation therapy

Last revised by Andrew Murphy on 23 Mar 2023

Intensity-modulated radiation therapy (IMRT) is a type of conformal radiation therapy where not only the shape but also the intensity profile (i.e. fluence) of each beam is varied, therefore, superior to the 3D-CRT

Early implementations involved building up a fluence profile by summing smaller beam 'segments' until the desired profile was achieved. The beam was turned off while the multi-leaf collimator (MLC) leaves were in motion and only turned on for a specific period to deliver each segment 1.

Modern 'sliding-window' techniques use carefully calibrated MCLs which slide across the beam path while the beam remains on. The variable speed of each MLC leaf allows the creation of hot and cold spots in the beam profile 1.

ADVERTISEMENT: Supporters see fewer/no ads

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.