1. Part No...., Module No....Lesson No
Module title
RTC on RADIATION PROTECTION OF PATIENTS FOR RADIOGRAPHERS Accra, Ghana, July 2011
Optimization of protection in fluoroscopy and image-guided interventional procedures
Part …: (Add part number and title)
Module…: (Add module number and title)
Lesson …: (Add session number and title)
Learning objectives: Upon completion of this lesson, the students will be able to: …
. (Add a list of what the students are expected to learn or be able to do upon completion of the session)
Activity: (Add the method used for presenting or conducting the lesson – lecture, demonstration, exercise, laboratory exercise, case study, simulation, etc.)
Duration: (Add presentation time or duration of the session – hrs)
Materials and equipment needed: (List materials and equipment needed to conduct the session, if appropriate)
References: (List the references for the session)
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

2. IAEA Fellows welcome!!

3. Fluoroscopy Continuous imaging of moving structures or contrast agents
The photographic plate replaced by fluorescent screen
Screen part of an Image Intensifier system coupled to a television camera
Now also have direct digital acquisition
Radiologist can watch the images “live” on TV-monitor; images can be recorded

4. Interventional (fluoroscopy) radiology
This are high dose procedures, and are covered in the next lecture, however the imaging principles are just the same

5. The image intensifier (I.I.)
I.I. Input Screen
Electrode E1
Electrode E2
Electrode E3
Electron Path
I.I.Output Screen
Photocathode +

6. Fluoroscopy – II vs Digital
Part No...., Module No....Lesson No
Module title
Fluoroscopy – II vs Digital
Image Intensifier
Image Chain
X-Ray Tube
Patient
Image
Intensifier
Optics
Video
Camera
Digitizer
X-Ray Tube
Patient
Digital
Detector
Digital Detector
Imaging chain much smaller than for image intensifier with fewer conversion steps along the chain from x-ray to image.
“Pure” digital image – no analogue to digital to analogue conversion
No pin cushion distortion, “flat plate” – whole image quality uniform with no “distortion at edges”
Claim approximately 40 % less skin dose on small to medium patients than with conventional systems and on large patients skin dose is comparable to previous systems.
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

7. Part No...., Module No....Lesson No
Module title
Digital Flat Panel A
X-ray efficiency
Up to 20% more
dynamic range
Up to x10 more
visualise arteries over all backgrounds
inherently digital
uniform resolution
uniform signal
no geometric distortion
magnification – less dose increase
X-Ray Tube
Patient
Digital
Detector
Digital Detector
Digital Detector produces an image with 10 times greater dynamic range which produces more shades of grey
The system improves vessel contrast by
Flattening out the background making it more homogenous
Intelligent image processing
Looks for an object of interest, enhances it and brings it forward
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

8. Receptor sensitivity: Fluoroscopy
Type of receptor
Fluoroscopy
µGy/s
Acquisition
µGy/frame
Intensifier – Cine (1988) 23
1.1
0.6 17
1.6
0.8
Intensifier – Digital (1994)
1.0
0.2
1.7
0.4
Digital flat panel (2002) 20
0.15
0.25

9. Spatial Resolution
GOOD RESOLUTION POOR RESOLUTION

10. Resolution and Field Size
Part No...., Module No....Lesson No
Module title
Resolution and Field Size
Resolution improves as magnification increased, but may decrease
as II field size increases Both effects related to the output screen
resolution
Normal Mag Mag. 2
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

11. Overall image quality can be checked with a suitable phantom

12. Part No...., Module No....Lesson No
Module title
Temporal frame averaging
Pooley, R. A. et al. Radiographics 2001;21:
Reduces noise, can reduce dose BUT object must
be slow-moving or even stationary (for high averaging)
Copyright ©Radiological Society of North America, 2001
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

13. Refresher slide: absorption and scatter
X-Ray tube
For every photons reaching the patient, about are scattered, about 20 reach the image detector, and the rest are absorbed (= radiation dose)
Scatter however also approximately obeys the Inverse Square Law, so distance from the patient improves safety
In radiology, scatter mainly directed towards the source

14. Factors affecting staff doses (I)
The main source of radiation for the staff in a fluoroscopy room is the patient (scattered radiation).
The scattered radiation is not uniform around the patient.
The level of dose rate around the patient is a complex function of a great number of factors.

