| PET CANCER CENTER Comprehensive guide to cancer diagnosis and treatment in cats and dogs |
| Advancements in Veterinary Radiation Oncology at Angell Publications from as early as 1958 describe the use of radiation therapy in veterinary medicine. Radiation therapy uses high-energy ionizing radiation to kill cancer cells by damaging DNA, resulting in cell death or the inability to replicate. Radiation therapy is often used in conjunction with surgery and/or chemotherapy. Many advances in technology have occurred since 1958, both involving radiation delivery and imaging. Alongside our technologic changes, our understanding of medical physics, radiation and molecular biology of cancers have drastically improved. Present day treatments have the fundamental goal of delivering a tumorical dose of radiation therapy while sparing the adjacent normal, healthy tissues. With these advances, radiation oncology has made massive strides in designing state-of-the-art treatment plans for pets, many of which we use at Angell. These developments, along with technological improvements of radiation delivery units, have allowed for delivery of higher conformal doses while sparing the surrounding healthy tissues and structures, minimizing side effects. The diagnostic imaging advancements in clinical veterinary radiation oncology at Angell include the use of computed tomography (CT) and magnetic resonance imaging (MRI) for both tumor imaging and radiation treatment planning. Newer technologies in treatment delivery unique to Angell include Intensity Modulated Radiation Therapy (IMRT), an advanced form of high-precision radiation therapy that allows for the computer-controlled radiation dose to conform precisely to the shape of the tumor by modulating (adjusting) the intensity of the radiation beams. The radiation dose intensity is elevated at the tumor, while radiation among neighboring normal tissue is decreased or avoided completely. The customized radiation dose is intended to maximize the dose intended for the tumor while simultaneously protecting the surrounding normal tissue, reducing side effects. IMRT also improves the ability to conform the treatment to tumor shapes, for example when a tumor is wrapped around a vulnerable structure such as the spinal cord, a major organ, or blood vessel. The effect is that doses can be “wrapped” around or “painted” within tumors, far more precisely than was previously possible. In order to reap the benefits of IMRT, our team must be able to perform well-executed delivery of a prescribed radiation dose. The two key factors here are patient immobilization and real-time imaging to verify the patient is in the correct position. Immobilization that is reproducible is essential; there is no sense in an elaborate setup that cannot be reproduced or leaves room for error. Various devices are used to position the patient into position, such as dental molds and bite blocks. A bite block is a custom-made dental mold used to immobilize and position the patient during radiation therapy. Bite blocks are specific for certain tumors in the head/neck area - there are other immobilization and positioning devices and methods for tumors located in other areas of the body. To aid in the immobilization, general anesthesia is needed. The vascular access port, an implanted catheter device, can be used to administer anesthesia for radiation therapy, for chemotherapy drugs, or even for administering fluids. Angell is the only veterinary hospital in the Boston area that routinely uses this technique for radiation patients. Using these ports allows for shorter treatment sessions and greater patient comfort. It eliminates the need, time, and discomfort involved for daily catheter placement and consequently eliminates the need for sedation. Clients are frequently happy to take their pet home following radiation treatments without the after-effects of sedation. We use the vascular access ports for all of our patients receiving full course radiation, including IMRT. Used for both cats and dogs, it is a great benefit for cats with small veins for whom placing an IV catheter can be difficult. Tumor types that can be effectively treated with radiation therapy include: oral, nasal, brain, pituitary and spinal cord, bladder and prostate, soft-tissue sarcoma, mast cell tumor, melanoma, osteosarcoma, and lymphoma. Consultation with a veterinary oncologist is the first step in designing such a tailored protocol for your pet. For more information about Angell Animal Medical Center’s Oncology service, please visit angell.org/oncology. Our oncology team, Lyndsay Kubicek, DVM, DACVR (Radiation Oncology), and Ivan Martinez, DVM, DACVIM (Oncology and Internal Medicine), are available for consultation via phone or e-mail (oncology@angell.org). To contact the Angell oncology team by phone or to refer a patient, please call 617 541-5136. |
Last updated 1/22/2015