Radiation Oncology

Whenever radiation therapy is planned for a pet with cancer, maintaining the quality of life and freedom from discomfort are our highest goals.

Because not every treatment modality is right for every patient, each plan is individualized.

Our Radiation Oncology team works with your family and your referring veterinarian to ensure your pet is as comfortable as possible while undergoing radiation treatments and any side effects are managed. We make it a priority to address any questions or concerns as they arise. 

We offer two types of stereotactic radiation therapy (SRT). The TrueBeam radiotherapy takes place at our Carlsbad hospital. We also have access to a partner facility that delivers SRT with the Cyberknife Radiosurgery System.

Each case is individually reviewed by our radiation oncologist to determine the best approach for caring for your pet.

Radiotherapy does not make your pet radioactive and is similar to the process of getting a chest or dental x-ray or radiograph.

During each treatment, your pet will be placed under a light level of anesthesia. Radiation therapy beams will be used to safely and precisely target the tumor while sparing healthy, normal tissue. The radiation oncologist will determine the appropriate dosage and number of treatments to ensure the best outcome possible.

When radiation is used with the intent of eliminating or controlling cancer for a long period of time this is referred to as definitive treatment. Depending on tumor size, location, and other factors the definitive treatment course may be as minimal as three to five treatments while other cases may require 16  to 19  treatments.  

Palliative treatment is when radiation is utilized to improve the quality of life, ease pain, and potentially decrease tumor size to help with the comfort of the patient. A palliative course of radiation is administered over one to five treatments.

Definitive Radiation Therapy:
Definitive radiation therapy is used to treat tumors with the intent of providing long-term disease control for the patient. Given the larger doses administered, this treatment requires breaking up the treatment into multiple smaller doses to reduce the risk of causing long-term side effects. Typically, this treatment will entail the delivery of anywhere between 16 to 19 treatments which are administered daily on a Monday through Friday basis. Using our advanced equipment, and depending on the individual patient, treatment may be delivered in as little as three to five doses by using Stereotactic Radiotherapy. Each case is individually reviewed by our radiation oncologist to determine the best approach for caring for your pet.

Stereotactic Radiotherapy (SRS/SRT):

SRS/SRT is a more advanced type of definitive therapy for patients with certain types of tumors. It is designed to treat tumors throughout the body non-invasively. It provides a pain-free, non-surgical option for patients who have inoperable or surgically complex tumors, or who may be looking for an alternative to surgery.

As with definitive radiation therapy, the objective of SRS/SRT is long-term disease control. The higher degree of precision attained with SRS/SRT allows for the delivery of higher doses of radiation without causing increased side effects. Most SRS/SRT treatments are administered over a period of three to five days.

Our Carlsbad location offers in house SRT treatment with our TrueBeam radiotherapy system. We also have access to a partner facilty that delivers SRT with the Cyberknife Radiosurgery System. Each case is individually reviewed by our radiation oncologist to determine the best approach for caring for your pet.

Palliative Radiation Therapy:

Palliative radiation therapy has a primary goal of reducing the discomfort caused by many tumors. Tumors frequently cause discomfort for patients due to its encroachment on surrounding tissues, inflammation and destruction of bone. This discomfort will frequently result in a diminished quality of life for cancer patients. The goal of palliative radiation is to improve a patient’s quality of life by reducing tumor-associated pain, inflammation and, in some cases, reduce the size of the tumor. Additionally, the intent is to deliver this treatment with minimal side effects. This goal is achieved by delivering lower doses of radiation than those delivered with a definitive course of radiation therapy. A typical palliative radiation treatment course would consist of 2 to 5 treatments over a relatively short period.

Before the procedure, the patient is imaged using a high-resolution CT scan, to determine the size, shape, and location of the tumor.  A treatment plan is then generated to match the desired radiation dose to the identified tumor location while limiting radiation exposure to the surrounding healthy tissue.

Once the treatment plan has been developed, the patient is ready to undergo the procedure. The treatment is delivered in house at our Carlsbad hospital. The advanced imaging capabilities allow us to provide the most advanced radiation therapy for the elimination of tumors while sparing healthy tissue.  The radiotherapy treatment is delivered from various angles for precision. Each treatment typically lasts for a few minutes.

TrueBeam is an advanced medical linear accelerator that uses photon or electron beams to target cancerous tumors precisely and accurately. It has built in imaging capabilities to pinpoint the location of a tumor prior to and during treatment, guiding the system to deliver treatment accurately.

TrueBeam employs a device called a multileaf collimator (MLC), a device with 120 computer-controlled mechanical “leaves” or “fingers” that shift as the machine rotates around the patient to change the shape of the beam to match the shape of the tumor. This helps maximize dose to the tumor and minimize dose to nearby healthy tissue.

Cyberknife Robotic Radiosurgery System:

Before the procedure, the patient is imaged using a high-resolution CT scan, to determine the size, shape, and location of the tumor.  A treatment plan is then generated to match the desired radiation dose to the identified tumor location while limiting radiation exposure to the surrounding healthy tissue.

Once the treatment plan has been developed, the patient is ready to undergo the procedure. The treatment is delivered at our partner facility. 

The CyberKnife System’s computer-controlled robot will slowly move around the patient to the various locations from which it will deliver radiation to the tumor.

Each treatment session will last between 20 and 40 minutes, depending on the type of tumor being treated. 

Dr. David Proulx discusses Cyberknife on KUSI- Video

The goals of palliative radiation treatment include improving the quality of life for many patients without causing significant side effects.

In the course of definitive or curative radiation treatment, some surrounding normal tissue will be affected. Radiation-induced effects on normal tissues usually do not begin until the end of the therapy period, and they continue for 2-3 weeks after the treatment has ended. These are called the acute side effects, and they usually resolve within weeks after radiation has been completed. Other adverse effects associated with radiation therapy may occur months or years after radiation is complete. These are called delayed adverse effects. Interestingly, the adverse effects associated with radiation therapy are much less in pets than in most other species, including people. Indeed, the majority of these adverse effects are mild and self-limiting. We will work with you to ensure that your pet is as comfortable as possible during this 1 to 3 week period when adverse effects are noted.

Not all types of radiation are suitable for each patient. A combination of your pet’s individual circumstances (age, tumor type, tumor location, stage of disease) and your family’s goals will help to determine which treatment is best for your pet. Our radiation oncologist is available to discuss these factors further with you.

A primary care veterinarian treats a broad variety of animals and conditions. Veterinary specialists, however, must complete an internship, a two to four-year specialized residency, publish a paper in a peer-reviewed journal, in addition to receiving their veterinary degree. Specialists must also undergo a series of rigorous examinations based on knowledge and skill in the given specialty.

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