Guidance

Breast screening: guidelines for medical physics services

Updated 25 September 2019

1. Overview

All local providers of NHS Breast Screening Programme (BSP) services must contract with medical physics services which conform to this guidance.

This document clearly sets out the legal requirements to help ensure the safety of individuals participating throughout the screening pathway.

1.1 Aim

This guidance specifies the scope and standards for medical physics services which are to be employed in the NHS BSP in England. It is aimed at both commissioners and providers of medical physics services.

Where regions are referred to, these are the regions in England for the organisation of the screening quality assurance service (SQAS).

The scope of this document does not currently cover magnetic resonance (MR) physics.

1.2 Background

Medical physics support

Medical physics support has been an essential part of quality assurance (QA) in the breast screening programme since its inception in 1988.

One of the main roles of the physicist in the NHS BSP is to advise services on the optimisation of image quality – how to achieve the required image quality while keeping radiation doses as low as practicable. Another important role is to detect any deterioration in image quality that might not be apparent in clinical images, but which would reduce the diagnostic accuracy and sensitivity of the programme.

Regulatory requirements

Employers that work with ionising radiation must comply with regulations aimed at ensuring such work is carried out safely. The 2 main sets of regulations that breast screening services must comply with are:

1. Ionising Radiation (Medical Exposure) Regulations 2017 (IRMER) regulate medical uses of ionising radiation such as mammography. These regulations require a medical physics expert (MPE) to be appointed to advise on and be involved with aspects such as optimisation of exposure, patient dosimetry, compliance with IRMER, equipment selection and quality assurance testing.

2. Ionising Radiations Regulations 2017 (IRR) regulate work with ionising radiation with particular focus on matters relating to protection of employees and the public. These regulations require a radiation protection adviser (RPA) to be appointed to advise on specific aspects of radiation protection such as risk assessment and radiation monitoring arrangements.

The role of medical physics in the breast screening programme

Areas which require significant input from medical physics services in the NHS BSP include:

• procurement and replacement of imaging equipment
• management of equipment performance and quality control
• introduction of new imaging technologies and techniques
• compliance with radiation regulations

2. Medical physics services

All breast screening services should have a written service specification with a medical physics service or services specifying the level, scope of services required and monitoring of service delivery.

2.1 Responsibilities

It is the responsibility of the host organisation of each breast screening service to make sure it has the appropriate support and involvement of a medical physics service or services. This provision must include:

• an MPE to provide expert advice on matters relating to the use of ionising radiation for medical exposures as defined by IRMER

• a radiation protection adviser (RPA) as required by the IRR to provide advice on matters relating to staff and public safety when working with ionising radiation

• performance testing of mammographic x-ray systems and associated equipment such as tomosynthesis functions, image display devices and biopsy attachments as required by IRMER and in compliance with recommended Institute of Physics and Engineering in Medicine (IPEM) and NHS BSP standards ^{[footnote 1] [footnote 2] [footnote 3]}

• performance testing of breast ultrasound equipment in accordance with NHS BSP protocols

• support for user quality control (QC) programmes for imaging equipment used in the NHS BSP ^{[footnote 4] [footnote 5]}

• respond to ad-hoc queries whether by phone, email or site visit in a timely manner

Additional radiation safety advisory services may be required where radioactive substances are used within the breast screening service, for example. radio-guided occult lesion localisation or sentinel node biopsy procedures. Additional safety advisory services can include a radioactive waste adviser to advise on waste disposal and environmental radiation protection.

It may also be appropriate for the medical physics service to provide advice and support on compliance with relevant NHS BSP and other professional guidance.

2.2 Service organisation and agreements

A breast screening service can contract with one or more medical physics providers to deliver different aspects of the service. These providers can be internal or external to the host organisation of the breast screening service. In either case, there must be a written agreement between both parties which includes scope and level of service. Each agreement should list the equipment covered, for example mammography (including relevant functionality such as magnification and stereotactic modes) and tomosynthesis systems, ultrasound scanners, image display devices and imaging specimen cabinets. The agreement should cover the physical locations of the equipment and arrangements for access.

Where multiple medical physics providers are contracted, the host organisation should take extra care to make sure all required activities are covered and that medical physics providers are clear on their responsibilities. This is likely where a medical physics service provides RPA or MPE services to a screening service but not to the rest of the radiology department of a host organisation. A clear division of activities relating to the screening service is required as MPE and RPA activities from radiology may overlap with breast screening specific activities (for example, the writing of IRMER procedures, local rules and radiation safety policies).

Procurement or other tender exercises for any aspect of the medical physics service must be done with the support of a suitably qualified and experienced medical physicist, in particular for the drafting of the service specification and the assessment of bids. SQAS must be contacted to identify an appropriate independent individual. SQAS should be made aware of any such procurement exercises when they happen. A national template service specification for the procurement for medical physics services is available.

