May the odds be ever in your favour!
The scattered radiation during a diagnostic x-ray examination arises mainly as a result of....
a) Coherent scattering
b)Compton Effect
c) Photoelectric effect
d) Rayleigh scattering
b) Compton effect
As the kV is increased, the contrast between soft tissue and bone seen in a radiographic image will...
a) Decrease regardless of choice of IR
b) Decrease when using photostimulable phosphor and increase when using digital radiography.
c) Increase regardless of choice of IR
d) Increase when using photostimulable phosphor and decrease when using digital radiography.
a) Decrease regardless of choice of IR
The x-ray tube current (mA) influences which one of the following parameters?
a) Anode absorption
b) Maximum x-ray energy
c) Number of x-ray photons
d) Tissue penetration
c) Number of x-ray photons
Which of the following would be the most suitable for measuring the absorbed dose to the fingers during fluoroscopy?
a) Film badge
b) Ionization chamber
c) Scintillation detector
d) Thermoluminescent dosimeter
d) Thermoluminescent dosimeter
The effective dose a patient receives from a single PA chest x-ray is approximately...
a) 0.02 mSv
b) 0.2 mSv
c) 2 mSv
d) 20 mSv
e) 200 mSv
a) 0.02 mSv
The effective dose of a chest radiograph is less than that of abdominal, pelvic or spinal radiographs. The approximate effective dose of a CT study of the chest is 2 mSv. These figures are likely to change/decrease over time alongside technological advancements.
The type of x-ray interaction with matter in which all of the energy of the incident photon is expended in dislodging a bound electron is called...
a) coherent scattering
b) pair production
c) photoelectric effect
d) Rayleigh scattering
c) Photoelectric effect.
Which one of the following has minimal effect on the patient's skin dose?
a) Beam filtration
b) Focal spot size
c)Irradiated field size
d) Total scan length
b) Focal spot size
The focal spot influences imaging geometry, but is not directly related to skin dose.
The x-ray tube current is dictated by the...
a) Anode rotation speed
b) Kilovoltage
c) Filament current and kilovoltage
d) Filament current
c) Filament current and kilovoltage
Which one of the following is a stochastic effect of radiation exposure?
a)erythema
b)epilation
c)genetic defects
d)reduced blood cell count
c) Genetic defects.
Stochastic effects occur by chance and can be compared to deterministic effects which result in a direct effect.
The average annual effective dose limit for pregnant occupationally exposed personnel is...
a) 0.1 mSv
b) 0.5 mSv
c) 1 mSv
d) 5 mSv
e)10 mSv
f) 15 mSv
c) 1 mSv
When a filter is used to harden a diagnostic energy x-ray beam, it does so mainly by...
a)Pair production
b) Rayleigh scatter
c) Pair production
d) Photoelectric absorption
d) Photoelectric absorption
The intensity of an x-ray beam is reduced as it passes through a material because of collisions between the x-ray photons and the atoms of the material. The beam is said to be attenuated because the collisions result in both the absorption and the scattering of photons. The main absorption process, the photoelectric effect totally removes photons from the radiation beam and is utilized in filtration.
In the context of radiobiology which is FALSE?
a)cells tend to be more radiosensitive when young
b)cells which divide rapidly are more radiation sensitive
c)greater metabolic activity increases radiation resistance
d)the radiation sensitivity of cells can be increased by certain drugs
e)water is the most abundant source of free radicals
c)greater metabolic activity increases radiation resistance
An apron with a 0.5 mm lead equivalent thickness typically attenuates scattered 100 kVp x-rays by what amount?
a)50%
b)75%
c)90%
d)95%
e)100%
d) 95%
A hypothetical patient receives an entrance skin dose of 20 Gy after a cardiac pacemaker insertion. The most likely effect is which of the following?
a) No effect
b) Transient erythema
c) Skin damage over the irradiated area with no healing after several months.
d) Gastrointestinal syndrome
c) Skin damage over the irradiated area with no healing after several months.
