Radiation Protection for Assistant Practitioners in Mammography Lecture 4

1. Radiation Protection for Assistant Practitioners in MammographyLecture 4 John Saunderson Radiation Protection Adviser (TPRH ext. 6690)

2. “IRMER Syllabus” • Production of X-rays • Absorption and scatter • Radiation hazards and dosimetry • Special attention areas • Radiation Protection • Laws & Guidelines • Equipment .

3. 2. Management and Radiation Protection of Patient

4. 2.1 Patient Selection • Justification of the individual exposure • Patient identification and consent • Use of appropriate radiological information • Alternative techniques • Clinical evaluation of outcome • Medico-legal issues .

5. Justification of the individual exposure • By law, all exposures must be justified • For breast screening • Women invited within NHSBSP invitation protocol • Women not invited, but fit NHSBSP protocol • For other, practitioner must decide (e.g. radiologist) • A written record must be made of who authorised each X-ray.

6. Patient identification and consent • (covered elsewhere) • By law, the Trust must have a patient ID procedure • ID should be positive (“Yes, dear” won’t do!).

7. General Points • Use of appropriate radiological information • (covered elsewhere) • Alternative techniques • Always use lowest dose technique, that will achieve the clinical result • Clinical evaluation of outcome • By law, all films must be reported • Medico-legal issues • e.g. X-rays for insurance purposes • Special procedures must be in place to ensure that exposures are justified .

8. 2.2 Radiation Protection • General radiation protection • Use of radiation protection devices • patient • personal • Procedures for untoward incidents involving overexposure to ionising radiation .

9. Justification • Optimisation • Limitation

11. All doses should be kept • As • Low • As • Reasonably • Achievable The ALARA Principle .

12. Basic Principles • Time • Distance • Shielding

13. Distance • Double distance = 1/4 dose • Triple distance = 1/9th dose.

14. Shielding

15. Shielding

16. Typical Mammo. Doses • Primary = 5 mGy @ 1 m from tube per shot • Through breast to film = 7 uGy • Max. scatter @ 1 m = 7.6 uGy (at 163o) • @ 30 kV 0.3 mm Pb transmits 0.00006 % (i.e. less than a millionth)

17. Organising radiation safety • Controlled Areas • Local Rules • Radiation Protection Supervisor • Radiation Protection Adviser • Radiographer • Assistant Practitioner.

18. Use of radiation protection devices patient personal

19. Untoward Incidents • Overexposure of patient • Overexposure of staff • ?.

20. Incidents • Any untoward occurrence which may result in excess radiation to staff or patients must be referred to the Radiation Protection Supervisor and the Radiation Protection Adviser, who will estimate the dose and liase with management, HSE, DoH, HMIP, etc. as appropriate • Suspect equipment must be withdrawn from service and labelled according .

21. Patient Doses Much Greater Than Intended • x 20 - extremities, skull, chest, etc. • x 10 - lumbar spine, abdomen, pelvis, mammography and other examinations not referred to elsewhere, • x 3 - fluoroscopy, digital radiography, C.T.

22. Investigation • establishing what happened • identifying the failure • deciding on remedial action to minimise the chance of a similar failure • estimating the doses involved • decide whether patient informed (usually yes).

23. 3. Statutory Requirements and Advisory Aspects

24. 3.1 Statutory Requirements and Non-Statutory Recommendations • Regulations • Local rules and procedures • Individual responsibilities relating to medical exposures • Responsibility for radiation safety • Routine inspection and testing of equipment • Notification of faults and Health Department hazard warnings • Clinical Audit .

25. UK Regulations • Ionising Radiations Regulations 1999 • “IRR99” • inspected by Health & Safety Executive • Mostly relate to staff and public safety (not patients) • Covers equipment • Ionising Radiation (Medical Exposures) Regulations 2000 • “IRMER” • Relate to patient safety .

26. IRR99 • Justification, optimisation, limitation • Optimisation • ALARP, • controlled areas, • local rules, • RPS, • RPA, • risk assessments, • equipment QA.

27. IRMER • Justification, optimisation, “constaints” • Procedures and protocols • Roles and responsibilities • Audit and adequate training.

28. Employer's Procedures to ... (a) identify patient correctly (b) identify referrers, practitioners and operator; (c) for medico-legal exposures; (d) for making enquiries of females of childbearing age to establish whether the individual is or may be pregnant or breastfeeding; (e) ensure that QA programmes are followed; (f) for the assessment of patient dose; (g) diagnostic reference levels;

29. (a) identify patient correctly (b) identify referrers, practitioners and operator; (c) for medico-legal exposures; (d) for making enquiries of females of childbearing age to establish whether the individual is or may be pregnant or breastfeeding; (e) ensure that QA programmes are followed; (f) for the assessment of patient dose; (g) diagnostic reference levels; (h) (biomedical research) Employer's Procedures to ... (i) (nuclear medicine) (j) recording result and exposure factors (k) minimise accidents.

30. Roles and Responsibilities • Employer • Referrer • Practitioner • Operator • Medical Physics Expert.

31. Referrer • Must provide sufficient info. for the practitioner to justify exposure • X-ray department must provide referral criteria.

32. Practitioner • Justifies X-ray - decides net benefit • Can delegate authorisation to an operator in written procedures • Usually a radiologist, but does not have to be - define in employer’s procedures • Must follow employer’s procedures .

33. Operator • Anyone who performs “practical aspects”, e.g. • radiographer • radiologist • assistant practitioner • medical physics • engineer • If procedures allow, can authorise exposure • Must follow employer’s procedures .

34. Training • Practitioners and operators must have adequate training • Schedule 2 lists theory, also do practical • Records must be available.

35. 4. Diagnostic Radiology

36. 4.1 General • Fundamentals of radiological anatomy • Fundamentals of radiological technique • Production of X-rays • Equipment selection and use • Factors effecting radiation dose • Dosimetry • Quality assurance and quality control .

37. 4.3 Fundamentals of Image Acquisition, etc. • Image quality v. radiation dose • Conventional film processing • Additional image formats, acquisitions, storage and display .

38. f i n

39. “Trash” next

40. Attenuation, Scattering and Absorption • 0.34 mm Al at 28 kV Mo/Mo • For average breast; • 0.2% of x-ray energy reaches film • 99.8% absorbed in breast