1. International Atomic Energy Agency Medical exposure in radiology: Accidental medical exposures Module VIII.5: Accidental exposures in radiological procedures

2. International Atomic Energy Agency Module VIII.5: Accidental exposure2Introduction Despite attention on safety measures, accidental doses can be delivered to patients or staff Roughly three categories can be distinguished: (possbly) pregnant women, staff and patients in high dose rate exposures such as interventional radiology Investigations are compulsory

3. International Atomic Energy Agency Module VIII.5: Accidental exposure3Topics 1.Accidental exposure of pregnant women 2.Patient exposure: accidental high doses 3.Accidental doses to staff 4.Investigations in accidental exposure

4. International Atomic Energy Agency Module VIII.5: Accidental exposure4Overview Some examinations can lead to relatively high doses to the fetus Deterministic effects (often skin) are not uncommon in fluoroscopic interventional procedures IR also can lead to high staff exposure to eye lens or hands

5. International Atomic Energy Agency Topic 1: Accidental exposure of pregnant women or women in reproductive age

6. International Atomic Energy Agency Module VIII.5: Accidental exposure6Definitions —Potential exposure is exposure that may result from an accident due to an event or sequence of events of a probabilistic nature; the probability, while not negligible, is significantly less than one. — Normal exposure is exposure which is expected to be received under normal operating conditions, including minor mishaps or errors whose probability of occurring is not significantly less than one — Accident refers to any unintended event, including operating errors, equipment failures or other mishaps, the consequences or potential consequences of which are not negligible from the point of view of protection or safety.

7. International Atomic Energy Agency Module VIII.5: Accidental exposure7 In order to avoid unwanted irradiation of the fetus, it is recommended to post warnings, both at the X Ray room entrance and in the waiting ward such as: "IF YOU THINK THERE IS ANY POSSIBILITY THAT YOU ARE PREGNANT, PLEASE TELL IT TO THE RADIOLOGIST OR TO THE OPERATOR, BEFORE THE X RAY EXAMINATION IS PERFORMED". Accidental exposure of pregnant women

8. International Atomic Energy Agency Module VIII.5: Accidental exposure8 It should be asked to the female patient about the possibility of being pregnant, even to the pediatric patient in puberty. In the affirmative case appropriate measures should be taken When a pregnant patient undergoes a radiological examination (in the abdomen), it might be advisable to make an individual evaluation of the expected fetus dose. Accidental exposure of pregnant women

9. International Atomic Energy Agency Module VIII.5: Accidental exposure9 Doses expected from accidental fetal exposures data from the UK 1998

10. International Atomic Energy Agency Module VIII.5: Accidental exposure10 Expected fetal doses from fluoroscopic and computed tomography procedures data from the U.K. 1998

11. International Atomic Energy Agency Module VIII.5: Accidental exposure11 Effects of antenatal exposure ý Mental retardation: ý ICRP establishes that mental retardation can be induced by radiation (Intelligence Quotient score < 100). ý It occurs during the most RS period: 8-25 week of pregnancy. ý Risks of antenatal exposure related to mental retardation are: Severe mental retardation with a Risk factor of 0.1/Sv Severe mental retardation with a Risk factor of 0.4/Sv 15-25 week8-15 week

12. International Atomic Energy Agency Topic 2: Patient exposure: accidental high doses

13. International Atomic Energy Agency Module VIII.5: Accidental exposure13 Effects of ionizing radiation Deterministic e.g. Lens opacities, skin injuries, infertility, epilation, etc Stochastic Cancer, genetic effects.

14. International Atomic Energy Agency Module VIII.5: Accidental exposure14 Deterministic effects Deterministic(Thresho ld/non-stochastic) Existence of a dose threshold value (below this dose, the effect is not observable) Severity of the effect increases with dose A large number of cells are involved Radiation injury from an industrial source

15. International Atomic Energy Agency Module VIII.5: Accidental exposure15 Skin reactions Skin damage from prolonged fluoroscopic exposure

16. International Atomic Energy Agency Module VIII.5: Accidental exposure16 Skin injuries

17. International Atomic Energy Agency Module VIII.5: Accidental exposure17 Skin injuries

18. International Atomic Energy Agency Module VIII.5: Accidental exposure18 Interventional Radiology CT Radiography Interventional radiology: high risk procedures

