← Combined Technical (NG)
Past Questions
CR uses which detector type:
A)
Direct amorphous selenium
B)
Indirect gadolinium scintillator
C)
Photostimulable phosphor plate
D)
CCD chip
Computed Radiography (CR) uses a photostimulable phosphor plate as the image receptor. The plate stores the x-ray energy and is later scanned with a laser to release light, which is converted into a digital image.
Why others are incorrect:
- Direct amorphous selenium: used in direct digital radiography (DR), not CR.
- Indirect gadolinium scintillator: also used in DR detectors.
- CCD chip: used in some older digital imaging systems, not the standard detector in CR.
What is a major disadvantage of time-of-flight (TOF) MRA, particularly in cases of high-grade stenosis?
A)
Venous contamination from the imaging volume.
B)
Inaccurate quantification of blood flow.
C)
Overestimation of the severity of stenosis due to signal loss from turbulent flow.
D)
The need for a contrast agent, which increases risk for patients with renal failure.
Time-of-flight (TOF) MRA depends on inflowing blood producing strong signal. In high-grade stenosis, blood flow becomes slower and more turbulent, which can cause signal loss (flow-related dephasing). This makes the narrowed segment look worse than it really is, so TOF MRA may overestimate the severity of stenosis. Option (a) is a limitation more associated with venous contamination in some settings, (b) is not the major classic disadvantage asked here, and (d) is incorrect because TOF MRA is typically non-contrast-based.
What is the primary purpose of an oral cholecystogram (OCG)?
A)
To assess the function of the liver.
B)
To visualize the gallbladder and assess for the presence of gallstones or other abnormalities.
C)
To image the pancreas and bile ducts simultaneously using an endoscope.
D)
To measure the contractibility of the stomach.
An oral cholecystogram (OCG) is an X-ray study in which an oral contrast medium is taken up by the liver and excreted into bile, allowing the gallbladder to be visualized. Its main purpose is to evaluate the gallbladder for gallstones, obstruction, or other structural abnormalities. Option (a) is incorrect because OCG is not primarily a liver function test. Option (c) describes endoscopic procedures like ERCP, not OCG. Option (d) is unrelated to the biliary system.
HU Hounsfield Unit of water is:
A)
+1000
B)
0
C)
– 1000
D)
+ 500
In CT imaging, the Hounsfield Unit (HU) scale is defined so that distilled water at standard conditions is assigned a value of 0 HU. By convention, air is -1000 HU and dense bone can be around +1000 HU. Therefore, the HU of water is 0, making option (b) correct. Option (a) and (d) are positive values associated with denser materials, while option (c) corresponds to air.
Mandatory patient identification before imaging is:
A)
Name and father’s name
B)
Name and age
C)
Name and registration number
D)
Name, age, registration number and confirmation from the patient
Mandatory patient identification before imaging requires using multiple identifiers and confirming with the patient to avoid wrong-patient imaging errors. Option (d) is the most complete and safest choice because it includes name, age, registration number, and direct confirmation from the patient. The other options use fewer identifiers and are therefore less reliable.
What is the role of ‘radiofrequency pulses’ in MRI?
A)
To excite the aligned hydrogen nuclei
B)
To generate the reversed electronic field
C)
To capture sonographic impulses
D)
To provide contrast enhancement
In MRI, the strong magnetic field aligns hydrogen nuclei (protons). Radiofrequency (RF) pulses then provide energy at the right frequency to excite these aligned nuclei and tip them away from equilibrium. When the RF pulse is turned off, the nuclei relax and emit signals used to form the image. Option (b) is incorrect because MRI does not use a reversed electronic field, (c) refers to ultrasound, not MRI, and (d) contrast enhancement is achieved by contrast agents, not by RF pulses themselves.
A delayed contrast reaction typically occurs within what time frame after contrast administration?
A)
Less than 1 hour.
B)
1 to 7 days.
C)
1 to 4 weeks.
D)
Immediately during injection.
Delayed contrast reactions are non-immediate hypersensitivity reactions that usually occur after 1 hour and most commonly within 1 to 7 days following contrast administration. Immediate reactions happen during injection or within the first hour, so options (a) and (d) are incorrect. Option (c) is too late for the typical delayed contrast reaction window.
What is the standard catheterization technique used to access blood vessels in conventional angiography?
A)
Retrograde puncture
B)
Seldinger technique
C)
Direct arterial injection
D)
Capillary insertion
In conventional angiography, blood vessels are typically accessed using the Seldinger technique. This method involves puncturing the vessel with a needle, inserting a guidewire, and then advancing a catheter over the guidewire into the vessel. It is the standard and safest widely used catheterization technique.
