CSLB General Building (B) — All Questions

Which description matches the paralleling technique for intraoral radiography?

• a.The receptor rests against the tooth and the beam is aimed at an imaginary bisector
• b.The receptor is placed parallel to the long axis of the tooth and the central ray is directed perpendicular to both✓
• c.The receptor is held by the patient's finger at a 45-degree angle
• d.The receptor is placed outside the cheek and the beam passes through the face

In the paralleling technique a holding device positions the receptor parallel to the long axis of the tooth, and the central ray is directed perpendicular to both, which minimizes dimensional distortion. Aiming at an imaginary bisector describes the bisecting technique. Finger holding is discouraged because it causes movement and unnecessary exposure, and placing the receptor outside the cheek describes extraoral imaging.

A processed periapical image shows teeth that appear stretched and longer than they actually are. What caused this error?

• a.Excessive horizontal angulation
• b.Excessive vertical angulation
• c.Insufficient vertical angulation✓
• d.The receptor was placed backward

Elongation results from insufficient vertical angulation, which projects an image longer than the actual tooth. Excessive vertical angulation causes the opposite error, foreshortening, in which teeth appear too short. Horizontal angulation errors produce overlapped contacts rather than length distortion, and a reversed receptor produces a light image with a herringbone pattern.

A maxillary premolar image shows teeth that look squat and shorter than normal, with crowns and roots compressed. The most likely cause is:

• a.Excessive vertical angulation✓
• b.Insufficient vertical angulation
• c.Incorrect horizontal angulation
• d.Underexposure of the receptor

Foreshortening, in which teeth appear shortened and compressed, is caused by excessive vertical angulation. Insufficient vertical angulation would produce elongation instead. Horizontal angulation errors cause overlapping of proximal contacts, and underexposure produces a light image without changing tooth length.

A finished radiograph has a clear, unexposed curved area along one border. What is this error called and what causes it?

• a.Reticulation, caused by a sudden temperature change in processing
• b.Fog, caused by an old developer solution
• c.Double exposure, caused by exposing the same receptor twice
• d.Cone cut, caused by misalignment of the position-indicating device with the receptor✓

A cone cut is the clear, unexposed area that appears when the beam does not fully cover the receptor because the PID was not properly aligned. Reticulation shows a cracked emulsion pattern from abrupt temperature shifts. Fog produces overall grayness and reduced contrast, and a double exposure shows two superimposed images rather than a blank border.

On a set of bitewings, the proximal contacts between the premolars are superimposed and cannot be read for caries. What should be corrected on the retake?

• a.Increase the exposure time
• b.Change the vertical angulation to +20 degrees
• c.Direct the central ray through the contacts by correcting the horizontal angulation✓
• d.Move the receptor closer to the lingual surface of the teeth

Overlapped contacts are a horizontal angulation error; the central ray must pass directly through the interproximal spaces, perpendicular to the curve of the arch in that region. Exposure time affects density, not overlap. Vertical angulation controls length distortion, and shifting the receptor lingually does not correct the beam direction through the contacts.

Which vertical angulation is customarily used for a posterior bitewing exposure?

• a.0 degrees, with the beam exactly horizontal
• b.About +10 degrees, angled slightly downward✓
• c.About -15 degrees, angled upward
• d.About +40 degrees, steeply downward

A vertical angulation of roughly +10 degrees is standard for bitewings; the slight downward angle compensates for the tilt of the receptor and the curve of the palate. A true 0-degree setting often produces overlapping of the occlusal surfaces. Negative angulation is used for some mandibular projections rather than bitewings, and +40 degrees is far too steep and would foreshorten the image.

A patient has a shallow palate and cannot tolerate a paralleling holder, so the bisecting technique is used. Where is the central ray directed?

