2. 3 Radiation Source Average Annual Whole Body Dose (millirem/year)
Natural: Cosmic 31
Terrestrial 19
Radon
229
Internal (K-40, C-14, etc.) 16
Manmade: Medical
300
Consumer Products 13
All others: Fallout, air travel,
occupational, etc. 12
Average annual total
620 millirem/year
Tobacco (if you smoke, add ~280
millirem) 3

3. REM and Sievert are use for radiation exposure in air.
Rad – Rem
EXPOSURE units
Rad - Radiation Absorbed Dose
mrad – millirad = rad
RAD and Gray are used for actually calculating the dose of radiation to a patient
Rem - Radiation Equivalent Man
mrem – millirem = rem
REM and Sievert are use for radiation exposure in air.
SI Units:
Gray (Gy)
1 Gy = 100 rad
Sievert (Sv)
1 Sv = 100 rem 4

4. Effective Radiation Dose In mrem (milliSievert)
Exam
Effective Radiation Dose In mrem (milliSievert)
Time for Equal Background Radiation
Hand/Foot X-ray1
0 weeks
Dental: Bitewing and full mouth survey1
0.5 (0.005) per image
<1 day per image
Dental Panoramic1
1.0 (0.01)
<1 day
Dental Cephalometric1
1.2 (0.012)
1.2 days
Dental i-CAT2
6.1 (0.061)
6 days
Chest X-ray1
10 (0.1)
2 weeks
Abdomen X-ray1
70 (0.7)
3 months
Head CT scan1
200 (2)
7 months
Abdomen/Pelvis CT scan1
1000 (10)
33 months
Nuclear Medicine Cardiac Perfusion scan1
1770 (17.7)
69 months
Radiation Exposure from
fluoroscopy:
Can be from 0.5 rem – 10 rem per minute!

5. Stochastic Deterministic Latent effects (cancer)
Neoplasm, heritable changes, and changes in genetic material
IT IS “ASSUMED” THAT FOR EVERY 1 REM OF EXPOSURE, YOUR CANCER RISK INCREASES 0.01%
Deterministic
Threshold – we know at certain levels of exposure effects will start to happen
Cataracts, epilation, erythema, and necrosis

6. Deterministic effect: Cath lab – multiple procedures in a period of a few weeks; this picture was taken 1 year after the last procedure; skin grafts were required.

7. Spinal arteriogram
October 10 – 30 min of fluoro and 4.4 min of CINE
October 28 – approx 90 min fluoro
Notice the collimation
Picture taken about 2 months after exposure

8. Why is the injury on their skin?
Most radiation injuries are due to multiple radiation procedures performed over a short period of time (i.e. multiple cath lab procedures over a few weeks)
Why is the injury on their skin?
Because the highest exposure to the patient is where the x-ray enters their skin – the Entrance Skin Exposure
Only 5-10% of the original x-ray produces makes up the image you see on the screen; the patient absorbs and scatters most of the radiation
BE MINDFUL OF PRIOR EXPOSURES THE PT HAS HAD.

9. EFFECT
DOSE
RAD / GRAY
TIME TO ONSET
Transient erythema
200 / 2
Hours
Temp epilation
300 / 3
3 weeks
Main erythema
600 / 6
10 days
Permanent epilation
700 / 7
Dry desquamation
1000 / 10
4 weeks

10. Wear your radiation badge!!
If you don’t wear your badge, we don’t know your exposure.
If you have 1 badge ALWAYS wear it on the outside of your lead apron to get your most conservative exposure
If you have 2 badges the WB (whole body) badge goes under your lead, the CL (collar) badge goes outside the lead

11. ONLY wear the badge assigned to you!
:12:55
Presenter
This is how you wear your badges. If you only have one WB badge, you must wear it on the outside of the Pb apron.
Collar badge: labeled CL, should be worn outside the lead apron at the collar e
Whole body badge: labeled WB, should be worn inside the lead apron at the chest or waist level
Ring badge should be worn with the label towards the x-ray
tube
ONLY wear the badge assigned to you!

12. Dosimetry reports? How do you know your exposure?
The Radiation Safety Officer monitors these reports as they come in and would contact you if your exposure is out of the normal range; each department is sent a report after they are received.

