18 Technique & Patient Positioning Practice Questions & Answers

1. 1. An assistant is setting up a maxillary molar periapical using a beam-alignment device and the paralleling technique. Which geometric relationship must be established before the exposure is made?

   • A.The receptor is placed parallel to the long axis of the tooth, and the central ray is directed perpendicular to that axis.✓ Answer
   • B.The receptor is placed at a slight angle to the long axis, and the central ray is directed perpendicular to the crowns of the teeth imaged.
   • C.The receptor is placed parallel to the occlusal plane, and the central ray is directed at a positive vertical angulation through the contacts.
   • D.The receptor is placed against the lingual surface of the tooth, and the central ray is directed perpendicular to the bisector of the angle formed.

   The paralleling technique has two inseparable geometric rules: the receptor is parallel to the long axis of the tooth, and the central ray meets both the receptor and that long axis at a right angle. Satisfying both keeps the projected image dimensionally accurate, because the tooth and the recording surface stay in the same plane and the beam does not distort length. Directing the ray at a bisector is the bisecting technique, not paralleling.

   Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — paralleling technique; DANB Radiation Health and Safety Exam Outline, imaging techniqueReport a problem with this question

2. 2. To keep the receptor parallel to the long axis of a maxillary molar, the assistant must position it away from the tooth toward the midline of the palate. This increased object-receptor distance enlarges the image. What compensates for that enlargement?

   • A.The receptor is tipped toward the crown so the object-receptor distance is reduced again before the exposure is made.
   • B.The target-receptor distance is increased with the longer position-indicating device, which limits enlargement and sharpens detail.✓ Answer
   • C.The exposure time is shortened so that fewer photons reach the receptor and the projected image spreads less widely.
   • D.The vertical angulation is increased so the central ray strikes the receptor more steeply and shortens the projected image.

   Parallelism can only be achieved by moving the receptor away from the tooth, and any object-receptor separation magnifies the image. Increasing the target-receptor (source-object) distance makes the beam that reaches the tooth more nearly parallel, so divergence and therefore magnification fall and penumbra narrows. That is why the longer position-indicating device is standard with paralleling; angulation and exposure time do not change image size.

   Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — object-receptor and target-receptor distance in the paralleling techniqueReport a problem with this question

3. 3. A patient has a shallow (low) palatal vault, and the receptor in its holder cannot be brought into a parallel position without the bite block tipping away from the teeth. What is the appropriate modification?

   • A.Increase the vertical angulation with the paralleling device still seated, and expose the projection exactly as planned.
   • B.Bend the corner of the receptor against the palate so it lies flat, and have the patient steady the holder with a finger.
   • C.Place a cotton roll on the bite block opposite the receptor, or change to the bisecting angle technique for the projection.✓ Answer
   • D.Change to the largest receptor so its width braces against the palate, and shorten the exposure time to limit blurring.

   A low vault leaves no vertical space, so the receptor cannot stand parallel to the long axes. A cotton roll placed on the bite block cushions the bite, keeps the receptor from tipping and moves it slightly away from the crowns, restoring usable geometry; when that fails, the bisecting angle technique is the recognized alternative because it accepts a receptor that touches the lingual surfaces. Receptors are never bent, and no one holds the receptor for a co-operative patient.

   Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — technique modifications for shallow palatal vaultReport a problem with this question

4. 4. A patient has large bilateral mandibular tori on the lingual surfaces of the premolar region. Where should the receptor be placed for the mandibular premolar periapical?

   • A.Between the tori and the teeth, so the receptor wedges into the space and the patient's own bite keeps it stable.
   • B.Between the tori and the tongue, so the receptor lies medial to the growths and settles toward the floor of the mouth.✓ Answer
   • C.Against the buccal surfaces of the premolars, so the tori are avoided and the receptor clears the floor of the mouth.
   • D.On top of the tori, so the bony growths support the receptor and hold it parallel to the long axes of the teeth.

