Computed Tomography Knowledge Questions and An Flashcards
7 cards from real Computed Tomography Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Computed Tomography Knowledge Questions and An flashcards as text
What is the primary safety concern when scanning a patient with a pacemaker using CT?
Answer: Potential image artifacts affecting diagnostic quality
While CT does not emit RF waves that affect pacemaker function, metallic pacemaker components cause streak artifacts that can limit evaluation of surrounding cardiac and mediastinal structures.
What is meant by 'isotropic voxels' in CT imaging?
Answer: Voxels with equal dimensions in all three spatial planes (x, y, z)
Isotropic voxels have equal length, width, and height, enabling high-quality multiplanar and 3D reconstructions without resolution loss in any plane.
A technologist notes that a CT image has a mottled, grainy appearance. Which adjustment would most directly improve this?
Answer: Increase mAs
Increasing mAs increases X-ray photon flux, reducing quantum (photon) noise and improving the signal-to-noise ratio of the image.
Which structure should be visible in a CT scan performed at the level of the carina?
Answer: Bifurcation of the trachea into the left and right main bronchi
The carina is the cartilaginous ridge at the inferior end of the trachea marking its bifurcation into the left and right main bronchi, located at approximately T4–T5.
What is the role of iterative reconstruction (IR) in modern CT imaging?
Answer: To reduce image noise at lower radiation doses compared to filtered back projection
Iterative reconstruction algorithms model the acquisition process and iteratively correct image data, enabling diagnostic image quality at significantly reduced radiation doses.
In CT, what does the acronym 'FOV' stand for and what does it control?
Answer: Field of View — controls the size of the reconstructed image area
Field of View (FOV) defines the diameter of the reconstructed image; a smaller FOV zooms in on a region of interest and improves apparent spatial resolution.
What is the typical HU range for simple fluid (such as pleural effusion or ascites) on CT?
Answer: 0 to 20 HU
Simple transudative fluid (water-density) typically measures 0–20 HU, as it is close to pure water (0 HU) in composition.