19. International Atomic Energy Agency Module VIII.5: Accidental exposure19 Coronary angioplasty twice in a day followed by bypass graft because of complication. Dose  20 Gy (ICRP 85) (a) 6-8 weeks after multiple coronary angiography and angioplasty procedures. (b) 16-21 weeks (c) 18-21 months after the procedures showing tissue necrosis. (d) Close-up photograph of the lesion shown in (c). (e) Photograph after skin grafting. (Photographs courtesy of T. Shope & ICRP). (d) (e) (a) (c) (b)

20. International Atomic Energy Agency Module VIII.5: Accidental exposure20 Photograph showing temporary epilation of the right occipital region of the skull 5-6 weeks following embolization (Courtesy W. Huda). Regrowth (grayer than original) reported after 3 months. Neuroradiology Trans-arterial embolization of para orbital AVM twice at a gap of 3 days Total dose  8 Gy

21. International Atomic Energy Agency Module VIII.5: Accidental exposure21 Transjuguslar Intrahepatic Portosystemic Shunt - TIPS - a) Sclerotic depigmented plaque with surrounding hyperpigmentation on the midback of a patient following three TIPS procedures. These changes were present 2 years after the procedures and were described as typical of chronic radiodermatitis. (Photograph from Nahass and Cornelius (1998) b) Ulcerating plaque with a rectangular area of surrounding hyperpigmentation on the midback (a) (b)

22. International Atomic Energy Agency Topic 3: Accidental doses to staff

23. International Atomic Energy Agency Module VIII.5: Accidental exposure23 Under normal working conditions, the doses incurred in a radiology department are lower than the dose limits. No specific radiation-related medical examinations are normally required for persons who are occupationally exposed to ionizing radiation, as there are no diagnostic tests which yield information relevant to exposures that are close to or below dose limits. Staff exposure (1)

24. International Atomic Energy Agency Module VIII.5: Accidental exposure24 It is therefore rare for the radiation component of the working environment of a radiology department to significantly influence the decision about the fitness of a worker to undertake work with radiation or the influence the general conditions of service However in the case of accidental exposure to high doses (of the order of magnitude of 0.2-0.5 Sv or higher), specific radiation-related medical investigation are necessary Staff exposure (2)

25. International Atomic Energy Agency Module VIII.5: Accidental exposure25 To control dose to the staff Personnel must wear protective aprons, use shielding, monitor their doses, and know how to position themselves and the machines for minimum dose. If the beam is horizontal, or near horizontal, the operator should stand on the image intensifier side [to reduce dose]. If the beam is vertical, or near vertical, keep the tube under the patient.

26. International Atomic Energy Agency Module VIII.5: Accidental exposure26 Avoiding staff exposures ICRP 85 Radiation induced opacities in the lens of an interventional radiology specialist subjected to high levels of scatter radiation from an over-table x-ray tube. (Photograph from Vano et al. (1998).

27. International Atomic Energy Agency Module VIII.5: Accidental exposure27 Effects in eye Eye lens is highly RS. Coagulation of proteins occur with doses greater than 2 Gy. There are 2 basic effects: From “Atlas de Histologia...”. J. Boya Histologic view of eye: Eye lens is highly RS, moreover, it is surrounded by highly RS cuboid cells. > 0.155.0 Visual impairment (cataract) > 0.10.5-2.0Detectable opacities Sv/year for many years Sv/single brief exposure Effect

28. International Atomic Energy Agency Module VIII.5: Accidental exposure28 Eye injuries

29. International Atomic Energy Agency Module VIII.5: Accidental exposure29 Fluoroscopic guidance of placement of spinal stimulation electrodes illustrating practices which can result in direct x-ray exposure of the hands of the physician performing the procedure: (a) physician’s hand in the area of the x-ray beam. If exposures are made in this circumstance, the hands receive direct exposure and are visible in the resulting images (b). (Photographs courtesy of S. Balter.) (a)(b)

30. International Atomic Energy Agency Module VIII.5: Accidental exposure30 Many of these injuries are AVOIDABLE – all of the serious ones are!