15. Factor affecting staff doses (I)
FACTORS
AFFECTING
RELATIVE POSITION WITH
STAFF DOSE
RESPECT TO THE PATIENT
IRRADIATED PATIENT VOLUME
X RAY TUBE POSITION
kV, mA and time (NUMBER AND
CHARACTERISTICS OF PULSES)
EFFECTIVE USE OF ARTICULATED
SHIELDING AND/OR PROTECTION
GOGGLES

16. Factor affecting staff doses (II)
ANGLE DEPENDENCE
Scattered dose rate is higher near the area into which the X-ray beam enters the patient
100 kV
0.9 mGy/h
1 mA
0.6 mGy/h
11x11 cm
0.3 mGy/h
1m patient distance
patient thickness 18 cm

17. Factor affecting staff doses (III)
FIELD SIZE DEPENDENCE
Scattered dose rate is higher when field size increases
11x11 cm
17x17 cm
17x17 cm
100 kV
0.8 mGy/h
1.3 mGy/h
1 mA
0.6 mGy/h
1.1 mGy/h
0.3 mGy/h
0.7 mGy/h
1m patient distance
Patient
thickness 18 cm

18. Factor affecting staff doses (IV)
DISTANCE VARIATION
mGy/h at 0.5m
mGy/h at 1m
Scattered dose rate is lower when distance to the patient increases
100 kV
1 mA
11x11 cm

19. Factor affecting staff doses (V)
THE BEST
CONFIGURATION
INTENSIFIER UP
X-RAY TUBE DOWN
SAVES A FACTOR OF
3 OR MORE IN DOSE
IN COMPARISON
TO:
X-RAY TUBE UP
INTENSIFIER DOWN
Tube undercouch position reduces, in general, high dose rates to the specialist’s eye lens

20. Factor affecting staff doses (VI)
Tube undercouch position reduces, in general, high dose rates to the specialist’s eye lens
X-Ray tube
mGy/h
100 kV
2.2 (100%)
1 m
2.0 (91%)
20x20 cm
1.3 (59%)
mGy/h
1 Gy/h
(17mGy/min)
1.2 (55%)
1.2 (55%)
1.2 (55%)
1 Gy/h
1m patient distance
(17 mGy/min)
1.3 (59%)
20x20 cm
2.2 (100%)
100 kV
1 m
1m patient distance
X-Ray tube

21. Example of dose rate around mobile C-arm (undertable tube)
Patient
Image Intensifier
100 cm cm
Scale
1.2 3 6 12
X-ray tube
All Contour values in µGy/min

22. Position AP
80kV,3.2mA,15cm diameter

23. Position lateral

24. Factors affecting staff and patient doses - I
PATIENT SKIN DOSE AND THE LEVEL OF SCATTERED RADIATION INCREASE SUBSTANTIALLY
IF PATIENT SIZE INCREASES

25. Factors affecting staff and patient doses - II
CHANGING FROM NORMAL FLUOROSCOPY MODE TO THE HIGH DOSE RATE MODE
INCREASES DOSE RATE BY A FACTOR OF 2 OR MORE

26. Factors affecting staff and patient doses - III
INCREASES PATIENT ENTRANCE DOSE BY A FACTOR OF 2 TO 6
THE USE OF THE ANTISCATTER GRID

27. Factors affecting patient doses - I
CHANGING FROM HIGH TO LOW NOISE MODE (FOR CINE AND DSA - Digital Subtraction Angiography)
INCREASES DOSE PER IMAGE BY A FACTOR OF 2 TO 10

28. Factors affecting patient doses - II
CHANGING FROM CONVENTIONAL FLUOROSCOPY TO DIGITAL MODE
CAN DECREASE DOSE RATE DOWN TO 25%

29. Factors affecting patient doses - III
INTENSIFIER
DIAMETER
RELATIVE PATIENT
ENTRANCE DOSE
12" (32 cm) dose 100
9" (22 cm) dose 150
6" (16 cm) dose 200
4.5" (11 cm) dose 300

