Test: General Radiology - 1 - NEET PG MCQ

In paediatric patients, the dosage should be decreased.

A Tc-thallium subtraction scan is a diagnostic imaging procedure that helps assess myocardial perfusion.

• It involves the use of two different radiopharmaceuticals: Technetium-99m (Tc-99m) and thallium-201.
• The Tc-99m is administered first, followed by thallium-201.
• This technique allows for the identification of ischaemic areas of the heart by comparing the uptake of these two substances.
• The results can help determine the presence and severity of coronary artery disease.

The inferior mesenteric artery is a crucial blood vessel that supplies the lower part of the colon and rectum. It branches from the abdominal aorta and provides blood to several key areas, including:

• The descending colon
• The sigmoid colon
• The rectum

This artery plays a significant role in ensuring adequate blood flow to these regions, which is vital for maintaining their function and health. Its branches include the left colic artery, sigmoid arteries, and the superior rectal artery, each contributing to the vascularisation of the lower gastrointestinal tract.

The linear attenuation coefficient is a fundamental parameter that characterises how materials absorb or scatter radiation. It is defined as follows:

• The coefficient represents the fraction of radiation that is absorbed or scattered per unit thickness of the material.
• It is typically denoted by the symbol μ.
• This value is crucial in fields such as radiology, nuclear engineering, and radiation physics.
• Understanding the linear attenuation coefficient helps in determining the necessary shielding required to protect against harmful radiation.

As the thickness of the material increases, the intensity of the radiation decreases exponentially according to the equation:

I = I₀e^-μx

Where:

• I is the intensity of radiation after passing through the material.
• I₀ is the initial intensity before entering the material.
• x is the thickness of the material.

The best X-ray view for diagnosing lumbar spondylosis is the Lateral view. This view provides a clear image of the lumbar spine's structure and alignment, making it easier to identify any degenerative changes or abnormalities.

• The Lateral view shows the spine from the side, allowing for better assessment of vertebral spacing and any potential disc issues.
• It helps in visualising the curvature of the spine and identifying conditions like osteophytes or narrowing of the spinal canal.
• Other views, such as the PA view and oblique views, are less effective for this specific condition.

The bone algorithm is a method used for reconstructing images, particularly in the field of medical imaging.

• It focuses on enhancing the quality and accuracy of images derived from various scanning techniques.
• This algorithm operates by applying specific mathematical models to improve visual representation.
• It is particularly beneficial in situations where traditional imaging methods may fall short.

In essence, the bone algorithm plays a crucial role in ensuring that medical images are as clear and informative as possible, aiding in accurate diagnosis and treatment planning.

Microwaves are a form of electromagnetic radiation with wavelengths ranging from one millimetre to one metre. They are commonly used in various applications, such as:

• Cooking food in microwave ovens
• Communication technologies, including mobile phones and satellite transmissions
• Radar systems for detecting objects and measuring distances

In microwave ovens, the radiation excites water molecules in food, generating heat. The advantages of using microwaves include:

• Rapid cooking times
• Energy efficiency compared to conventional ovens
• Ability to reheat food without drying it out

However, there are some concerns associated with microwave use, such as:

• Potential nutrient loss in some foods
• Uneven cooking, which may leave cold spots
• Safety issues related to improper use of microwave containers

Open fontanelles are the soft spots on an infant's skull where the bones have not yet fused together. These areas are crucial for:

• Allowing for the baby's brain to grow
• Facilitating passage through the birth canal

Typically, fontanelles close as the child grows, with the anterior fontanelle usually closing by the age of 18 months and the posterior fontanelle by 2 to 3 months.

Position emission tomography (PET) is a sophisticated imaging technique that allows for the observation of metabolic processes within the body. It works by detecting gamma rays emitted from a radiotracer, which is a substance introduced into the body that emits positrons as it decays.

• The radiotracer is typically a form of glucose, labelled with a radioactive isotope.
• As cells metabolise the glucose, the emitted positrons collide with electrons, leading to the production of gamma rays.
• The PET scanner detects these gamma rays and constructs detailed images of the metabolic activity in various tissues.

This technique is particularly valuable in oncology, as it helps to identify cancerous tissues by highlighting areas of increased metabolic activity. Additionally, it can be used in neurology to assess brain function and in cardiology to evaluate heart conditions.

It’s a poorly constructed question, my friends; ideally, the body section of the CT should have been specified.

Placenta previa is a condition during pregnancy where the placenta is positioned abnormally low in the uterus. This can lead to complications, particularly during delivery.

