MDS PREP
Filament in X-ray tube is heated by
1) Step-up high voltage transformer
2) Auto transformer
3) Step-down low voltage transformer
4) Ammeter
Radiology
Answer: 3
In an X-ray tube, the filament (cathode) is heated to produce electrons through a process called thermionic emission. This heating is accomplished by a step-down low voltage transformer, which reduces the high voltage from the power supply to a lower voltage suitable for heating the filament. The step-down transformer ensures that the filament receives the correct amount of current to achieve the necessary temperature for electron production.
Quality of x-ray beam is dependent on which component of dental unit
1. Autotransformer
2. Ammeter
3. Temperature of cathode filament
4. Step-down transformer
Radiology
Answer: 1
Quality of the x-ray beam is dependent on the temperature of the cathode filament.
Fractures of remus and body of mandible can be best seen in
1. Lateral oblique 30 degrees
2. Lateral oblique 15 degrees
3. PA view of mandible
4. Occipitomental view
Radiology
Answer: 2
Fractures of the ramus and body of the mandible can be best seen in lateral oblique 15 degrees.
Best X-ray for mesiodens is
1. Occlusal
2. PA view
3. Panorex
4. Bitewing
Radiology
Answer: 1
The best X-ray for mesiodens is occlusal.
Submentovertex is useful in viewing
1. Body of mandible
2. Fractures of zygomatic arch
3. Fractures of base of skull
4. All of the above
Radiology
Answer: 4
Submentovertex is useful in viewing all of the above: body of mandible, fractures of zygomatic arch, fractures of base of skull.
Ghost like shadow seen in
1. MRI
2. OPG
3. CT
4. Cephalogram
A ghost-like shadow is seen in an OPG.
Filament in X-ray tube is heated by
1. Step-up high voltage transformer
2. Auto transformer
3. Step-down low voltage transformer
4. Ammeter
Radiology
Answer: 3
The filament in the X-ray tube is heated by the step-down low voltage transformer.
Loss of lamina dura and ground glass appearance of bone is an early radiographic feature of
1) Osteogenesis imperfecta
2) Hyperparathyroidism
3) Osteopetrosis
4) Osteitis deformans
Radiology
Answer: 2
Hyperparathyroidism is a condition characterized by an
overproduction of parathyroid hormone (PTH), which leads to increased bone
resorption and changes in bone density. The radiographic features associated
with hyperparathyroidism include:
Loss of Lamina Dura: The lamina dura is the thin layer
of dense bone that lines the tooth socket (alveolus). In
hyperparathyroidism, the loss of lamina dura can be observed due to the
increased osteoclastic activity and bone resorption.
Ground Glass Appearance: This refers to a radiographic
appearance of bone that looks hazy or "ground glass" rather than having a
clear, well-defined structure. This appearance is due to the alteration in
bone density and the presence of fibrous tissue replacing normal bone.
Other Options:
Osteogenesis Imperfecta: This condition is characterized
by brittle bones due to a defect in collagen formation. Radiographically, it
may show thin cortices and osteopenia, but not typically a ground glass
appearance.
Osteopetrosis: This is a condition of excessive bone
density due to impaired osteoclast function. Radiographically, it shows
increased radiopacity (dense bones) rather than a ground glass appearance.
Osteitis Deformans (Paget's Disease): This condition is
characterized by disorganized bone remodeling. Radiographically, it can show
a "cotton wool" appearance and enlarged bones, but it does not typically
present with a loss of lamina dura or a ground glass appearance in the early
stages.