C.8.8.15.7 Brachy Control Point Sequence

The Control Points shall be arranged such that the first Control Point for a particular Channel describes the first dwell position and the final Control Point for the Channel describes the final dwell position. If Brachy Treatment Type (300A,0202) is PDR, the Brachy Control Point Sequence (300A,02D0) shall specify the sequence of machine configurations for a single pulse. Similarly, if Source Movement Type (300A,0288) is OSCILLATING, the Brachy Control Point Sequence (300A,02D0) shall specify the sequence of machine configurations for a single period.

Some examples of Brachytherapy specification using control points are as follows:

a) Stepwise motion; Four equally weighted dwell positions; Step size = 10; Final Cumulative Time Weight = 100:

Control Point 0: Control Point Relative Position = 30, Cumulative Time Weight = 0

Control Point 1: Control Point Relative Position = 30, Cumulative Time Weight = 25

Control Point 2: Control Point Relative Position = 20, Cumulative Time Weight = 25

Control Point 3: Control Point Relative Position = 20, Cumulative Time Weight = 50

Control Point 4: Control Point Relative Position = 10, Cumulative Time Weight = 50

Control Point 5: Control Point Relative Position = 10, Cumulative Time Weight = 75

Control Point 6: Control Point Relative Position = 0, Cumulative Time Weight = 75

Control Point 7: Control Point Relative Position = 0, Cumulative Time Weight = 100

b) Fixed (manually placed) sources; Final Cumulative Time Weight = 100:

Control Point 0: Control Point Relative Position = 0, Control Point 3D Position = (x,y,z),Cumulative Time Weight = 0

Control Point 1: Control Point Relative Position = 0, Control Point 3D Position = (x,y,z),Cumulative Time Weight = 100

c) Oscillating movement; Final Cumulative Time Weight = 100 :

Control Point 0: Control Point Relative Position = 100, Cumulative Time Weight = 0

Control Point 1: Control Point Relative Position = 0, Cumulative Time Weight = 100

d) Unidirectional movement; Final Cumulative Time Weight = 100 :

Control Point 0: Control Point Relative Position = 0, Cumulative Time Weight = 0

Control Point 1: Control Point Relative Position = 100, Cumulative Time Weight = 100

e) Stepwise motion with consideration of source transit times between dwell positions; Three equally weighted dwell positions; Step size = 10; Final Cumulative Time Weight = 79:

Control Point 0: Control Point Relative Position = 30, Cumulative Time Weight = 0

Control Point 1: Control Point Relative Position = 30, Cumulative Time Weight = 25

Control Point 2: Control Point Relative Position = 20, Cumulative Time Weight = 27

Control Point 3: Control Point Relative Position = 20, Cumulative Time Weight = 52

Control Point 4: Control Point Relative Position = 10, Cumulative Time Weight = 54

Control Point 5: Control Point Relative Position = 10, Cumulative Time Weight = 79

f) Stepwise motion with consideration of source transit times between dwell positions and to first and from last dwell position; Three equally weighted dwell positions; Step size = 10; Final Cumulative Time Weight = 383:

Control Point 0: Control Point Relative Position = 1200, Cumulative Time Weight = 0

Control Point 1: Control Point Relative Position = 30, Cumulative Time Weight = 150

Control Point 2: Control Point Relative Position = 30, Cumulative Time Weight = 175

Control Point 3: Control Point Relative Position = 20, Cumulative Time Weight = 177

Control Point 4: Control Point Relative Position = 20, Cumulative Time Weight = 202

Control Point 5: Control Point Relative Position = 10, Cumulative Time Weight = 204

Control Point 6: Control Point Relative Position = 10, Cumulative Time Weight = 229

Control Point 7: Control Point Relative Position = 1200, Cumulative Time Weight = 383