Chapter 22 CT Sim Procedures Flashcards
It may be used in a variety of forms, including
EPID, an in-room CT scanner, kV cone beam computed tomography, MV cone beam computed tomography, ultrasound and others. Rational for IGRT is to image the patient just prior to treatment, compare the position of external set-up marks and internal anatomy to the treatment plan.
image guided radiation therapy (IGRT)
Diagnostic, nonionizing means of visualizing
internal anatomy through noninvasive means. Imaging is based on the magnetic properties of the hydrogen nuclei.
magnetic resonance imaging (MRI)
Nuclear medicine procedure that has become
useful in oncology to examine the biochemical or physiological (functional) aspects of a tumor. This diagnostic tool is useful in determining the physiology of the organ in question. Beneficial diagnostic
tool that may be useful in determining differences
between necrosis and malignancy, which are associated with areas of high metabolism.
positron emission tomography (PET)
Single-photon emission computed tomography
Single photons are imaged from gamma ray source. SPECT can be used to assess lung perfusion and assess amount of functional lung tissue.
Devices that restrict movement but require a patient’s
voluntary cooperation.
immobilization devices
Geometrical definition of the tumor and anatomic structures using surface and/or fiducial marks for
reference
Localization
Process carried out by the radiation therapist under the supervision of the radiation oncologist. It is part of the treatment planning procedure, which delineate
the treatment fields and construct any
necessary immobilization or treatment devices.
Simulation
Final check that each of the planned treatment beams does cover the tumor or target volume and does not irradiate normal tissue structures.
Verification
Material with a high atomic number used to document structures radiographically.
Radiopaque marker
High-density substances used radiographically to visualize internal anatomy for imaging.
Contrast media
Measurement of the thickness of a patient along the central axis or at any other specified point within the
irradiated volume.
Separation
Dimensions of a treatment field at the isocenter (usually represented by width ¥ length)
Field size
Based on acquired CT information, these are images that render a beam’s eye view display of the treatment field anatomy and areas of treatment interest. These images resemble conventional radiographs
Digitally reconstructed radiograph
This is the change in target position from one fraction to another
Interfraction motion
Changes or motion during the treatment administration.
Intrafraction motion
