Radiation Therapy at MSK

Nurse Janice Reid

Before you begin external-beam radiation treatment, we’ll schedule you to come in for a simulation session, which allows our staff to ensure that we deliver the correct dose of radiation to the precise spot needed to treat the cancer effectively while minimizing exposure to nearby tissue. Our doctors will incorporate imaging methods (CT, PET, or MRI) to map out the treatment area. The simulation session will be followed by a setup appointment in the treatment room to confirm that the treatment planned for you will be delivered as prescribed.


For the simulation, you’ll change into a gown and our therapists will help position you on the same type of table that will be used during your actual radiation therapy treatment. During the simulation, we’ll take a CT scan to record images of the parts of your body to be treated. We may also use PET, MRI, or some combination of the two, depending on your specific case. We’ll also take x-rays and mark your skin to define the treatment area. Depending on where the tumor is located, our radiation therapist may recommend using foam sponges, headrests, molds, or specially designed plaster casts to ensure that you stay in exactly the same position throughout each radiation treatment.

The simulation may take two to four hours, but you shouldn’t feel much, if any, discomfort. At the end of the simulation, we’ll give you an appointment for your initial setup, which is the final appointment before your treatment begins. The setup and actual treatment usually begin within a week of simulation.

Based on information and CT images gathered from your simulation, our radiation oncologists will carefully design your treatment plan. Three-dimensional planning computers can show the size and shape of the targeted tumor from all angles. This technology assists the radiation oncologist in determining the exact points at which radiation will enter your body, minimizing exposure to surrounding normal tissues.

Setup for Treatment

Usually within a week after your simulation, you’ll come for a setup appointment, which allows us to verify that the treatment planned for you will be delivered as prescribed. The setup appointment usually takes about an hour.

During the setup, you’ll again change into a gown and our radiation therapists will bring you to the actual room where you’ll receive your treatment each day. The therapist will help position you on the treatment table exactly as you were the day of your simulation, and x-rays of the radiation beams will be taken to make sure your position is correct and that the treatment will go to the right place. We’ll schedule you to begin treatment within several days after your setup.

Our Westchester County outpatient location in West Harrison


Depending on the extent and type of your cancer, your treatment may occur in just one day or be given over a number of weeks. You need to come in every day you have treatment scheduled in order for it to be effective. During each session, you’ll change into a gown and be properly positioned on the table. The actual treatment takes only a few minutes, but overall you’ll be in the treatment room for about 20 minutes.