Set the program mode on the panoramic unit – Even the simplest panoramic units can be used in a variety of modes. It is important that the operator ensure that the correct mode is selected prior to patient exposure.
Set the exposure – For most panoramic units, patient exposure is adjusted by alteration of the kilovoltage (kVp) and milliamperage (mA). This adjustment should be based on the physical stature of the patient. Basic guidelines follow that assist the clinician in this decision-making process. While the operator should follow the general guidelines recommended by the manufacturer, consideration needs to be given to the patient size, thickness of tissues, presence of teeth and bone density characteristics. Patients that are considered above the norm in each of these characteristics would require an increase in the kVp and mA settings while patients below the norm would indicate a decrease. If the unit is manually adjusted, an exposure chart is available in the user’s manual. For manually adjusted panoramic units it is necessary and mandated by law that an exposure chart be posted adjacent to the exposure control.
Table 3. Sample Exposure Chart.
|Patient Size Category
|Child Patient ≤ 6 years old
|Child Patient 7-12 years old
|Adult Female/Small Male Patient
|Adult Male Patient
|Large Adult Male Patient
|Additional Factors to Consider
|Obese, Large-boned, Dense Bone
|Frail, Small-boned, Edentulous
Assemble and insert bite block – Bite blocks can be either disposable or designed to be reused. Disposable bite blocks are usually made of a material that is unable to be autoclaved. Reusable bite blocks are either chemically sterilized or autoclavable.
Position machine slightly higher than patient’s chin – Prior to patient preparation the approximate height of the patient should be determined, and the chin rest adjusted to be slightly higher than the patient’s chin. When the patient attempts to bite in the grooves of the bite block, they must, therefore, raise their head. This helps to keep the spine straight. It is easier to adjust the vertical placement of the patient’s head downwards from this position than to force the head up with the action of the panoramic unit.