13. These limits are set by the Nuclear Regulatory Committee.
Whole Body limit:
Extremity:
Lens of eye:
Fetus:
5000 mrem / year (50 mSv)
50000 mrem / year (500 mSv)
15000 mrem / year (150 mSv)
900 mrem / 9 months (9 mSv)
The RSO looks over all badges when they are received; these are reviewed at the Radiation Safety Committee Meeting
If you receive a reading that is outside of your normal range, the RSO will contact you. 14

14. For personnel exposure, we want to keep everyone’s exposure ALARA (As Low As Reasonably Achievable)
TIME
DISTANCE
SHIELDING

15. DOSE FROM 30 mCi OF TC-99M AT 1 METER: 2.2 mR/hr DOSE FROM I-131:
The duration of exposure of the individual is directly proportional to the occupationally received radiation dose. Therefore, personnel doses are directly linked to patient doses.
DOSE FROM 30 mCi OF TC-99M AT 1 METER:
2.2 mR/hr
DOSE FROM I-131:
0.22 mR/hr PER mCi AT 1 METER
DOSE AT 1 METER FROM FLUORO PATIENT
1/1000 OF WHAT PATIENT RECEIVES
PATIENT RECEIVES ANWHERE FROM 0.5 – 10 R/min FOR NORMAL FLUORO, MORE FOR CINE (or “runs”) 16

16. More Distance = Less Radiation Exposure
Effective & Easy
Inverse Square Law
Doubling distance from the source of exposure (the patient),decreases dose by factor of four
Tripling it decreases dose nine-fold
More Distance = Less Radiation Exposure

17. Radiation scatter
The primary source of radiation exposure to physicians and staff during fluoroscopy is radiation scattered from the patient, NOT from the x-ray tube.
At 1 m from where the center of the x-ray beam enters the patient, the exposure rate to the operator (above the table) is on the order of 1/1000th the patient’s entrance exposure rate.
e.g., If the patient is receiving 4 R/min, then you are receiving  4 mR/min.
Scatter between the x-ray tube and the patient (called backscatter) is about twice as intense as that above.
backscatter
X-ray tube
1 m
Richard H. Behrman, PhD

18. ALWAYS Stand Closer to the Image Intensifier
Scatter radiation intensity is less on the image intensifier side as compared to the x- ray tube side.
For Lateral and oblique projections: position the x-ray tube on the opposite side of the patient from where you are standing.
Always stand further from the X-Ray Tube

19. Scatter radiation does not linger in the room
Scatter radiation does not linger in the room. It is only present when the x-ray beam is on. (i.e.. Someone is standing on the beam-on foot pedal. ) TAKE YOUR FOOT OFF THE PEDAL WHEN YOU DON’T NEED IT.
The patient is the main source of scatter radiation during radiographic and fluoroscopic procedures.
Fluoroscopy is real time x-ray imaging captured on a TV monitor, while radiography is a single image captured with one radiation exposure.

20. The inverse square law (again)
1. Step as far back from the patient as is reasonably possible when holding down the fluoro pedal. This is especially true for high dose rate modes such as cine and DSA.
1/16
4x 1
1/4
relative exposure rate
By standing 2 m instead of
0.5 m from the center of the table, you will reduce your exposure by a factor of 16.
0.5 m 0.5 m
1 m
1 m
2.0 m
Richard H. Behrman, PhD

21. REGULATION AND POLICY: If you are in the room during
fluoroscopy you must wear a lead apron.
Wear apron and t-shield with no gap in between
Do you need a thyroid shield?
If you have it, wear it! But it is not a regulatory requirement.

22. Lead Apron Thickness Percentage of x-rays blocked
Lead aprons
2. It is a legal requirement that all personnel in the room either wear a lead apron or stand behind a lead barrier when fluoroscopy is being performed.
Lead Apron Thickness Percentage of x-rays blocked
kV 0.25mm 0.5mm 70
88%
98% 90
78%
95%
110
72%
92%
Richard H. Behrman, PhD

23. Depends on the thickness of the lead
Anywhere from 85-99%
Depends on the thickness of the lead
REGULATION – LEAD MUST BE AT LEAST 0.25 MM LEAD EQUIVALENT; most that are purchased are at least
0.35 mm lead equivalent.
Depends on the energy of the x-ray
Lead gloves??? May reduce hand exposure by 15-30% if OUTSIDE primary beam.
All fluoro units have Automatic Exposure Control. If your hands get in the field of view, it will increase the exposure to get through them.

24. If you place lead shielding on the patient, place it on the side of the x-ray tube. (i.e. if the x-rays are generated in the tube underneath the table, put the lead apron on the table, then the patient on top of the apron).
MAKE SURE the lead will not be in the field of view, otherwise the unit will compensate to get through the lead and give a higher dose to the patient.

25. Additional shielding
Place any additional lead shielding between your face / neck and the patient.
The patient is the source of scatter and the lead apron is already protecting your trunk organs.
Extremities - tissue below the elbows and knees are the least radiosensitive parts of the body.
If it’s there, use it!! Many times the pull down shields are over in the corner and never used.
Richard H. Behrman, PhD

26. The person holding the patient should be protected with a lead apron.
If you wear lead gloves, if your hands get in the field of view, the radiation exposure will increase exponentially to get through the lead in turn increasing the exposure to the patient and personnel in the room.
Radiologic technologists shall not hold a patient during a radiation exposure, except in a life- threatening situation.
No person under the age of 18 shall be asked to hold a patient during radiographic procedures.

