Image Formation and Processing in Computed Tomography

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What is the primary function of an analog-to-digital converter (ADC) in a digital computer?

To display the output digital image on a monitor

To convert analog signals into digital signals (correct)

To convert digital signals into analog signals

To process the digital image

What does each pixel in a digital image represent?

The average attenuation of all tissue being imaged (correct)

The brightness level of a single tissue type

The size of the pixel in the image

The color of the tissue being imaged

What is the effect of decreasing the Field of View (FOV) on pixel size, assuming the matrix size is constant?

The pixel size decreases (correct)

The pixel size becomes undefined

The pixel size increases

The pixel size remains the same

What is the purpose of converting the output digital image back into an analog signal?

To display the image on a monitor (C) Signup and view all the answers

What is the formula to calculate the pixel size?

Pixel size = FOV / Matrix size (A) Signup and view all the answers

What can be adjusted to alter the image contrast and brightness in computed tomography?

Window Width and Window Level (B) Signup and view all the answers

What is the formula to calculate the upper grey level in computed tomography?

WL + (WW ÷ 2) (D) Signup and view all the answers

What is the purpose of post-processing in computed tomography?

To manipulate raw data and image data (A) Signup and view all the answers

What is the lower grey level when the Window Level is 0 and the Window Width is 1000?

-500 (D) Signup and view all the answers

What is the name of the window with a Window Width of 150 and a Window Level of 600?

Lung window (A) Signup and view all the answers

What will be the value of the upper grey level when the Window Level is 80 and the Window Width is 40?

120 (B) Signup and view all the answers

What is the typical window width value used to image the mediastinum?

350 (A) Signup and view all the answers

What is the effect of a narrow window width on an image?

It decreases the number of shades of grey (A) Signup and view all the answers

What is the purpose of adjusting the window width and level in CT imaging?

To optimize the image quality for a specific area of interest (C) Signup and view all the answers

What is the typical window level value used to assess the lung fields?

-600 (C) Signup and view all the answers

What is the effect of a wide window width on an image?

It decreases the contrast between different structures (B) Signup and view all the answers

Which of the following structures has a high attenuation value?

Bone (A) Signup and view all the answers

What is the main advantage of Volume Rendering in Computed Tomography?

It allows the image to display multiple tissues and their relationship to one another. (D) Signup and view all the answers

Which 3D image technique is favored in Computed Tomography?

Volume Rendering (VR) (A) Signup and view all the answers

What is the main characteristic of 3D Maximum Intensity Projection (MIP) Rendering?

It selects pixels with highest attenuation value along any arbitrary line. (C) Signup and view all the answers

What is the result of using 3D Maximum Intensity Projection (MIP) Rendering in Computed Tomography?

It tends to display bone and contrast filled structures. (D) Signup and view all the answers

What is the purpose of 3D Minimum Intensity Projection (MinIP) Rendering in Computed Tomography?

To reconstruct an image by selecting the pixels with lowest attenuation value from the line. (A) Signup and view all the answers

What is the purpose of defining a Region of Interest (ROI) on an image?

To perform statistical calculations such as mean and standard deviation (D) Signup and view all the answers

Which of the following is a function of the 'tools' in image display?

Region of Interest (ROI) definition (D) Signup and view all the answers

What is the unit of measurement for average CT numbers?

Hounsfield Units (HU) (A) Signup and view all the answers

What is the purpose of a histogram in Computed Tomography?

To display the distribution of CT numbers (D) Signup and view all the answers

What is the term for the area on the image defined by the operator for statistical calculations?

Region of Interest (ROI) (B) Signup and view all the answers

What is the benefit of using Virtual Reality (VR) and Maximum Intensity Projection (MIP) in image display?

To enhance the visualization of complex structures (C) Signup and view all the answers