IMRT VS 3D CRT Patient Decision Guide

Information about the treatment planning

After the decision to treat the breast with radiation therapy has been made, the next step is to decide which areas of the breast are at risk and the dosage.

There are several machines and techniques available to deliver the treatment. Most of the times doctors will end up choosing between a 3DCRT based treatment or a VMAT based treatment.

Similarities

In both treatment plans a CT scan will be performed in a position that can be replicated during treatment.

Another similarity is that the volumes of radiation will be adapted to your anatomy and both techniques are equal in terms of disease control and overall survival.

3DCRT

In this type of treatment, the machine is positioned in a way the radiation oncologist calls tandem beams. In this configuration there will be a direct beam of radiation that will cover the area in a straight line.

The main advantage is that outside of this straight line there is very little radiation that will reach other organs, this leads to less fatigue, esophagitis and nausea.

The main disadvantage is that organs that lie inside this straight line will receive as much radiation as the main area of the breast, so important organs may receive the full dose if they are close to the area at risk.

This may also translate in certain types of side effects not seen in VMAT planning. This also leads to more skin reaction and implant related complications.

IMRT/ VMAT

This treatment variation involves rotating a beam moving around the body in an arc to target areas deemed at risk by the physician.

The advantage is that the treatment machine can focus on specific areas while sparing others, especially if the radiation treatment volume is close to a sensitive organ that should be avoided.

This approach may be preferred in patients with certain lung anatomy that may require circling around the lungs or if the tumor is near the sternum.

By selecting which areas to focus on, the technique has demonstrated a reduction in reconstruction failure rates.

However, a disadvantage is that a larger volume of the chest receives a low dose of radiation, leading to potential long-term side effects such as an increased risk of heart damage and the development of a second cancer.

Here is a side by side comparison of how both plans look

The high area doses are the redder zones, while the blue ones are areas that receive low dose of radiation.

Notice how in 3DCRT there is a slightly greater volume that receives a high dose and in IMRT there is a big volume that receives a low dose.

Advantages and Disadvantages to each Technique

Advantage 3DCRT	Advantages IMRT
Decreased risk of secondary malignancies	Might reduce heart dose in certain cases
Less gastrointestinal symptoms	Less time to perform
Less fatigue	Less skin reaction
Less esophagitis	Less implant reconstruction failure
	In advanced cases may allow contouring certain hard to get areas
Same
Chances of cancer control
Need for a CT scan to plan treatment
Number of sessions needed to complete treatment

Variables to consider when making a decision

You can print this and show it to your doctor to help guiding the decision.

How much do you worry about skin reactions? Not much Very Much

How much do you worry about the acute side effects, specially fatigue? Not much Very Much

How much do you worry about the risk of second malignancies? Not much Very Much

Will you be able to attend to regular followup visits after the treatment? Yes Might be difficult

Are you worried about your future cardiovascular health? Not much Very much

Would you like to be involved in the decision? I prefer the doctor make it Shared decision making