   Mandibular tori occupy the space where the receptor would normally sit, and resting a receptor on top of them tips it, causes pain and cuts off the apices. Directing the receptor between the tori and the tongue lets it drop into the floor of the mouth medial to the bone, so the full root length is covered and the patient is comfortable. Receptors are never placed on the buccal side, where the beam would pass through the entire arch.

   Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — technique modifications for mandibular toriReport a problem with this question

5. 5. In the bisecting angle technique the receptor rests against the lingual surfaces of the teeth and forms an angle with the long axis of the tooth. How is the central ray directed?

   • A.Parallel to the imaginary bisector, so the beam travels along that line and passes through the contacts of adjacent teeth.
   • B.Perpendicular to an imaginary line that bisects the angle formed by the long axis of the tooth and the receptor plane.✓ Answer
   • C.Perpendicular to the plane of the receptor itself, aligned exactly as the central ray is aligned in the paralleling technique.
   • D.Perpendicular to the long axis of the tooth alone, so that the tooth is recorded at its true length on the resulting image.

   The bisecting technique applies the rule of isometry: two triangles sharing a common side are equal when they have two equal angles, so a ray aimed perpendicular to the bisector records the tooth at approximately its true length even though the receptor is not parallel to it. Aiming perpendicular to the receptor produces elongation and aiming perpendicular to the tooth produces foreshortening, which is why the bisector, not either structure alone, governs vertical angulation.

   Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — bisecting angle technique and the rule of isometryReport a problem with this question

6. 6. An adult with a narrow arch and a small mouth cannot tolerate the size 2 receptor in its holder for the anterior periapicals; the corners impinge painfully on tissue every time it is seated. What is the appropriate modification?

   • A.Use the next smaller receptor positioned with its long dimension vertical, adding projections to cover the region.✓ Answer
   • B.Use the largest occlusal receptor held between the arches, exposing one image in place of all the anterior projections.
   • C.Use the same size 2 receptor turned with its long dimension horizontal, and raise the exposure time to cover the region.
   • D.Use the same receptor without any holder, asking the patient to steady it so it can be pushed further back with a finger.

   A narrow arch limits the width available, so the correct adjustment is to reduce receptor size and orient the receptor vertically, which follows the curve of the anterior segment and spares the soft tissue; more projections are then taken because each covers less area. Enlarging the receptor or turning it horizontally worsens the impingement, and fingers are never used to hold a receptor because the digit is then in the primary beam.

   Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — receptor size selection and technique modification for the narrow archReport a problem with this question

7. 7. A patient with a strong gag reflex is scheduled for four bitewings and gags as soon as the holder approaches the posterior region. Which approach best manages this during the appointment?

   • A.Seat the patient upright, expose the premolar projections first, and have the patient breathe through the nose.✓ Answer
   • B.Have the patient rinse with cold water, expose the molar projections first, and slide the receptor along the palatal midline.
   • C.Ask the patient to hold the receptor with a finger, expose the anterior projections first, and pause between images.
   • D.Recline the patient fully, expose the molar projections first while co-operation is highest, and have the patient hold the breath.

   Gagging is triggered by contact with the posterior palate and by anxiety, so the working rules are to keep the patient upright, work from the least provocative projection to the most provocative one, and give the patient a competing task such as nasal breathing. The premolar bitewing is far less likely to provoke the reflex than the molar view, so it goes first; reclining the patient and sliding the receptor along the palate both make gagging worse.

   Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — patient management of the gag reflexReport a problem with this question

8. 8. The assistant has seated a horizontal bitewing on its tab with the patient closed in centric occlusion. How should the central ray be directed for this projection?

   • A.Straight ahead at zero vertical angulation, aimed at the mesial surface of the first molar rather than at the interproximal contacts.
   • B.Downward at a steep positive vertical angulation, aimed at the crestal bone lying below the contacts of the posterior teeth.
   • C.Downward at a slight positive vertical angulation, passing horizontally through the interproximal contacts of the posterior teeth.✓ Answer
   • D.Upward at a slight negative vertical angulation, passing horizontally through the interproximal contacts of the posterior teeth of both arches.

