Therapy Medical Events in 2016

2016 Event 1
Summary A patient undergoing radiation therapy to the right breast received an unintended dose of approximately 118 cGy to an area 12.0 cm from midline lateral to the intended treatment site due to an incorrect shift toward the contralateral breast. Therapists observed the misalignment after treatment of the medical tangential breast field. Patient alignment was corrected and patient received the remaining fractional dose to the prescribed treatment volume from the lateral tangential field.
Root Cause The event was due to human error in patient alignment.
Corrective Action Treatment setup will be verified inside the treatment room by verifying the SSD after any shift along with the gantry rotation and field light. Both ortho pair and MV portal images will be taken on the first day of treatment. On the second day, one or both of the tangent fields need to be filmed to verify treatment position. At least weekly portal images are now required. Therapist will not overwrite couch parameters after the first treatment session unless they have verified with their co-worker and with physician approval.
Effect on Patient Physician does not expect any acute or long term adverse effects on the patient from the delivery of 118 cGy to the unintended site. The prescribing physician has discussed the incident and the expected outcome with the patient.
2016 Event 2
Summary Stereotactic body radiation therapy (SBRT) that was meant for a patient's malignant liver tumor was instead delivered to a benign tumor in a different part of the liver. The patient received the entire prescribed dose (50 Gy in 5 fractions) to the unintended liver lesion. Follow-up imaging was performed four months after the treatment and it was noted that the liver metastasis had increased in size. It was then discovered that the wrong lesion had been treated.
Root Cause The gross tumor volume (GTV) contour initially created by a resident covered the wrong liver lesion (a benign hemangioma instead of the metastasis). During the approval of the GTV contour by the prescribing physician, a check against the primary diagnostic imaging was not performed.
Corrective Action The facility will henceforth require physicians to attest to confirming treatment locations using diagnostic images and that an additional attending physician will independently verify correct treatment.
Effect on Patient An unintended dose of 50 Gy was delivered to a benign liver hemangioma. While the patient did not experience any toxicity from the unintended treatment, the untreated liver metastasis increased in size. The patient was notified and a new treatment plan was created considering the doses already delivered to the surrounding structures and was delivered to the patient.
2016 Event 3

A patient undergoing skin treatments at eight separate treatment sites with 6 MeV electrons received two fractions of 3 Gy each to an incorrect lesion.

Sites were all correctly treated on Day 1. On Day 2 the treatment was scheduled with a different therapist. In the time since the simulation (12 days) the skin marks had faded. Also, the patient had developed a new lesion adjacent to the target lesion at site #7. The radiation therapist thought she could identify faded skin marks around this lesion. This incorrect site was marked as the intended treatment site and was treated on Day 2 and Day 3. On Day 4 the Day 1 therapists was scheduled to treat the patient. She noticed the skin marks for site #7 were around a different lesion than treated on Day 1. The prescribing physician was called to confirm the intended lesion. The patient was remarked and treated.
Root Cause

The length of time between the simulation with initial skin marking and the start of treatment was 11 days and the skin marks had faded during this time.

It was difficult to clearly identify the intended treatment sites in the simulation photos because they were zoomed in and it was difficult to identify additional anatomy for context.

The setup of site #7 on day 2 was not visually verified by a second radiation therapist.

The attending physician was not called on day 2 to confirm the treatment site prior to remarking because the treating RRTs believed they were reinforcing the correct marks from simulation.
Corrective Action Corrective action is to reduce time between simulations and treatments (11 days to 5 days), limit the number of lesions that are simulated during a single simulation appointment, improve patient photo policy, and educate patients on preserving treatment site marks. Consider testing alternative skin marking for electron treatments.
Effect on Patient Two treatments were added to the correct lesion and it is expected that the desired palliative effect will be achieved with no acute or long-term effects from the unintended treatments.

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