Radiotherapy Simulator (Radiation Therapy) Flashcards
Uses diagnostic x-ray tube as a radiation source and mimics the rafiotherapy machine.
Radiotherapy Simulator
Is the process of developing, evaluating and accpeting a treatement startegy for a given patient situation.
Simulation
The two purposes of a radiotherapy simulator
Tumor localization and Treatment Verification
Determines the extent of tumor and location of ctitical structures
Tumor Localization
Using of diagnostic quality images, it verifies the accuracy of the treatment plan befofe the actual treatment
Treatment Verificaction
The 2 process of simulation
Conventional simulation and Computed tomography simulation
Patient data is obtained using fluoroscopy, radiograph and physical measurements of patient
Conventional simulation
Patient data gathered using detailed CT images on the transverse plane
Fused process of patient scanning, tumor and target localizaton, treatment planning and treatment field verification unto single operation
Computed tomography simulation
It has the major advantagr of being able to construct a 3D image of the patient.
CT simulators
Mechanical Components of a conventional radiotherapy simulator
- Isocenter
- Gantry head
- Image intensifier system
- Patient table top
- Control area
Is referred to as the reference point in space where the gantry rotates (not done)
ISOCENTER
What are the Gantry Head components?
- Collimator assembly
- Optical distance indicator
- X-ray tube
- Field defining wires
- Beam imitating diaphragm
- Accessory holder
Directs the path of the beam toward the patient, after it emerges from the x-ray tube.
Collimator Assembly
Projects scale onto patients skin which corresponds to the SSD
Optical Distance Collimator (ODI)
X-ray tube
- Must have a large and small (no greater than 0.6mm) focal spot.
Field Defining Wires
Simulate a maximun fieldsize of 40 x 40 cm at 100cm SSD
Wires represent edge of treatment field within larger
image.
Beam restricting diaphragms
Optically indicates coverage of x-ray
field
Fiducial Plate
Plexiglas or plastic trays imbedded with
lead markers
Accessory Holder
Serves as holder for block tray holder
and electron cone holder
Patient Table Top
- Hard flat surface that minimally attenuates
the beam - Constructed out of carbon fiber
- Provide support identical to that of treatment
unit to maintain reproducibility
Mechanical Components of the Control Area
X-ray Generator
TV Monitor
Remote Control Panel
Observation Window
Room Design
X Recommended minimum size of 400sq.ft.
X Counter with sink, work space and writing area
X Storage for immobilization devices
X Ventilation
X Adjustable lighting for both treatment room and
control area
X Positioning lasers
X Provide therapist several external reference points in
relationship to the position of the isocenter
