Three inherent characteristics of a radiographic film:

 # Three inherent characteristics of a radiographic film:

a. density, distortion, contrast 

b. sharpness, contrast, density 

c. definition, sharpness, penumbra 

d. distortion, detail, sharpness 

The correct answer is: B. Sharpness, contrast, density.

Image quality describes the subjective judgment by the clinician of the overall appearance of a radiograph. It combines the features of density, contrast, latitude, sharpness, resolution, and perhaps other parameters.

Use of intensifying screen is:

 # Use of intensifying screen is:

a. to decrease scattered radiation 

b. to decrease patient radiation 

c. to increase contrast 

d. to increase number of photons striking the anode filament 

The correct answer is B. To decrease patient radiation.

The presence of intensifying screens creates an image receptor system that is 10 to 60 times more sensitive to x-rays than the film alone. Consequently, the use of intensifying screens substantially reduces the dose of x radiation to the patient. Intensifying screens are used with films for virtually all extraoral radiography, including panoramic, cephalometric, and skull projections.

Digital radiography differs from conventional in:

 # Digital radiography differs from conventional in:

a. X-rays not used 

b. Rays other than X-rays are used 

c. Radiation receptors are different 

d. No hard copy is formed 

The correct answer is C. Radiation receptors are different.

Digital image receptors encompass numerous different technologies and come in many different sizes and shapes. Numerous different and sometimes confusing names are in use to identify these receptors in medicine and dentistry. The most useful distinction is that between two main technologies: (1) solid-state technology and (2) photostimulable phosphor (PSP) technology. Although  solid-state detectors can be subdivided further, these detectors have in common certain physical properties and the ability to generate a digital image in the computer without any other external device.

In medicine, the use of solid-state detectors is referred to as digital radiography. In dentistry, intraoral solid-state detectors are often called sensors. The other main technology, PSP, consists of a phosphor-coated plate in which a latent image is formed after x-ray exposure. The latent image is converted to a digital image by a scanning device through stimulation by laser light. This technology is sometimes referred to as storage phosphor on the basis of the notion that the image information is temporarily stored within the phosphor. Other times the term image plates is used to differentiate them from film and solid-state detectors. The use of PSP plates in medical radiology is referred to as computed radiography.

Tzanck smear test is used in the diagnosis of:

 # Tzanck smear test is used in the diagnosis of :

a. Pemphigus 

b. ANUG 

c. Aphthous disease 

d. Lichen planus 

The correct answer is A. Pemphigus.

Pemphigus as an entity is characterized microscopically by the formation of a vesicle or bulla entirely intraepithelially, just above the basal layer producing the distinctive suprabasilar ‘split’. Prevesicular edema appears to weaken this junction, and the intercellular bridges between the epithelial cells disappear. This results in loss of cohesiveness or acantholysis, and because of this, clumps of epithelial cells are often found lying free within the vesicular space. These have been called ‘Tzanck cells’ and are characterized particularly by degenerative changes which include swelling of the nuclei and hyperchromatic staining. These changes are particularly obvious in cytologic smears taken from early, freshly opened vesicles.