| Tag | (300A,02D6) |
|---|---|
| Type | Required, Empty if Unknown (2) |
| Keyword | CumulativeTimeWeight |
| Value Multiplicity | 1 |
| Value Representation | Decimal String (DS) |
Cumulative time weight to current Control Point (where the weighting is proportional to time values delivered). Cumulative Time Weight for first Item in Brachy Control Point Sequence (300A,02D0) is always zero. See Section C.8.8.15.6 and Section C.8.8.15.8.
The treatment time at a given Control Point is equal to the Channel Total Time (300A,0286), multiplied by the Cumulative Time Weight (300A,02D6) for the Control Point, divided by the Final Cumulative Time Weight (300A,02C8). If the calculation for treatment time results in a time value that is not an exact multiple of the timer resolution, then the result shall be rounded to the nearest allowed timer value (i.e., less than a half resolution unit shall be rounded down to the nearest resolution unit, and equal or greater than half a resolution unit shall be rounded up to the nearest resolution unit).
Note also that if Final Cumulative Time Weight (300A,02C8) is equal to 100, then Cumulative Time Weight (300A,02D6) becomes equivalent to the percentage of Channel Total Time (300A,0286) delivered at each control point. If Final Cumulative Time Weight (300A,02C8) is equal to Channel Total Time (300A,0286), then the Cumulative Time Weight (300A,02D6) at each control point becomes equal to the cumulative treatment time delivered at that control point.
If Treatment Type (300A,0202) is PDR, then the Channel Total Time (3008,0286) shall specify the duration of a single pulse.
The Source transit times between dwell positions of a remote afterloader may be considered by specifying a non-zero increment in the Cumulative Time Weight (300A,02D6) when the Source moves between Control Points. In this case the Channel Total Time (300A,0286) shall include the overall Source transit time for the Channel.