Derived from the Greek word “brachy,” which means short or small, brachytherapy uses small radioactive isotopes or seeds placed in close proximity to the tumor to deliver radiation to targets either deep within the body (typically for gynecological and prostate cancers) or to a superficial surface such as the skin. This is accomplished by locating the radiation source near the tumor site for a brief period of time. Since the amount of radiation falls off significantly within a few centimeters of the source, the radiation is highly localized and exposure to adjacent normal tissues is limited.
Brachytherapy takes advantage of isotopes with different energies that are able to penetrate tissues to varying depths. Over the last decade, brachytherapy technique, treatment planning and delivery has become more sophisticated with advances in image guidance, as well as surgical and medical therapy.
Our brachytherapy program encompasses a wide variety of techniques and modalities for patients with cancer, as well as those with noncancerous proliferative diseases. Our gynecologic, prostate cancer and general brachytherapy programs routinely perform image-based brachytherapy application using real-time guidance via ultrasound, CT and/or MRI in a state-of-the-art surgical environment and brachytherapy procedure suite.
For those seeking a more detailed technical description of brachytherapy modalities, the following describes the techniques commonly performed at our institution:
Prostate brachytherapy is performed for patients with early, intermediate and high-risk disease with or without external beam radiotherapy. Treatment may be delivered with a permanent seed implant using a very low dose rate (vLDR) iodine or palladium source or a temporary implant using a high dose rate (HDR) technique with an iridium source. Seeds are typically implanted with ultrasound guidance and seed placement is confirmed by CT and/or MRI.
Gynecologic brachytherapy is commonly performed in the outpatient setting for patients with endometrial and cervical cancer. The vast majority of our patients are treated with brachytherapy, which uses an iridium seed that travels through an applicator for a treatment time that ranges from 5 to 15 minutes.
For patients treated with hysterectomy, vaginal cylinder brachytherapy with or without external beam radiotherapy may be recommended to reduce the risk of recurrence at the vaginal cuff. This outpatient treatment is delivered 2 days per week for a total of 2-6 treatments.
For patients who have not had a hysterectomy, tandem-based brachytherapy application is performed under general anesthesia. The total number of treatments may vary from 3-5, either as an outpatient (2 days per week), or inpatient (3-4 day hospitalization).
Select patients with gynecologic cancer may require interstitial brachytherapy, where the radiation oncologist places catheters directly within and surrounding a tumor. Interstitial brachytherapy is performed under image-guidance using a combination of ultrasound, CT and/or MRI. These procedures are performed under anesthesia and require an inpatient hospitalization. At the time of treatment, an iridium source is inserted through each individual catheter to deliver a highly conformal brachytherapy dose. Interstitial brachytherapy is given twice daily for a treatment time of 10-15 minutes.
Our department is constantly exploring innovative uses of advanced technologies to achieve improved patient outcomes. Here is one of the innovative protocols we are currently investigating with brachytherapy:
Optimizing Brachytherapy Delivery with MRI-Guidance for Gynecologic Cancer
Lead physician: Larissa Lee, MD
Lead physicist: Robert Cormack, PhD
Image-guided brachytherapy for gynecologic cancer offers significant potential to improve tumor control and increase cure rates. CT and MR-based brachytherapy planning also reduces the risk of bladder or bowel toxicity. With guidance via MRI at the time of the procedure, we are developing novel methods to track catheter placement and positioning for real-time evaluation of the HDR brachytherapy dose. We are also developing novel MRI sequences to identify residual tumor in collaboration with the Surgical Planning Laboratory within the Advanced Multimodality Image Guided Operating (AMIGO) suite.
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