The commissioning process

Question 1

List the main parts of the equipment lifecycle.

Answer 1

• Equipment specification.
• Option appraisal/tender.
• Purchase contract.
• Installation.
• Critical examination.
• Acceptance testing.
• Commissioning.
• Clinical use.
• Maintenance and routine performance testing. This may require removing from clinical use before additional maintenance. Major maintenance (e.g. new tube) may require additional critical examination/commissioning tests.
• Disposal or alternate use.
• Replacement.

Question 2

What must the MPE contribute to regarding the commissioning process?

Answer 2

• Advise on specification and selection of equipment.
• Be involved in commissioning and acceptance testing of equipment.
• Preparation of technical specifications for equipment and installation designs.

Question 3

What should be considered for equipment specification?

Answer 3

• Clinically required features.
• Performance of unit.
• Compliance with standards.
• EM compatibility.
• Ease of use/familiarity.

Question 4

What might local specification and evaluation involve?

Answer 4

• Input from various teams to advise on aspects relevant to their role (e.g. medical physics, clinical staff, engineering, estates etc.).
• Site visits/loan/demo units.
• Local scoring of equipment against specification (allows for transparency if suppliers query why they were not awarded business).

Question 5

How does the tender process work?

Answer 5

• Manufacturers are provided with the specification and asked to provide their best solution.
• Any contract in excess of £123 000 must be advertised on the ‘Find a Tender’ site.
• NHS Supply Chain bulk buy items from suppliers allowing for savings in individual purchase price. This bypasses the formal tender process.
• NHS Supply Chain use Multi Trust Aggregation to combine similar capital requirements from multiple organisations to achieve greater discounts.

Question 6

What is the first thing that should be tested after equipment installation? Who typically does this?

Answer 6

• Electrical safety.
• Installation engineer, local estates, medical electronics or, sometimes, medical physics.

Question 7

What is the purpose of a critical examination? Who must be involved?

Answer 7

• To ensure all safety features and warning devices are working as expected.
• An RPA must be involved.

Question 8

Is a critical examination required for a new tube on a mobile x-ray unit?

Answer 8

Yes. Shielding/collimation will likely have been disturbed. This will mean that the critical examination performed by the manufacturer at the factory will no longer be valid.

Question 9

Is a critical examination required for:
1. Tube shielding?
2. Room shielding?
3. Ceiling mounted shields?
4. Mammography unit screen?

Answer 9

1. Yes.
2. No. Not within the remit of the equipment but should still be assessed.
3. No. Not considered part of the equipment but should still be assessed.
4. Yes. Part of console so considered to be integral to equipment.

Question 10

Who is responsible for the critical examination? Do they always perform the critical examination themselves?

Answer 10

• The installer.
• Local medical physics or third party often contracted to undertake instead.

Question 11

What is the purpose of acceptance testing?

Answer 11

• To verify that the contractor has supplied all equipment specified and has performed adequate tests to demonstrate specified requirements are met.

Question 12

What is the purpose of commissioning tests?

Answer 12

• To ensure equipment is ready for clinical use and to establish baseline values against which routine QA can be compared.
• Check T&G performance.
• Check AEC performance.
• Check imaging performance.
• Check dosimetry.

Question 13

Who typically performs these tests? When are commissioning tests required?

Answer 13

• Performed by a representative of the employer (typically local medical physics).
• After final setup and following any major changes (e.g. new tube, new image receptor, software changes etc.). Also, often re-visits for commissioning are performed after final applications setup to confirm clinically relevant programmes are okay.

Question 14

What is the purpose of commissioning for new techniques in radiotherapy?

Answer 14

To determine if the intended treatment dose is delivered to the intended volume.

Question 15

What are the main steps in the linac commissioning process?

Answer 15

• Initial linac beam characterisation (e.g. depth dose, profiles, coordinate systems etc.).
• Model of linac beam produced and input into TPS.
• Validation of model using different equipment from initial tests.