A Radiation Oncology Center in Michigan reported an event causing an unplanned total patient dose differing from the total prescribed dose by +20%.  This event was reported pursuant to the Ionizing Radiation Rules and to the "Machine Conditions of Use", as specified on the Radiation Machine Registration Certificate issued to the facility.

Based on the facility's event report to the Radiation Safety Section, on July 31, 2004, the patient received a dose of 600 centiGray (cGy) to an area of the brain that was 5 centimeters away from the intended site of treatment.  The total prescribed dose was 3000 cGy to be delivered in 5 fractions with a stereotactic radiotherapy treatment technique. The patient and patient's family were informed of the event.

The error in treatment occurred due to incorrect placement of the immobilization aid that was used for holding the patient's head in place for treatment.  The immobilization device is a mask system that holds the patient's head still and in a reproducible position.  The device consists of a U-frame with two sets of vertical posts, called low frame posts and high frame posts.  The posts differ in attachment positions on the U-frame by 5 centimeters. Two patients concurrently under treatment were using the low frame posts. This patient was to be treated with the high frame vertical posts. The same U-frame is used for all patients. The low frame posts were inadvertently left in for the treatment of the patient. This caused the treatment position to be shifted 5 centimeters towards the feet of the patient with respect to the intended site of treatment.

The error was detected due to the mask fitting so tightly that the patient was uncomfortable. The tight fit prompted scrutiny of the set up conditions that were initially intended for the patient. Upon investigation, the facility discovered that the wrong vertical posts were being used. They had been left on from the other patients also under treatment with stereotactic radiotherapy.

To prevent reoccurrence the facility has implemented the use of digital photography in addition to strict adherence to labeling of the vertical posts. The digital photography will indicate that the mask fits properly and that the correct posts are being used.

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A Radiation Oncology Center in Michigan reported an event involving patient treatment delivered to an incorrect site. This event was reported pursuant to the Ionizing Radiation Rules and to the "Machine Conditions of Use", as specified on the Radiation Machine Registration Certificate issued to the facility.

Based on the facility's event report to the Radiation Safety Section, the patient was under treatment to the left hip for metastatic disease. The patient's right hip had been treated a month earlier with a similar field size and setup. On July 15, 2004 the patient was inadvertently set up for treatment using the tattoos from her previous treatments to the right hip. The treatment was delivered to the right hip.

On July 19, 2004 one of the two therapists involved in the patient's treatment asked to meet their supervisor and indicated that they believed the right hip rather than the left hip had been treated on the previous Thursday (July 15, 2004)

Through the facility's analysis of their treatment verification and recording system, it was confirmed that the right hip rather than the left hip had been treated. The right hip received 250 cGy in error.

To prevent reoccurrence of similar events, the tolerance limits for the lateral table position programmed in the facility's treatment verification and recording system was tightened so that errors of this nature are red flagged. A red flag on the treatment parameters will not allow treatment until the inconsistency is resolved.