30. Factors affecting patient doses - IV
CAN INCREASE PATIENT ENTRANCE DOSE OF A FACTOR UP TO 3
CHANGING TO A SMALLER IMAGE INTENSIFIER FIELD

31. Example of entrance dose rate in fluoroscopy
LOW DOSE MODE 10 mGy/min
MEDIUM DOSE MODE 20 mGy/min
HIGH DOSE MODE 40 mGy/min
BE AWARE OF YOUR OWN UNIT’S DOSES!
(if digital, these will probably be displayed
in real time)

32. Protection tools (I)
SCREEN AND GOGGLES
CURTAIN
THYROID

33. One (or more) personal dosemeters are recommended
Personal dosimetry
One (or more) personal dosemeters are recommended
From: Avoidance of radiation injuries from interventional procedures. ICRP draft 2000

34. To control dose to the staff in fluoroscopy
Personnel must 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.

35. Practical radiation protection rules (I)
LEAD (equivalent) APRONS, GLOVES, THYROID PROTECTORS, ETC, MUST BE USUALLY AVAILABLE IN THE X-RAY ROOMS
POSSIBLE
PROBLEM:
THEY MUST BE USED ALWAYS AND CORRECTLY, AND REGULARLY CHECKED

36. Practical radiation protection rules (II)
IMPORTANT PARAMETERS:
FOCUS-PATIENT SKIN DISTANCE
PATIENT-IMAGE INTENSIFIER DISTANCE
PATIENT DOSE WILL INCREASE IF :
THE FOCUS-SKIN DISTANCE IS SHORT
THE PATIENT-IMAGE INTENSIFIER DISTANCE IS LARGE

37. Equipment and specialist (I)
EQUIPMENT CHARACTERISTICS
THE ROLE OF THE SPECIALIST
TO KNOW THE ACTUAL INTENSIFIER PERFORMANCES AND THE REQUIRED DOSE RATE
POOR INTENSIFIER PERFORMANCE CAN REQUIRE INCREASE IN INPUT DOSE RATE

38. Equipment and specialist (II)
EQUIPMENT CHARACTERISTICS
THE ROLE OF THE SPECIALIST
GOOD FUNCTION OF THE AUTOMATIC BRIGHTNESS CONTROL AND THE POSSIBILITY TO DISABLE IT
USE IT PROPERLY IN ORDER TO AVOID HIGH DOSE RATE

39. Equipment and specialist (III)
EQUIPMENT CHARACTERISTICS
THE ROLE OF THE SPECIALIST
EFFECTIVE USE OF COLLIMATION
EASY SELECTION OF FIELD COLLIMATION

40. Equipment and specialist (IV)
EQUIPMENT CHARACTERISTICS
THE ROLE OF THE SPECIALIST
GRID FACTOR
INTENSIFIER PERFORMANCE
RECOMMENDED OR PROGRAMMED OPERATIONAL PROCEDURE : LEVEL OF NOISE, PULSE RATE, PULSE LENGTH, ETC.
PROTOCOL ACTUALLY IN USE  TOTAL PATIENT DOSE PER PROCEDURE

41. Radiation risk for staff
EQUIPMENT CHARACTERISTICS
THE ROLE OF THE SPECIALIST
DISTANCE AND RELATIVE POSITION OF THE STAFF WITH RESPECT TO THE PATIENT
# ROOM DIMENSIONS
# SHIELDING THICKNESS
# X-RAY SYSTEM POSITION

42. Particular Issues for Interventional Radiology

43. Principle of Interventional Radiology
Part No...., Module No....Lesson No
Module title
Principle of Interventional Radiology
Interventional radiology (fluoroscopically-guided) techniques are being used by an increasing number of clinicians not adequately trained in radiation safety or radiobiology
Patients are suffering radiation-induced skin injuries due to unnecessarily high radiation doses.
Younger patients may face an increased risk of future cancer
Lecture notes: ( about 100 words)
Instructions for the lecturer/trainer
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

