Another Set of Eyes?
The incidental findings debate expands to radiation-treatment-planning studies.
A previous professor of mine, working as a locum tenens, performed a radiotherapy-treatment-planning CT scan. Such scans are used to identify both the area of interest for treatment but also to point out normal critical structures to avoid. Months later, the professor was named in a lawsuit because he did not see a new finding that had presented on the treatment-planning scan.
As luck may (or may not) have it, a patient I recently simulated for radiotherapy-treatment planning presented with a new finding on our treatment-planning scan. The patient came in for radiotherapy-treatment planning for a recurrence in the abdominal wall area. Although the patient was asymptomatic, the patient's partner mentioned the patient having slight abdominal distention. A quick review of the treatment-planning CT scan revealed the development of ascites two weeks after a PET scan that showed no ascites.
These two occurrences beg the question, should radiotherapy-treatment scans be over-read by diagnostic radiologists in the era of image-guided therapy? Advanced imaging is becoming the standard of care in radiotherapy (including MRI, PET CT, and 4-D CT scan simulation) in an effort to concentrate radiation on tumors while sparing normal tissues. The comfort level of radiation oncology trainees interpreting diagnostic imaging is low, as radiation oncologists do not receive formal diagnostic radiology training.
The literature has been relatively silent recently on the benefit of a diagnostic radiologist over-read of radiotherapy-treatment-planning scans. Smitt and Mehta evaluated 162 radiotherapy-treatment-planning scans in patients to be treated with curative intent. All of the scans were interpreted with formal reports from the medical records with documentation of previously unknown benign or cancer-related findings. Thirty-two patients had incidental benign findings, while 20 patients had potentially cancer-related findings. A review of previous records and images found only three of the previously unknown findings required further investigation: two aneurysms and one metastatic neck node. Therefore less than 1 percent of scans had a potential to change management in the scanned patients. Should further study be done to evaluate if the same percentage holds with new imaging techniques, such as MR and PET scanners?
Acknowledging differences in spatial resolution, imaging protocols, and patient position between diagnostic and treatment-planning studies, should treatment-planning scans undergo diagnostic radiology evaluation? In other words, should radiotherapy-treatment scans be over-read by diagnostic radiologists? Would another pair of eyes be useful? For the diagnostic radiologists, how many of you are over-reading radiation-treatment-planning studies?