3D & 4D Conformal Radiation Therapy and Intensity Modulated Radiation Therapy (IMRT)
The goal of radiation therapy for cancer treatment is to reduce or to eliminate the tumor and spare as much healthy tissue and organ functioning as possible. Radiation kills and disrupts the growth of cancer cells and radiated cancer cells are not able to repair themselves or replicate.
Radiation often damages all cells, both healthy and cancerous, in the exposed area. In the past, external sources of radiation therapy involved aiming high-beam energy rays at a treatment area. Conventional radiation was associated with side effects and the loss of healthy tissue leading experts in the field to look for better ways to use radiation.
Today, sophisticated technology has refined the way that radiation treatment is delivered. Modern radiation methods target the cancer more effectively, spare more healthy tissue, and are associated with fewer side effects and improved cure rates. Some of the modern methods include three dimensional conformal radiation therapy (3D CRT), four dimensional conformal radiation therapy (4D CRT), and intensity modulated radiation therapy (IMRT).
State-of-the-art technology has advanced radiation methods to help make them more effective and tolerable. Three dimensional conformal radiation therapy (3D CRT) maps a tumor with imaging scans before treatment. Magnetic resonance imaging (MRI) scans, computed tomography (CT) scans, and positron emission tomography (PET) scans are used to produce images of a tumor and its surrounding tissue. The images from the scans are combined with images combined in the treatment planning system (TPS).The TPS is used by the Physician, physicist, and dosimetrist to design the optimal radiation treatment approach. It is then used to program the treatment machine and its Multileaf collimator(MLC). The MLC allows division of the standard rectangular beam into multiple (even hundreds) of beamlets. The programing allows these beamlets to open and close, thereby modulating the standard radiation output. This directs multiple beams of radiation to be targeted precisely at the tumor and spare as much healthy tissue as possible.
Four dimensional conformal radiation therapy (4D CRT) measures the motion of tumors during natural small movements that occur during treatment, such as breathing. Four-dimensional CRT is especially useful when treating lung cancer. The motion measurements are included in the treatment formula configurations. This ensures that the tumor is targeted during motions and as much healthy tissue as possible is spared.
Intensity modulated radiation therapy (IMRT) is a refined type of 3D CRT. CRT allows the radiation oncologists to sculpt the edges of a tumor sparing healthy tissue. With IMRT, the radiation dose can be modified (modulated) during a treatment session. In the past, radiation was delivered based on dose calculations to one point in the treatment field. IMRT allows calculation and delivery to virtually every point throughout the treatment region. Imrt modulates the treatment so the proper dose is more uniformly delivered to each area.
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The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Authors Dr. Mary Car-Blanchard, OTD/OTR/L and Valerie K. Clark, and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. This content complies with the HONcode standard for trustworthy health information. The library commenced development on September 1, 2005 with the latest update/addition on February 16, 2022. For information on iHealthSpot’s other services including medical website design, visit www.iHealthSpot.com.