The Oregon Clinic - Radiation Oncology - Portland & Clackamas

Oncology: Radiation


The Oregon Clinic - Radiation Oncology offers a team-oriented approach combined with the latest technological advances to provide the most effective treatment plan available to patients with cancer. We work closely with surgeons, medical oncologists and primary care physicians to help our patients understand their disease and support them throughout their treatment.

We do our utmost to create an atmosphere that communicates this spirit to our patients and their families.

Radiation Oncology is the use of high-energy rays to stop cancer cells from growing and dividing. Like surgery, radiation oncology is a local treatment. It affects cancer cells only in the treated area. Radiation can come from a machine (external radiation), and can also come from an implant (a small container of radioactive material) placed directly into or near the tumor (internal radiation or brachytherapy). Some patients receive both kinds of radiation therapy.

  Latest News

Dr. Eric Hansen & Dr. Stephen Bader announced as Portland Monthly Magazine 2016 Top Doctors
Portland Monthly invited every licensed doctor, physician assistant, and registered nurse in Multnomah, Washington, and Clackamas Counties (more than 20,000 practitioners) to nominate up to three peers in any medical specialty.

After all the nominations were tallied, Portland Monthly narrowed the list to the top 5 percent of vote getters in each field. Read more.

  Press Releases
  Referring Physicians

Refer a Patient:

For referrals from a hospital location, please be aware that we are not set up to accept referrals electronically through EPIC; please call us directly (using the list of our office locations to the right) for immediate and personalized service.

Physician Resources:

An Overview of Radiation Therapy for Health Care Professionals
Provided by the American Society for Radiation Oncology (ASTRO)


The Oregon Clinic – Radiation Oncology offers a comprehensive approach to cancer care with a wide range of world-class cancer therapy modalities implemented by a multidisciplinary team of experts. Our extraordinary team, coupled with state-of-the-art technology, creates the environment for superior treatment outcomes for cancer patients. Our physicians and staff are dedicated to delivering compassionate care for our patients while offering support to their families; patient-centered care is our philosophy. 

Meet Our Providers:

Areas of Focus:
Prostate Cancer, Stereotactic Radiosurgery using the Gamma Knife, Breast Cancer, Gastrointestinal Cancer, Head & Neck Malignancies
Areas of Focus:
Brain Cancer, Gastrointestinal Cancer, Head & Neck Cancer, Lung Cancer, Immunotherapy
Areas of Focus:
Benign & Malignant Diseases of the Central Nervous System, Breast Cancer, including Accelerated Partial Breast Irradiation, Image Guided Intensity Modulated Radiation Therapy (IGRT/IMRT), Prostate Cancer, Gamma Knife Stereotactic Radiosurgery
Areas of Focus:
Image-guided Intensity Modulated Radiotherapy (IGRT/IMRT), Stereotactic Radiosurgery (Gammaknife), Stereostatic Ablative Body Radiotherapy (SBRT/SABR), High Dose Rate (HDR) Brachytherapy, 3D Conformal Radiotherapy
Areas of Focus:
Head & Neck Cancer, Prostate Cancer, Breast Cancer, Lung Cancer, CNS malignancies
Areas of Focus:
Breast Cancer, Lung Cancer, Gastrointestinal Cancer, Gynecologic Cancers, Soft Tissue Cancers
Areas of Focus:
Benign & Malignant Diseases of the Central Nervous System, Gamma Knife Stereotactic Radiosurgery, Head & Neck Malignancies, Lung Cancer, Stereotactic Body Radiation Therapy (SBRT)
Areas of Focus:
Gamma Knife Stereotactic Radiosurgery, Gastrointestinal Cancer, Image Guided Intensity Modulated Radiation Therapy (IGRT/IMRT), Stereotactic Body Radiation Therapy (SBRT), Lung Cancer
Areas of Focus:
Breast Cancer, including Deep Inspiration Breath Hold technique, Accelerated Partial Breast Irradiation, Gastrointestinal Cancer, Gynecologic Cancer, including High Dose Rate Brachytherapy, Head & Neck Cancer, Brain Tumors, including Stereotactic Radiosurgery
Areas of Focus:
Breast Cancers, Gastrointestinal Cancers, Head & Neck Cancers, Lung Cancers, Stereotactic Body Radiation Therapy (SBRT)


Procedures Offered:

  • Gamma Knife Stereotactic Radiosurgery
  • Stereotactic Body Radiation Therapy (SBRT)
  • HDR Brachytherapy & LDR Brachytherapy
  • Accelerated Partial Breast Irradiation (APBI)
  • Intensity Modulated Radiation Therapy (IMRT)
  • Image-Guided Radiation Therapy (IGRT)
  • Iodine-125 Eyeplaque Treatment for Ocular Melanoma
  • Intraoperative Radiation Therapy (IORT)
  • Total Skin Electron Radiotherapy
  • Respiratory Motion Management (4DCT)
  • Total Body Irradiation (TBI)
  • Deep Inspiration Breath Hold (DIBH) technique for Breast Cancer Treatment


An Introduction to Radiation Therapy: Radiation Therapy for Breast Cancer:
Radiation Therapy for Prostate Cancer:  



Below you will find answers to common patient questions, answered by our board-certified team of radiation oncologists.

What radioactive substance is used for brachytherapy?

Iridium-192 is an isotope of Iridium which has a ½ life of 74 days. For treatment, the source is deployed from a small machine about the size of a college dorm refrigerator. Iridium-192 emits gamma rays with an average energy of 380KeV, which results in limited penetration in the body away from the treated area. Most brachytherapy treatments with Iridium-192 are used for breast, uterine, and cervical cancer in our departments.

Does treatment hurt?

No. Although the table on the machine may be hard and uncomfortable to lie on for prolonged periods, radiation treatments do not cause pain. If you experience pain during treatment, the radiation can be stopped so that the medical team can evaluate the situation and make adjustments if necessary.

Why does radiation kill cancer cells better than normal cells?

It turns out that our body’s normal cells have a good mechanism for radiation repair from exposure from ultraviolet radiation from space and ionizing radiation from the earth. Most cancer cells are putting all of their energy into cell division and are generally not good at repairing damage to DNA from radiation. Therefore, radiation preferentially affects cancer cells instead of the body’s normal cells.

Who administers my treatment?

Your radiation treatments will be given under your radiation oncologist’s supervision by radiation therapists. Radiation therapists are trained professionals who are licensed by the state to deliver radiation therapy safely and accurately. It is actually not legal for your doctor to operate the radiation machine to deliver your treatment.

Do I wear any shielding (such as a lead apron that is used at the dentist)?

No. The type of radiation produced by our linear accelerators is powerful enough to penetrate lead up to an inch or two thick. Wearing a lead apron would not protect you and would slightly increase the dose received by the skin in the treatment area. The risk of developing a cancer related to radiation therapy is typically very low (well under 1%) for most patients.

How many treatments will I receive? How often?

Nearly all treatments are delivered five days a week (Monday-Friday). There are some situations where treatment is not delivered on a daily basis, but this is not common. Typical treatment courses last between two and eight weeks, however some situations may require as few as one treatment. Your doctor will provide you with information regarding the best treatment schedule based on your specific situation.

What is simulation?

Simulation is an important process where your radiation treatment position will be established and images of your body will be obtained for treatment planning. Most patients have a CT scan (low radiation dose protocol, no contrast in the bloodstream in most cases) performed in our department as part of this process. The information from the simulation process is used to create a unique three-dimensional treatment plan based on your specific anatomy and treatment location. Small tattoos are placed on the skin at this time to ensure reproducible and accurate positioning on a daily basis for radiation treatment.

Why do I have to have another CT scan before starting radiation?

Most patients have a CT before starting radiation treatments as part of the simulation procedure. The scan utilizes a low radiation dose protocol and often does not involve contrast in the bloodstream. Another scan is obtained as the body’s position for radiation treatment is different than the position for diagnostic scans. Also, the radiation oncologist is present during this procedure to assist with your positioning and any other procedures necessary for planning your course of radiation.

Do I need to have blood tests during radiation?

In most cases, you do not need to have routine blood work during radiation therapy. Radiation can inhibit bone marrow function (mostly located in the spine and pelvis in adults) which may reduce the number of red cells, white cells, and platelets in cases where a moderate amount of bone marrow is in the radiation fields. Your radiation oncologist will help you monitor your blood counts if needed.

What side effects can I expect?

The side effects of radiation depend on the treatment site. In most cases, the side effects will be limited to the area of the body receiving treatment. Most patients can expect mild to moderate fatigue which resolves within 4-6 weeks of completing treatment. Skin reaction consists of redness, itching, and dry peeling in many cases with the chance of a radiation burn (blistering or moist peeling of the skin) of less than 15% in most cases. Your doctor will describe expected side effects in your case based on your treatment type and area of the body receiving radiation treatments.