   A bitewing receptor is not exactly vertical in the mouth: it tilts slightly because of the curve of Spee and the tab, so a small downward (positive) vertical angulation puts the beam at a right angle to the receptor and keeps the crowns of both arches on the image. The horizontal component matters just as much, since only a ray passing through the contact areas keeps the proximal surfaces open rather than overlapped.

   Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — bitewing technique and vertical angulationReport a problem with this question

9. 9. Where should the anterior edge of the receptor be aligned for a premolar bitewing so that every required contact is captured?

   • A.At the midline of the mandibular first premolar, so the receptor is centred between the two premolars of the quadrant.
   • B.At the distal surface of the mandibular first molar, so the receptor reaches back far enough to include the third molar.
   • C.At the midline of the mandibular lateral incisor, so the anterior teeth are included together with the premolar contacts.
   • D.At the midline of the mandibular canine, so the distal of the canine and both premolar contacts are recorded.✓ Answer

   The premolar bitewing must open the contact between the canine and the first premolar as well as the two premolar contacts, and the only placement that achieves this is with the front edge of the receptor at the middle of the mandibular canine. Positioning further forward wastes receptor area on the anterior teeth and cuts off the distal contacts; positioning further back loses the canine contact entirely and forces a retake.

   Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — premolar and molar bitewing receptor placementReport a problem with this question

10. 10. Before seating a patient in the panoramic unit, the assistant checks what the patient is wearing and what is in the mouth. Which set of items must be removed first?

    • A.Fixed crowns, bridges and orthodontic bands, since cemented metal casts the same artifact as removable metal does.
    • B.Intraoral metal alone, such as a denture, since objects outside the mouth fall outside the focal trough and are not recorded.
    • C.Earrings and necklaces alone, since eyeglasses, hairpins and removable prostheses sit outside the path of the beam.
    • D.Earrings, necklaces, hairpins, eyeglasses, oral piercings and any removable complete or partial denture.✓ Answer

    In panoramic imaging the source rotates around the head, so dense objects anywhere in that path are recorded, and metal outside the focal trough also produces a ghost image projected to the opposite side, higher and magnified. Every removable radiopaque object worn on the head and neck or carried in the mouth therefore comes off before positioning. Cemented restorations cannot be removed and are simply accepted as part of the anatomy.

    Source: Bird & Robinson, Modern Dental Assisting — panoramic imaging patient preparation; Iannucci & Howerton, Dental Radiography — ghost imagesReport a problem with this question

11. 11. A patient is standing in the panoramic unit with the chin on the chin rest. Which combination of positioning landmarks is correct before the exposure is started?

    • A.Midsagittal plane tilted toward the side of interest, Frankfort plane parallel to the floor, mandibular incisors ahead of the bite groove.
    • B.Midsagittal plane perpendicular to the floor, chin raised well above the Frankfort plane, anterior teeth edge to edge on the bite stick.
    • C.Midsagittal plane perpendicular to the floor, Frankfort plane parallel to the floor, anterior teeth end to end in the bite groove.✓ Answer
    • D.Midsagittal plane parallel to the floor, Frankfort plane perpendicular to the floor, anterior teeth end to end in the bite groove.

    Panoramic geometry records only what lies inside the focal trough, and the trough is shaped to an average arch positioned in a specific way: the midsagittal plane vertical prevents rotation and unequal magnification, the Frankfort plane horizontal sets the correct chin height, and the end-to-end bite in the groove places the anterior teeth in the centre of the trough rather than in front of or behind it.

    Source: Bird & Robinson, Modern Dental Assisting — panoramic patient positioning; Iannucci & Howerton, Dental Radiography — focal troughReport a problem with this question

12. 12. Immediately before starting the panoramic exposure the assistant gives one final instruction. Which instruction prevents a radiolucent air shadow from crossing the maxillary apices?