• a.Perpendicular to the long axis of the tooth only
• b.Perpendicular to the plane of the receptor only
• c.Perpendicular to an imaginary line that bisects the angle formed by the tooth's long axis and the receptor✓
• d.Parallel to the occlusal plane at 0 degrees

In the bisecting technique the central ray is aimed perpendicular to an imaginary bisector of the angle between the long axis of the tooth and the plane of the receptor, which keeps the projected length close to the true length. Aiming perpendicular to the tooth alone causes elongation and perpendicular to the receptor alone causes foreshortening. A 0-degree parallel beam does not apply to periapical projections.

A developed film is very light overall and shows a faint pattern of tiny diamonds or a herringbone design. What happened?

• a.The developer was too warm
• b.The film was left in the fixer overnight
• c.The patient moved during the exposure
• d.The film packet was placed in the mouth backward, so the beam passed through the lead foil first✓

The herringbone or tire-track pattern is imprinted by the lead foil backing when the packet is reversed, and the foil also absorbs much of the beam, producing a light image. A warm developer produces a dark image rather than a light one. Prolonged fixing bleaches the image but leaves no herringbone pattern, and patient movement produces blurring.

Every film processed this morning came out much darker than normal, although patient positioning was correct. Which cause is MOST likely?

• a.Overexposure or developer solution that is too warm or too concentrated✓
• b.Depleted fixer solution
• c.Insufficient vertical angulation
• d.A cracked lead apron

Excessive density across an entire batch points to overexposure or to developer that is too warm, too strong, or used too long, since all of these increase image darkness. Depleted fixer leaves films cloudy or milky rather than dark. Vertical angulation errors change tooth length, not density, and the lead apron plays no part in image density.

A radiograph appears too light and washed out even though the exposure settings were verified as correct. Which processing problem should be checked first?

• a.Developer temperature that is too high
• b.Developer solution that is too cold, too weak, or developing time that was too short✓
• c.Excessive fixing time
• d.Safelight bulb wattage that is too low

A light image with correct exposure settings usually means underdevelopment from cold, exhausted, or diluted developer, or from pulling the film too early. A developer that is too hot would produce a dark image instead. Excessive fixing gradually bleaches the image but is a much less common cause, and a low-wattage safelight makes the darkroom dimmer without lightening the image.

Films from one box consistently appear gray with poor contrast, even on unexposed control films. What is the most likely explanation?

• a.The vertical angulation was too steep
• b.The patient was not wearing a lead apron
• c.The PID was too long
• d.Film fog from a light leak, scatter radiation, or outdated or improperly stored film✓

Overall grayness with reduced contrast, including on unexposed control films, is classic fog caused by stray light in the darkroom, storage near a radiation source, heat and humidity, or expired film. Angulation errors distort shape, not overall density and contrast. The lead apron does not affect the image, and a longer PID improves sharpness rather than causing fog.

Several archived radiographs have turned yellowish-brown over the past year. What most likely caused this deterioration?

• a.The films were exposed at too high a kVp
• b.Insufficient rinsing or exhausted fixer left chemicals in the emulsion✓
• c.The films were developed for too long
• d.The patient moved during the exposures

Yellow-brown discoloration that develops over time indicates residual fixer or thiosulfate left in the emulsion because of exhausted fixer or inadequate final washing. High kVp lowers contrast at the time of exposure but does not cause later staining. Overdevelopment darkens the image immediately, and patient movement causes blurring rather than color change.

On a panoramic image the anterior teeth appear narrow and blurred while the posterior teeth look acceptable. What positioning error occurred?

• a.The patient was positioned too far forward, anterior to the focal trough✓
• b.The patient was positioned too far back in the focal trough
• c.The patient's chin was tipped too far up
• d.The patient's spine was too straight

When the patient stands too far forward, the anterior teeth fall in front of the focal trough and are projected narrow and blurred. Positioning too far back produces the opposite appearance, with anterior teeth wide and magnified. A raised chin flattens the occlusal plane into a reverse smile, and a slumped rather than straight spine causes a radiopaque shadow over the anterior region.

