Intensity modulated radiation therapy

Status: Decision completed

Policy context

There is increasing use of IMRT for a variety of cancers. The impact of this technology on patient-important outcomes compared to current conventional (coronal or standard) EBRT is unclear.

Primary criteria ranking

  • Safety = High
  • Efficacy = Medium
  • Cost = High

Assessment timeline

  • Draft key questions published: February 21, 2012
  • Public comment period: February 21 to March 6, 2012
  • Draft report published: July 6, 2012
  • Public comment period: July 6 to August 6, 2012
  • Final report published: August 20, 2012
  • HTCC public meeting: September 21, 2012


Current conventional or standard EBRT uses three-dimensional (3D) imaging technology from computed tomography (CT), positron-emission tomography (PET), and/or magnetic resonance imaging (MRI) for planning purposes and delivers photon beams of uniform intensity to the target tumor using a medical linear accelerator (LINAC). Conformal refers to the ability to precisely conform the delivery of the EBRT to the shape and size of the tumor, so current conventional EBRT is often referred to as 3D conformal radiation therapy (3DCRT).

Over the past ten years, significant advances have been made in the techniques available to deliver EBRT including stereotactic radiation surgery (SRS) limited to the central nervous system and a single dose, stereotactic body radiation therapy (SBRT), intensity modulated radiation therapy (IMRT), and proton or particle beam radiation therapy. Intensity modulated radiation therapy uses multiple beams and angles (multi-leaf collimator) that can deliver varying intensities of radiation to the tumor to maximize the dose to the tumor and decreased or no dose to the surrounding tissue.

For IMRT, the technical goal is to improve the targeting of the radiation to the tumor to minimize damage of normal tissue. The intended patient-important outcome from this technique is to reduce acute and chronic radiation side-effects since surrounding tissues receive less radiation. The focus of this report will be on IMRT. However, it should be noted that SBRT and IMRT are not mutually exclusive.