Nominal Range Modulation Fractions Attribute
| Tag | (300A,0503) |
|---|---|
| Type | Conditionally Required (1C) |
| Keyword | NominalRangeModulationFractions |
| Value Multiplicity | 2 |
| Value Representation | Single (FL) |
Fractions of the Reference Dose Definition (300A,0512) defining the proximal and distal limits at which the range-modulated region is defined.
Contains two values. The first value defines the modulation fraction value at the proximal limit and the second value defines the modulation fraction value at the distal limit.
A value of 1.0 refers to the 100% reference dose level as defined in Reference Dose Definition (300A,0512).
Required if Nominal Range Modulated Region Depths (300A,0504) is present.
See Section C.8.8.25.9.
Section C.8.8.25.9
C.8.8.25.9 Depth Dose Parameters Sequence
Some delivery systems determine the settings of the range shifter (or beam energy) and range modulators internally based upon clinical parameters.
The Attributes mentioned in this section represent those clinical parameters.
When the Depth Dose Parameters Sequence (300A,0505) is present, those specifications have precedence over the definitions of the Range Shifters defined in Range Shifter Settings Sequence (300A,0360) and the Range Modulator defined in Range Modulator Settings Sequence (300A,0380).
The following three figures explain the use of the Range Modulated Region Attributes.
Figure C.8.8.25.9-1 shows an example of those Attributes with the following values:
-
Nominal Range Modulated Region Depths (300A,0504) = 147\298
-
Reference Dose Definition (300A,0512) = CENTER
-
Distal Depth (300A,0502) = 301
-
Distal Depth Fraction (300A,0501) = 0.9
-
Nominal Range Modulation Fractions (300A,0503) = 0.95\0.98
Figure C.8.8.25.9-1. Attributes specifying a depth dose distribution parameters in case of Reference Dose Definition (300A,0512) = CENTER
Figure C.8.8.25.9-2 is an expansion of the steep-gradient part of the depth dose curve for better readability of the parameters annotating this part.
Figure C.8.8.25.9-2. Attributes specifying a generic depth dose distribution. Abscissa expanded near distal edge of dose distribution.
Defined Terms for Reference Dose Definition (300A,0512):
- HIGHEST
-
The maximum dose for the highest energy of the non-range modulated component is used for determining the fractions.
- MAXIMUM
-
The maximum dose of the range modulated depth dose distribution is used for determining the fractions.
- CENTER
-
The dose measured at the center of the range modulated region of the depth dose distribution is used for determining the fractions.
Figure C.8.8.25.9-3 shows the usage of the Defined Terms of Reference Dose Definition (300A,0512).
In Figure C.8.8.25.9-3, the modulated region is defined the same as in Figure C.8.8.25.9-1:
-
Nominal Range Modulated Region Depths (300A,0504) = (147\298)
In this example, the 100% reference level for the dose definition is determined for the Defined Terms specified in Reference Dose Definition (300A,0512) as follows:
- HIGHEST
-
The maximum dose for the highest energy of the non-range modulated component is located at 304 mm and used for determining the fractions.
- MAXIMUM
-
The maximum dose of the range modulated depth dose distribution is located at 300 mm and used for determining the fractions.
- CENTER
-
The dose measured at 220 mm depth at the center of the range modulated region of the depth dose distribution is used for determining the fractions.
Figure C.8.8.25.9-3. Representation of the different Reference Dose Definition (300A,0512) using the range modulated depth dose distribution or highest energy component depth dose distribution.