How Radiation Therapy Works

The photon beam used in radiation treatment is the same kind of beam used in ordinary chest x-rays or CT scans. However, it has much higher energy and can cause changes in the nucleus of cells. Both normal tissues and the tumor tissues will undergo these tiny breaks; however the normal cells will repair these changes better than tumor cells can. Patients will not feel the invisible beam passing through them. External Beam Radiation is a local treatment. It only works where we aim the beam. The radiation does not circulate through your body and your friends and family are not exposed to any radiation.

For some cancers, an implant is used to deliver the radiation therapy. In some gynecologic cancers, a radioactive source is placed within the vagina or uterus for a short time, to deliver highly localized radiation. A radioactive source may also be used to focally the cavity left after lumpectomy to remove a breast cancer.

Adverse effects vary from patient to patient and are determined by the location of the treatment, the dose required for treatment and the patients’ pre-existing condition. The radiation oncologist, nurse and therapist will discuss the likely side effects with each patient individually.

Every aspect of the patient’s care is given meticulous attention to ensure that the patient is treated efficiently and precisely and will experience the fewest possible side effects. Our physicists, dosimetrists and radiation therapists conduct daily, weekly and monthly checks on the department’s equipment to ensure optimum performance. The treatment team has weekly meetings where every patient’s treatment is reviewed and discussed in detail.

Targeted Personal Treatment

Radiation oncology at Torrance Memorial gives patients access to the most progressive cancer imaging, computer-aided planning and targeted treatments available. The precise delivery of treatment limits the exposure of healthy tissue to radiation and reduces side effects.

Typically, radiation treatments are applied daily for several minutes and are not painful. Normal courses of treatment range between 1 day to 7 weeks, depending on the type of cancer, the location in the body and the goal of the treatment. Radiation treatments can be prescribed as a stand-alone treatment, but are often in combination with other cancer treatments such as surgery, chemotherapy/biotherapy or hormonal therapy. While the treatments usually require no special preparation or fasting, it is recommended you wear comfortable clothing, as you will need to change in and out of a hospital gown as part of your treatment.


An initial consultation with a radiation oncologist is the first step in determining a radiation therapy plan for a patient. Normally two hours in length, the consult begins with a discussion with a radiation oncology nurse and completing a health questionnaire. You then meet with a radiation oncologist for a physical examination and assessment of your medical history.

At that time, the radiation oncologist reviews all imaging and pathology results to fully understand your specific disease. Should further testing be required, your appointment is coordinated with your other physicians.

Following these examinations, the radiation oncologist will discuss with you or a loved one how radiation therapy may fit in to the treatment of your individual case. This discussion includes the benefits of the therapy, as well as the potential adverse side effects you may encounter. It is at this point that the recommendation whether or not to proceed with radiation therapy is made.

Should you be a candidate for radiation treatments, a return appointment for a planning session, called "simulation," will typically be made within a few days of your consult. No radiation treatments are delivered at the time of consultation or the simulation.

Simulation and Planning

As radiation treatments are personalized to each individual, planning is necessary to tailor the dosage of radiation, treatment position, and treatment approach to your specific cancer site. We will also guide you through how the treatments will work once underway. This appointment - normally 45 minutes to 2 hours in length - works as a "simulation" of the actual therapy you will receive and insures the proper application of radiation to maximize its benefits and minimize side effects.

The first step of the planning appointment is to place you on a special treatment couch. If necessary an immobilizing device may be used to help you stay still, but as comfortable as possible during your treatments. A series of images will be taken. These may include CT, MRI or PET scans to pinpoint the location of your cancer. We use these computerized images to create a targeted radiation plan.

During this targeting planning, you may be asked to receive one or more tiny tattoos - less than the size of a pinhead. These permanent blue ink marks serve two very important purposes: they help assure accurate application of radiation for each visit during your treatment plan and create a fixed physical record of which area of your body received radiation. Should you require additional radiation therapy in the future, this can be very helpful information for your physicians.

Personalized Treatment

Torrance Memorial offers many state-of-the-art options in radiation technology combined with sophisticated planning and imaging equipment. These powerful and precise tools help physicians develop an individualized treatment plan. Each has a specific function to pinpoint the location of cancerous cells for treatment and provide the optimum dosage.

Specific treatments include:

  • Intensity Modulated Radiation Therapy (IMRT) - A highly advanced technique, IMRT delivers high doses of radiation to tumors while substantially reducing the risk to normal tissue. IMRT is a complex form of three-dimensional conformal radiation therapy and one of the most precise and sophisticated treatment techniques currently available. This relatively new technology is used effectively to treat many kinds of cancer, especially prostate cancer and cancers of the head and neck.
  • 3-D Conformal Radiation Therapy - 3-D conformal radiation therapy uses CT based treatment planning with three-dimensional rendering of the tumor and surrounding structures. This allows for very precise delivery of radiation doses and better avoidance of normal tissues.
  • Conventional External Beam Radiation Therapy - This radiation therapy technique uses a linear accelerator to deliver radiation treatments to somewhat larger treatment areas. CT based treatment planning is always used and every effort is made to exclude as much of the normal tissues from the treatment area as possible.
  • Partial Breast Brachytherapy - "Brachy" comes from the Greek word for "up close." This new method of internal partial breast radiation delivers radiation to the tissue surrounding the lumpectomy site and avoids radiation exposure to breast tissue not adjacent to the cancer. A precise dose of radiation therapy is delivered through a small tube to a highly localized portion of the breast over a one-week period, then the tube is removed. Patients who are candidates for post-lumpectomy brachytherapy are carefully chosen based on tumor characteristics.

Torrance Memorial also offers a computer-assisted merge of images from your CT, MRI and PET scans. Combining or "fusing" these images into a single master image gives physicians and therapists a better understanding of your tumor and its relationship to the surrounding tissue. This combination allows for even more precise treatment with less damage to healthy cells.

Start of Treatment

You can expect to receive your first radiation treatment about one week after your planning session. Treatments are typically given five days per week, Monday through Friday, except legal holidays. The radiation therapists will coordinate a treatment time that is convenient for you.

You will meet with a nurse before the start of treatment to discuss management of side effects that you might experience and education re: what to do to prepare for treatment. Each week during treatment you will meet with the radiation oncologist to assess how well you are tolerating the treatments, keep track of side effects, discuss ways to manage side effects and review your overall level of health.

The radiation therapists, in collaboration with the nurse, will provide on-going skin and side effect assessment and education throughout your course of treatment.


About three weeks following the completion of your radiation therapy treatment, you will meet with your radiation oncologist to discuss the initial impact of your treatment, and to help you manage any adverse effects of treatment. Other follow-up appointments will then be scheduled so that we can track your recovery and measure your response to treatment. All follow-up appointments are coordinated with your other oncology physicians.

Safety and Quality

Every aspect of your treatment planning and delivery is given meticulous attention