Technical Assistance

Accurad Patient Positioning

Tips for Quality Cephalograms

Tips for Quality Submental Vertex Radiographs

Tips for Quality PA Townes Radiographs

Tips for Quality PA Skull (Frontal) Radiographs

It is imperative that a tight object (subject TMJ) to film relationship is maintained. Reducing this distance will result in less distortion, less magnification and a sharper image of the condylar head. Failure to maintain this relationship will generally result in an acceptable image of the glenoid fossa, but will result in a blurred, magnified and distant appearance of the condylar head. The reason being that the condylar head is anatomically further away from the film cassette than the glenoid fossa and the patients failure to hold their head tightly up against the cassette holder will exaggerate the effect.

Begin by setting the Accurad-200 Twin Axis Wheel ear piece at 22 mm. For the Accurad-100, set the adjustable ear rod on the letter "L" for the Right TMJ and conversely for the Left TMJ. Such positioning will rotate the patients' mid-saggital plane in towards the cassette for more accurate positioning of the subject TMJ based on anatomical averages.

In order to insure an optimum object to film relationship, the operator must instruct the patient to insert the adjustable ear rod (Twin Axis Wheel in the Accurad-200) in to its MAXIMUM extension. THE OPERATOR CANNOT insert the ear rod as effectively as it needs to be done particularly with a patient with a posteriorly displaced condyle. The patient must be instructed as follows:

1. When radiographing the right side, instruct the patient to "place the right hand on the right shoulder, palm up".

2. Instruct the patient to "grasp the cassette holder and place the fixed ear piece in your right ear HOLE".

3. The operator is to bring the Twin Axis Wheel ear rod into the left ear hole.

4. The patient is instructed to "bring your left hand up to your left ear, grasp the wheel and wiggle your head around and wiggle the wheel as you bring the ear piece into your ear hole until you cannot hear me anymore".

5. With the ear piece in its innermost position, hold slight pressure on the end of the adjustable ear rod shaft as you tighten the lock nut.

6. If the patient cannot close into maximum intercuspation at this point, back out the ear rod only until the point where they can comfortably achieve intercuspation.

7. With the horizontal bar of the Twin Axis wheel always pointing anteriorly, site through the slot in the horizontal bar to visualize the patient's orbitale. Adjust the patients head up or down accordingly. Adjust the nasion support to support the patient with the frankfort plane parallel to the floor.

8. If the patient properly inserts the adjustable ear rod into its maximum extension, the nasion settings should be identical left side and right. A 1-2 mm discrepancy on the horizontal scale is acceptable. If the discrepancy is significant by 5 mm or more, it indicates either a severe auricular discrepancy or an uncooperative patient.

If anatomic detail continues to be unacceptable and the above criteria has been satisfied verbatim, the operator must review the suggested darkroom procedures.

Note: It is suggested that small dimples be made in the outer circumference of the twin axis wheel both at the 0° and 180° points where the locking thumb screw makes contact. This will assure you that the twin axis wheel will always be in the correct position.

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1. Adjust your X-ray control to the highest KVP and MA available.

2. Adjust your exposure time according to the schedule on the following page (based on Dr. Goos' graduated, ISI Wicor-400 or Lanex Regular screens and Clear Image™ OGA film). Density must be adequate to clearly visualize the lambdoidal suture in the back of the skull. This suture is your "density barometer". Increase/decrease the time as necessary.

3. Adjust the collimator and cassette holder for the 8x10 horizontal format.

4. Seat (position) and shield the patient in a natural posture. Duplicate their natural "plumb-line" (center of shoulder to center of hip) and cervical posture. Observe the relationship of the ear hole to this plumb-line and duplicate.

5. The patient must answer "NO" to the following four questions:

(A). Do you feel as if you are stretched up?

(B). Do you feel as if you are slouched?

(C). Do you feel as if you are leaning back?

(D). Do you feel as if you are leaning forward?

6. Bring the cassette in contact with the side ear support or as close to the patient as possible.

7. For systems NOT utilizing the Dr. Goos graduated intensifying screens or filtration at the beam source, adjust the soft tissue shield according to the figure 1. Block type shields must be flush with the edge of the cassette with the cassette and shield moved anteriorly/posteriorly as an ssembly keeping the tip of the nose 1" in from the edge.

Use a 12" ruler to align the tip of the nose with a mark 1" in from the edge of the cassette.

8. Position the patient's Frankfort Plane (ear piece to orbitale, most inferior surface of the orbit) Parallel With The Floor.