Which of the following dose reduction techniques will improve image quality?
a)increasing kVp
b)increasing beam filtration
d)gonad shielding
e)collimating to minimum field size
f)increasing exposure time
e)collimating to minimum field size
Skull Bone sutures typically hinder the extension of...
a) extradural (epidural) hematomas
b) subarachnoid hematomas
c) subdural hematomas
d) subgaleal hematomas
a) extradural (epidural) hematomas
Skin damage following irradiation is an example of an early somatic effect. This means the severity of erythema...
a)is dependent on dose and it occurs in the irradiated area after a few days to a few weeks
b)is dependent on dose and it occurs in the irradiated area within a few minutes
c) is not dependent on dose but occurs in the irradiated area after a few days to a few weeks
d) is not dependent on dose but occurs in the irradiated area within a few minutes
a) Is dependent on dose and it occurs in the irradiated area after a few days to a few weeks
Skin injury has been found to be sensitive to factors such as previous high dose exposure, medication, connective tissue disease and diabetes mellitus. Single-site skin doses in interventional radiology above 2 Gy, for example, have been found to cause erythema and epilation and higher doses to cause permanent skin damage.
A radiologist wants to improve the spatial resolution of the anatomy being examined. The change most likely to lead to this is...
a)decreased collimation
b)increased field of view, same matrix size
c)increased matrix size, same field of view
d)selection of a smoothing algorithm
c)increased matrix size, same field of view
The image matrix comprised of columns (M) and rows (N) that define the elements or pixels within an image. The size of an image is:
The field of view is the size of the displayed image. However, if you maintain the same FOV and increase the matrix the pixels will be smaller and hence spatial resolution is improved.
Patient skin dose rate will decrease with kV only when the...
a) collimators are fully open
b) grid is removed
c) pulse rate is increased
d) tube current is reduced
d) tube current is reduced
Increasing either the current or time will increase the quantity of radiation; therefore the amount of radiation in an examination is represented as mAs.
The image file format most widely used throughout digital medical imaging is...
a)BMP
b)GIF
c)DICOM
d) HDR
e) JPEG
f) TIFF
c)DICOM
An 8:1 grid is replaced with a 12:1 grid. This will have the effect of...
a)decreasing contrast and patient radiation dose
b)increasing contrast and patient radiation dose
c)increasing contrast and reducing patient radiation dose
d)increasing contrast with no change in patient radiation dose
b)increasing contrast and patient radiation dose
The working ability of a grid is described by the grid ratio, which is the ratio of the height of the lead strips to the distance between two strips (the interspace). The higher the grid ratio, the better the image contrast but at a cost of increased patient dose. Grid ratio of 8:1 is generally used for 70-90 kVp technique and 12:1 is used for >90 kVp technique.
In computed tomography, an undersampling artefact is also known as...
a) aliasing artefact
b) cupping artefact
c) metal artefact
d) out of field artefact
e) windmill artefact
a) aliasing artefact
Aliasing artefact, otherwise known as undersampling, in CT, refers to an error in the accuracy proponent of analog to digital converter (ADC) during image digitization.
In computed tomography, streak artifact appears as a result of...
a) beam hardening
b) motion
c) partial volume averaging
d) tube arcing
e) undersampling
a) beam hardening
Streak artifact occurs as a result of beam hardening, it appears between two dense objects; it has the appearance of multiple dark bands. It is the result of the polychromatic X-ray being ‘hardened’ at different rates in the tube position.
The most suitable plain radiographic chest projection to examine the area of the lung apices often obscured in a PA projection is...
a) AP erect view
b) lateral view
c) lordotic view
d) right anterior oblique view
e) supine view
c) lordotic view
The plain radiographic projection named the Coyle view is utilized to evaluate the...
a) acetabulum
b) calcaneus
c) glenohumeral joint
d) radial head
e) talus
d) radial head
The Coyle view of the elbow is an axial projection that is performed in addition to the standard elbow series when there is suspicion of a radial head fracture. The projection isolates the radial head using a modified radiographic technique.