| Reason for the Action |
When exporting a plan with a 3D Static Arc delivery type, the exported DICOM plan does not include a value for the end angle for beams with a counterclockwise (CCW) rotation, DICOM attribute (300A,011E). When the plan is promoted for delivery, the record and verify system may set the end angle as equal to the start angle (i.e., a 360-degree rotation).
If the gantry rotates beyond the intended stop angle, patient harm could be caused by:
1. Collision: the cone or treatment head of the gantry may collide with the patient and cause serious harm such as a crushing injury or bone fracture. The severity of patient injury will depend on:
a. The distance between the end of the cone and the patient.
b. Touch guard protection on either the cone or linear accelerator. Touch guard protection may not be available on the cone and may be disabled on the gantry.
2.Dosimetric error: Although the intended dose is delivered, the dose is delivered over a longer arc than planned. As a result, organ doses will be affected. However, Elekta’s dosimetric calculations concluded that in a realistic, worst-case scenario, the dosimetric error would be minimal and result in
non-serious patient harm.
Elekta have not received any reports of patient injury related to this problem. |