Case 0004: Dose Error on Second Day of Electronic Brachytherapy Treatment

Introductory Information: Reported to the SAFRON incident report system. This medical event took place in 2014 and it is related to a patient who received electronic brachytherapy treatment with the Xoft Axxent system. The radiation oncologist discovered the incident during a regular chart check.

Below is the original text describing the medical event that was submitted to SAFRON:

“On the first day of the electronic brachytherapy treatment with the Xoft Axxent system, the calculations were performed and double checked by the physicist. The treatment was delivered correctly, according to the prescription, for 500 cGy (5 Gy). On the 2nd day of the treatment, the operator inadvertently treated the patient with 436.6 sec (instead of 230.7 sec). Upon review of the treatment log file the Physician called the physicist to investigate the situation, and the physicist determined the reason to be incorrect source strength measurement before the patient treatment. The physicist checked the machine and all the patients treated for the day. Everything was in the correct working order and so the reason for this event is attributed to be that the source was not inserted all the way into the well chamber for the source strength measurement before this patient’s treatment. Therefore, the weekly dose is about 145% of the prescribed weekly dose. Over the whole course of the treatment if we don’t do any changes to the remaining treatment the delivered dose will be 112.5% of the prescription dose (the dose will not exceed 20% of the prescribed dose).”

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