The medical physics provision must be of adequate capacity for the breast screening service. There must be a suitably qualified and experienced whole-time equivalent (WTE) staff member for every 14 standard x-ray mammography units, of which around 30% should be an MPE as recommended by European guidelines. Ultrasound physics support provision should be approximately a third of that for x-ray equipment. Additional support will be required for tomosynthesis, image display devices and specimen X-ray cabinets.

The prospective medical physics service must have current experience and evidence of procurement, optimisation and involvement with user QC.

The provider must understand and comply with NHS BSP guidance on confidentiality, information governance and screening incidents.

2.3 Services to be provided in relation to imaging equipment

Advice on equipment selection

The medical physics service should provide advice on:

• equipment specification and selection
• relocation of existing equipment
• the need for equipment replacement
• instruments used for performing quality control tests

Commissioning tests for new equipment

A critical examination of the installation of X-ray units is also required to ensure the correct function of the radiation safety features of the equipment. The installer has the responsibility for carrying out this examination under the IRR. However, they may separately contract the local physics service to do this on their behalf.

Acceptance and commissioning tests for new imaging equipment must be conducted before clinical use. Separate arrangements should be made for inventory checks or tests of electrical and mechanical safety by the appropriate bodies.

As part of commissioning, the medical physics service should work in conjunction with the supplier and the user to make sure image quality and dose are optimised.

Performance testing protocols and schedule

Imaging equipment used in connection with the NHS BSP must be subject to a routine schedule of performance testing. The table below lists the recommended frequency for testing. Performance testing must take place no later than 4 weeks after the date indicated by these frequencies although it should be noted that specific tests may be required less frequently ^{[footnote 1] [footnote 2] [footnote 3]}. It is important that breast screening services make sure equipment is available for testing at appropriate intervals and as required.

Equipment area	Recommended testing frequency
Mammography equipment and associated attachments and functions, such as tomosynthesis	6 months
Ultrasound scanners and probes	6 months
Image display devices	12 months
Specimen x-ray cabinets	12 months
Emerging technologies, for example contrast enhanced spectral mammography	6 months

In exceptional circumstance, and by agreement with both parties, it may be appropriate to exceed these frequencies provided this has been risk assessed, by using appropriate information such as the results of user QC. If equipment is not used clinically it is sufficient to only carry out the required testing before its entry into clinical use.

All measurements on equipment will be performed using the test instruments and methods defined in the most recent national protocols published by IPEM ^{[footnote 1]} and Public Health England (PHE) ^{[footnote 2] [footnote 3] [footnote 6]}. Additional testing before clinical use may be required following equipment repairs, component replacements or software upgrades as advised by the medical physics service. In other situations it may be sufficient for the breast screening service to perform user QC tests under medical physics advice in order to return equipment to clinical use. This will be in accordance to local QA documentation.

Performance testing reports

A written report must be provided for all performance testing to include:

• date of survey, operator, MPE (or ultrasound expert) taking responsibility for the report, date of report issue and details of the test(s) performed
• summary of the measurement results
• comparison with appropriate remedial or suspension levels ^{[footnote 1] [footnote 2] [footnote 3]}
• confirmation of satisfactory performance or recommended corrective action

Relevant data from each set of tests must be submitted to national or regional databases as directed by the national programme team or SQAS.

The report should be submitted to the director of breast screening or their delegated representatives within 4 weeks of the survey visit. A recommendation requiring urgent action must be drawn to the attention of appropriate breast screening staff (for example, director of breast screening, programme manager, lead radiographer, radiographers) in writing (including email) on completion of the test. It is the responsibility of the director of breast screening to make sure appropriate action has been taken by the screening service. The medical physics service must inform the RPA promptly of any faults or incidents which have consequences for radiation protection.

Routine user quality control (QC)

Routine daily, weekly and monthly quality control checks on equipment performance in the NHS BSP are conducted by the breast screening service staff. The system of quality control checks should follow national protocols ^{[footnote 4] [footnote 5] [footnote 6]}. There should be close collaboration between the medical physics service and radiographers in the development and running of this system. The medical physics service should offer advice to screening radiographers on the practice and results of their routine quality monitoring. A review of the programme of quality control checks should be carried out and documented as part of a 6-monthly review by the medical physics service. An effective system of medical physics oversight and review of user QC results must be in place.

Equipment QA systems and work instructions

The medical physics service should help establish and review appropriate parts of the equipment QA systems and work instructions for the breast screening service.

Assessment of patient dose

The medical physics service should be involved in the measurement of radiation dose to the breast. This involvement includes advice on the process for dose assessment, and the critical evaluation of results and their implications. In particular, the medical physics service should verify whether the mean glandular dose to the standard breast and local diagnostic reference levels conform to current NHS BSP standards and national diagnostic reference levels (DRLs).