31. International Atomic Energy Agency Module VIII.5: Accidental exposure31 Direct Fluoroscopy: danger to staff! In older fluoroscopic examinations radiologist stands behind screen and view the picture Radiologist receives high exposure; despite protective glass, lead shielding in stand, apron and perhaps goggles Main source to staff exposure is NOT the patient but the direct beam

32. International Atomic Energy Agency Module VIII.5: Accidental exposure32 Direct fluoroscopy AVOID USE OF DIRECT FLUOROSCOPY Directive 97/43Euratom Art 8.4. In the case of fluoroscopy, examinations without an image intensification or equivalent techniques are not justified and shall therefore be prohibited. Direct fluoroscopy will not comply with BSS App.II.25 “… performance of diagnostic radiography and fluoroscopy equipment and of nuclear medicine equipment should be assessed on the basis of comparison with the guidance levels

33. International Atomic Energy Agency Module VIII.5: Accidental exposure33 ANGIOGRAPHY Over 50 reports appeared in 1990’s Over 100 cases Likely thousands of unreported

34. International Atomic Energy Agency Module VIII.5: Accidental exposure34 Why do they occur? No training in radiation protection for those performing these studies, like Cardiologist Urologist Gastro-enterologist Orthopedic Surgeon Vascular Surgeon Traumatologist Pediatrician Anesthesiologist

35. International Atomic Energy Agency Topic 4: Investigations in accidental exposure

36. International Atomic Energy Agency Module VIII.5: Accidental exposure36 Investigation of exposure (B.S.S. II.29) Registrants and licensees shall promptly investigate: any diagnostic exposure substantially greater than intended or resulting in doses repeatedly and substantially exceeding the established guidance levels any equipment failure, accident error, mishap or other unusual occurrence with the potential for causing a patient exposure significantly different from that intended.

37. International Atomic Energy Agency Module VIII.5: Accidental exposure37 BSS requirements (1) Any equipment failure, accident, error, mishap or other unusual occurrence with the potential for causing a patient exposure significantly different from the one intended.” [ANY radiation source [RT - RL - NMed] Following an investigation, the BSS requires the licensee to: "(a) calculate or estimate the doses received and their distribution within the patient; (b) indicate the corrective measures required to prevent recurrence of such an incident;

38. International Atomic Energy Agency Module VIII.5: Accidental exposure38 BSS requirements (2) (c) implement all the corrective measures that are under [the local] responsibility; (d) submit to the Regulatory Authority, as soon as possible after the investigation or as otherwise specified by the Regulatory Authority, a written report which states the cause of the incident and includes the information specified in (a) to (c), as relevant, and any other information required by the Regulatory Authority; and (e) inform the patient and his or her doctor about the incident."

39. International Atomic Energy Agency Module VIII.5: Accidental exposure39 Investigation of exposure (B.S.S. II.30) Registrants and licensees shall: a) calculate or estimate the doses received and their distribution within the patient b) indicate the corrective measures required to prevent recurrence of such an incident c) implement all the corrective measures that are under their own responsibility

40. International Atomic Energy Agency Module VIII.5: Accidental exposure40 Investigation of exposure (B.S.S. II.30) Registrants and licensees shall: d) submit to the Regulatory Authority, as soon as possible after the investigation or as otherwise specified by the Regulatory Authority, a written report which states the cause of the incident and includes the information specified in (a) to (c), as relevant, and any other information required by the Regulatory Authority; and e) inform the patient and his or her doctor about the incident.

41. International Atomic Energy Agency Module VIII.5: Accidental exposure41Summary Distincyion is amde between Normal, Potential and Accidental exposure We learned that exposure of fetus can occur, but usually doses are low Interventional radiology can lead to high staff exposure and deterministic effects in patients Most of the can be avoided, but when it happened investigation is compulsory Direct fluoroscopy should no longer be tolerated

42. International Atomic Energy Agency Module VIII.5: Accidental exposure42 Wagner LK and Archer BR. Minimising risks from fluoroscopic x rays. Third Edition. Partners in Radiation Management (R.M. Partnership). The Woodlands, TX 77381. USA 2000. Vano, E and Lezana, A. Radiation Protection in Interventional Radiology. 9th European Congress of Radiology, Vienna (Austria), March 5 ‑ 10, 1995. Refresher Course. Avoidance of radiation injuries from medical interventional procedures. ICRP Publication 85. Ann ICRP 2000;30 (2). Pergamon. Where to Get More Information