What to Expect Before Treatment

Fox Chase Cancer Center Information

RT Answers is a free service provided by ASTRO (American Society for Therapeutic Radiology and Oncology) to answer your radiation therapy questions.

Where to Stay


Schedule an appointment at Fox Chase to learn about our advanced programs and ability to tailor treatment especially for you. Your doctor will evaluate your need for radiation therapy and its likely results. Your doctor will review your current medical problems, past medical history, past surgical history, family history, medications, allergies and lifestyle. A physical examination will be performed, including a review of x-rays and biopsy results to assess the extent of your disease and judge your general physical condition.

After reviewing your medical tests, including CT scans, MR scans and positron emission tomography scans (PET scans) and completing a thorough examination, your radiation oncologist will discuss the potential benefits and risks of radiation therapy and answer your questions.

Simulation and Treatment Planning

To be most effective, doctors at Fox Chase aim the radiation therapy precisely at the same target or targets each and every time treatment is given. The process of measuring your anatomy and marking your skin to help your team direct the beams of radiation safely and exactly to their intended locations is called simulation. 
Read more about CT Simulators, MRI and PET Scans at Fox Chase.

During simulation, you are placed on the machine in the exact position you will be in during the actual treatment. Your radiation therapist marks the area to be treated directly on your skin or on immobilization devices.

Immobilization devices are molds, casts or headrests that are constructed and placed on a certain part of your body before each treatment to help you remain in the same position during the entire treatment. The radiation therapist marks your skin and/or the immobilization devices either with a bright, temporary paint or a set of small permanent tattoos.

A machine called a linear accelerator delivers your radiation treatment via several, invisible radiation beams. A sophisticated computer system takes information gathered from your treatment planning session (prior to treatment) and tells the linear accelerator how and where to deliver the radiation. The radiation beams are shaped by iron blocks, or plates, called multi leaf collimators, or MLC, found inside the head of linear accelerator. The MLC allows your doctor to shape the beams and precisely target your cancer while avoiding normal tissues.

Although simulation is typically only one session, your physician may schedule additional sessions depending on the type of cancer you have and the type of radiation therapy that is being used.

After simulation, your radiation oncologist and other team members review the results along with your previous medical tests to develop a treatment plan. Often, a special treatment planning CT scan (in addition to your diagnostic CT scan) is done to help with the simulation and treatment planning. Often, sophisticated treatment-planning computer software is used to help design the best possible treatment plan. After reviewing all of this information, your doctor writes a prescription that outlines the exact course of your radiation therapy treatment.

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