    • A.Press the tongue flat against the hard palate and keep it there through the whole exposure cycle.✓ Answer
    • B.Keep the tongue relaxed on the floor of the mouth and swallow once as the tubehead passes the front.
    • C.Hold the lips slightly apart so the air anterior to the teeth is not compressed during the rotation.
    • D.Push the tongue forward between the incisors so the bite stick is gripped firmly during the rotation.

    If the tongue is not held against the hard palate, the air space between tongue and palate is in the beam path and records as a dark palatoglossal air shadow superimposed on the maxillary apices, which can obscure structures or be mistaken for pathology. The correction is prospective and free: instruct the patient to seal the tongue to the palate and hold it there for the full rotation, and confirm the lips are closed.

    Source: Bird & Robinson, Modern Dental Assisting — panoramic technique errors and patient instructionsReport a problem with this question

13. 13. A patient who uses a wheelchair and cannot transfer to the dental chair needs posterior bitewings, and cannot hold the receptor because of a hand tremor. Who may stabilize the receptor during the exposure?

    • A.The assistant taking the images, using one gloved finger for the fraction of a second the exposure actually lasts.
    • B.A second staff member from the clinical team, with the duty rotated among employees so that no one is exposed often.
    • C.A family member who accompanied the patient, after being given protection and clear instructions on how to hold it.✓ Answer
    • D.The dentist who prescribed the images, since the dentist carries clinical responsibility for the projections ordered.

    Occupational exposure is cumulative and repeated across a working life, so no member of the dental team ever holds the receptor, the patient or the tubehead, and rotating the task among staff does not solve the problem because it still irradiates employees. When stabilization is genuinely unavoidable, an accompanying adult who is not pregnant and is not an employee assists, positioned and protected and instructed by the operator.

    Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — operator protection rules and patients requiring assistanceReport a problem with this question

14. 14. The assistant is about to expose a maxillary anterior periapical using the bisecting angle technique. How should the head be positioned, and why does head position matter more here than with a beam-alignment device?

    • A.Occlusal plane parallel to the floor and the head turned toward the tubehead, because the beam must enter the cheek at a right angle.
    • B.Occlusal plane tipped down toward the chest and midsagittal plane perpendicular, because the receptor must clear the palatal vault first.
    • C.Mandibular occlusal plane parallel to the floor and the chin raised, because the maxillary apices then sit directly above the beam path.
    • D.Maxillary occlusal plane parallel to the floor and midsagittal plane perpendicular, because vertical angulation is referenced to the floor.✓ Answer

    In the bisecting technique the operator sets vertical angulation from a scale on the tubehead that is calibrated against the floor, so the patient's occlusal plane must actually be horizontal or every angulation reading is wrong and the image elongates or foreshortens. A rigid beam-alignment device instead fixes the beam to the receptor mechanically, which is why head tilt is far less critical with the paralleling technique.

    Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — patient head position and vertical angulation in the bisecting techniqueReport a problem with this question

15. 15. During the health history review a patient states that she is ten weeks pregnant. The dentist has examined her and prescribed two bitewings for a symptomatic posterior contact. What should happen?

    • A.The prescribed images are replaced with a panoramic projection, because the rotating beam keeps radiation off the abdomen.
    • B.The prescribed images are exposed with careful technique, because pregnancy is not a contraindication to necessary imaging.✓ Answer
    • C.The prescribed images are postponed until the second trimester, because organogenesis makes the first trimester unsafe.
    • D.The prescribed images are postponed until after delivery, because exposure of any kind during pregnancy must be avoided.

    Diagnostically necessary dental imaging is not withheld because a patient is pregnant: the beam is confined to the head and neck, the dose to the uterus from intraoral imaging is negligible, and delaying the diagnosis of an active problem carries its own risk to both patient and pregnancy. The assistant confirms the prescription with the dentist, answers the patient's questions honestly and uses careful technique to avoid retakes.

