Information Notice 2001-08s1: Supplement 1:Update on the Investigation of Patient Deaths in Panama, Following Radiation Therapy Overexposures

WASHINGTON, D.C. 20555-0001

June 6, 2001



All medical licensees.


The U.S. Nuclear Regulatory Commission (NRC) is issuing this supplement to information notice (IN) 2001-08, to inform addressees of the preliminary findings from the International Atomic Energy Agency (IAEA) investigation of patient overdoses received during radiation therapy treatments at the National Oncology Institute (ION) in Panama. It is expected that recipients will review this information for applicability to their facilities and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this IN are not new NRC requirements; therefore, no specific action or written response is required.

Description of Circumstances

On June 1, 2001, NRC issued IN 2001-08 to promptly alert licensees to an ongoing investigation concerning cancer patients in Panama who had received excessive radiation therapy doses. As noted in IN 2001-08, ION representatives announced on May 18, 2001, that 28 patients treated at the institute for colon, prostate, and cervical cancer may have received radiation doses from 20 to 100 percent above what was prescribed. Eight patients are reported to have died, and five of the deaths have been attributed to the excess radiation received during the treatments. Panamanian authorities initiated an investigation of the cause of the radiation overdoses and patient deaths. Subsequently, the Panamanian government requested IAEA assistance, and IAEA sent an investigation team to Panama on May 26, 2001.

On June 2, 2001, the IAEA issued an Advisory Information Notice (attached) on the initial findings of the investigation. The notice indicates that the apparent cause of the radiation overexposures was the incorrect entry of data into the computer used for the treatment planning system, resulting in incorrectly calculated radiation doses. The team determined that the radiotherapy equipment itself worked properly. An associated report, issued by the Panamanian government, states that the therapy unit and associated computerized treatment planning system worked properly and were not the cause of the incident.

The IAEA notice suggests that users of computerized treatment planning systems for radiotherapy should ensure that treatments are performed in accordance with an appropriate quality assurance program. This is consistent with 10 CFR 35.32, which requires NRC medical licensees to establish and maintain a written quality management program.

NRC is continuing to evaluate this incident, and plans to update this IN if additional findings or significant information become available.

This IN requires no specific action or written response. If you have any questions about the information in this notice, please contact the technical contact listed below or the appropriate NRC regional office.

  /RA/Susan M. Frant

Donald A. Cool, Director
Division of Industrial and Medical Nuclear Safety
Office of Nuclear Material Safety and Safeguards

Technical Contacts: Robert Ayres, NMSS
  Donna-Beth Howe, NMSS
  Roberto J. Torres, NMSS
  1. IAEA Advisory Information Notice, dated June 2, 2001
  2. List of Recently Issued NMSS Information Notices
  3. List of Recently Issued NRC Information Notices

(ADAMS Accession Number ML011570330)

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IN 2001-08, Supp. 1

2001-06-02 01:00 UTC


On 22 May 2001, the IAEA informed Contact Points identified under the Convention on Early Notification of a Nuclear Accident ("Early Notification Convention") and the Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency ("Assistance Convention") of a radiological emergency at the National Oncology Institute in Panama affecting 28 patients undergoing radiotherapy. The emergency involved a radiotherapy unit using a cobalt-60 teletherapy machine and a computerized treatment planning system for calculating the radiation doses to be delivered to patients. The IAEA received a request for assistance from the Panamanian Government under the auspices of the Assistance Convention and you were informed that an expert team was being sent to Panama.

The IAEA team, composed of experts in radiation protection, radiopathology, radiotherapy, radiology and medical physics, from France, Japan, the United States of America and the IAEA, joined by an expert from the Russian Federation representing the World Health Organization, has in the meantime reached preliminary conclusions on the factors contributing to the emergency and the consequences thereof. There is concordance between the findings of the international team of experts and those of national experts.

The team reported that of the 28 affected patients, eight have died, the deaths of five of whom are probably attributable to radiation overexposure. Of the other three deaths, one was considered to have been related to the patient's cancer, while there was insufficient information to draw conclusions with respect to the other two. Of the 20 patients who are alive, some have developed serious radiopathological complications.

The team of experts found that the radiotherapy equipment had been working properly and that it was adequately calibrated. A preliminary assessment of the situation by the team suggests that the apparent cause of the emergency lay with the entering of data into the computer used for the treatment planning system. The computerized treatment planning system used in the National Oncology Institute requires that the data on the spatial co-ordinates of shielding blocks used to protect healthy tissue during radiotherapy be entered into the system one block at a time, following a certain sequence and subject to a limitation on the number of blocks. It is reported that, as from August 2000, the practice used at the National Oncology Institute was changed whereby, in the case of the affected patients, the co-ordinates for all of the blocks were entered as a single block, resulting in incorrect calculated radiation doses and, consequently, treatment times. Together with an apparent lack of written procedures, and of a manual check when the data input procedure was changed, the combination of circumstances resulted in substantial over-exposure to radiation of the patients involved.

The Ministry of Health of Panama has just been briefed by the team on these preliminary conclusions and has agreed that the lessons identified should be shared on an urgent basis with the international community in order to prevent overexposures wherever this configuration of treatment might be in use. While the team's final report has not yet been completed, under the arrangements set out in the Emergency Notification and Assistance Technical Operations Manual (ENATOM), the IAEA is informing Contact Points about the essential facts that have come to its attention surrounding this emergency in order that national authorities and users of computerized treatment planning systems for radiotherapy, including those similar to that involved in this situation, are informed of the unfortunate circumstances that occurred at the National Oncology Institute in Panama. The Contact Points are urged to draw this matter to the attention of the relevant national authorities and users, who are encouraged to check that any relevant systems are being operated in accordance with an appropriate quality assurance programme.

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