Tomotherapeutic Leaf Initial Closed Durations Attribute
| Tag | (3010,009A) |
|---|---|
| Type | Conditionally Required (1C) |
| Keyword | TomotherapeuticLeafInitialClosedDurations |
| Value Multiplicity | 1-n |
| Value Representation | Double (FD) |
The time in seconds each leaf is closed at the beginning of the Control Point interval, see Section C.36.17.1.
The number of leaves (N) is equal to Number of Parallel RT Beam Delimiters (300A,0648).
The N values shall be provided in the order of Parallel RT Beam Delimiter Boundaries (300A,0649).
Required if RT Record Flag (300A,0639) equals NO and at least one leaf open time is not symmetrical about the mid-point of the Control Point interval and the conditions in Section C.36.2.2.5.1.1 are satisfied.
Section C.36.17.1
C.36.17.1 Tomotherapeutic Leaf Closed and Open Durations
Typically, the Tomotherapeutic Leaf Open Durations (3010,0099) are symmetric about the mid-point of the Control Point interval. If they are not, Tomotherapeutic Leaf Initial Closed Durations (3010,009A) is present, which specifies the duration of time that each leaf is closed starting from this Control Point. Tomotherapeutic Leaf Open Durations (3010,0099) then specifies the duration of time that each leaf is open after Tomotherapeutic Leaf Initial Closed Durations (3010,009A).
For each leaf, the sum of the Tomotherapeutic Leaf Initial Closed Durations (3010,009A) and the Tomotherapeutic Leaf Open Durations (3010,0099) shall not exceed the Control Point interval.
Figure C.36.17-1. Diagram of Tomotherapeutic Leaf Open and Closed Durations
Table C.36.17-2. Tomotherapeutic Leaf Open and Closed Durations
|
N Control Point Index |
Attribute |
Leaf 1 |
Leaf 2 |
Leaf 3 |
|---|---|---|---|---|
|
1 |
Tomotherapeutic Leaf Open Durations |
0.4s |
0.3s |
0.1s |
|
Tomotherapeutic Leaf Initial Closed Durations |
0 |
0 |
0.1s |
|
|
2 |
Tomotherapeutic Leaf Open Durations |
0.5s |
0.3s |
0.1s |
|
Tomotherapeutic Leaf Initial Closed Durations |
Not present |
|||
|
3 |
Tomotherapeutic Leaf Open Durations |
0.3s |
0.1s |
0 |
|
Tomotherapeutic Leaf Initial Closed Durations |
Not present |
|||
In Figure C.36.17-1, the gray sections indicate when the leaves are open during radiation delivery. Table C.36.17-2 illustrates the use of Tomotherapeutic Leaf Open Durations (3010,0099) and Tomotherapeutic Leaf Initial Closed Durations (3010,009A) based on the diagram. In the Control Point interval between Control Point 1 and 2, the leaf openings are not symmetric within the Control Point interval, so Tomotherapeutic Leaf Initial Closed Durations (3010,009A) is provided.
In the Control Point interval between Control Point 2 and 3, all leaf opening durations are symmetric about the mid-point of the Control Point interval, therefore only Tomotherapeutic Leaf Open Durations (3010,0099) is provided.
Section C.36.2.2.5.1.1
C.36.2.2.5.1.1 Requirements for Changing Values within RT Control Point Sequence Attributes
This Section specifies when individual Attributes shall be present in a Sequence.
The RT Control Point Sequence specifies a certain order of execution.
At each RT Control Point the value of various Attributes may be specified as an explicit value (which in the case of a type 2C Attribute may be a null value) and if absent remain at the same value as specified previously. There are physical and mechanical implications of specifying a new value as opposed to staying at the same value, for example gear lash, floating point jitter, etc.
At the first Sequence Item in RT Control Point Sequences (i.e., with an RT Control Point Index (300A,0600) equal to 1) all Attributes affected by this Section shall be present if applicable conditions are met.
For Sequence Items other than the first Sequence Item, Attributes shall be present if applicable conditions are met and the value is different from the previously populated value for the same Attribute (in the case of a type 2C Attribute, a null value is considered as a value). The previously populated value is the value from the Item where the Attribute was present with the greatest value of RT Control Point Index (300A,0600) less than the value of the RT Control Point Index (300A,0600) in the current Item.
This means that for an Item in which an Attribute is absent, the application stays at the value of the previously populated Item.
For Sequences inside a RT Control Point Sequence Item, the Sequence shall be present if any of the nested Attributes affected by this Section differ from the corresponding previously populated Item.
For multi-valued Attributes, such as Parallel RT Beam Delimiter Positions (300A,064A), all values shall be present if any value changes.