| DICOM PS3.3 2024e - Information Object Definitions |
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Each RT Beam of a treatment plan is typically included in a Fraction Group. The number of fractions to be delivered is defined in the Number of Fractions Planned (300A,0078).
The Clinical Fraction Number (300A,0705) tracks the clinical progress of treatment delivery.
It is established as a counter that represents an incremental count of deliveries of fractions within a radiotherapy treatment serving a given combination of prescriptions, starting from 1 and monotonically increasing by 1.
When it is used prospectively in instructions, the value indicates the ordinal count of the treatment fraction to be delivered in the upcoming treatment session. When the upcoming delivery of therapeutic radiation is intended to consist of the complete delivery of the RT Beams referred to by the Fraction Group serving the same combination of prescriptions as the previous fraction, the value is incremented. When the upcoming delivery of therapeutic radiation is intended to resume the delivery of a previously incomplete fraction, the value is not incremented, i.e., the value is the same as that of the resumed fraction.
When it is used retrospectively in recording, the value indicates the ordinal count, irrespective of any modification of the treatment plan, of the fraction which has been delivered.
The Current Fraction Number (3008,0022) tracks the clinical progress of treatment delivery for a Referenced Beam within the referenced RT Plan.
When it is used prospectively in instructions, the value indicates the ordinal count of the treatment to be delivered with the referenced RT Plan. When the upcoming delivery of therapeutic radiation is intended to consist of the complete delivery of the RT Beams referred to by the Fraction Group, the value is incremented. When the upcoming delivery of therapeutic radiation is intended to resume the delivery of a previously incomplete fraction, the value is not incremented, i.e., the value is the same as that of the resumed fraction.
When it is used retrospectively in recording, the value indicates the ordinal count for the treatment plan of the fraction which has been delivered.
If the same RT Plan is used for all treatments, the values of Current Fraction Number (3008,0022) and the Clinical Fraction Number (300A,0705) have the same values.
For some adaptive treatment approaches, details of the device parameters may be altered at the treatment session to accommodate the current position and shape of the patient. In this case, a new RT Plan SOP Instance is used for the subsequent RT Treatment Fractions serving the same set of RT Prescriptions and the Current Fraction Number (3008,0022) re-starts at 1.
The Clinical Fraction Number (300A,0705) is continuously incremented to reflect the clinical progress of a therapeutic series of treatments. In the RT Beams Session Record for the last of the intended RT Treatment Fractions, this value will usually be equal to the Number of Fractions Planned (300A,0078) present in the corresponding Fraction Group.
Example
RT Plan P contains RT Beams A, B in a Fraction Group; Adapted RT Radiations indicated by (') and ('') ; RT Plans created are P, P' and P''.
Table C.8.8.21-2. Delivery of Multiple RT Plan Instances
|
Treatment Session |
RT Plan |
Delivered RT Beams |
Clinical Fraction Number (300A,0705) |
Current Fraction Number (3008,0022) |
|---|---|---|---|---|
|
1 |
P |
A,B |
1 |
1 (of P) |
|
2 |
P |
A,B |
2 |
2 (of P) |
|
3 |
P' |
A',B' |
3 |
1 (of P') |
|
4 |
P' |
A',B' |
4 |
2 (of P') |
|
5 |
P'' |
A'',B'' |
5 |
1 (of P'') |
|
6 |
P |
A,B |
6 |
3 (of P) |
| DICOM PS3.3 2024e - Information Object Definitions |
|---|