Two Newer Therapies: 3D-CRT and IMRT

3D-CRT stands for three-dimensional conformal radiation therapy. This treatment delivers higher doses of radiation more accurately. It uses CT scanners to send images of the tumor to a computer. The computer then measures the size and location of the tumor. It does the same for nearby healthy tissue. These measurements determine how much radiation needs to be aimed at the tumor.

CT scans aren’t the only source of information for treatment planning. MRIs can also be used. And so can PET scans. Coleman says it’s a more precise way to define the tumor size an shape.

3D-CRT can be especially useful for treating certain kinds of tumors:

  • tumors that are irregular in shape
  • tumors found in a delicate area such as the brain
  • tumors surrounded by normal tissue that’s highly sensitive to radiation

3D-CRT is commonly used to treat certain parts of the body:

  • prostate
  • brain
  • lung
  • head
  • neck

New computer programs and careful review of treatment plans are helping to improve this therapy.

IMRT stands for Intensity Modulated Radiation Therapy. This is an enhanced form of 3D-CRT. It treats the tumor with small beamlets of radiation from multiple angles. The combined doses of the beamlets treat the tumor. This also shields normal tissues. IMRT may allow higher doses of radiation to be applied to certain tissues. That can improve control rates while limiting toxicities.

The use of IMRT is still in the early phases. Coleman says hospitals are just starting to use it. The technology needed is very complex. And IMRT is not needed in every case.