Table 3 4DCT acquisition options in the NeoSCOPE trial
From: Driving developments in UK oesophageal radiotherapy through the SCOPE trials
| Â | 4DCT method 1 | 4DCT method 2 |
|---|---|---|
Pre-delineation | From the 4DCT data sets, identify the extreme phases of motion (MaxIn and MaxEx). Also identify the phase that best represents the time-weighted average (Mid). | From the 4DCT data sets, identify the extreme phases of motion (MaxIn and MaxEx). |
GTV | Contour as per the 3D protocol on each of the three phases as defined above, giving: GTVMaxIn, GTVMid and GTVMaxEx. | Contour as per the 3D protocol on the 3D contrast enhanced CT scan and label it GTV3D. Also contour the GTV in the extreme phases of the 4D scan, giving GTVMaxIn and GTVMaxEx. Combine these three to obtain a composite structure, label GTVmotion. Review GTVmotion on all 4DCT phases and manually increase the contour for any areas not covered. |
CTVA | Contour as per the 3D protocol on each of the three phases, giving: CTVAMaxIn, CTVAMid and CTVAMaxEx. | Contour as per the 3D protocol on the 3D contrast enhanced CT scan using GTVmotion as the starting point. Label CTVA3D. |
CTVB | Contour as per the 3D protocol on each of the three phases, giving: CTVBMaxIn, CTVBMid and CTVBMaxEx. | Create CTVB3D from CTVA3D as per the 3D protocol on the 3D contrast enhanced CT. Make two copies of CTVB3D, labelled CTVBMaxIn and CTVBMaxEx then proceed to manually increase these on their respective respiration phases for any areas not covered. |
ITV | The ITV is defined as the composite CTVB volumes. Review the ITV on all 4DCT phases and manually increase the contour for any areas not covered. | The ITV is made by combining CTVBMaxIn and CTVBMaxEx. Check that this volume covers any unusual motion patterns noted in the respiratory phases above. |
PTV | Apply the margin to the ITV | Apply the PTV margin to the ITV |
Planning | The mid phase CT is used for planning the dose distribution | The 3D CT is used for planning the dose distribution |