9. Guide the patient into the desired occlusal and lip position and expose.

10. For proper density and resolution, process in automatic processors at a CONFIRMED 83°F (28.3°C) for 5.5 minutes using only IMAGING SYSTEMS' AUTOCHEM PRE- MIXED or KODAK RP X-OMAT developer and fixer or in manual tanks at 68°F for 5 minutes using Kodak GBX solutions (fix for a maximum of 4 minutes).

Suggested Exposure Guidelines for Cephalograms using

Dr. Goos/ISI Wicor-400 Rare Earth/Lanex Regular Intensifying Screens/Clear Image™ OGA Film

Focal Spot to Mid-sagittal plane: 60 in

Exposure Time in impulses (60 impulses in 1 sec.)

 * Use of Kodak TMAT-H film will reduce the above exposure time by 1/2 but will result in grainer appearance

Conversion Chart for Fractions/Decimals to Impulses

CEPHALOMETRIC QUALITY ASSURANCE CHECKLIST

1. Absence of Hypo (wavy, flat black matte appearance).

2. Lead Letters must be in the image (the word/letter LEFT/L if the left cheek is against the cassette)

3. Absence of a lead apron, necklace and/or ear rings, etc. in the image.

4. Lambdoidal suture must be clearly evident (your "density barometer").

5. Frankfort Plane must be parallel with the floor.

6. Adequate soft tissue profile.

7. Single inferior border of the mandible indicating either mid-sagittal plane symmetry or facial asymmetry.

8. "Natural" lordotic curve (George's line).

9. 8-10mm spacing between cranial base and the spinous process of CI.

10. 6-8mm nasopharynx airway in the area of the posterior-superior aspect of the soft palate.

What else to look for on a LATERAL CEPHALOGRAM / LATERAL CERVICAL SPINE

1. Pharyngeal airway in area of soft palate.

2. Spatial relationship of C1 to cranial base.

3. Cervical spine contours.

4. Elevation of hyoid bone.

5. Anti-gonial notching (aka. bone deposition at the gonial angle).

6. Ossification of stylohyoid ligament.

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1. Adjust your x-ray control to the highest KVP and MA available.

2. Adjust your exposure time according to the schedule on the following pages (based on ISI Wicor-400/ Lanex Regular screens and Clear Image™ OGA film). Density must be adequate to clearly visualize the mandibular condyles and cervical spine. Increase/ decrease the time as necessary.

3. Adjust the collimator and cassette holder for the 8x10 horizontal format. Adjust the cassette holder posteriorly to its stop.

4. Adjust the cephalostat to the AP/Frontal position and lock.

5. Install 1/4" thick lead washers (Imaging Systems) over the ear pieces (to be utilized in the tracing procedure). Attach lead letters "R" and "L" to the cassette with self adhesive velcro.

6. Position and center a chair/stool approximately 12" in front of the cephalostat.

7. Seat and CENTER the patient. Adjust the seat up or the cephalostat down to a point where the patient's ear holes are a level approximately 3-4" above the level of the ear pieces.

8. If using a lead apron, it must be kept below the patient's chest.

9. Align and position the patient's torso and head directly in front of the ear pieces. The patient's head should now be positioned approximately 8-10" directly in front of the ear pieces.

10. With one hand FIRMLY in the patient's lumbar and other hand supporting their head, guide the patient back into a "back-dive" position until their FRANKFORT PLANE is PERPENDICULAR with the floor. Take a visual reference as to the height of their ear holes to the ear pieces. Advise the patient to "slouch down" and come forward.

11. Readjust the chair or cephalostat accordingly.

12. Once again with one hand FIRMLY in their lumbar and the other hand supporting their head, guide the patient back into the "back-dive" until their Frankfort Plane is at least perpendicular with the floor. Note: If the Frankfort Plane is not perpendicular, the gonial angles will obscure the condyles.

13. With the ear pieces now in line with the ear holes, support their head, guide the ear pieces into the ear holes and secure.

14. Bring the cassette holder in contact with the patient's head for additional support.

15. Adjust the patient's head to eliminate any rotation and/or angulation.

16. Advise the patient to clench and expose.

17. Immediately release the ear supports and with your hand as head support, instruct the patient to "slouch down and come forward".

18. Remove the lead washers from the ear support.

Suggested Exposure Guidelines for Submental Vertex Radiographs using

ISI Wicor-400 Rare Earth/Lanex Regular Intensifying Screens/Clear Image™OGA Film

Focal Spot to Mid-sagittal plane: 60 in

Exposure Time in impulses (60 impulses in 1 sec.)

