C.8.8.25.7 Ion Control Point Sequence

The control point sequence for RT Ion Beams is defined using the same rule set as in the RT Beams module (see Section C.8.8.14.5 Control Point Sequence). Specifically, the following rules apply:

This definition allows unambigous and explicit determination of those parameters changing while irradation is occuring, as opposed to those parameters that change between irradiation segments. No assumptions are made about the behavior of machine parameters between specified control points, and communicating devices shall agree on this behavior outside the standard.

The following example illustrates this rule (not all parameters are shown), in the case of a scanning beam with 2 segments and Total Cumulative Meterset of 70.

Control Point 0: All applicable treatment parameters defined, Cumulative Meterset Weight = 0Nominal Energy: 200Scan Spot Position Map: -40, -35, -40, -30 (Positions for 1 st segment)Scan Spot Meterset Weight: 0.5, 0.3, 1.2, (Values add up to meterset difference between Control Points 0 and 1)

Control Point 1: All applicable treatment parameters defined, Cumulative Meterset Weight = 30.0Nominal Energy: 200Scan Spot Position Map: -40, -35, -40, -30 (Positions for 1 st segment)Scan Spot Meterset Weight: 0.0, 0.0, 0.0, … (All values are 0.0, because Meterset Weight difference betweeen Control Point 1 and 2 is 0.0)

Control Point 2: All applicable treatment parameters defined, Cumulative Meterset Weight = 30.0Nominal Energy: 180Scan Spot Position Map: -55, -40, -55, -35, (Positions for 2 nd segment)Spot Meterset Weight: 0.7, 0.8, 1.5 (Values add up to meterset difference between Control Points 2 and 3)

Control Point 3: All applicable treatment parameters defined, Cumulative Meterset Weight = 70.0Nominal Energy: 180Scan Spot Position Map: -55, -40, -55, -35, (Positions for 2 nd segment) Spot Meterset Weight: 0.0, 0.0, 0.0, (All values are 0.0, because there is no following control point (end of sequence).