Week 3 (Chpater 19): Paralleling technique

What is the paralleling technique also known as?

Extension cone paralleling technique, right-angle technique, long-cone technique.

If you follow the shallow palate protocol and increase the vertical angulation by 15 degrees, what is a potential side effect on the resulting image?

There will be a slight amount of foreshortening compared to a perfect paralleling shot.

A clinician is struggling to keep the sensor parallel to the maxillary molars because the patient has a very shallow palate. What is the first clinical 'hack' to try?

Place cotton rolls on either side of the biteblock.

A patient has a shallow palate, the clinician may need to:

Use a cotton roll to help tip the sensor into a more parallel position.

How do film holders reduce exposure?

Reducing retakes, stabilize receptor

What is the basic principle of the paralleling technique?

The receptor must be placed parallel to the long axis of the tooth being radiographed.

What is the purpose of a beam alignment device in the paralleling technique?

To keep the receptor parallel with the long axis of the tooth.

What are the two distances that must be increased in the paralleling technique?

Object-receptor distance and target-receptor distance.

What does the term 'object-receptor distance' refer to?

The distance between the tooth and the receptor.

The central ray of the x-ray beam should be directed in what manner to satisfy the principles of the paralleling technique?

Perpendicular to both the tooth and the receptor.

What does the term 'target-receptor distance' refer to?

The distance between the source of x-rays and the receptor.

What is the primary reason for using a 16-inch PID in the paralleling technique?

To ensure only the most parallel rays hit the receptor, reducing magnification.

n the paralleling technique, why is the sensor placed further away from the tooth?

To ensure the receptor stays parallel with the long axis of the tooth.

What are the components of the XCP holder?

Aiming ring, bite-block, metal indicator arm.

What sizes of receptors are used in the paralleling technique?

Size 1 receptor for canine exposures (vertical) and size 2 receptor for posterior exposures (horizontal).

What is the first rule of the five basic rules of paralleling?

Receptor must be positioned to cover the prescribed area of the teeth.

What is the second rule of the five basic rules of paralleling?

Receptor must be positioned parallel to the long axis of the tooth.

What is the third rule of the five basic rules of paralleling?

The central ray of the x-ray beam must be directed perpendicular to the receptor and the long axis of the tooth.

What is the fourth rule of the five basic rules of paralleling?

The central ray of the x-ray beam must be directed through the contact areas between the teeth.

What is the fifth rule of the five basic rules of paralleling?

The x-ray beam must be centered on the receptor to ensure all areas are exposed.

What is a potential consequence of failing to observe the rules of paralleling?

Non-diagnostic images.

What should be done to prepare a client for the paralleling technique?

Explain the procedures, adjust the chair and headrest, and secure a lead apron.

What is the recommended exposure sequence for receptor placement?

Anterior exposures first, followed by posterior exposures.

What modifications can be made for patients with a shallow palate?

Use cotton rolls and increase vertical angulation by 5 to 15 degrees.

How should receptors be placed for patients with bony growths (tori)?

Place the receptor on the far side of the torus for maxillary and between the tori and tongue for mandibular.

What are the advantages of the paralleling technique?

Accuracy, simplicity, and validity in comparison of serial images.

What are the disadvantages of the paralleling technique?

Difficult receptor placement and potential discomfort from the beam alignment device.

What is the purpose of effective communication during the paralleling technique?

To help clients tolerate discomfort by explaining the need for specific receptor placements.

What should be avoided in communication with clients during the procedure?

Using words like 'hurt' and saying 'oops' if a receptor is dropped.

What is the significance of the 'dot in the slot' for periapicals?

It indicates the proper orientation of the receptor.

What is the significance of the 'dot down' for bitewings?

It indicates the proper orientation of the receptor for bitewing exposures.

What is the role of the central ray in the paralleling technique?

It must be directed perpendicular to the receptor and the long axis of the tooth.

What is the recommended approach for exposure sequencing?

Stick to a routine consistent from client to client.

What is the importance of PID placement before receptor placement?

To reduce the time the receptor/bite block is in the client's mouth.

When a patient has a large maxillary torus, why is the receptor placed on the 'far side' of the growth rather than directly against the teeth?

To allow the receptor to remain parallel to the long axis of the tooth.

What is the primary risk of placing a sensor directly on top of mandibular tori during a premolar periapical exposure?

It will cause significant pain and potentially lacerate the thin tissue covering the torus.

A patient like 'Ava' from your CAL notes has mandibular tori and needs a molar bitewing to check her 2 mm of recession. Where should the sensor be placed?

Between the tori and the tongue.

If a maxillary torus prevents a sensor from being high enough in the palate, which previously learned 'shallow palate' technique could be applied?

Increase the vertical angulation by 5 to 15 degrees

How will a torus appear on a finished radiograph?

As a radiopaque (white/light) area superimposed over the teeth or bone.

When dealing with mandibular tori, the clinician should be careful not to scrub the receptor against the bone. What is the best way to avoid this?

Place the sensor in the middle of the mouth and have the patient slowly close to let the floor of the mouth relax.

A patient with a mandibular torus is in pain during a Size 2 sensor placement. What is a reasonable alternative?

Use a Size 1 sensor for the posterior shot.

Advantages of paralleling techniques?

Accuracy, simplicity, and duplication

Disdavantages of paralleling techniques?

Receptor placement and discomfort