• In cases of placenta previa, the placenta may cover the cervix partially or completely.
• This condition can cause significant bleeding during pregnancy and delivery.
• It is crucial for pregnant individuals diagnosed with this condition to receive proper medical care and monitoring.
• Management may involve bed rest or a planned cesarean delivery, depending on the severity of the situation.

• A PET scan, or Positron Emission Tomography scan, is a sophisticated imaging procedure.
• It enables medical professionals to observe metabolic processes in the body.
• The scan employs a radioactive substance, known as a tracer, which is introduced into the body.
• This tracer emits positrons, which are detected by the PET scanner.
• The resulting images provide insights into the functional activity of organs and tissues.
• PET scans are particularly useful in oncology, cardiology, and neurology.
• They can help in diagnosing conditions such as cancer, heart disease, and brain disorders.

Magnetic Resonance Imaging (MRI) is a non-invasive medical imaging technique that utilises strong magnetic fields and radio waves to generate detailed images of organs and tissues inside the body. It is particularly useful for visualising soft tissues, such as:

• Muscles
• Brain
• Spinal cord
• Joints

MRI does not involve ionising radiation, making it a safer alternative to other imaging methods such as X-rays or CT scans. The process typically involves the following steps:

• The patient is positioned on a movable table that slides into a large, cylindrical magnet.
• Radiofrequency pulses are applied to the area being examined.
• Images are generated based on the response of the hydrogen atoms in the body.

These images can then be analysed by healthcare professionals to diagnose and monitor various medical conditions, including:

• Brain disorders
• Musculoskeletal injuries
• Tumours

Overall, MRI is a vital tool in modern medicine, providing crucial insights into a patient's health without the need for invasive procedures.

A CT-guided biopsy is a medical procedure used to obtain a tissue sample for diagnostic purposes. This technique involves the following:

• Utilising computed tomography (CT) imaging to accurately locate the area of concern within the body.
• Inserting a thin needle through the skin and into the targeted tissue.
• Extracting a small sample of tissue for laboratory analysis.

The advantages of this method include:

• Precise targeting, which minimises damage to surrounding healthy tissues.
• It can be performed on various parts of the body, including the lungs, liver, and kidneys.
• It typically requires only local anaesthesia, making it less invasive than surgical biopsies.

After the procedure, the sample is examined by a pathologist to determine the presence of any abnormalities, such as cancer or infections. The results aid in diagnosing the patient's condition and planning further treatment if necessary.

In magnetic resonance imaging (MRI), paramagnetic substances have a significant effect on relaxation times. They lead to:

• Shortening of T1 relaxation time, which affects how quickly the protons return to their equilibrium state after being disturbed.
• Shortening of T2 relaxation time, which relates to how quickly the protons lose coherence among themselves.

This means that paramagnetic substances can reduce the time it takes for both T1 and T2 relaxation processes in MRI imaging.

Ultrasound waves used in medical imaging have frequencies that vary significantly. In ultrasound imaging, the frequency is crucial for determining how well the images are produced and the depth of penetration into tissues.

• 2000 Hz is too low for effective imaging.
• 5000 Hz is also inadequate for medical purposes.
• Frequencies below 2 MHz are typically not used in ultrasound imaging.
• Frequencies above 2 MHz are ideal and commonly used in ultrasound.

Thus, the correct frequency range for ultrasound in medical imaging is above 2 MHz.

Gadolinium is a rare earth element that belongs to the lanthanide series on the periodic table.

It is represented by the symbol Gd and has the atomic number 64.

• Gadolinium is known for its high magnetic susceptibility, making it useful in various applications.
• It is commonly employed in magnetic resonance imaging (MRI) as a contrast agent.
• Additionally, gadolinium compounds are used in the manufacturing of phosphors for television screens and LED lights.

This element is typically obtained through the reduction of its oxides.

Due to its properties, gadolinium plays a significant role in the field of medical imaging and other technological advancements.

Water is a vital substance for all known forms of life. It covers approximately 71% of the Earth's surface, primarily in oceans, rivers, and lakes. Water is essential for various biological processes, including:

• Regulating temperature
• Transporting nutrients
• Facilitating chemical reactions

Its unique properties, such as high specific heat and solvent capabilities, make it crucial for sustaining ecosystems. Water exists in three states: solid (ice), liquid, and gas (vapour), depending on the temperature and pressure conditions.

Iodinated nonionic, water-soluble contrast

They are utilised in magnetic resonance imaging.