Quality Control: A Crucial Component In Ensuring Quality Patient Care
[ continued ]

from the November 2006 issue

<< BACK

A review of ASNC's recently revised Imaging Guidelines for Nuclear Cardiology Procedures, published June 2006, will aid nuclear laboratories with information addressing the advancement of imaging equipment and specific equipment requirements. Some of this is information not currently included in the ICANL Standards.

Furthermore, Part II, Section 3.3 of the ICANL Standards requires non-imaging equipment quality control. A policy must exist and be followed for routine inspection and testing of all non-imaging equipment, such as dose calibrators, uptake probes, survey meters, and glucometers, if indicated, and be in accordance with all federal, state and local requirements. The dose calibrator must be calibrated in accordance with nationally recognized standards or the manufacturer's specifications.

ASNC's Imaging Guidelines for Nuclear Cardiology Procedures, published June 2006, provide detailed explanations of quality control procedures and are available for review and download from www.asnc.org. An example of some of the QC recommendations included in the ASNC guidelines that provide clarification for the ICANL requirements in Part II, Section 3 of the Standards include:

1) Daily floods may be intrinsic or extrinsic acquired in 128x128 or 256x256 matrix of 3 million counts or greater. CFOV, UFOV or time/acquisition should be documented for tracking sensitivity and drift.

2) Energy windows should be symmetric about the photopeak and checked daily for each isotope used.

3) Dose Calibrator background must be checked daily and at least one constancy source checked for all isotopes used (e.g., CS-137).

4) Survey meter, GM counter must be checked for battery function, background and assure constancy with a check source.

5) Scintillation/wipe test counter/well counter - daily background and sealed source constancy.

6) PET scanner - Specific to system, blank scan, transmission image

7) Hybrid SPECT/CT and PET/CT must be quality controlled for each system independently as well as together for fusion accuracy and reliability

The Procedure Guidelines Manual August 2003 published by the SNM, Version 2.0, February 1997, is another valuable reference for QC procedure guidelines. The ICANL Standards are based upon these published guidelines as well as the ASNC guidelines referenced above; therefore, nuclear medicine laboratories applying for accreditation are encouraged to carefully review these documents.

In the course of reviewing laboratory operations, ICANL reviewers often find that applicant laboratories are not in full compliance with required quality control guidelines. Deficient areas are most often found in uniformity corrections, sensitivity testing for tracking change over time, and collimator integrity. The purpose and history of these parameters is discussed below to provide further insight to applicant laboratories.

UNIFORMITY VALUES

The National Electrical Manufacturers Association (NEMA) standards are not the same for all cameras, thus the Integral and Differential Intrinsic Uniformity is not the same for all cameras. However, ASNC guidelines recommend these numbers be under five percent (5%) and preferably in the range of three percent (3%). Each laboratory should be aware of their system limits and monitor uniformity closely for evidence of drift accordingly. The Central Field of View (CFOV) is the most sensitive in that one percent (1%) non-uniformity at the center of the image will become a 20% non-uniformity in the reconstructed image. Establishing trigger levels for service calls is a safe and reliable way to maintain camera integrity. Recommended but not required by the ICANL is the use of a phantom to ensure that all corrections are working: uniformity, energy, linearity, center of rotation, head registration and attenuation correction. But without daily, weekly, monthly, and quarterly QC, the semi-annual or yearly phantom cannot indicate when a problem has developed or how long the camera has been drifting toward irregularities.

NEXT PAGE >>

Top of Page