A panoramic image shows a blurred radiopaque shape on the opposite side of the arch, higher than the real object. What is this artifact and how is it prevented?

• a.A cone cut, prevented by aligning the PID
• b.Reticulation, prevented by controlling solution temperature
• c.A ghost image, prevented by removing earrings, necklaces, and other metal objects before the exposure✓
• d.Elongation, prevented by increasing vertical angulation

A ghost image is created when the rotating beam passes through a dense object such as an earring twice, projecting a blurred, magnified duplicate on the opposite side and slightly higher. Removing all jewelry, eyeglasses, hairpins, and removable appliances before the exposure prevents it. Cone cut, reticulation, and elongation are intraoral or processing errors unrelated to this rotating-beam phenomenon.

A child with a suspected fractured anterior alveolus cannot tolerate periapical placement. Which projection shows a broad view of an entire arch on a single large receptor?

• a.Vertical bitewing
• b.Occlusal radiograph✓
• c.Cephalometric radiograph
• d.Interproximal radiograph

An occlusal radiograph uses a large receptor held between the occlusal surfaces and shows a wide segment of the maxilla or mandible, making it useful for locating fractures, impacted teeth, and salivary stones. Vertical bitewings show crowns and bone levels of a limited region. A cephalometric image is an extraoral skull projection, and interproximal is another name for the bitewing.

When taking a maxillary molar periapical with the paralleling technique, where should the receptor be positioned?

• a.Toward the midline of the palate, away from the teeth, so it stays parallel to their long axes✓
• b.Pressed directly against the lingual surfaces of the molars
• c.Angled 45 degrees against the palatal tissue
• d.Outside the cheek over the zygomatic arch

The receptor must be placed toward the middle of the palate so it can remain parallel to the long axes of the molars, with the holder maintaining that relationship. Pressing it against the lingual surfaces tilts the receptor and destroys parallelism. A 45-degree angle belongs to the bisecting approach, and placement outside the cheek describes an extraoral projection.

The dentist orders a posterior bitewing survey on an adult with all posterior teeth present and closed contacts. How many images are typically taken?

• a.One image centered on the midline
• b.Two images, one per arch
• c.Four images, premolar and molar on each side✓
• d.Twelve images covering every posterior tooth individually

A standard adult posterior bitewing survey consists of four images: a premolar and a molar view on each side, which together show interproximal surfaces and crestal bone. A single midline image cannot open posterior contacts. One image per arch is not how bitewings work, since each bitewing records both arches, and twelve images would deliver unnecessary radiation.FDA/ADA Dental Radiographic Examinations: Recommendations for Patient Selection and Limiting Radiation Exposure

Which routine quality-assurance test lets an office detect gradual changes in processing solutions before image quality suffers?

• a.Weighing the lead apron each month
• b.Counting the number of retakes per patient
• c.Measuring the length of the position-indicating device
• d.Exposing a stepwedge daily and comparing the densities with a reference film✓

A stepwedge exposed under identical conditions each day produces a strip of known densities that can be compared with a reference, so drift in developer strength or temperature is caught early. Weighing the apron and measuring the PID check equipment condition, not solution performance. Retake counts are a useful indicator but reveal problems only after images have already failed.

An image of an elderly patient shows the entire radiograph blurred, with no sharp outlines anywhere. What is the most likely cause?

• a.Reversed placement of the receptor
• b.Exhausted fixer solution
• c.Movement of the patient, receptor, or tubehead during the exposure✓
• d.Vertical angulation set at 0 degrees

Generalized blurring with loss of detail throughout the image indicates motion of the patient, the receptor, or the tubehead during exposure, and it is prevented by stabilizing the head and instructing the patient to hold still. A reversed receptor produces a light image with a herringbone pattern rather than blur. Exhausted fixer leaves a milky appearance, and a 0-degree vertical angulation distorts length instead of blurring the entire image.