    Source: ADA/FDA, The Selection of Patients for Dental Radiographic Examinations — patients who are pregnant; Iannucci & Howerton, Dental RadiographyReport a problem with this question

16. 16. A new patient reports having had a full series exposed at another office six months ago. Before anything is exposed today, what should the assistant do?

    • A.Have the patient describe what was found, and expose only the projections the patient recalls being uncomfortable.
    • B.Have the patient authorize release, and request the existing images from the previous office for the dentist to review.✓ Answer
    • C.Expose a complete new series today, because images acquired on another office's equipment cannot be interpreted here.
    • D.Expose a complete new series today, because images more than three months old no longer show the patient's status.

    Obtaining and reviewing existing diagnostic images is an explicit dose-reduction step: if a recent series answers the clinical question, re-exposing the patient adds risk without adding information. The images are released on the patient's written authorization and go to the dentist, who then decides which, if any, additional projections are needed. Age alone does not invalidate an image, and no fixed expiry interval exists.

    Source: ADA/FDA, The Selection of Patients for Dental Radiographic Examinations — use of previous radiographs and individualized prescriptionReport a problem with this question

17. 17. The dentist has prescribed four bitewings. After the procedure is explained, the patient declines to have any images taken today. What is the correct handling?

    • A.Enter nothing in the record, since images that were never exposed generate no entry in the patient's clinical chart.
    • B.Have the patient sign the consent form for the prescription, then expose the projections the dentist considers essential.
    • C.Explain that the office cannot treat anyone without images, and expose the bitewings once the patient stops objecting.
    • D.Inform the dentist, document the refusal and the explanation given, and continue with the remainder of the visit.✓ Answer

    Consent is required for every exposure and it can be withdrawn, so a patient who declines is not exposed. The clinically and legally protective step is to notify the dentist, who explains the diagnostic consequences of proceeding without images, and to record in the chart that the recommendation was made, the risks of non-diagnosis were explained and the patient refused. An informed-refusal entry or form documents the conversation.

    Source: Iannucci & Howerton, Dental Radiography: Principles and Techniques — informed consent, informed refusal and documentationReport a problem with this question

18. 18. An operatory is being set for a periapical series with a solid-state sensor and rigid beam-alignment holders. How are these two items handled between patients?

    • A.The holder components are heat-sterilized, and the sensor is covered with a single-use barrier and then disinfected.✓ Answer
    • B.The holder components are wiped with a surface disinfectant, and the sensor is heat-sterilized inside the same cassette.
    • C.The holder components are discarded after a single use, and the sensor is wiped and reused without any barrier over it.
    • D.The holder components are heat-sterilized, and the sensor is immersed in a high-level disinfectant solution after each use.

    Both are semicritical items because they contact mucous membranes, but they differ in heat tolerance. Beam-alignment holders are heat-stable, so they must be heat-sterilized between patients. A solid-state sensor is destroyed by heat and by immersion, so the accepted substitute is an FDA-cleared single-use barrier during use, followed by cleaning and an EPA-registered intermediate-level disinfectant applied according to the manufacturer's instructions.

    Source: CDC, Guidelines for Infection Control in Dental Health-Care Settings — semicritical patient-care items; Miller, Infection Control and Management of Hazardous Materials for the Dental TeamReport a problem with this question

Practice questions only — not real exam items, and not affiliated with or endorsed by the Dental Assisting National Board. Questions are written to the domains published in DANB's current RHS and ICE exam outlines, and cover digital radiography only, matching DANB's statement that film-based concepts are no longer tested. This bank does not cover the chairside assisting or dental anatomy component exams. What a dental assistant is legally allowed to do — including who may expose radiographs and what training a state requires first — is set by each state's dental board and is deliberately out of scope here. Exam format, eligibility, and scoring are set by DANB and change from time to time; confirm the current requirements with DANB and your state board before you register. Official DANB exam outlines →