Safety Code 35: Safety Procedures for the Installation, Use and Control of X-ray Equipment in Large Medical Radiological Facilities

Section C: Quality Assurance Program

1.0 Introduction

All radiological facilities must develop and maintain an effective quality assurance program. Quality assurance in radiology is defined as the planned and organized actions necessary to provide adequate confidence that the X-ray equipment and its related components reliably produce diagnostic information of satisfactory quality with minimum doses to the patients and staff. A quality assurance program includes quality control procedures for the monitoring and testing of X-ray equipment and related components, and administrative methodologies to ensure that monitoring, evaluation and corrective actions are properly performed. The owner of an X-ray facility has the responsibility of establishing a quality assurance program which examines all practices of the facility which effect:

1. Information Quality--to ensure all diagnostic information produced provide for accurate clinical assessment;
2. Clinical Efficiency--to ensure all steps leading to accurate diagnosis and intervention are taken and the information is made available in a timely fashion to the patient's physicians or primary medical professionals; and
3. Patient Dose--to ensure that the X-ray examination is performed with the lowest possible radiation dose to the patient consistent with clinical imaging requirements.

1.1 Goals of the Quality Assurance Program

The ultimate goal of a quality assurance program is to ensure accurate and timely diagnosis and treatment at the minimum dose to the patient and staff. In order to have a successful quality assurance program it is essential that equipment is in proper working condition and all staff members understand the goals of the program and are committed to the implementation of the program through full participation.

Information obtained from X-ray equipment must be of utmost quality to ensure accurate diagnosis and treatment. If critical elements are missing or artifacts are added to images, the image is considered to be of poor quality. The consequence of poor quality diagnostic information may be incorrect diagnosis resulting in repeat radiographic procedures, unnecessary radiation doses to the patient, delayed or improper patient treatment and increased cost.

1.2 Costs-Benefits of the Quality Assurance Program

The initial implementation and the general operation of a quality assurance program will involve cost in both money and time from staff. However, savings from the operation of the program will offset some of these costs. For some facilities, there may be a reduction in the overall operating costs.

1.2.1 Costs of Quality Assurance Program

Some of the costs associated to the quality assurance program are as follow:

1. Personnel--The staff will be required to perform new duties, which include generating test images for the X-ray equipment and record keeping.
2. Test Equipment--Test equipment to perform quality control tests, such as phantoms, will be required. However, the cost of such equipment is small compared to the cost of the X-ray imaging unit and it may be used for several X-ray systems. It would not be necessary to purchase some of the test equipment if the facility decides to have some of the quality control tests performed by an external organization or individual, who would then be responsible for providing their own test equipment.
3. Test Images--For film-based systems, and CR and DR systems using laser printers, 2 to 5% of films used by a facility may be required for the performance of sensitometry, phantom imaging, equipment and test imaging.
4. External Organizations--If the facility does not have the capacity to perform internally all quality control tests, it may choose to contract an external organization or individual to perform some of these tests and equipment assessments. In addition, the facility may retain the service of a medical physicist as an advisor during implementation and for consultation during operation of the facility.

1.2.2 Benefits of Quality Assurance Program

In addition to improved diagnostic quality some of the savings associated with the quality assurance program are as follow:

1. Film and Processing Chemicals--For film-based systems, and CR and DR systems using laser printers, a decrease in the number of retakes may result in the reduction in the number of films and processing chemicals used.
2. Equipment--The reduction in the number of retakes will lead to a reduction in workloads which in turn will put less stress on X-ray equipment and image processors. Problems with equipment may be diagnosed earlier before more serious and costly problems occur thus reducing down time and equipment service costs.
3. Patient Flow--The reduction in the number of repeats, and better image quality will allow efficient use of time for both responsible users and the X-ray equipment operators. This will result in better predictability of scheduling and possibly greater patient throughput.

1.3 Implementation of Quality Assurance Program

The implementation of a quality assurance program need not be complicated. It consists in establishing quality control procedures for the equipment along with an administrative methodology to ensure that monitoring, evaluation and corrective actions are properly performed.

1.3.1 Policies and Guidelines Development

One useful step is to develop a series of policies and guidelines where various issues are addressed. The following list presents some of these policies and guidelines. Each facility may require different sets of policies and guidelines depending on the type of work being performed and the organizational structure of the facility. These policies should be established by management with participation from staff. It is recommended that all safety policies, procedures and processes be reviewed by a Joint Health and Safety Committee. The policies should be present in the Quality Assurance (QA) manual. The following information should be readily available to radiology staff:

1. Radiology Personnel
   • A list of staff and an outline of their duties, authority and responsibilities.
2. Policies for Minimizing Radiation Exposure to X-ray Operators and Staff
   • Policy for minimizing exposure to pregnant workers.
   • Policy for holding patients.
   • Policy for the presence of individuals in the X-ray room during procedures.
   • Policy for training/orientation program for X-ray equipment operators.
   • Policy for the proper use and maintenance of X-ray equipment.
   • Policy for personnel radiation dosimetry monitoring.
   • Policy for the use of protective devices and radiation protection equipment.
   • Policy for the maintenance and testing of radiation protection devices and equipment.
3. Policies for Minimizing Radiation Exposure to Patients
   • Policy for carrying out X-ray examinations.
   • Policy for the radiological examination of pregnant patients.
   • Policy for the use of protective devices and radiation protection equipment.
   • Policy for patient positioning (positioning manual).
   • Policy for exposure loading factors (technique charts).
   • Policy for the quality acceptance of diagnostic radiograms.
   • Policy for a reject analysis of radiographic images.
4. Guidelines for Equipment Quality Control (QC) Testing
   • Guidelines listing all X-ray equipment and system components to be tested.
   • Guidelines for all equipment parameters to be measured and the frequency of monitoring (schedule) for each X-ray system and system component.
   • Guidelines for the performance standards for each equipment tested and the specific performance tolerance limits expected for each QC test.
   • Guidelines for the measurement of each parameter and recording of the data.
   • Guidelines to evaluate the test data and to take the corrective action necessary to maintain equipment optimum performance.
   • Guidelines for patient exposure measurements (ESEs, DRLs).
   • Guidelines for the calibration and maintenance of radiation measuring equipment and other test equipment.
5. Policies for the Acquisition of New X-ray Imaging Equipment
   • Policy for a needs analysis.
   • Policy for equipment specification writing.
   • Policy for equipment acceptance testing.
   • Policy for equipment appraisal and replacement.
6. Policy for Record Keeping
   • Policy for the review of the QA Program.
   • Policy for the review of the QC Procedures.
   • Policy for the retention of records (patient information, QC test results, survey reports, personal dosimetry records).

1.3.2 Establishment of Quality Control Procedures

The following four steps must be included for the establishment of quality control procedures:

1. Equipment Operation--It is essential that the X-ray equipment and image processing equipment function properly before a quality assurance program is implemented. Manufacturers and vendors should provide proper operating characteristics for their equipment. For film-based systems, films and processing must meet manufacturers' speed and contrast values. For CR and DR systems, the imaging system must be properly calibrated with the X-ray systems. This may involve replacement, repair, upgrading or calibration of the equipment.
2. Baseline Performance--Baseline performance values of X-ray equipment and image processing system must be established after verifying that the equipment functions properly. This baseline performance will be used to diagnose any changes in equipment performance. It is important to keep records of equipment operation data and baseline performance measurements. These records will be needed to diagnose any changes in image quality. Baselines values must be determined when new equipment is introduced into the facility, when there are changes in components which effect image quality and patient dose and also when testing equipment is changed.
3. Reference Test Image--To evaluate image quality a reference test image is needed. This reference test image is made by using the X-ray equipment, image processing system and a quality control phantom and will be used for comparison of quality control test images.
4. Result Evaluation and Action Levels--An effective quality control monitoring program includes not only a routine quality control testing schedule, data recording and record keeping, but also test result evaluation, such as determination of acceptable or unacceptable limits of equipment operation coupled with a list of corrective actions that may be required. A set of limits should be established which indicates a level of operation outside of which the system or the function should be closely monitored but where no immediate action is required. Another set of limits should also be established where immediate remedial action must be taken.

1.3.3 Establishment of Administrative Procedures

The following administrative procedures must be included in the establishment of an effective quality assurance program.

1. Responsibility--Although the owner of the facility is ultimately responsible for the implementation and operation of the quality assurance program, to obtain the optimal level of radiation safety and quality diagnostic information, it is imperative that full cooperation exists among all concerned parties. Staff members may be assigned duties with regard to equipment monitoring, record keeping and general operations of the quality assurance program. It is essential that the level of responsibilities and involvement of the owner and staff be clearly identified, communicated and understood.
2. Record Keeping--It is essential that measurements and information gathered for the quality assurance program is clearly documented and readily available for evaluation. As far as practicable, recorded data should be indicated as data points on a control chart for each day the measurement is made. For example, it includes the densitometric results of the sensitometric film strips, and the charting of temperature for the film processor. In this form, trends can be more easily detected. A log book or other easily identifiable method of recording must be used.
3. Evaluation of Data--Recorded data should be evaluated immediately and necessary actions taken.
4. Limits of Acceptability of Data--Upper and lower limits of acceptability of recorded data must be determined and documented. When these limits are reached, corrective actions must be taken. For example, they can be the range of acceptable temperatures for the film processor. These limits should be set such that they are just within the range allowable before diagnostically significant image changes are evident. They should not be so restrictive that they exceed the capability of the equipment, or that frequent corrective actions are taken without any evidence of problems. These limits should be reviewed from time to time, especially when major components of the X-ray system are replaced or repaired.
5. Testing frequency--Testing frequency must be such that a balance is reached between the cost of testing, disruption to the operation of the facility and the maintenance of quality. The frequency of testing should be increased if the equipment exhibits significant changes between scheduled quality control tests, or if the equipment is used for exceptionally high volume of procedures. Additional testing should be performed if the results of testing fall outside of limits of acceptability for the tests, or after any corrective actions are made. Equipment must be retested after service to any part which may affect the image density, image quality or radiation output from the X-ray tube. The quality control program should not be discontinued if the results indicate relatively stable equipment performance. The purpose of a quality control program is to control quality, and periodic measurement of equipment performance is essential.
6. Corrective Actions--There must be established repair and calibration procedures to deal with significant problems. A decision tree system should be developed to provide guidance to deal with events such as equipment failure and to deal with circumstances when equipment performance deviates beyond the set limits. A list of individuals having the authority to stop operation of an X-ray unit should be established. The decision tree should include the following steps:
   1. repeat the test to confirm;
   2. what to do if repeated test confirms performance failure;
   3. what to do if test fails only marginally;
   4. what to do if test shows a history of failure; and
   5. what to do if test fails substantially.