44. Principle of Interventional Radiology
Part No...., Module No....Lesson No
Module title
Principle of Interventional Radiology
Many interventionists are not aware of the potential for injury from procedures, their occurrence or the simple methods for decreasing their incidence utilising dose control strategies.
Many patients are not being counselled on the radiation risks, nor followed up for the onset of injury, when radiation doses from difficult procedures may lead to injury.
Lecture notes: ( about 100 words)
Instructions for the lecturer/trainer
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

45. Principle of Interventional Radiology
Part No...., Module No....Lesson No
Module title
Principle of Interventional Radiology
Interventionalists who are not “dose aware” may have their practice limited or suffer injury, and are exposing their staff to high doses.
Occupational doses can be reduced by reducing unnecessary patient dose, the correct use and procurement of equipment (including the use of shielding devices).
Lecture notes: ( about 100 words)
Instructions for the lecturer/trainer
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

46. NON-VASCULAR PROCEDURES:
IR procedures may be classified into:
cardiac (cardiologists), non cardiac (radiologists)
vascular, non vascular
VASCULAR PROCEDURES:
EMBOLIZATION
DRUG INFUSION (Tumor catheter placement), ANGIOPLASTY (PTA, Atherectomy, stent graft placement),
CARDIAC INTERVENTION (PTCA, radiofrequency ablation)
TRANSJUGULAR INTRAHEPATIC PORTOSYSTEMIC SHUNT
NON-VASCULAR PROCEDURES:
DRAINAGE & PUNCTURE
PERCUTANEOUS NEEDLE BIOPSY
STENT PLACEMENT
COAGULATION THERAPY

47. Interventional Radiology CT Radiography
RISK LEVEL – PATIENTS (AND STAFF)
Interventional
Radiology CT
SIMPLE FLUOROSCOPY
Radiography

48. Neuroradiology Trans-arterial embolization of para orbital AVM twice at a gap of 3 days
Total dose  8 Gy
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.

49. Transjugular Intrahepatic Portosystemic Shunt - TIPS -
(b)
(a)
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

50. Many of these injuries
are avoidable –
ALL of the serious ones
are!

51. 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

52. Patient Weight and Habitus [ESD = Entrance Skin Dose]
Thicker tissue masses absorb more radiation, thus much more radiation must be used to penetrate a large patient. Risk to skin is greater in larger patients!
[ESD = Entrance Skin Dose]
15 cm
20 cm
25 cm
30 cm
ESD = 1 unit
ESD = 2-3 units
ESD = 4-6 units
ESD = 8-12 units
Example: 2 Gy
Example: 4-6 Gy
Example: 8-12 Gy
Example: Gy

53. Part No...., Module No....Lesson No Topic 5: Examples of dose values
Module title
Topic 5: Examples of dose values
Part …: (Add part number and title)
Module…: (Add module number and title)
Lesson …: (Add session number and title)
Learning objectives: Upon completion of this lesson, the students will be able to: …
. (Add a list of what the students are expected to learn or be able to do upon completion of the session)
Activity: (Add the method used for presenting or conducting the lesson – lecture, demonstration, exercise, laboratory exercise, case study, simulation, etc.)
Duration: (Add presentation time or duration of the session – hrs)
Materials and equipment needed: (List materials and equipment needed to conduct the session, if appropriate)
References: (List the references for the session)
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

54. Examples of dose values

55. Examples of dose values
(TIPS:Transjugular Intrahepatic Portosystemic Shunt )

56. INDICATIVE VALUES – X-ray Time75
TIPS 25
HEPATIC EMBOLIZ. 24
BILIAR DRAINAGE 17
ABDOM. ANGIOPLAST. 15
HEPATIC MANOM. 12
CEREBRAL ARTER. 10
ABDOM. ARTERIOGR. 9
BRONQUIAL ARTERIOGR.
6,3
RENAL ARTERIOGR. 5
LOWER LIMB ARTER.
3,3
UPPER LIMB FISTUL. 1
LOWER LIMB PHLEBOGR. 20 40 60 80
100
FLUOROSCOPY TIME (min.)

