Using intraoperative radiation therapy—a case study - Clinical

AORN Journal, Feb, 2003 by Mary Ann Domanovic, Malika Ouzidane, Rod J. Ellis, Timothy J. Kinsella, A. Sam Beddar

Intraoperative radiation therapy (IORT) is the delivery of radiation therapy during a surgical procedure. A linear accelerator that produces high-energy electron beams is used to deliver precise, highly concentrated doses of radiation directly to the tumor site while avoiding adjacent normal tissues. A single dose delivered in one treatment during a surgical procedure is equivalent to several weeks of daily radiation therapy treatments. (1) An IORT treatment can deliver a single high dose of radiation to a tumor or tumor bed after surgical resection or surgical exposure of high risk areas. These high doses of radiation are delivered to the target while normal structures are kept out of the radiation field.

The availability of a mobile linear accelerator in the OR has made IORT more accessible to larger medical centers and easier to deliver to patients with various types of cancer. Treatment can be accomplished in any OR suite, using standard physics and techniques for measuring radiation doses. In addition, this method does not require additional shielding, which may make it more cost effective. High standards for patient and staff member safety are maintained, and flexibility and efficient use of the OR are increased. The use of IORT means that patients do not have to be transported from the OR to the radiation oncology department for treatment, which helps avoid possible anesthetic complications and wound infection.

PERIOPERATIVE CARE FOR PATIENTS UNDERGOING IORT

Preoperative care for patients undergoing IORT is performed by two different teams. The nursing team assesses and prepares the patient as the physics team prepares the mobile linear electron accelerator (Figure 1), which is composed of three separate units--control console, modulator, and therapy module. (2) The mobile linear electron accelerator is moved to the OR and set up by the radiation oncology therapist the night before surgery. The console is placed outside the OR because the radiation treatment delivery is controlled remotely from outside the room. (3)

[FIGURE 1 OMITTED]

A morning quality assurance test also is performed. The dose rate output of the accelerator is measured for all energies (ie, 4, 6, 9, 12 MeV). (4) The measured dose rate output is used by the medical physicist to calculate the amount of radiation to be delivered to the patient according to the total dose prescribed by the radiation oncologist intraoperatively after the tumor bed is exposed.

The circulating nurse performs the preoperative assessment. He or she verifies the patient's identity, informed consent, history, laboratory results, and NPO status. The nurse also answers the patient's questions and provides him or her with support and reassurance.

The IORT nurse, who coordinates the IORT procedures in the OR and helps the circulating nurse as needed, checks and verifies that the necessary sterile and nonsterile IORT supplies are readily available. (5) He or she starts documentation on the nursing IORT checklist, (6) and then helps plan patient positioning based on the height and location of the tumor.

The docking procedure for the mobile linear electron accelerator comprises moving the OR bed toward the mobile linear accelerator and precisely aligning the aluminum alloy cone that directs the electron beam to the treatment area under the treatment head. This is accomplished via a coordinated team effort involving the anesthesia care provider, the nursing team, the radiation oncology team, and the surgical team. All the tubes and cords (eg, suction, electrocautery) are disconnected from the sterile field to facilitate moving the OR bed. This process is done slowly and carefully to maintain sterility and to prevent patient injury. The patient's position and the location of the cone applicator are reassessed after this transfer to ensure they have not moved.

CASE STUDY

Mr T is a 68-year-old Caucasian male with recurrent adenocarcinoma of the sigmoid colon at the previous anastomosis. His complaint of dizziness sent him to the hospital about one year ago. He was found to be anemic. A colonoscopy performed the next day showed a left side colon mass consistent with invasive, moderately differentiated adenocarcinoma.

Mr T underwent surgical resection and postoperative chemotherapy for what was a 5.5-cm invasive, moderately differentiated adenocarcinoma. The lymph nodes were negative for cancer. Pelvic radiotherapy at that time was not indicated as the lesion was above the peritoneal reflection.

Two months later, Mr T developed recurrence of the tumor at the anastomosis and underwent a second resection. Wide margins of resection were obtained. Further postoperative treatment was not recommended; however, a repeat colonoscopy eight months later resulted in a biopsy that confirmed invasive, moderately differentiated adenocarcinoma, again at the anastomosis.

Mr T had postoperative complications after the previous resection and damage to the left ureter, which required him to undergo a nephrectomy on the left side. Now, in addition to a colon resection, Mr T would undergo IORT. No preoperative radiation treatment was given.