The medical physics service should also be involved in the assessment of clinical doses for samples of women for all new mammography equipment. This should be repeated at least every 3 years thereafter and following any changes made to the equipment which may impact on dose. Samples will consist of at least 50 women for each X-ray unit. Dose audits should also consider alternate modes of operation, for example tomosynthesis. Software for the calculation of these doses is provided by the NHS BSP. The dose data should contribute to a review of whether the x-ray system is being operated optimally and should be compared to European, national and local DRLs where available, as required under IRMER.

Summaries of the patient dose surveys should be sent to the director of breast screening and the MPE. Patient dose surveys are subject to periodic national reviews.

Regulatory compliance

The medical physics service must contribute to the provision of advice to the breast screening service in relation to compliance with the radiation regulations. In general, the MPE must contribute to the provision of advice relating to compliance with IRMER, while advice relating to compliance with IRR will be provided by the RPA. This should be clearly detailed in the written service agreement. A review of compliance with IRMER should be carried out by the breast screening service and documented as part of an annual audit, with the support and advice of the MPE. It is the employer’s responsibility to make sure there is a QA programme in place for IRMER procedures. However, the medical physics service should be able to give support in this regard.

Trouble shooting

Problems with equipment performance may be identified at commissioning or by the routine performance tests. Some problems will be highlighted by the local quality control checks. Medical physics services can, where appropriate, assist in the resolution of these problems by further investigation of the initial finding and by liaison with the equipment manufacturers and service agents. The medical physics service may, where appropriate, also provide advice regarding breakdowns and emerging concerns about the performance of the equipment.

2.4 Medical physics departments

Test equipment

The medical physics service must have access to a suitable and sufficient set of test instruments as defined in national protocols ^{[footnote 1] [footnote 2] [footnote 3] [footnote 6]}. Test instruments used to measure the physical properties of the X-ray beam and display luminance levels must be calibrated at the frequency recommended by the instrument manufacturer. Where no calibration frequency is suggested by the manufacturer, an annual check is recommended.

Procedures and protocols

Medical physics services should develop procedures and protocols for all activities included in the service agreement(s). These documents should cover the scope of work specified in the service agreement and be adhered to by all staff. Staff must act in accordance with current professional guidelines and the procedures should reflect the detailed guidance given in national protocols.

Each medical physics service should have a local quality management system (QMS) for breast screening and should ideally be working towards an externally accredited QMS. The QMS should include the objectives of the quality programme, the methods used to attain these objectives and a list of standards and requirements to be met. Provision should also be made for the evaluation of practice against current guidelines, evaluation of service users’ satisfaction and for audit of the service.

Responsibility for reporting to PHE

PHE contracts an external organisation to provide scientific and technical advice to the NHS BSP. This contract is currently held by the National Co-ordinating Centre for the Physics of Mammography (NCCPM). NCCPM is contracted to test new mammographic equipment to ensure that it meets the requirements of the programme and is acceptable for use from a technical perspective. NCCPM co-ordinates, hosts and analyses the online reporting tool on which breast screening services log equipment faults.

Medical physics departments which provide services to the NHS BSP should:

• supply key performance indicators (KPIs) and other performance measures as required by NCCPM at the required frequencies to ensure national monitoring of physics data
• participate in dose surveys organised by the NCCPM
• supply reports to include KPIs on request to the SQAS on the performance and state of equipment in breast screening services
• respond to requests relating to queries about their service provision
• participate and respond to any surveys and evaluations organised by PHE
• network together in order to share knowledge and experience by actively participating in the regional QA structures such as annual breast imaging physics meetings organised by the SQAS

Medical physicists who are also professional and clinical advisors (PCAs) to SQAS have an additional role. PCAs are experienced staff that actively practice their profession within the breast screening programme. They advise SQAS on the technical aspects of processes and practices in the breast screening programme. Their role includes the peer review of breast screening services and advising the SQAS on service requirements.

For more information on the role of SQAS and the PCA in the NHS BSP see the Operating Model for PHE Screening Quality Assurance Service.

If the medical physics provider becomes concerned that the breast screening service is not acting on its advice in a manner that places patient or staff safety at risk, this should be escalated in accordance with the appropriate policies in the breast screening service’s host organisation.

3. Qualifications and experience

Scientific and technical staff providing the breast imaging physics service must have adequate qualifications, training and experience.

3.1 Introduction

Medical physics services to the NHS BSP will normally be provided by a team of clinical scientists and technologists. One clinical scientist – the lead physicist – should be managerially and scientifically responsible for, and closely involved in, the work of the staff providing medical physics services. Consideration should be given to resilience, diversity of experience and knowledge. All medical physics providers must complete suitable and sufficient risk assessments of their service provision. Where weaknesses are identified, formal arrangements to work closely with other experienced medical physics services must be made.