* Use of KodakTMAT-H film will reduce the above exposure time by 1/2 but will result in grainer appearance

Conversion Chart for Fractions/Decimals to Impulses:

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1. Adjust your x-ray control to the highest KVP and MA available.

2. Adjust your exposure time accordingly to the schedule on the following page (based on ISI Wicor-400/Lanex Regular screens and OGA film). Density must be adequate to clearly visualize the mandibular condyles. Increase/decrease the time as necessary.

3. Adjust the collimator and cassette holder for the 10 x 8 vertical format.

4. Adjust the cephalostat to the PA/Frontal position and lock.

5. Position and center a chair/stool directly under the cephalostat.

6. Seat or position the patient directly in front of the opened ear pieces. If using a lead apron, it must be kept below the patient's chest.

7. Position the patient's FRANKFORT PLANE DOWN 25-30 ° by instructing the patient to slightly arch their back forward and look down at their toes.

8. Position the patient into the ear pieces and secure.

9. Instruct the patient to OPEN WIDE. If the mandible does not open at least 35 mm, the condyles will be slightly obscured by the zygoma and eminentia.

10. Bring in the cassette holder as close to the patient's head as possible. Optional: In order to capture any mandibular deviation, take the patient out of the ear supports, raise the patient to where the top of the head lightly touches the bottom of the cephalostat. This has the net effect of dropping the cassette down to capture the chin upon wide opening.

11. Align the patient's midsagittal plane and expose.

Suggested Exposure Guidelines for PA Townes Radiographs using

 Imaging Systems-400 Rare Earth/Lanex Regular Intensifying Screens/Clear Image™ OGA Film

Focal Spot to Midsagittal plane: 60 in

Exposure Time in impulses (60 impulses in 1 sec.)

* Use of Kodak TMAT-H film will reduce the above exposure time by 1/2 but will result in grainer appearance

Conversion Chart for Fractions/Decimals to Impulses:

PA TOWNES QUALITY ASSURANCE CHECKLIST

1. Absence of Hypo (wavy, flat black matte appearance).

2. Lead Letters must be in the image (the word/letter LEFT/L and/or RIGHT/R.

3. Absence of a lead apron, necklace and/or ear rings, etc. in the image.

4. Condyles must be clearly evident, neither too dark, nor too light.

5. Condyles must be down below the zygoma, if not the patient did not open at least 35mm and/or the frankfort plane was not down far enough, 25-30°.

6. Is the patient's chin captured on the image to document any mandibular deviation.

7. Patient, date, etc. information printed on film.

What else to look for on the PA TOWNES

1. Mandibular condyles, morphology, symmetry.

2. Condylar translation, does one translate (drop down) further than the other?

3. Does the mandible deviate to one side upon opening?

4. Evaluate the stylohyoid processes and any ossification of the stylohyoid ligaments.

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1. Adjust your x-ray control to the highest KVP and MA available.

2. Adjust your exposure time according to the schedule on the following page (based on Imaging Systems-400/Lanex Regular screens and OGA film). Density must be adequate to clearly visualize the sutures in the skull. These sutures are your "density barometers". Increase the time as necessary for increased density (ie. to darken the image).

3. Adjust the collimator and cassette holder for the 10x8 vertical format.

4. Center a fresh cassette into the cassette holder in the 10x8 vertical position. The height of the cassette holder must be such as to incorporate both the top of the skull and chin.

5. Adjust the cephalostat for the PA or Frontal position and lock.

6. Seat (position) and shield the patient in a natural posture with the lead apron positioned over the patient's back.

7. With the patient's Frankfort Plane parallel with the floor, bring the cassette in to slight contact with the tip of the patient's nose.

8. Instruct the patient to "bite firmly on their back teeth and hold".

9. Expose per the exposure chart below.

10. For proper density and resolution, process in automatic processors at a CONFIRMED 83°F (28.3°C) for 5.5 minutes using only IMAGING SYSTEMS' AUTOCHEM PRE-MIXED or Kodak Readymatic developer and fixer. Use Kodak GBX for manual tanks at 68°F for 5 minutes (fix for a maximum of 4 minutes).

Suggested Exposure Guidelines for PA Skull Radiographs using

Imaging Systems-400 Rare Earth/ Lanex Regular Intensifying Screens/Clear Image™ OGA Film

Focal Spot to Mid-sagittal plane: 60 in

Exposure Time in impulses (60 impulses in 1 sec.)

* Use of Kodak TMAT-H film will reduce the above exposure time by 1/2 but will result in grainer appearance

Conversion Chart for Fractions/Decimals to Impulses:

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