(a) Retrograde puncture is not the standard named catheterization method for conventional angiography.
(c) Direct arterial injection is not the usual catheter-based access technique.
(d) Capillary insertion is not used for angiographic catheterization.
HRCT lungs require which algorithm?
A)
Soft tissue
B)
Bone/ high-resolution kernel
C)
Standard
D)
Low-pass filter
HRCT (High-Resolution CT) of the lungs is reconstructed using a sharp, high-spatial-frequency algorithm, commonly called a bone or high-resolution kernel, to best show fine lung detail and interstitial changes. Soft tissue and standard kernels are too smooth and reduce edge definition, while a low-pass filter blurs fine structures, so they are not used for HRCT lung detail.
DSA stands for:
A)
Digital system angiography
B)
Digital Subtraction Angiography
C)
Digital Sound Analysis
D)
Digital Subtraction Analysis
DSA is the standard medical abbreviation for Digital Subtraction Angiography, a radiographic technique used to visualize blood vessels after subtracting pre-contrast images from contrast-enhanced images. The other options are incorrect because they do not represent the recognized full form of DSA.
MRI works on the principle of interaction between magnetic fields and:
A)
Carbon
B)
Oxygen
C)
Hydrogen
D)
Sodium
MRI primarily works by aligning the nuclei of hydrogen atoms (protons) in the body using a strong magnetic field. When these protons are disturbed by radiofrequency pulses, they emit signals that are used to create images. Hydrogen is abundant in water and fat, making it ideal for MRI. Carbon, oxygen, and sodium are not the main basis of standard MRI imaging.
What is ‘road mapping’ in DSA?
A)
A 3D reconstruction of the vascular system.
B)
A tool to measure the distance between two vessels.
C)
An overlay of a mask image onto the fluoroscopic image to guide catheter placement.
D)
A technique to identify the contrast’s flow rate.
In Digital Subtraction Angiography (DSA), ‘road mapping’ means superimposing a previously acquired contrast-filled mask image on the live fluoroscopic image. This creates a visual guide of the vessels, helping the operator advance and place the catheter accurately. Option (a) is incorrect because it refers to 3D reconstruction, which is a different imaging technique. Option (b) is incorrect because road mapping is not used to measure distance. Option (d) is incorrect because it has nothing to do with determining contrast flow rate.
Which of the following is a common contraindication for the use of iodinated contrast in CT scans?
A)
Allergies to food like shellfish
B)
History of asthma
C)
Pregnancy
D)
All of the above
Iodinated contrast media can be used with caution or avoided in certain patients because of a higher risk of adverse reactions. A history of asthma is a known risk factor for contrast reactions. Pregnancy is generally considered a relative contraindication unless the scan is necessary, because CT involves radiation exposure and contrast use must be carefully justified. Allergy history, including reported shellfish allergy, is commonly asked in exams as a precautionary concern, although shellfish allergy is not a true specific predictor of iodinated contrast allergy. Since the question asks for a common contraindication in a broad exam sense, the intended answer is 'All of the above.'
The process of converting the raw CT data (projections) into a visible cross-sectional image is called:
A)
Windowing.
B)
Filtering.
C)
Reconstruction.
D)
Compression.
In CT scanning, the raw projection data collected by the detectors is mathematically processed to create a visible cross-sectional image. This process is called reconstruction. Windowing only adjusts image brightness and contrast for viewing, filtering modifies data to improve image quality, and compression is for reducing data size, not image formation.
The contrast used in MRI is
A)
Iodinated contrast
B)
Gadolinium based contrast
C)
Barium
D)
Air
MRI commonly uses gadolinium-based contrast agents to improve image visibility and highlight blood vessels, tumors, inflammation, and other abnormalities. Iodinated contrast is typically used in CT scans and angiography, barium is used for gastrointestinal X-ray studies, and air may be used as a negative contrast agent in some procedures but not for MRI contrast.
DICOM stands for:
A)
Digital Communication
B)
Digital Imaging and Communications in Medicine
C)
Data Interchange for Medical Images
D)
Digital Compression
DICOM is the standard used in medical imaging for storing, transmitting, and sharing images and related data. It stands for Digital Imaging and Communications in Medicine. The other options are incorrect because they either expand only part of the term or describe unrelated concepts.
What is the function of the TFT (Thin-Film Transistor) array in a digital mammography detector?
A)
To focus the X-ray beam onto the breast.
B)
To read out the electrical charges that form the digital image.
C)
To compress the breast during the exposure.