It is essential that during a period of re-procurement, experience and expertise of other medical physics services should be sought, particularly where the physics service has limited experience or exposure to multi-vendors equipment.

3.2 Qualifications and training for breast imaging physics

The lead physicist for mammography must be a medical physics expert (as defined under IRMER) with particular experience in mammography. The named lead for ultrasound must be an individual with particular experience in ultrasound physics.

All staff providing mammography medical physics services to the NHS BSP (except trainees working under supervision) must:

• have received basic training in general diagnostic radiological physics and radiation protection

• have received training in mammography physics by attending the IPEM Mammography Physics basic training and update courses, or equivalent

• undertake practical training in medical physics departments with recognised expertise in mammography physics (if necessary, SQAS can be contacted to advise on suitable services to provide such training)

• periodically make visits to other centres active in mammography physics to compare techniques, especially before the introduction of new equipment or techniques

In larger services, visits may be limited to the staff directly involved with the development of testing protocols with an internal cascade to all relevant members of the team.

Staff providing ultrasound physics services must meet equivalent training requirements.

3.3 Experience and knowledge

To achieve and maintain adequate awareness of current technology and techniques, the medical physics service must be able to demonstrate evidence of continuing support for breast imaging equipment and its clinical use. This should include work relating to:

• dose assessments
• liaison with equipment suppliers
• procurement
• optimisation
• incident investigation

Knowledge and experience may also be demonstrated by participation in relevant scientific meetings and training events, reviewing scientific literature or research and development activities.

To achieve and maintain adequate awareness of current technology and techniques, all scientists and technologists who are working unsupervised must carry out at least 6 episodes of QA testing on each relevant modality (mammography or ultrasound) in a 12-month period. For those supporting both X-ray and ultrasound modalities, this means 6 episodes or more from each modality taking into consideration the diversity of equipment supported. For less common manufacturers or technologies such as tomosynthesis, consideration should be given to finding a balance between ensuring that individuals have an adequate depth of experience while ensuring service resilience.

For the purposes of this requirement, an episode should be considered to be a visit to carry out a full set of routine performance tests on a piece of relevant imaging equipment. Visits to equipment that is tested to NHS BSP standards but is not within the screening programme, for example symptomatic or private units, can count towards this requirement. Individual medical physics staff that are unable to achieve the minimum activity levels outlined above must seek the support of other, experienced services and join them on ‘buddy visits’ to increase their activity and develop peer-support networks.

The lead physicist must also:

• participate in a regional (or sub-regional) review of the data from equipment performance testing at least once a year, and have access to such data when necessary and available
• participate with other lead physicists in the organisation of more frequent informal meetings (which could be via teleconference) to support the sharing of knowledge and experience in regions where smaller services operate
• develop knowledge and skills with other mammography scientists and technologists and attend meetings on mammography or ultrasound physics, within their region and nationally
• keep updated with developments in mammography or ultrasound physics by attending relevant training and scientific meetings and reading relevant scientific papers
• periodically make visits to other centres to compare techniques, especially when new equipment or techniques are introduced

3.4 Continuing professional development

Medical physics staff working in the NHS BSP must maintain their expertise and knowledge by appropriate continuing professional development (CPD). This which may include attendance at the update training day in mammography physics organised by the IPEM and participation in professional meetings such as the UK Mammography Physics Group and Symposium Mammographicum.

Staff may also make ‘buddy’ visits with other medical physics services providing QA services for the breast screening programme. Scientists and technologists should also participate in a recognised CPD scheme such as that run by the IPEM with a proportionate amount of that CPD activity being mammography related.

4. References

1. The Commissioning and Routine Testing of Mammographic Systems. Institute of Physics and Engineering in Medicine, 2004 (Report 89). ↩ ↩² ↩³ ↩⁴ ↩⁵

2. Commissioning and routine testing of full field digital mammography systems. NHS BSP Equipment Reports 0604 Version 3. PHE, 2009. ↩ ↩² ↩³ ↩⁴ ↩⁵

3. Routine quality control tests for breast tomosynthesis (physicists). NHS BSP Equipment Report 1407. PHE, 2015. ↩ ↩² ↩³ ↩⁴ ↩⁵

4. Routine quality control tests for breast tomosynthesis (radiographers). NHS BSP Equipment Report 1406. PHE, 2014. ↩ ↩²

5. Routine quality control tests for full-field digital mammography systems. Equipment report 1303: fourth edition. PHE, 2013 ↩ ↩²

6. Guidance notes for the acquisition and testing of ultrasound scanners for use in the NHS breast screening programme. PHE, 2011 ↩ ↩² ↩³