57. DOSE AREA PRODUCT INDICATIVE MEAN VALUES
353,7
TIPS
96,42
VALVULOPLASTY
92,92
RENAL ARTERIOGR.
87,5
PTCA
81,68
HEPATIC EMBOLIZ.
68,87
BILIAR DRAINAGE
68,16
CEREBRAL ARTERIOG.
66,63
LOW EXTREM. ART.
66,51
CORONARIOGRAPHY
25,3
HEPATIC MANOMETRY
24,7
AORTIC ARTERIOGR.
8,71
UPPER EXTREM. FISTUL.
2,94
LOW EXTREM. PHLEBOG. 2
100
200
300
400
Gy.cm

58. INDICATIVE VALUES – No. of Images10
160
CEREBRAL ARTERIO. 6
120
LOWER LIMB ARTERIO. 4 64
UPPER LIMB FISTUL.
SERIES OF IMAGES 4
NUMBER OF IMAGES 60
BRONCHIAL ARTERIO. 3 60
RENAL ARTERIO. 3 60
ABDOMINAL ARTERIO. 50
100
150

59. CINE ACQUISITION DOSES
Patient entrance doses for cine can require between 70 and 130 µGy/frame
1 minute of cine at 25 fr/s would lead to 150 mGy, almost equivalent to:
15 abdomen X Rays or to 400 chest X Rays

60. Influence of patient thickness and operation modes in scatter dose rate

61. (from 2 to 20 mSv/h for normal size)
Influence of operation modes: from low fluoroscopy to cine, scatter dose rate could increase in a factor of 10
(from 2 to 20 mSv/h for normal size)

62. Different C-arm angulations, involve very different scatter dose rates (Philips Integris 5000)

63. THE SCATTERED DOSE RATE AT 1 METRE FROM THE PATIENT CAN BE HIGHER THAN 1 mGy/min FOR SOME ARC POSITIONS
WITH DIGITAL FLUOROSCOPY MODE, DOSE RATE COULD BE REDUCED (25%) WITH RESPECT TO CONVENTIONAL MODE

64. Practical Actions in controlling dose
Keep beam-on time to an absolute minimum ---
The Golden Rule for control of dose to patient and staff
Remember that dose rates will be greater and dose will accumulate faster in thicker patients.
Keep the X Ray tube at maximal distance from the patient.
Keep the image intensifier as close to the patient as possible.

65. Don’t over-use geometric magnification.
Remove the grid during procedures on small patients or when the image intensifier cannot be placed close to the patient.
Always collimate closely to the area of interest.

66. When the procedure is unexpectedly prolonged, consider options for positioning the patient or altering the X Ray field or other means to alter beam angulation so that the same area of skin is not continuously in the direct X Ray field.
Dose rate varies continuously during the procedure

67. Fluoroscopy time is only a very rough indicator of whether radiation injuries may occur.
Patient size and procedural aspects such as location(s) of the beam, beam angle, normal or high dose rates, distance of the tube from the patient and number of acquisitions can cause the maximum patient skin doses to be tenfold different for a specific total fluoroscopy time.

68. Minimize Exposure Time
Part No...., Module No....Lesson No
Module title
Minimize Exposure Time
Everything you do to minimize exposure time reduces radiation dose!!
Minimize fluoro and cine times
Whenever possible, step out of room
Step behind barrier (or another person) during fluoro or cine
Use pulsed fluoroscopy– minimizes time X ray tube is producing X rays
Whatever reduces patient doses reduces staff dose– minimizing fluoro and cine times, and using pulsed fluoroscopy can reduce doses by factors of 2 to 8 or greater.
Stepping out of the room or behind a barrier, especially during a cine run, will reduce staff doses dramatically.
IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

69. Angiography - Patient Protection
Patients should be counseled on radiation risks if the procedure carries a significant risk of such injury.
Records of exposure should be kept if the estimated maximum cumulative dose to skin is 3Gy or above.
All patients with estimated skin doses of 3 Gy or above
should be followed up 10 to 14 days after exposure.
The patient’s personal physician should be informed of the possibility of radiation effects.
If the dose is sufficient to cause observable effects,
the patient should be counseled after the procedure.
A system to identify repeated procedures should be set up.