Frequency of Quality Control Procedures

A gamma camera is a sophisticated piece of technology. In order to maintain it in the best possible working order, certain Quality Control Procedures need to be performed on a regular basis. These procedures can be divided into 3 distinct sets, based upon the frequency the procedure needs to be performed:

Daily Procedures,
Weekly to Quarterly Procedures and
‘As Needed’ Procedures.

The first group of procedures need to be performed on a Daily basis. These procedures are designed to quickly test the camera’s basic performance. The purpose of these procedures is to assure that the camera system is operating correctly and can be used to image patients. These procedures usually include Peaking and Uniformity procedures. The Peaking procedure assures the operator that the camera system is properly focused on the photopeak caused by the detection of the incident photons. The Uniformity procedure assures the operator that the camera system is providing an even response, with no ‘hot’ or ‘cold’ spots, upon exposure to a uniform radiation field.

The second group of procedures need to be performed on a Weekly to Quarterly basis. These procedures are more time consuming, more detailed and are designed to test the performance of components and features that are very important to producing quality images but are more stable relative to the first group. These procedures usually include Linearity/Resolution (LR), Center-or-Rotation (COR) and Multi-Detector-Alignment (MDA) procedures. The LR procedure uses a series of equally spaced lead bars of different thickness to produce an image of ‘hot’ and ‘cold’ lines. The image is subjectively evaluated to determine the smallest bar that can be resolved and also if any nonlinearity is observed in the lines. Another less frequent procedure, the COR procedure, is performed to verify and correct the alignment of the mechanical and electronic point around which the camera rotates. Errors in this calibration can lead to image artifacts. Similar to the COR procedure, the MDA procedure is used to verify and correct the alignment in a multi-detector imaging system. Again, errors in this calibration can lead to image artifacts.

The third group of procedures need to be performed on an ‘As Needed’ basis. These procedures can be both corrective as well as diagnostic in nature. These procedures are performed for many reasons. The reasons may include: (1) in response to a detected problem, (2) for Regulatory Compliance, (3) per Manufacturer Recommendation and (4) at Significant Events.

Detected Problem. Often procedures from the Daily or Weekly to Quarterly category illuminate a performance issue with the imaging equipment. That is after all, the main purpose of performing those procedures. When an issue is detected, a corrective calibration procedure is performed to bring the imaging equipment back into proper working order. Alternately, a service call may be needed for the imaging equipment.
Regulatory Compliance. Certain procedures are required or recommended by various Professional and Governmental Organizations. Again, these procedures can be corrective or diagnostic in nature. These procedures are often required to be performed on an annual basis.
Manufacturer Recommendation. These procedures can be corrective or diagnostic in nature and are designed to assure that the imaging equipment is operating correctly. These procedures may also be required to keep the Manufacturer’s Warranty in effect.
Significant Events. Significant events are major events in the imaging equipment’s lifetime, such as ‘Initial Installation’, ‘Equipment Relocation’ or ‘Major Repair’. At these times, a more stringent regiment of procedures, both corrective as well as diagnostic in nature, need to be performed to assure that the imaging equipment is in proper working order.