Using the bisecting technique, how does vertical angulation differ between maxillary and mandibular projections?

• a.Both arches always use 0 degrees
• b.Maxillary projections use negative angulation and mandibular projections use positive angulation
• c.Both arches use the same positive angulation
• d.Maxillary projections use positive (downward) angulation and mandibular projections use negative (upward) angulation✓

Maxillary projections require the beam to be directed downward, which is a positive vertical angulation, while mandibular projections require an upward, negative angulation. Using 0 degrees for both would badly distort tooth length. Reversing the two, or applying the same positive value to both arches, produces elongation or foreshortening depending on the arch.

What is the purpose of the raised identification dot on intraoral film, and how should it be oriented during placement?

• a.It marks the lead foil side and must face away from the beam
• b.It allows the operator to determine the patient's left and right during mounting, and the convex side faces the beam, toward the occlusal or incisal edge✓
• c.It indicates the expiration date and should face the tongue
• d.It has no clinical function and may be oriented in any direction

The identification dot establishes orientation so the mounted series can be correctly assigned to the patient's right and left; the raised convex side faces the beam and is positioned toward the occlusal or incisal edge to avoid obscuring apical structures. It does not mark the lead foil, which is on the back of the packet facing away from the beam. The dot carries no date information, and orienting it randomly makes accurate mounting impossible.

Which head position is correct when preparing a patient for a panoramic radiograph?

• a.Midsagittal plane perpendicular to the floor and Frankfort plane parallel to the floor✓
• b.Midsagittal plane tilted 30 degrees to the right
• c.Chin raised as high as the patient can comfortably hold it
• d.Head turned so the patient can watch the machine rotate

Correct panoramic positioning centers the midsagittal plane perpendicular to the floor and keeps the Frankfort plane parallel to the floor, which places the arch within the focal trough and yields a level occlusal plane. Tilting or turning the head magnifies one side and reduces the other. A raised chin produces a flat or reverse-smile occlusal plane and distorts the anterior region.

A panoramic radiograph shows a dark radiolucent band across the apices of the maxillary teeth. What instruction was missed?

• a.The patient should place the tongue firmly against the roof of the mouth during the exposure✓
• b.The patient should breathe deeply throughout the exposure
• c.The patient should close the eyes during the exposure
• d.The patient should hold the receptor with both hands

A dark band over the maxillary apices is the palatoglossal air space, which appears when the tongue is not pressed against the palate and air is trapped between them. Deep breathing increases motion artifact rather than preventing this shadow. Closing the eyes has no radiographic effect, and panoramic receptors are held by the machine, never by the patient.

Which darkroom test verifies that the safelight is not fogging film?

• a.Exposing a stepwedge and comparing densities
• b.Placing a thermometer in the developer for five minutes
• c.The coin test, in which a coin is placed on an unwrapped film under the safelight before processing✓
• d.Running a cleaning film through the automatic processor

In the coin test an unwrapped film is left under the safelight with a coin on it for a few minutes; if the coin's outline is visible after processing, the safelight is fogging the film and the bulb, filter, or distance must be corrected. The stepwedge test monitors solution activity rather than safelight integrity. Checking developer temperature and running a cleaning film address processing quality, not light leakage.

An office uses photostimulable phosphor (PSP) plates. A faint image from the previous patient appears on a new radiograph. What was omitted?

• a.The plate was not sterilized in the autoclave
• b.The plate was not soaked in disinfectant for ten minutes
• c.The plate was not exposed at a higher kVp
• d.The plate was not erased with the light source after scanning before being reused✓

PSP plates retain latent image data until they are erased by exposure to a bright light source, so skipping the erasure step leaves a ghost of the previous image on the next radiograph. Autoclaving and prolonged soaking would destroy the plate; PSP plates are barrier-protected and disinfected according to the manufacturer's instructions instead. Raising kVp changes beam energy and does not remove residual image data.