27. Do you know which part is the x- ray tube and which
is the image intensifier where
the image is captured?

28. (II) (where the radiation is “captured” to make the image)
Image Intensifier
(II) (where the radiation is “captured” to make the image)
X-RAY TUBE
(where the radiation is
generated) The side between the pt and x-ray tube has the most scatter; be mindful where you and others stand when the x- ray tube is in oblique/lateral positions.

29. Training for operators of fluoro
Presenter
It is essential that radiation be properly managed to minimize risks to patients, operators, and personnel. The FDA has recommended steps to be taken to ensure that equipment is being used properly and adequate measures have been taken to limit the risks involved.
:13:08
Last, the FDA would like documentation of radiation dose that is given to the patient during the procedure. Large exposures should be recorded in the medical record.
The first recommendation is training for all persons who operate fluoroscopy equipment. This includes radiation safety training on how using different techniques can minimize fluoro time, training on the actual equipment and how it is used, and education to be able to assess the risks and benefits to the patient about the procedure to be done. Patients should be informed prior to receiving a procedure that will have high exposure to fluoroscopy. Long fluoro time can lead to erythema and epilation, and patients need to be informed that these could be adverse effects from the procedure they are about to receive.
Training for operators of fluoro
Anyone operating fluoroscopy equipment should have proper training
Patients be informed prior to the procedure
Do you inform your patients that their procedure involves radiation exposure? A lot of patient’s do not know this.
Documentation be recorded of dose
Facilities should record the dose to the patient – most machines do monitor this automatically, or at least record the fluoroscopy time.

30. Fluoroscopy
All fluoroscopy equipment transforms x-rays exiting the patient into real-time visual images.
This transformation is made possible by either an image intensifier
or a flat panel digital detector.
Image intensified system
Digital flat panel system (latest technology)
Richard H. Behrman, PhD

31. Automatic brightness control
The Image Intensifier (I.I.) entrance exposure rate (set by Vref in the ABC) affects both the patient exposure rates and the image “noise” (image graininess). Noise is determined primarily by the number of x-rays used to form the image. The higher the dose rate the lower the noise and vice versa.
If Vref is set too low  Dose rates will be low but images will be noisy.
If Vref is set too high  Dose rates will be high and images will contain very little noise.
This requires Vref to be properly set (trade off between dose and noise).
It is therefore important that I.I. entrance exposure rates be set appropriately by the installation/service engineer and checked at least annually by a qualified medical physicist. It one of the key parameters affecting both patient dose and image quality.
Many fluoro units have “low”, “medium”, and “high” dose-rate selections. Each corresponds to a different Vref setting.
Richard H. Behrman, PhD

32. The use of CINE (or runs they are sometimes called)
Size of the patient
Larger pt – decrease in image quality so the unit increases the kV and mA to compensate. This means an increase in dose to the pt and personnel.
mA = the # of x-ray produced. Dose to the pt and personnel are proportional to mA
kV = increases the penetrability of the x-ray. High kV with low mA = lower doses
Magnification
The use of CINE (or runs they are sometimes called)

33. Electronic Magnification
Changing the Field of View (FOV) to see smaller objects
Brightness gain decreases as the mag mode increases so it compensates with ABC; therefore increasing the x-ray exposure rate
Increase in exposure rate is = ration of FOVs
From 12” to 9” = (12/9)2 = 1.8 increase in dose to pt.

34. Normal fluoroscopy mode has a regulatory limit of 10 R/minute (0
Normal fluoroscopy mode has a regulatory limit of 10 R/minute (0.1 Sv/min) to the patient at a level where you measure the output a 30 cm from the image intensifier (this means put the patient closer to the image intensifier and farther from the x-ray tube)
There is no regulatory limit on CINE! CINE usually gives around times the dose of normal
fluoroscopy.
Use CINE sparingly if you can.

35. There is usually a dose reduction choice on the unit
Larger patient require more radiation to give you a good picture.
Pulsed fluoro will give less radiation to the patient.
Less radiation to the patient means less scatter in the room.
Use Last Image Hold when you can
Be aware of the fluoroscopy time!

