Internal Radiation (Brachytherapy)
Internal radiation therapy or brachytherapy (close-up therapy) refers to treatment delivered with the use of radioactive sources or seeds, which are inserted into a natural body cavity or implanted into soft tissue. Gynecologic implants for endometrial and cervical cancer are examples of brachytherapy. Some people may receive this type of treatment combined with external beam radiation. The advantage of brachytherapy is that the radiation dose is "concentrated in the tumor" and falls off rapidly as the distance from the tumor increases.
The common types of brachytherapy used at the St. Peter's Cancer Care Center are:
High-Dose-Rate (HDR) Brachytherapy
High-Dose Rate (HDR) Brachytherapy is a more effective way of providing the radiation therapy used to treat gynecological cancers, as well as bronchial and tracheal tumors. The radiation source is placed directly into the cancerous area. The radiation is delivered quickly and the actual treatment time is usually less than 15 minutes. In the past, low-dose rate (LDR) brachytherapy required inpatient hospitalization in a specially shielded room.
Ring and Tandem for Treatment of Gynecologic Malignancies
Brachytherapy for early stage cervical cancer is delivered using an applicator called a tandem and rings, which are round hollow metal holders that are placed adjacent to cervix. Prior to the first treatment is the intraoperative placement of a sleeve, a hollow plastic tube, custom-fitted to the patient's uterine cavity. The sleeve is inserted through the cervical opening into the uterus and sutured in place onto the cervix. This sleeve stays in the uterus for the duration of the treatments. The purpose of the sleeve is to keep the cervix open, allowing for comfortable, reproducible positioning of the tandem. The tandem is a hollow metal tube that is inserted into the sleeve. The ring is positioned around the cervix, and there are shields in the apparatus to reduce the radiation exposure to the bladder and rectum. After placement of the applicator, special X-ray images are taken for treatment plan calculations. After the treatment plan has been approved by the physician, the treatment is given. Following each treatment, the ring and tandem are removed. Generally, five treatments are given once a week. After the final treatment, the sleeve is removed.
Vaginal Cylinder for Treatment of Gynecologic Malignancies
Following a hysterectomy for endometrial (uterine) cancer, postoperative brachytherapy may be required. Treatment is delivered with brachytherapy to the upper vaginal area, which is at high risk for recurrence. A vaginal cylinder is a smooth, plastic cylinder, measuring about one inch in diameter, with a single channel where the radioactive source can travel. During this procedure, the physician inserts the cylinder and secures it in position. Then, a CT scan is done to show the cylinder in relationship to the surrounding organs. A computerized treatment plan is created, using these images, to treat the areas at risk to the prescribed doses, while sparing the nearby healthy tissue from excessive radiation. After the plan is reviewed and approved by the physician, the treatment given. The radioactive source travels in and out of the cylinder, delivering the radiation dose accordingly. The source is inside of the patient for approximately 10 to 15 minutes. After the treatment, the vaginal cylinder is removed.