Radiotherapy - Fields and Ports

Radiation therapy is the use of ionizing radiation to treat cancer. Ionizing radiation damages quick-growing cells, such as tumors, so that they can’t replicate.

The area that an oncologist applies radiation is called a field or port. The fields for lymphomas are as follows:

Mantle field

Neck, chest, and armpits

Middle field (para-aortic field)

Abdomen, from the heart to spleen

Pelvic field

The groin

Inverted Y field

Middle and pelvic fields radiated together

Total Nodal Irradiation

Mantle and inverted Y fields together

In order to determine your radiation field, the radiation oncologist, physicist, and dosimetrist will conduct a simulation. During a simulation, which can take a few hours, the patient lies still on a table. The oncologist then uses x-rays to identify the areas where your tumors are located.

These areas will be marked with ink, or, in some cases, with small tattoos that look like freckles. When the patient comes in for treatment, these marks are used to align the radiation machine so that the treatment is administered to the appropriate areas. This also ensures that the same area is irradiated during every treatment session.

The oncologist may also use the simulation to determine what kind of shielding a patient needs. Special blocks made of lead, called shields, are inserted into the radiation machine in order to block an area from treatment. The oncologist will use the x-rays from the simulation to create the appropriate block. This may be necessary if you are receiving treatment in an area with reproductive organs or other sensitive organs.

Additional Radiation Therapy Topics:

• General
• Delivery
• Side Effects

Radiation Theraphy, NCI