D)
To filter the X-ray beam.
In a digital mammography detector, the TFT (Thin-Film Transistor) array is used as the readout matrix. It collects and sequentially reads the electrical charges produced in the detector pixels after X-ray exposure, converting them into a digital image. Option (a) is incorrect because focusing the X-ray beam is not the detector’s job. Option (c) is incorrect because breast compression is done by the mammography unit, not the TFT array. Option (d) is incorrect because X-ray beam filtration is done by filters, not the detector readout system.
Which colour typically represents blood flow moving away from the transducer in a standard colour map?
A)
Red
B)
Green
C)
Yellow
D)
Blue
In standard colour Doppler ultrasound mapping, blood flow moving toward the transducer is typically shown in red, while flow moving away is shown in blue. Therefore, the correct answer is Blue. Green and yellow are not the standard direction codes in the usual colour map.
A CT tube has a rotating:
A)
Filament
B)
Cathode
C)
Anode
D)
Target
In an X-ray tube used in CT, the **anode** is made to rotate to spread the heat produced by the electron beam over a larger area. The filament and cathode are stationary parts of the electron source, and the target is usually part of the anode assembly.
ECG gating in CT coronary angiography for:
A)
Reducing motion artifacts
B)
Removing noise
C)
Increasing pitch
D)
Detecting calcifications
ECG gating in CT coronary angiography synchronizes image acquisition with a specific phase of the cardiac cycle, usually during minimal coronary motion. This reduces motion artifacts and improves visualization of the coronary arteries. It is not primarily used for removing noise, increasing pitch, or detecting calcifications.
Which property of a medium primarily determines how much sound is reflected at the boundary between two different media?
A)
Density
B)
Stiffness
C)
Acoustic impedance
D)
Speed of sound
The amount of sound reflected at the boundary between two media depends mainly on the difference in their acoustic impedances. Acoustic impedance is the product of density and speed of sound in the medium (Z = ρc). A larger mismatch in acoustic impedance causes greater reflection. Density, stiffness, and speed of sound each influence acoustic impedance, but by themselves they do not directly determine reflection as accurately as acoustic impedance does.
Post-procedure care after a myelogram typically includes which instruction?
A)
Engage in strenuous activity immediately to circulate the contrast.
B)
Lie flat for a prolonged period (e.g., 24 hours).
C)
Fast for 12 hours after the procedure.
D)
Rest with the head elevated (less than 30 degrees) for several hours and drink plenty of fluids.
After a myelogram, the patient is usually advised to rest with the head slightly elevated and to increase fluid intake to help clear the contrast and reduce the risk of headache or other post-lumbar puncture symptoms. Strenuous activity is avoided, so (a) is incorrect. Lying flat for 24 hours is not the typical instruction in routine post-myelogram care, so (b) is incorrect. Fasting after the procedure is not required, so (c) is incorrect.
The ideal time to perform HSG is:
A)
During menstrual period
B)
During ovulation
C)
7-10 days after menstruation
D)
20-30 days after menstruation
Hysterosalpingography (HSG) is ideally performed in the early proliferative phase of the menstrual cycle, usually 7–10 days after menstruation ends. At this time, the endometrium is thin, which gives better visualization, and the procedure is done before ovulation to avoid the risk of disturbing an early pregnancy. During menstruation it may cause more bleeding and poor imaging, during ovulation there is pregnancy risk, and 20–30 days after menstruation is too late in the cycle.
What type of X-ray beam is used in a multi-slice CT scanner?
A)
A cone-shaped beam.
B)
A pencil beam.
C)
A fan-shaped beam.
D)
A parallel beam.
In a multi-slice CT scanner, the X-ray beam used is a fan-shaped beam that covers multiple detector rows simultaneously. This allows the scanner to acquire several slices in one rotation. A pencil beam is used in older single-slice or some special scanning setups, and a parallel beam is not used in CT. A cone-shaped beam is more associated with cone-beam CT systems, not standard multi-slice CT.
What should the patient be told to expect during the intravenous contrast injection?
A)
A warm, flushed sensation and a metallic taste in their mouth.
B)
A feeling of coldness spreading through their body.
C)
Pain and numbness at the injection site.
D)
Shortness of breath and difficulty breathing.
During an intravenous contrast injection, a patient is commonly told to expect a brief warm or flushed feeling and sometimes a metallic taste in the mouth. These are normal, transient effects of contrast media. Option (b) is less typical for IV contrast, while (c) suggests an abnormal injection-site reaction or extravasation, and (d) indicates a possible allergic or adverse reaction, not a routine expected sensation.