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Information Notice No. 84-62 Therapy Misadministrations to Patients Undergoing Cobalt-60 Teletherapy Treatments
SSINS No.: 6835 IN 84-62 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 August 10, 1984 Information Notice No. 84-62 THERAPY MISADMINISTRATIONS TO PATIENTS UNDERGOING COBALT-60 TELETHERAPY TREATMENTS Addressees: All NRC licensees authorized to possess and use sealed sources in teletherapy units. This information notice is intended to bring to the attention of medical licensees two recent therapy misadministration cases to patients undergoing teletherapy treatments. They illustrate what can happen when internal policies and procedures for checking dose calculations are not clear, and/or are not followed, by the licensee's personnel. Licensees are expected to review the information for applicability to their facilities and take actions, as appropriate. Suggestions contained in this notice do not constitute NRC requirements and, therefore, no specific action or written response is required. Description of Circumstances: In the first case, an NRC medical licensee who is authorized to use a cobalt-60 teletherapy unit has reported a therapy misadministration to a patient undergoing treatments for a brain tumor. The radiation therapy physician gave a written prescription of a total radiation dose of 6,000 rad to be delivered in fractions of 200 rad per day, 5 days per week for 6 weeks. The 200 rad per day were to be delivered to the central axis midplane of the head, equally divided between the right and left lateral portals. The dosimetrist reviewed the physician's prescription, but wrote down on the Physics Dose Calculations form a dose of 200 rad per treatment for each field rather than the desired 100 rad for each field. Beam on-time was calculated for 200 rad per field and, therefore, was twice the time needed for the prescribed dose. The licensee's radiation therapy technologists, typically, do not review the Physics Dose Calculations form. They refer to the Treatment Planning Chart before each treatment. In this instance, the treatment planning chart showed a beam on-time which would deliver 200 rad per field. Subsequent Treatment Planning Chart checks by department supervisors (chief therapy technologists) failed to find the error because these Treatment Planning Chart checks do not include review of the dose calculations form. Although the licensee has an internal procedure that requires all dose calculations to be checked for accuracy before the second treatment, the delegation of such responsibility, as to who is supposed to check for accuracy, was not 8408070376 . IN 84-62 August 10, 1984 Page 2 of 2 clearly described in the procedure. Consequently, the procedure was not implemented in this case. After 15 treatments at the elevated dose, the patient exhibited erythema. Because this reaction was not uncommon, the treating physician was not suspicious. To reduce patient discomfort, the physician reduced the prescribed dose to a total dose of a 150 rad per treatment. New exposure times were calculated by another dosimetrist who, continuing with the same Physics Dose Calculations form, repeated the original error and calculated times which would deliver 150 rad to each side of the patient's head. Again, no checks were made on the second set of calculations. Nine treatments were given at 150 rad per field until the patient exhibited severe reaction and the physician requested that exposure times be recalculated. The error was discovered and treatments were terminated. The patient had received a dose 45% higher than the prescribed dose, 15 treatments of 400 rad and 9 treatments of 300 rad (total of 8,700 rad) instead of the prescribed 30 treatments of 200 rad (total of 6,000 rad). In the second case, a therapy misadministration to a patient undergoing teletherapy treatments resulted from similar causes. After the patient received 16 of the scheduled 20 treatments, the error was, found during a review of the patient's treatment record by the attending physician. The patient received 6,400 rad instead of the prescribed total of 4,000 rad. The licensee plans to take corrective action by having the attending physician, who originally prescribed the dose, review the patient's treatments on a timely basis. Guidance: Even though there are no NRC requirements to have formal written procedures for prescribing and administering teletherapy doses, good practice indicates the desirability of establishing and implementing a written procedure to prevent future misadministrations of this type. The procedure should define the format of the dose prescription and the responsibility of the licensee's personnel to check dose calculations. If you have any questions regarding this matter, please contact the Administrator of the appropriate NRC regional office, or this office. J. Nelson Grace, Director Division of Quality Assurance, Safeguards and Inspection Procedures, IE Contact: H. Karagiannis (301) 492-9655 Attachment: List of Recently Issued IE Information Notices
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