C.8.8.21.2 Specified and Delivered Meterset Values
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##### C.8.8.21.2 Specified and Delivered Meterset Values

###### C.8.8.21.2.1 Beam Level

The value of Specified Primary Meterset (3008,0032) shall be the value specified by Beam Meterset (300A,0086) in the corresponding Fraction Group of the referenced RT Plan. The referenced RT Plan is found in the Referenced RT Plan Sequence (300C,0002), and within this plan the Fraction Group is found using the Referenced Fraction Group Number (300C,0022) in this module. The Beam is found in the referenced RT Plan using the Referenced Beam Number (300C,0006) in the same item of the Treatment Session Beam Sequence (3008,0020) as the Specified Primary Meterset (3008,0032).

The value of Delivered Primary Meterset (3008,0036) shall be the accumulated value of the delivered Meterset across all Control Points, which is recorded in this item of the Treatment Session Beam Sequence (3008,0020).

Note that, for example, when a partial treatment has occurred and resumption(s) have been delivered that complete delivery of all control points remaining, the sum of the Delivered Primary Meterset (3008,0036) values in all RT Beams Session Records for the beam in question and the fraction being treated will match the specified Meterset for the whole fraction.

###### C.8.8.21.2.2 Control Point Level

Specified Meterset (3008,0042) contains the MU as specified in the corresponding RT Plan at a given control point.

Delivered Meterset (3008,0044) shall contain one of the following three values:

- the Meterset value at which the delivery of the current beam started

- the Specified Meterset

- the Meterset value at which the delivery of the current beam ended

Control points that already have been treated in an earlier session shall contain the Meterset value at which the delivery of the current beam started. Control points that have been completely treated during the current session shall contain the Specified Meterset value for this Control Point. Control Points that have not yet been treated or not completely shall contain the total delivered MU up to the point where the interruption has occurred (i.e., the last control point treated).

This can be expressed by the following equation:

DelMS[CPn] = MAX (StartMS, MIN (SpecMS[CPn], EndMS))

with

DelMS[CPn]

  Delivered Meterset value at control point n

SpecMS[CPn]

  Specified Meterset value at control point n

StartMS

  Meterset value where delivery of current beam started

EndMS

  Meterset value where delivery of current beam ended

By this definition it is unambiguously recorded, which 'segments' of control points have been delivered in case of partial treatments.

Figure C.8.8.21-1. Control Point Example 1: 2 Control Points, 2 Complete Partial Treatments

Figure C.8.8.21-2. Control Point Example 1: 2 Control Points, 2 Complete Partial Treatments

Figure C.8.8.21-3. Control Point Example 3: 7 Control Points, 2 Partial Treatments with Small Gap

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