Radiation 101: Top 10 patient and provider Q&A

Shea Liu Contributor

Dr. Shea Liu is currently medical physicist and assistant professor working at Memorial Sloan Kettering Cancer Center. Dr. Liu has solid clinical skills as well as rich research experience on a wide variety of radiotherapy treatments. He obtained his PhD in Optics at University College Dublin, Ireland, and did postdoctoral research on health informatics and machine learning in radiation oncology at Washington University St. Louis. His medical physics resident experience at Stanford University pushed him further to become the expert in this field.
What is radiation therapy?
A   type of cancer treatment that is used to shrink tumors and stop the growth of cancer cells. Radiotherapy is very effective in treating some types of cancer that in fact, nearly two-thirds of patients will receive radiation therapy, according to American Society for Radiation Oncology (ASTRO).

Radiotherapy can be used as a stand-alone treatment, and often it is used in combination with surgery, chemotherapy, targeted therapy, etc. For example, prostate and larynx cancer are often treated with radiotherapy alone, while a woman with breast cancer may be treated with surgery, radiation therapy and chemotherapy.
Why radiation?
Radiation therapy is often used to cure cancer, and sometimes also to reduce the symptoms, and therefore improve a patient’s quality of life. For instance, it can shrink a lung tumor that is causing shortness of breath. It will also reduce the risk that cancer will return after surgery or chemotherapy to control the growth of remaining cancer cells.
How is radiation delivered?
D epending on the location, size and type of cancer, you may receive one or a combination of techniques. There are 2 primary types of delivery:

1) External beam radiation: using high-energy specialized machine to deliver the prescribed dose directly at the cancerous cells.

2) Brachytherapy:implanting radioactive material into the body at the local treated site.
Does radiation therapy hurt?
I t does not hurt while being treated, and you will not become radioactive from the treatments either.
Is radiation safe?
R adiation has been used successfully to treat patients for more than 100 years. In that time, many advances have been made to ensure that radiation therapy is safe and effective. The prescribed dose is delivered precisely to the tumor while sparing healthy tissue around it and minimize side effects. For example, for breast cancer patients, to avoid introducing radiation dose into the lung and heart, a set of treatment beam angles were carefully chosen for each patient.
What to expect for a complete course of radiation therapy?
G enerally, a patient will go through: referral, consultation, simulation, treatment planning, treatment delivery, and follow-ups.
What are the types of radiation therapy equipment?
T he type of equipment used will depend on the location, size and type of cancer. Here is a list of some common types of radiation therapy:

1. Three-dimensional conformal radiation therapy (3D-CRT)

This is a technique where beams of radiation used in treatment are shaped to match the tumor and are delivered accurately from several directions.

2. Intensity modulated radiation therapy (IMRT)

A form of 3D CRT in which the physician designated specific doses of radiation that the tumor and normal surrounding tissues receive. It allows radiation to be more exactly shaped to fit the tumor.

3. Proton therapy

A type of radiation therapy that uses high-energy protons rather than photons (x-rays) to treat certain types of cancer. The physical characteristics of the proton therapy beam may allow doctors to more effectively reduce the radiation dose to nearby healthy tissue. Most commonly used in the treatment of pediatric, CNS and intraocular cancers.

4. Stereotactic Body Radiotherapy (SBRT) or Stereotactic Radiosurgery (SRS)

A specialized form of radiation therapy that focuses high-power energy on a small area of the body. Despite its name, radiosurgery is a treatment, not a surgical procedure. Radiosurgery generally implies a single high dose or just a few high dose treatments.

5. Brachytherapy

Radioactive material is placed into or close to the tumor. In this way large prescribed doses can damage the cancer cells and it allows minimal radiation exposure to normal tissue. Radioactive sources used are normally thin wires, ribbons, capsules or seeds. These can be either permanently or temporarily placed in the body
Are there side effects, and what are they?
S ome patients experience few side effects from radiation therapy or even non. Others, side effects may occur because the radiation used to destroy cancer cells can also damage healthy cells and tissues located near the treatment area.

The occurrence and probability of side effects depend on the type and location of radiation therapy, and of course depend on individual patient. Common side effects include: skin reactions, fatigue, diarrhea, fatigue, hair loss, mouth and throat changes, nausea and vomiting, sexuality and fertility in men and women, etc2. Side effects may last for several weeks after the final day of treatment, or even longer.
Who is the radiotherapy team?
T he radiation therapy team includes:

Radiation oncologists (physicians)

Dosimetrists (treatment planning)

Physicists (quality assurance and machine calibration)

Therapists (treatment delivery)


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