Panoramic x-ray machines are composed of an exposure control panel, a C-arm, and a patient positioning device.
Control panel and exposure switch - The control panel typically contains the program selector, exposure selectors (milliamperage control, kilovoltage control), head positioning lights, temple bar operation, anteroposterior (AP) operation and other features. Control panels will vary among manufacturers as well as direct digital and plate/film-based machines. The complexity of the control panel increases with the incorporation of features such as multiple program options and automatic exposure control (AEC) features.
Figure 20. Digital Panoramic Unit Control Panels.
1 - Kilovoltage Display
2 - Milliamperage Display
3 - Program
4 - Patient Size → Set Exposure Factors
5 - Up and Down
6 - Temple Bars
7 - Anteroposterior Lights and Positioning
8 - Jaw Shape - Adjustable
C-arm (x-ray tubehead/receptor assembly) - The relationship of the x-ray tubehead is fixed spatially to the receptor assembly by a fixed C-arm support. The panoramic x-ray tubehead is similar to an intraoral x-ray tubehead. However, unlike the intraoral tubehead, there is both pre- and post-patient linear collimation to provide a slit beam.
Patient Positioning Device - The radiographer must be familiar with the operation of the patient positioning device as it is this apparatus that is used to position the patient’s head into the focal trough of the machine. This device comprises a head holder and a chin rest/bite block. The chin rest/bite block is used to stabilize the patient’s dentition in the anteroposterior direction whereas the head holder is used to stabilize the orientation of the patient’s head in both the vertical and horizontal planes.
Figure 21. Patient Positioning Devices.