Why must a gamma camera be "peaked" every morning before use?

Which is the correct order of events that occur when a gamma ray is emitted from the patient?

1. A count is added at the x,y pixel location on the image matrix
2. The photocathode produces electrons which accelerate and multiply through the dynodes
3. The scintillation travels through the light pipe to the photocathode
4. The pulse travels through the PHA
5. A gamma ray passes through the collimator
6. The position circuit determines the x & y signal locations
7. A gamma ray interacts with the NaI(Tl) crystal to produce scintillation
8. The amplifier manipulates the Z-pulse

A nuclear medicine department receives a new gamma camera. The new camera has a larger number of smaller photomultiplier tubes than the older cameras currently in use. Which imaging characteristic will be most improved with the new camera?

When determining the X and Y coordinates of a gamma event, the positional signals are divided by the energy signal (Z) to normalize the signal. Failure to normalize the positional signal may have what result on the resulting image?

Which of the following is the correct definition of spatial resolution as it relates to conventional nuclear medicine imaging?

A static image is acquired with a 128x128 matrix. The minimum pixel value is 120 and the maximum pixel value is 18540. If using an 8-bit LUT array, what shade of grey will a pixel with a value of 18000 be assigned?

To obtain high resolution images of a small organ, gland, or joint, which collimator would be most useful?

A technologist changes the collimator on a gamma camera from a LEAP to a LEHR collimator. If the same number of counts is acquired, how will the acquisition time change when the high-resolution collimator is used?

For a parallel hole collimator, the best resolution is at:

Which of the following will increase the resolution of a "spot view" bone image obtained with a parallel hole collimator?

A technologist forgets to change the LEAP collimator before imaging a patient who has been injected with I-131 for a whole body metastatic survey. The resulting image is most likely to be affected by:

As a pinhole collimator is moved farther away from the thyroid, how will it affect the image?

A gamma camera is equipped with a parallel hole collimator. Sensitivity is affected by all of the following except:

The modulation transfer function (MTF) is a quantitative measure of a camera system's spatial and contrast resolution capabilities. Which of the following will result in a higher MTF value?

Temporal resolution is related to which of the following acquisition parameters?

It would be appropriate to apply temporal smoothing in which of the following studies?

If an image is acquired into a 128x128 matrix on a scintillation camera with a 350mm diameter field of view, what are the dimensions of each pixel?

Static frame mode acquisition is the most appropriate type of image acquisition for which of the following procedures?

Which of the following matrix sizes and acquisition modes would be most appropriate for a blood flow study of the feet?

When performing a whole-body bone scan, why is it important to have a 5 minute delay before the bed/detectors start(s) moving over the length of the patient after the acquisition is started?

Background correction is sometimes employed to enhance which of the following image characteristics?

Image resolution may be improved when imaging small objects by all of the following EXCEPT:

A static image of the femur is acquired to 100k counts on a 128x128 matrix. The average pixel noise is 6%. If the technologist wants to improve resolution by repeating the image with a 256x256 matrix, how many counts must be acquired to avoid increasing the average pixel noise?

A 50 cm camera with an image matrix of 128x128 is used to acquire an image of the spine. Information density in the region of the spine is 1850 cts/cm^2. What is the average count density per pixel?

The system resolution of a gamma camera is 9.5 mm. What is the largest pixel dimension that should be used with this system if we are to take full advantage of the system resolution?

Which of the following statements about an image acquired with zoom is true?

In which scenario may a logarithmic grey scale enhance visualization of the organ of interest?

A MUGA study is performed and the ROIs drawn by the technologist yield the following results:

ED counts: 143908
ES counts: 78094
Background counts: 7564
ED ROI size: 645 pixels
ES ROI size: 323 pixels
Background ROI size: 102 pixels

Calculate the LVEF.

How much memory will be needed for a MUGA study that is acquired in 30 frames with a 128x128 matrix in byte mode?

A daily uniformity flood for a scintillation camera should contain a minimum of how many counts?

In quantitating scintillation camera detector uniformity, the central field of view (CFOV) is defined as the diameter of the useful field of view (UFOV) multiplied by:

To perform pixel calibration, two capillary sources are placed on the camera surface 15 cm apart. From an image acquired using a 128x128 matrix, an activity profile is generated on the computer. If the profile shows that there are 45 pixels between the two activity peaks, the pixel size is:

If a PLES transmission phantom is used, how many images must be acquired to assess linearity over the entire field of view of a scintillation camera?

Using a 125 MBq source, 30,500 cpm were collected during a camera sensitivity determination. If the background count is 1200 cpm, what is the sensitivity of the instrument?

Which of the following radionuclide sources is used to acquire an extrinsic uniformity flood?

Sources of intrinsic non-uniformity include all of the following except:

Extrinsic quality control on a gamma camera means the quality control is done:

If a technologist is preparing a Tc-99m point source for an intrinsic uniformity flood, how much activity is sufficient for the image?

Linearity correction involves:

For the majority of physiologic studies, "cold" spots are areas on the image display that indicate:

A 1M count extrinsic flood is acquired with a Co-57 sheet source and is uniform in appearance, but it takes 2 minutes longer to acquire than normal. What is a possible explanation?