Treatment Simulation & Immobilization Flashcards
7 cards from real CMD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Treatment Simulation & Immobilization flashcards as text
What is the primary purpose of CT simulation in radiation therapy treatment planning?
Answer: To define the patient's 3D anatomy and establish treatment geometry
CT simulation provides volumetric anatomical data necessary for target volume delineation, beam arrangement, and dose calculation in treatment planning.
Which immobilization device is most commonly used for head and neck cancer treatments?
Answer: Thermoplastic mask
Thermoplastic masks are custom-molded to the patient's facial contour and harden at room temperature, providing reproducible immobilization for head and neck treatments.
What is the recommended CT slice thickness for treatment planning of head and neck tumors?
Answer: 3 mm or less
Slice thicknesses of 3 mm or less provide superior anatomical detail for delineating complex structures in the head and neck region and improve dose-volume histogram accuracy.
What is the purpose of using a flat couch insert during CT simulation?
Answer: To match the flat treatment couch geometry for consistent patient positioning between simulation and treatment
A flat couch insert replicates the flat linac treatment couch surface so the patient geometry at simulation matches treatment delivery conditions.
Which patient preparation protocol is typically followed during prostate cancer CT simulation to reduce normal tissue dose?
Answer: Supine position with full bladder and empty rectum
A full bladder displaces the small bowel superiorly out of the treatment field while an empty rectum minimizes rectal volume receiving high dose.
What is the primary function of intravenous (IV) contrast during CT simulation?
Answer: To enhance visualization of blood vessels and tumor boundaries for target delineation
IV contrast enhances hypervascular tissues and blood vessels, helping to distinguish tumor margins from surrounding normal anatomy during target volume delineation.
Radio-opaque BB markers placed on a patient's skin during CT simulation serve what primary purpose?
Answer: To mark reference or isocenter locations visible on CT images for planning and tattoo placement
BBs appear as bright high-density objects on CT images, allowing the dosimetrist to identify the precise anatomical location of planned isocenter or reference marks.