36. 10 R/minute (0.1 Sv/min) 10-60 x higher than
Presenter
The entrance skin exposure is the dose received by the patient at the surface of the skin. This is measured at 30 centimeters from the x-ray tube and is done on an annual basis. The regulations state that the entrance skin exposure to the patient from regular fluoroscopy, such as a C-arm, can be up to 10 R/min at 30 cm from the x-ray tube.
:13:13
Fluorography includes digital angiography, digital subtraction angiography, and cineangiocardiography. The image is much better because the entrance skin exposure to the patient is anywhere from times higher than regular fluoroscopy. With the higher dose rate there is a better image quality. Physician’s must not allow the superior-quality images to lure them into the unnecessary application of these elevated-dose techniques. The lateral L spine, Chest and CT are all one time exposure x-rays that are usually less than a few seconds, but I just wanted to give you a comparison of the exposure from fluoroscopy versus one regular x-ray.
C-arm
Cine/Fluorography
10 R/minute (0.1 Sv/min) x higher than
regular fluoroscopy.
500 mR (5 mSv)
10 mR (0.1 mSv)
3 - 7 Rads ( Gray)
Lateral L. Spine
Chest -PA
C.T. Scan (Abd.)
The ESE is calculated annually by a physicist and reports should be posted in the room. MOST fluoroscopy equipment at normal fluoro levels do not go over 5 R/min; the regulatory LIMIT is 10 R/min.

37. Typical patient entrance exposure rates
For an average 70 kg (155 lb) adult, typical patient entrance exposure rates for posterior-anterior or anterior-posterior projections are,
30cm
2- 3 R/min
4 - 6 R/min
R/min
Normal Fluoro
High Dose Fluoro
Fluorography (cine, DA, DSA)
Richard H. Behrman, PhD

38. Distance between x-ray tube and skin.
Presenter
X-ray originate from small area inside the tube about 1 mm wide called the focal spot. As the distance from the focal spot increases, the intensity rapidly decreases.
:13:14
The amount of radiation scattered into the room depends on how collimation and the distance between the x-ray source and image intensifier change. Keeping the collimation confined to the area of interest will keep the scatter in the room to a minimum. Some machines have a separator cone that is used to keep the patient’s skin at least a specified distance from the x-ray source. If a machine has one of these, this should always be kept on the machine, and not taken off.
The distance between the x-ray tube and the patient’s skin plays a large factor in the patient dose. The potential for skin injury is reduced markedly as the distance from the source of the x-rays increases.
Distance between x-ray tube and skin.
The farther the x-ray tube from the patient, the less exposure the patient receives
Distance between the patient and II:
The closer the II is to the patient the less scatter in the room and less noise on the image
Collimate to the area of interest
ONLY radiate the portion of the patient you need to see
Separator cone – use this if available.

39. The difference in the patient / II / x-ray tube:
:13:15
Presenter
A grid is a flat plate device that improves image quality by removing scatter radiation. It also increases patient dose and doses to personnel in the room. In some cases you might be able to remove them without much image degradation. Some grids are retractable, others can be manually removed; remember they are fragile and costly. There are 2 circumstances where it might be advantageous to remove the grid: Children or small adults generate very little scatter and it may be possible to do the procedures without the grid. 2) Procedures that employ a large space between the patient and the II, very little scatter reaches the image intensifier, so removing the grid may not have a noticeable affect on image quality, but will reduce the dose to the patient and personnel in the room.
The difference in the patient / II / x-ray tube:
Keep the patient close to the image intensifier and farther away from the x-ray tube! Less Scatter all around

40. SCAN
EFFECTIVE DOSE in mSv (mrem)
Brain PET F-18
14.1 (1400)
Brain Tc HMPAO
6.9 (690)
Bone Tc MDP
6.3 (630)
Lung Perfusion/Vent
2.5 (250)
Cardiolite (stress/rest)
9.4 (940)
Various PET Studies F-18
14 (1400)
Barium Enema
7.0 (700)
CT Chest
CT Abdomen/Pelvis
10.0 (1000)
Coronary Angiography
20.0 (2000)
Cardiac Diagnostic & Intervention
30 (3000)
Lumbar Spine
1.5 (150)

41. Use Shielding
Normal work practices should NOT keep you from working in a radiation area.
Can Declare pregnancy to the Radiation Safety Office
Use of radiation badge at waist level
Contact the Radiation Safety Officer if you have questions.

42. Lead causes more exposure – wear your lead, it shields
Presenter
Lead does not cause more exposure in the personnel who wear it. Lead can shield up to 90% of the scatter radiation received Radiation scatter from the patient follows a 360% path at the area of radiation no matter where it hits the patient.
:13:18
Scatter radiation from the fluoro that is used in the OR is not strong enough to bounce off of the floor and cause hair loss.
Lead causes more exposure – wear your lead, it shields
Radiation follows easiest path and comes out pt’s mouth
No – radiation scatter from where it enters the patient.
Scatter radiation hits floor and bounces up to cause hair on legs to fall off
Wouldn’t that be nice? At least for women.