The first step in the planning process is to obtain CT
cross-sectional images of the part of your body needing radiation. A positioning
device will usually be made before the scan to limit patient motion on the scanner
and on the linear accelerator later. The scan itself takes only 10-15 minutes.
You will leave with reference marks on your skin that should not be washed off
until your first appointment.
M.D.
draws target on CT study
Radiation
Beams are placed on the target
Each
beam is shaped to fit the target shape
Dose
distribution is optimized
3-D Virtual Simulation / Treatment Planning
Computer System
The
images from the your CT are sent to our 3-D treatment planning computer where
the radiation oncologist can outline the cancer and potential areas of cancer
on each CT image. Normal tissues to be avoided can also be accurately outlined
so radiation to those organs is minimized. This is where radiation beam angles
and field shapes are optimized and the dose is calculated.
CT image of
a brain tumor (not well visible)
MRI
image with visible tumor
CT-MRI
Fused image
Cut-away view of 3-D image showing precise fusion
CT image of nasopharynx
cancer
PET image only
Targets drawn on Fused CT-PET image
IMRT dose distribution conforms to the target
Image Fusion Technology
Our ADAC Pinnacle Treatment Planning System provides the latest Image Fusion Technology,
which dramatically increased our accuracy in targeting the cancer. As in
the example above for a brain tumor, MRI studies show greater image resolution
of soft tissue. However, dose calculations must be done on CT images for tissue
density corrections. Image Fusion Technology solves the problem by taking advantage
of both modalities. After image fusion is made, the physician outlines the
target on the MRI image. Corresponding target outline appears on the CT image,
ready for treatment planning and dose calculations. Another example above
demonstrates the benefit of fusion with PET scan images for a nasopharynx cancer.
PET Scan (Positron Emission Tomography) is a diagnostic examination that detects
cancer in our body. With CT-PET fusion technology, doctors can provide better
therapeutic outcome using its ability to precisely differentiate cancer cells
and normal tissue.
Treatment
parameters in Record & Verify system
In-room
monitor shows set-up instructions
IMPAC
Viewstation shows comparison
Record and Verify System
The
Record and Verify computer software on the treatment units helps the therapists
verify accurate treatment parameters.
SIEMENS
MX2 Linear Accelerator
BAT
Ultrasound Targeting Device
Elekta Synergy Image Guided Radiation Therapy Unit
Linear Accelerators
Radiation
treatments are done on a linear accelerator after the careful planning process
is completed. From one to seven or more beams may be treated daily each taking
about a minute. Digital films of each radiation beam are taken on the first day
and compared to the planned fields by the radiation oncologist to ensure accurate
field placement, before treatment begins.
