1.2a lecture
- DRR -> Digitally Reconstructed Radiography
o BEV -> Beams Eye View
- CT- scan Requirements:
o Flat table (no cradle (only radiology))
o Posture and devices similar to the radiation execution
o Tools should not be ‘’disruptive’’ on the CT scan
o Lasers present in CT space, we need those lasers to define the patients position
o Reference point (CT-isocenter). They have to stay on, because we need them for
repositioning the patient.
- From CT to RT:
o Reference point (CT-isocentre), isocentre radiation field
We have to move the table in lateral way (right), vertical way (up) and also
longitudinal way (out)
Your treatment planning system is going to calculate how much your table
needs to move in each direction to end up in the isocenter you used in your
treatment plan.
- Definition lasers and tabletop:
o When we create the Ct scan, we make some lat palets on the cross-sectional of our
laser lines. You can find them as white dots on your CT scan.
We have to put our virtual laser lines on the white dots so they match with
each other and your planning system knows where the reference point is
located exactly.
o We have to locate where the table top is located exactly.
The red horizontal line. You have to match the redline to the exact table top.
Why do we do that? Everything behind the tabletop is not calculated in your
dose distribution. We don’t want that because, we don’t want the CT table
to interfere with our dose distribution.
if we don’t calculate the table top at the right place then the parts
below the table top wont be calculated in our dose distribution. So
you miss halfway your patient in your calculation.
- Delineation:
o We delineate the critical organs or organs at risk (OAR) -> MBB’er
o We delineate the target area (GTV, CTV, PTV) -> doctor
o For planning target volume (PTV), we use it for our treatment planning. We want
95% coverage.
- Patient Route: (planning)
o 1. Virtual simulation: we define our radiation field by anatomical structures.
o 2. 3D- conformal planning: we start delineating OAR and the doctor delineates target
volume.
- DRR -> Digitally Reconstructed Radiography
o BEV -> Beams Eye View
- CT- scan Requirements:
o Flat table (no cradle (only radiology))
o Posture and devices similar to the radiation execution
o Tools should not be ‘’disruptive’’ on the CT scan
o Lasers present in CT space, we need those lasers to define the patients position
o Reference point (CT-isocenter). They have to stay on, because we need them for
repositioning the patient.
- From CT to RT:
o Reference point (CT-isocentre), isocentre radiation field
We have to move the table in lateral way (right), vertical way (up) and also
longitudinal way (out)
Your treatment planning system is going to calculate how much your table
needs to move in each direction to end up in the isocenter you used in your
treatment plan.
- Definition lasers and tabletop:
o When we create the Ct scan, we make some lat palets on the cross-sectional of our
laser lines. You can find them as white dots on your CT scan.
We have to put our virtual laser lines on the white dots so they match with
each other and your planning system knows where the reference point is
located exactly.
o We have to locate where the table top is located exactly.
The red horizontal line. You have to match the redline to the exact table top.
Why do we do that? Everything behind the tabletop is not calculated in your
dose distribution. We don’t want that because, we don’t want the CT table
to interfere with our dose distribution.
if we don’t calculate the table top at the right place then the parts
below the table top wont be calculated in our dose distribution. So
you miss halfway your patient in your calculation.
- Delineation:
o We delineate the critical organs or organs at risk (OAR) -> MBB’er
o We delineate the target area (GTV, CTV, PTV) -> doctor
o For planning target volume (PTV), we use it for our treatment planning. We want
95% coverage.
- Patient Route: (planning)
o 1. Virtual simulation: we define our radiation field by anatomical structures.
o 2. 3D- conformal planning: we start delineating OAR and the doctor delineates target
volume.
