The following information was received from the
Oregon Health Authority via e-mail:
The following is a report of a medical event corresponding to Subpart M, 35.3045(a)(1)(iii) for a high dose rate afterloader (HDR) dose to the skin other than the treatment site that exceeds 50 rem and 50% of expected dose to the location.
Description of event: A patient was scheduled for two HDR (Varian GammaMed Plus iX) treatments, one each for two separate lesions located on the patient's lower right leg. The first lesion treatment (5100 cGy total; 17 fractions @ 300 cGy ea) was performed in February without incident. The first fraction of 500 cGy for the second lesion was performed on June 7th. The second treatment was scheduled for June 10th, however, during set-up and after drawing a circle on the patient's leg to help align the second lesion and monitor positioning during treatment, the patient informed the physicist that after the first fraction on June 7th, he noticed the circle had been drawn at that time around the first lesion treated in February. Treatment staff immediately alerted the patient's physician. Images from the patient's treatment on June 7th were compared to the February treatment and found to be the same location as the first lesion. The physician stated there is no adverse effect to the patient since the dose went to the site of the previous February treatment that was 'well tolerated' by the patient and 'the additional one HDR fraction of 500 cGy is likely of benefit to the patient.' The patient's written directive was updated to reflect an additional fraction to be given to the second lesion.
Cause and corrective actions: The licensee is still gathering information but from the preliminary data received, verification of the treatment site was not performed for the June 7th fraction and former treatment plan location was used. No corrective actions have been submitted at this time.
Concerns: Verification of treatment site may not be robust enough in separating separate treatment sites that are close together. Only through patient notification was this event identified. Awaiting further information/explanation from licensee."
Oregon Report Identification Number: 22-0028
A Medical Event may indicate potential problems in a medical facility's use of radioactive materials. It does not necessarily result in harm to the patient.
- * * UPDATE FROM DARYL LEON TO DONALD NORWOOD AT 1544 EDT ON 6/16/2022 * * *
The following updated / revised information was received via E-mail:
Description of event: The patient was scheduled for two treatments, one each for two separate lesions located on the patient's lower right leg. The first lesion treatment (5100 cGy total dose; 17 fractions @ 300 cGy ea) using beam therapy (SBRT) was performed in February without incident. The second lesion was not present during this treatment but appeared shortly after. On June 7th, the first fraction of 500 cGy (4000 cGy total dose; 8 fractions at 500 cGy ea) was performed. The second treatment was scheduled for June 10th, however, during set-up and after drawing a circle on the patient's leg to help align the second lesion and monitor positioning during treatment, the patient informed the physicist that after the first fraction on June 7th, he noticed the circle had been drawn at that time around the first lesion treated in February. Treatment staff immediately alerted the patient's physician. Images from the patient's HDR fractionated dose on June 7th were compared to the February external beam treatment and found to be the same location. The physician stated there is no adverse effect to the patient since the dose went to the site of the previous February treatment that was "well tolerated" by the patient and "the additional one HDR fraction of 500 cGy is likely of benefit to the patient". The patient's written directive was updated to reflect an additional fraction to be given to the second lesion.
Cause and corrective actions:
Facts to note:
- The second lesion was not present during the February external beam treatment.
- The written directive for the HDR treatment plan for the second lesion stated it was "lateral" than the "more medial" first lesion. Both were within approximately 1.5 inches of each other.
- The patient positioning for external beam was supine and for the HDR, prone.
This event occurred due to human error. The licensee failed to note the change in patient positioning from supine to prone while using photos of the treatment area resulting in `visual flip' of image nor confirm treatment site from the written directive. A contributing factor is the proximity of the two lesions and another is that the second lesion was not present during the February external beam treatment.
Stated corrections are to add a pretreatment step for multiple lesions close to each other that include:
- Asking the patient to point to the site to be treated.
- Verification by including more images of the body (hand or foot) along with the lesions to better identify the site and orient treatment personnel.
Source: Irridium-192
Activity: Approximately 4.8 Ci
Model: Gammamed 232
Serial number: 24-01-0285-001-020422-15242-99
Leak test date: March 17, 2022.
Notified R4DO (Azua) and the
NMSS Events Notification E-mail group.