When will I see the doctor during treatment?

You will meet with the radiation oncologist at least once per week during treatment. This usually consists of a short visit immediately after your treatment on a weekly basis and does not require a separate appointment. Although not required by law, our policy is that a physician is in the department whenever radiation therapy treatments are delivered. Your doctor or one of his/her partners is available to see you on any day during the week; just let our staff know if you have any questions or concerns.

What about my medications or supplements?

In most cases, there is not an interaction between most drugs or supplements and radiation therapy. Chemotherapy agents are an important exception and your radiation oncologist will work closely with your chemotherapy doctor in cases where chemotherapy and radiation are given at the same time.  Your doctor will need to have a complete list of all of your medications and supplements so you can be informed of any potential interactions. If you start or stop a medication or supplement during treatment, please let your radiation oncologist or nurse know so that we can keep your medication record up to date and provide you with advice if needed.

What about my medications or supplements?

Most radiation treatments are delivered in less than five minutes once you are set up in the exact treatment position. You are monitored (audio and visual) during treatment and the radiation treatments are designed to take into account normal breathing and swallowing during this time. If you are having pain or difficulty during treatment, the therapists will be able to recognize this and interrupt your treatment to provide assistance if needed.

What is “cone beam CT”?

Cone beam CT is a type of image guidance where the radiation machine will spin around you one to two times before your treatment is delivered. Images (similar to CT images) are produced and reviewed by your doctor at the control panel just before treatment is delivered. This allows for fine tuning of the aim of the radiation beams for your treatment on a daily basis by the physician and results in more accurate delivery when additional precision is necessary in some treatment cases (typically used for head and neck and prostate cancer treatment).

Why does my doctor want to wait 1-2 months before getting a scan to assess my response to radiation?

Radiation therapy works by causing mutations in the cell’s DNA. Fortunately, our normal cells are quite good at repairing damage to DNA while cancer cells are not good at this process. Treated cancer cells do not die immediately; the damage to their DNA causes the cell to die the next time it tries to divide. Therefore, it can be several weeks between treatment and when a response would be expected. If your physician is concerned about growth of disease or other symptoms, he/she will obtain imaging (if indicated) at that time to help to determine the best course of treatment or intervention.

Where can I get more information about radiation therapy or cancer in general?

There is excellent, comprehensive, easy to understand information available from The American Cancer Society (, The National Cancer Institute (, and The American Society of Clinical Oncology ( Detailed information and videos about radiation therapy can be found from the American Society for Radiation Oncology ( Your radiation oncologist can be helpful with any questions or by helping you research specific topics as well.

Patient Resources

Trying to understand the implications of a diagnosis of cancer can be overwhelming and frightening. The list of excellent third-party websites below provide comprehensive and clear, unbiased information regarding a variety of cancers and common treatment options. Please feel free to discuss any information you learn online with your physician:

* is the patient website for the American Society for Radiation Oncology previously known as ASTRO.  This is an excellent resource for patients and caregivers to find detailed information about radiation therapy including what to expect before, during and after treatment, questions for patients to ask about radiation safety, and a dictionary to help patients understand the terms they will hear.  In addition, ASTRO’s patient information brochures are available for download on the website and are optimized for viewing on mobile devices.


The Choosing Wisely campaign was initiated by the American Board of Internal Medicine in 2012 and now there are 70 participating specialty societies with combined lists of over 400 recommendations to reduce the amount of overused or unnecessary tests, treatments and procedures. The campaign has also been adopted in 11 other countries including Australia, Canada, New Zealand, and Italy. The work of the campaign continues with additional health systems receiving funding through the Robert Wood Johnson Foundation later this year to reduce overuse of unnecessary tests in their communities. The recommendations for radiation oncology are listed below:

Ten Things Physicians and Patients Should Question
Choosing Wisely - An initiative of the ABIM Foundation
Provided by the American Society for Radiation Oncology (ASTRO)

This document outlines ten things that radiation oncology patients should think about discussing with their physicians.

Ask Your Doctor - Questions about radiation for cancer
ConsumerReports Health
Provided by the American Society for Radiation Oncology (ASTRO)

This document outlines common questions about radiation oncology. Your radiation oncologist would be happy to answer questions specific to you.

Understanding Radiation Therapy
For Patients, Care Givers and the General Public
Provided by the American Society for Radiation Oncology (ASTRO)