Intensity-Modulated Radiation Therapy (IMRT) - Information and Specialists

In IMRT, doctors divide the area (tumor tissue) into fields. They then irradiate these fields with varying intensities of radiation.

Special metal blades allow the radiation field to be partially blocked or opened, similar to the slats on a venetian blind. This enables doctors to irradiate parts of the tumor for shorter or longer periods than others, depending on how long the blades remain open.

IMRT is a highly technical and very targeted treatment method. However, it is not appropriate for all types of tumors.

IMRT is suitable for:

• Tumors that are difficult to operate on
• Tumors located near other important tissues or organs

Patients with head and neck tumors or prostate cancer benefit from this procedure.

In the head and neck region, the salivary glands in particular are structures that need to be protected, as they are highly sensitive to radiation. Delivering a targeted radiation dose to a tumor while sparing the salivary glands prevents long-term complications from cancer treatment.

The situation is very similar with the prostate. It is located very close to the rectal area, which is also sensitive to radiation. Without the use of targeted techniques such as IMRT, the sphincter muscle, for example, could be damaged. This could lead to fecal incontinence. IMRT makes it possible to prevent damage to the rectal area and to irradiate only the prostate cancer.

In addition to adjusting the radiation dose within a treatment field, IMRT can also deliver radiation around corners. This gives the procedure much greater flexibility in three-dimensional space than conventional radiological methods.

Essentially, there are two main types of IMRT:

• The faster RapidArc technique and
• Volume-modulated arc therapy

Rapid-Arc is significantly more time-efficient and is used when radiation therapy needs to be administered quickly. It targets the tumor area from all sides while sparing the surrounding tissue. The short treatment duration reduces the risk of the patient shifting position, ensuring that the tumor remains better targeted. 

With the volume-modulated approach, IMRT continuously adapts to the spatial characteristics of the tumor. This allows for shorter radiation times in a specific area.

Preparing for IMRT is time-consuming and resource-intensive. To create an optimal radiation plan, doctors must take multiple images of the tumor and the surrounding tissue. 

This is typically done using magnetic resonance imaging (MRI) or computed tomography (CT). The patient must lie in a predefined position during the procedure. 

Vacuum mattresses and other devices help secure the patient in place.

Imaging, treatment planning, and specific positioning are crucial for the subsequent course of treatment. Each patient therefore receives a personalized treatment plan tailored by radiation oncology specialists.

The medical physics team then calculates the radiation dose—specifically the target dose in the tumor tissue—based on the data from the imaging and positioning. This ensures that surrounding healthy tissue is spared. Before the procedure begins, the treatment plan is reviewed and approved according to the dual-review principle.

Radiation is then delivered in fractionated doses to the predetermined treatment fields. During this process, the IMRT specialist can adjust the radiation dose in terms of direction, shape, and intensity. This allows the specialist to deliver the optimal therapeutic dose to the tumor tissue while protecting adjacent structures. This helps reduce the rate of side effects, resulting in less severe impairment of patients’ quality of life.

IMRT can precisely distribute the radiation dose even in complex tumors and spare surrounding organs @ Mark Kostich /AdobeStock

IMRT is performed only at specialized radiation therapy centers. For one thing, the highly complex equipment is not available at all locations in Germany. Second, an IMRT specialist at such a radiation therapy center has the necessary experience with patients and the IMRT procedure. This significantly increases the treatment’s chances of success.

After IMRT, the patient is once again under the care of the physician originally assigned to them. This physician takes over the follow-up care. Specialized radiation therapy follow-up care is always coordinated between the patient’s primary care physician’s office and the radiology specialists.

IMRT specialists can be found in the fields of radiology or radiation oncology. They work primarily in specialized radiation therapy centers. Above, we have compiled a list of suggestions for potential radiation therapy centers and radiation oncologists specializing in IMRT.