Equipment Life Cycle
Four stages of the checks and measurements applicable to x-ray imaging equipment, Administered by client's Radiation safety Officer (RSO), are:
1. Critical examination.
2. Acceptance.
3. Commissioning.
4. Routine performance testing.
All four stages are part of quality assurance life cycle of imaging equipment. The complete life cycle includes seven stages:
1. Specifications.
2. Tender.
3. Contract.
4. Installation.
· Critical examination.
· Acceptance.
· Commissioning.
· Routine performance testing.
5. Clinical use.
6. Maintenance, and
7. Disposal.
In this document we mainly discuss the involvement of Medical Physicist and Radiation Safety Officer in the four stages. However for better understanding, we also comment on the whole process. The enclosed checklist in the appendix will be of help to the manager of the process.
In this document:
RSO Radiation Safety Officer
RFP Request for Proposal
BME Biomedical Engineering
OEM Original Equipment Manufacturer
RPS Radiation Protection Services
The life cycle begins with an agreed specification, possibly followed by a formal tender, option appraisal exercise or RFP
Technical professional translates agreed specifications in a form that can be used in the RFP. Specifications must be specified only if they can be tested, therefore the involvement of the personnel that will perform the testing is recommended. Client provides input regarding preferred maintenance program.
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COORDINATION<br />
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The successful bidder coordinates installation with the client and architect, and is responsible for providing all data for construction documents. Upon receipt of purchase order, the successful bidder conducts coordination meeting with the medical imaging representative, architect, contractor, and client representative.<br />
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SITE INSPECTION<br />
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Prior to the installation the OEM will determine that the room is, or will be, prepared for installation upon equipment arrival.</p>
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1. Shielding calculations performed by a qualified Medical Physicist.<br />
2. Floor plans approved and signed off by RPS, BC Ministry of Health prior to the start of the construction.<br />
3. Medical Physicist approval of lead installation before covering the lead with the finishing materials.<br />
4. Documentation is complete including pictures showing wall-shielding material.<br />
5. Plaques made up indicating amount of lead in the walls, doors, and in the control window.<br />
6. RPS Ministry of Health is notified that room is ready for service.</p>
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To determine the shielding necessary for a diagnostic x-ray installation certain preliminary information is essential. The required thickness of shielding can be calculated using the formular. In both instances answers to the following questions are required:</div>
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1. What is the distance between the nearest point of the area to be shielded and the mean operational position of the x-ray tube?</div>
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2. Is the area to be designated as a controlled or uncontrolled area, i.e. will the area be occupied by radiation workers (subject to the limit of 20 mSv per year) or non-radiation workers (subject to the limit of 1 mSv per year)?</div>
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3. What will be/is the occupancy factor (T) of the area? The occupancy factor is defined as the time an area is normally occupied, expressed as a fraction of the working week.</div>
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4. Will the intervening shield between the x-ray tube and the occupied area act as a primary or secondary protective barrier, i.e. will the barrier be required to attenuate the direct useful beam or stray (leakage and scattered) radiation only?</div>
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5. What will the use factor (U) of the required protective barrier? The use factor is defined as the fraction of the operational time during which the useful beam will be/is directed at the barrier or area under consideration.</div>
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6. What will be/is the workload (W) of the x-ray unit? The workload indicates the operational time of an x-ray machine expressed in terms of milliampere-minutes per week.</div>
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7. What will be/is the maximum and average operating tube potential, and output?</div>
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COORDINATION OF THE INSTALLATION SCHEDULE</div>
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Installation schedule must be coordinated with the overall construction schedule.</div>
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CRITICAL EXAMINATION AND TESTING IN ACCORDANCE WITH REGULATIONS</div>
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After a contract is placed and the installation is complete, the installer, in conjunction with a RSO, has to undertake a critical examination in accordance with regulations.</div>
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The critical examination is to ensure that the safety features and warning devices incorporated into the equipment are operating correctly and that there is sufficient protection of the staff, visitors and patients awaiting diagnosis or treatment against unnecessary exposure to ionizing radiation. A critical examination is appropriate when there could be radiation protection implications associated with the incorrect installation, such as the failure of the safety features or warning devices to operate correctly, poor siting or inadequate shielding. Although this requirement is concerned primarily with radiation protection aspects that affect staff and visitors, the safety features and warning devices may be relevant to patient safety as well. It requires an examination of the manner in which the equipment is erected and installed. An experienced surveyor selectively examining those features, which are most likely to affect safety can achieve this, and then to probe more deeply depending on the results obtained.</div>
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Often, the customer's RSO or Medical Physicist on behalf of the installer undertakes the critical examination.</div>
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client should not allow the equipment to be used for medical exposures unless the results of the critical examination are satisfactory.</div>
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ACCEPTANCE TESTING (HAND OVER BY THE CONTRACTOR AND BY THE OEM)</div>
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Acceptance is then undertaken by a representative of the client to verify that the contractor has supplied all the equipment specified and has performed adequate tests to demonstrate that the specified requirements in the contract have been met. The onus is on the contractor to undertake the tests. Client can contract out this work to OEM or this work can be done in combination with client Maintenance, BME and OEM. In any case, confusion must be avoided by identifying responsible individuals. Acceptance may be a matter of simply completing a checklist. Any significant discrepancy should be notified formally to the contractor, who is required to undertake corrective action. Mechanical and electrical safety tests are required in addition to radiation safety tests. During testing, Medical Physicist, BME, and Facility Planing work with OEM and in an organized way.</div>
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COMMISSIONING BY MEDICAL PHYSICIST</div>
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Commissioning is a set of tests carried out by the purchaser's representative to ensure that the equipment is ready for clinical use and to establish baseline values against which the results of subsequent routine performance tests can be compared. An important objective at this stage is to help confirm that the requirements of regulations are being met.</div>
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Some of the commissioning tests take the form of checks and measurements and may have already been included in the critical examination undertaken by the installer or the OEM. Duplication can be avoided if the installer and the surveyor undertaking the commissioning undertake these tests jointly. The opportunity can then be taken to take corrective action, if necessary, so that the performance of the imaging system is optimized, which is the other purpose of commissioning. After major work on the equipment, the relevant commissioning tests may have to be repeated to establish new baseline values, for example, after an X-ray tube is replaced.</div>
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One Medical Physicist may undertake the critical examination, acceptance and commissioning. Although the tests may be combined, their purpose should remain distinct.</div>
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ROUTINE PERFORMANCE TESTING</div>
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Routine performance (or constancy) testing comprises those tests, which are undertaken either regularly, or after maintenance or repairs, to detect whether any change in the performance of the equipment has occurred; if so, corrective action can be initiated. Routine performance tests are in effect a sub-set of the commissioning tests.</div>
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Generally, routine performance testing will involve both internal and external staff. Internal staff necessarily undertakes the frequent tests, which are quick to perform. External staff undertakes the more time-consuming tests, which may require special expertise and instrumentation. As many of these tests have implications for radiation safety, they are usually undertaken under the auspices of the user's radiation protection adviser. This also provides a measure of independence from the user and the maintenance contractor. The service engineer, medical physicist or other external agency may also undertake the tests. A collaborative, multi-disciplinary approach to routine performance testing is essential.</div>
Turning a room over for clinical use prior to commissioning and user application training is unacceptable. This would be a major error and it defeats the entire process.
Maintenance and routine performance testing are complementary. Equipment has to be maintained to ensure that it is safe to use and that it is working properly.
Another aim of maintenance is that the detailed performance specification, which was demonstrated at commissioning, continues to be achieved during the working life of the equipment.
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BME consider disposal of equipment on the recommendation of the Medical Imaging Department.</p>