Intensity-modulated radiotherapy (IMRT) is a treatment method used in radiation oncology. Doctors deliver a high dose of radiation to the center of a tumor. Areas around the tumor are spared. IMRT is one of the 3D therapy methods and is based on the cross-sectional imaging of computer tomography (CT).
This article explains how IMRT works and where you can find specialists.
In IMRT, doctors divide the area (tumor tissue) into fields. They irradiate these with different radiation intensities.
Special metal slats allow the irradiation field to be darkened or opened up in sections. Similar to the slats on a Venetian blind. This allows doctors to irradiate parts of the tumor for shorter or longer than others. Depending on how long the slats are open.
IMRT is a highly technical and very targeted treatment method. Nevertheless, it is not suitable for all tumor types.
IMRT is suitable for:
Patients with head and neck tumors or prostate cancer patients benefit from this procedure.
In the area of the head and neck, the salivary glands in particular are structures worth protecting and are very sensitive to radiation. A targeted dose of radiation to a tumor while avoiding the salivary glands prevents late effects of tumor therapy.
The situation is very similar with the prostate. This is located very close to the rectum, which is also sensitive to radiation. Without the use of targeted procedures such as IMRT, the sphincter muscle, for example, could be damaged. Fecal incontinence would then be possible. IMRT makes it possible to prevent damage to the rectal area and only irradiate the prostate cancer.
In addition to dosing the radiation within an irradiation field, IMRT can also irradiate around corners. This gives the procedure much greater degrees of freedom in three-dimensional space than conventional radiological procedures.
There are essentially two major types of IMRT:
Rapid-Arc is significantly less time-consuming and is used when radiation is to be delivered in a short time. It covers the tumor area from all sides while sparing the surrounding tissue. The short treatment duration reduces the risk of the patient's position changing so that the tumor remains better focused.
With the volume-modulated approach, the IMRT constantly adapts to the spatial conditions of the tumor. This enables shorter irradiation times in a specific area.
The preparation for IMRT is time-consuming and resource-intensive. Doctors need to take several images of the tumor and the surrounding tissue to create an optimal radiation plan.
This is usually done using magnetic resonance imaging (MRI ) or computer tomography (CT). The patient must lie in a predefined position.
Vacuum mattresses and other aids help to hold the patient in place.
The imaging, treatment planning and special positioning are important for the subsequent course of treatment. Each patient therefore receives an individualized therapy concept tailored by the specialists in radiation oncology.
Medical physics then calculates the radiation dose as the target dose in the tumor tissue based on the data from the imaging and positioning. This spares the surrounding healthy tissue. Before the procedure begins, the planning is checked and approved according to the dual control principle.
The radiation is then fractionated in the predetermined treatment fields. The IMRT specialist can change the radiation dose in terms of direction, shape and intensity. In this way, he delivers the optimum therapy dose to the tumor tissue and protects adjacent structures. This reduces the rate of side effects. The patient's quality of life is less severely restricted as a result.
IMRT can precisely distribute the radiation dose even in complex tumors and protect surrounding organs @ Mark Kostich /AdobeStock
IMRT is only carried out by specialist radiotherapy centers. Firstly, because the highly complex equipment is not available at all locations in Germany. Secondly, an IMRT specialist at such a radiotherapy center has the necessary experience with patients and the IMRT procedure. This significantly increases the chances of successful treatment.
After IMRT, the doctor originally assigned to the patient is responsible for the patient again. This doctor takes over the aftercare. Specialized radiotherapy aftercare is always carried out in consultation between the family doctor's practice and the radiology specialists.
IMRT specialists can be found in radiology or radiation oncology. They mainly work in specialized radiotherapy centers. Above we have put together some suggestions for possible radiotherapy centers and radiation oncologists specializing in IMRT.
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