nuc med instrumentation gamma camera jeopardy board

An Oncologist told a patient they DID NOT have cancer when they actually had breast cancer

false negative

Iodine escape peaks happen at lower energies because they can penetrate further into the crystal and are absorbed by the crystal?

true or false?

false

In a Geiger counter, __________ is determined by how long it takes for the detector to recover from the Geiger discharge.

dead time

This factor increases in nuclear medicine images when count statistics are low, producing a grainy appearance that can obscure small lesions or fine detail.

noise

In this type of system, each detected event renders the detector completely unresponsive until the dead time has fully elapsed — no new events can be processed during that interval.

paralyzable system

As total counts in an image increase, this unwanted random fluctuation decreases, making the image appear smoother and more uniform.

noise

This nuclear medicine acquisition mode captures a series of rapid sequential images to assess changing tracer distribution over time

dynamic imaging

A higher number of smaller pixels allows finer detail to be displayed — this characteristic of the image improves.

resolution

This distribution is used to predict the probability of detecting zero, one, or more photon events in a given time when the events occur independently.

poisson distribution

This simple equation determines pixel size when you know the detector's field of view and the number of samples used to digitize it.

pixel size = field of view ÷ number of pixels (matrix dimension)?

When performing intrinsic flood testing without a collimator, the activity of Tc-99m should never exceed this value.

<1mCi

FDG PET/CT can show uptake in many inflammatory or malignant processes — it's great for detection, but not always for distinction, meaning it is what type of test?

sensitive

High-energy photons are more likely to penetrate the septa. To reduce this effect, the collimator design should include this change in septal thickness.

increase septal thickness

A technologist performing an Indium-111 Octreotide scan should choose this collimator to reduce septal penetration from the 173 and 247 keV photons.

medium energy collimator

Ideal for localizing adenomas in the neck, this collimator type produces an inverted, magnified image.

pinhole collimator

Increasing the NaI crystal thickness from 3/8 inch to 5/8 inch raises this property for high-energy photons but may blur fine detail.

detector sensitivity

When performing the weekly resolution test, the phantom should be placed this way relative to the detector face to assess intrinsic resolution.

directly on detector face with collimator removed?

A technologist switches from a LEAP to this collimator type to improve image detail for a spot view bone image, accepting longer acquisition time.

LEHR collimator

As the object-to-collimator distance becomes smaller, this image quality factor of a pinhole collimator improves.

spatial resolution

A technologist switches from a LEAP to a LEHR collimator, effectively reducing hole diameter. The image requires a longer acquisition time because this parameter drops sharply.

sensitivity

This acquisition parameter affects pixel resolution and image detail, but not the speed of collecting a fixed number of counts.

matrix size

During a bar phantom test, straight lines appear wavy or curved, even though energy peaking is accurate. This correction needs adjustment.

linearity correction

This process enlarges the image after acquisition by simply stretching existing pixels on the screen—no new detail is gained.

magnification

This QC test requires around 5 million counts to detect non-uniformities greater than 5% across the useful field of view.

daily uniformity flood

When using a pinhole collimator for thyroid imaging, the technologist should always remember: the image will be

inverted and magnified

When imaging high-energy isotopes, this peak may appear as an additional bump below the photopeak due to photons produced inside the collimator, not the patient.

lead xray peak

This isotope contaminant in a Co-57 flood source increases integral uniformity readings because its higher-energy photons cause septal penetration and scatter.

Co-58

A technologist is going to conduct an intrinsic uniformity test today. What do they need to complete the test?

a <1mCi Tc99m point source

To correctly assess linearity in the X and Y directions, two images are taken with what type of phantom used for QC testing of resolution?

PLES phantom

This phantom measures linearity only and requires acquiring two perpendicular images, while the other measures both linearity and distortion from one image.

PLES phantom and orthogonal hole phantom

As counts increase, this factor decreases, improving the ability to detect low-contrast lesions in organs such as the liver or lungs.

noise

The star artifact becomes more prominent when imaging isotopes with this photon energy characteristic.

high gamma ray energy

This test ensures that photons from Tc-99m (140 keV) and In-111 (171 and 245 keV) appear in the same spatial location when imaging simultaneously.

multiple window spatial registration

When a disease is very common, this predictive value decreases because negative test results are more likely to be false negatives.

negative predictive value

Linearity correction compensates for non-uniform response of these components that determine event position.

PMT

A technologist repeats a liver image using double the counts. The cold lesions are now easier to see because this image factor improves with increased counts.

contrast to noise

Proper peaking of this region ensures the system accepts only full-energy photons and rejects scatter, resulting in improved image contrast and accuracy.

photopeak

When imaging a bar phantom, a wavy or striped interference pattern appears instead of clean, straight bars. This artifact is known as this.

moire pattern

When a radiopharmaceutical doesn't properly bind to its intended target, the unbound portion circulating through the body contributes to this in the final image.

background activity

A dose calibrator that gives the same value every time, but that value is 10% lower than true activity, demonstrates this property?

precision

A technologist performs a flood with the collimator on and notices ring-like defects. The issue could be from collimator damage, so this test should be repeated under these conditions.

What is intrinsic uniformity (without the collimator)

This correction file is created for each isotope used in the clinic to adjust for detector response differences at that isotope's specific photon energy.

uniformity correction map

This type of uniformity measures variations over the entire field of view and is typically larger than the value calculated for adjacent pixel pairs.

integral uniformity

Peaking the gamma camera on a patient results in a spectrum dominated by Compton scatter, causing the true photopeak to shift in this direction on the energy scale.

toward lower energies

For a properly functioning gamma camera, daily flood is considered acceptable if it falls within what limits?

5-6%

This smaller peak appears below the photopeak and results from photons that scatter off the camera housing, table, or collimator before re-entering the detector.

backscatter peak

This early nuclear medicine imaging system was the first to produce visual maps of radionuclide distribution, paving the way for the development of the gamma camera.

rectilinear scanner

Applying this process too aggressively can make bar phantoms or bone edges appear blurred, masking fine detail.

over smoothing