Technique

Radiographic Technique
The recommended technique for imaging intraoral radiographs is the use of the paralleling technique. Rectangular collimation is encouraged with the use of a beam alignment device. Two film-holding devices that align the beam to the receptor are the Rinn XCP Instruments (Rinn Corp., Elgin, Illinois) or Precision Instruments (Isaac Masel, Philadelphia, Pennsylvania). Although all of the systems discussed can be used with a paralleling sensor-holding device, the PSP detector most easily adapts to the majority of film holding devices.

The CCD/CMOS sensors have specially designed devices since these detectors are thicker than film. The holding devices are very similar to the Rinn XCP Instruments and should be positioned in that manner. Manufacturer’s instructions should be followed for determining the display of the images and saving of the images in the patient record. Prior to making an exposure with the PSP sensors, images should be cleared from the sensors by placing them with the phosphor side down on an illuminated viewbox for a minimum of two minutes. Each sensor should then be placed in a plastic barrier envelope with the phosphor side facing the non-transparent side of the barrier envelope. The sensors are then ready to be placed in the film-holding device and exposed with ionizing radiation. After exposure, the sensor is removed from the barrier envelope and immediately placed in a specially designed light-tight plastic receptacle. At the completion of the radiographic exam, the sensors then are processed to display the digital image.

Processing
The digital processor for the PSP sensor looks similar to a large bread maker. (Figure 9). A removable drum is loaded with each exposed sensor placed into the appropriate sized slot, and the sensors are positioned with the phosphor side showing or positioned outward. The loaded drum is then placed in the processor so that the laser can read the sensors. Depending on the number and size of the receptors to be read, the processing can take from two to four-and-a-half minutes. Once processing is completed, the digital image will be displayed on the computer monitor or can be printed or saved. At this time, the image can be enhanced with the several features available on the software package (i.e. magnification, brightness, contrast, etc.).

Since the CCD and the CMOS receptors render an image almost immediately, no additional processing steps are required. Enhancements can be made once the image is displayed.

Technique Pitfalls
Although the sensors are similar in size to conventional dental film, the CCD/CMOS sensors present additional challenges when positioning them in the oral cavity due to their thickness, rigidity, and cord. Both Versteeg et al. and Malarkey et al. reported more errors and more retakes with the CCD receptor when it was compared to conventional film. Specific technique errors that were observed included cone cuts, incorrect packet placement, and vertical alignment.22,23

Care of Sensors
Care should be taken to protect the PSP sensors from being scratched. Once scratched, a permanent artifact will be displayed during subsequent receptor use (Figure 7). Scratches can occur from fingernails or from sliding the sensor across the viewbox or counter top. As with conventional film, bending the corners of the sensor will leave a permanent artifact on the image. The CCD and CMOS sensors should be checked routinely for damage of the casing or frayed wires where most of the damage occurs.