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Image-Guided Radiotherapy—A Case Study

US Oncology Review, 2005;1(1):62-4 DOI: http://doi.org/10.17925/OHR.2005.00.00.62

Abstract:

Curing patients of cancer requires a constant commitment on many levels in a healthcare system. To ensure top-notch patient treatment, St Agnes has invested in the latest technology available. The radiation oncology group complements this sophisticated technology with university-level leadership and experience. This site highlights the latest and greatest in radiation therapies for the treatment of all types of cancers, as well as the people behind the equipment.

Advanced Technology in Cancer Care
Improved cure rates for different types of cancers are the result of advances in surgery, chemotherapy, and radiation therapy.A majority of cancer patients receive radiation therapy as part of their overall course of treatment. Radiation therapy may be in the form of external beam irradiation, using powerful X-ray (electron, photon) machines called linear accelerators, or by placement of radioactive sources inside the tumor, a technique called brachytherapy.

Over the past decade, improvements in computers and networking, radiotherapy treatment planning software, and medical imaging modalities computerized tomography (CT), magnetic resonance imaging (MRI), ultrasound (US), and positron emission tomography (PET) have been incorporated into radiotherapy practice. This has lead to the development of image-guided radiotherapy radiotherapy that uses cross-sectional images of the patient s internal anatomy to better target the radiation dose in the tumor while reducing the radiation exposure of healthy organs. Image guidance leads to improved control of the tumor while simultaneously reducing the potential for acute side effects due to irradiation of healthy tissue surrounding the tumor.

Advanced technologies are currently in use in the St Agnes Cancer Center that enable image-guided radiotherapy treatments.These technologies represent a continuum of advances allowing sophisticated treatments available only in select centers across the nation.

Image-guided Prostate Brachytherapy
Prostate cancer is the most commonly occurring cancer in men today, second only to lung cancer as a cause of cancer-related death in men. The use of the prostate-specific antigen (PSA) test has lead to earlier detection of prostate cancer, resulting in a greater number of candidates for prostate brachytherapy , or radioactive seed implantation.

Brachytherapy is the placing of rice-sized, radioactive pellets, or seeds, directly into the prostate using needles guided by realtime transrectal US imaging. The optimal number and location of the seeds are determined in the operating room by the oncologist using specialized treatment planning software. Typically, rows of seeds are deposited uniformly throughout the prostate so that the radiation can cover the entire gland. The metallic seeds emit lowenergy radiation that is highly absorbed in the prostate gland close to the seed. With the correct placement of seeds, a very high dose of radiation can be given throughout the prostate gland with little exposure of the healthy tissue and organs surrounding the prostate. Radiation is gradually emitted from the seeds over a period of six to 12 months, after which they become completely inert and can safely remain in the prostate for the rest of the patient s life. The procedure is well-tolerated by most men, with typically no long-term side effects.