Radiation Protection Course For Radiologists Lecture 7 of 8 Radiation Monitoring

1. Radiation Protection Course For Radiologists
Lecture 7 of 8
Radiation Monitoring
Prof Amin E AAmin
Dean of the Higher Institute of Optics Technology
&
Prof of Medical Physics
Radiation Oncology Department
Faculty of Medicine, Ain Shams University

2. Monitoring

3. Recommended Dose Limits In Planned
Exposure Situations (ICRP 103)
PublicOccupationalType of limit
1 mSv in a year20 mSv per year
averaged over defined
periods of 5 years
Effective dose
15 mSv
50 mSv
150 mSv
500 mSv
500 mSv
Lens of the eye
Skin
Hands and feet

4. Dose Limit To Embryo-fetus Of Pregnant
Females In Restricted Areas
• In no case an individual who is known or suspected to be
pregnant be permitted to receive a radiation dose to the fetus in
excess of 2 mSv during the entire 9 –month gestation period.

5. Radiation Reports
• Results of the periodic personal monitoring are forwarded to the
operation Departments by the Radiation Safety Office.
• If the investigational levels are exceeded a review process will
initiate by the RSO and/or the RSC.

6. Investigational Levels
Level 2Level 1
3.75 mSv1.25 mSvWhole body
55.00 mSv17.50 mSvDistal
Extremities

7. Radiation Reports
The reporting process shall proceed as follows:
• Quarterly exposures less than level 1. There will be no
notification.
• Quarterly exposures from level 1 to level 2. The report form will
be sent to each using department listing the personnel so
affected, without further action.
• Quarterly exposures exceeding level 2. The using department
will be advised via the radiation report notification. The RSO
shall investigate and if warranted, take action. A report if the
investigation and recommended remedial action shall be
submitted to the RSC for review and final approval.

8. Personnel Request for Monitoring Service
• It is the responsibility of the Department Chairman to Request
personnel monitoring for an employee(s).
• Each employee will fill out a separate form and return the same
to the Radiation Safety Office.

9. Personnel Monitoring Distribution
• Badges will normally be exchanged on the first of the month.
Frequency of exchange will usually be monthly or quarterly as
needed.
• Each person is requested to leave his badge on the
Department’s badge rack at the end of each work day. Fewer
badges will be lost and badge exchange will be much easier,
especially if exchange occurs while the person is away on
leave.

10. Surveys
• A complete radiation survey shall be performed for each X-ray
installation, at the time of acceptance and after any important
change or repair to confirm the adequacy of structural shielding
required, added shielding, or its accessories.

11. Personnel Monitoring

12. Personnel Monitoring

13. • The radiation monitor shall be worn outside the protective
garment in such a manner as to record the maximum incident
exposure.
Personnel Monitoring

14. • A second monitor shall be issued to pregnant radiation workers
to be worn under the protective garment in order to more
accurately assess the fetal dose.
Personnel Monitoring

15. • Secondary ring TLDs may be
issued to selected radiation workers
as required.
Personnel Monitoring

16. • Monitoring is conducted at either monthly or quarterly intervals
depending upon the radiation level associated with the work
environment.
Personnel Monitoring

17. Types Of Dosimeters
• Immediate Read
– Pocket Ionization Chambers, Solid state detectors, handheld
GM/Ionization detectors with dose accumulation function
• Delayed read / Personnel monitors
– Film Badges, TLD (Thermo Luminescent Dosimeters), OSL
(Optically Stimulated Light-emitting Dosimeters)

18. Different Types Of Personal
Dosimeters
❖ film
❖ termoluminescence (TLD) and optically stimulated
luminescence (OSL) dosimeters
❖ ”electronic” dosimeters

19. Film Badges
• Most common type of radiation
dosimeter used.
• Works by darkening of x-ray film in
proportion to radiation absorbed.
• Cheap
• Not durable
• Short monitoring period per badge (6
months or less)

20. Film Badge
plastic filter metal filters open windows
open window
detects beta, gamma, X Ray

21. Film Badges
Copper
Tin
Image filter
Open window
Al2O3 strip

22. Film Badge Advantages
Inexpensive
Easy to handle
Reasonably accurate
Provides a permanent dose record

23. TLD

24. TLDs
whole body extremity

25. TLD
• “Captures” radiation dose information in a
crystal matrix
• Releases light when heated, light intensity
proportional to radiation dose absorbed
• Durable
• Can be expensive (reusable chips)
• Information destroyed when processed

26. Personal Dose Monitoring
Extremity
TLD
“ring badge”
• Wear facing
source
• Wear under
gloves
• Exchange every
3 months

27. OSL
• “Captures” information in an Aluminum Oxide matrix
• Releases information by laser stimulation
• Can be reread after processing
• Durable
• Landauer Only

28. OSL
1 cm

29. Pocket Ionization
• Electro-statically charged “leaf”
discharges as it is exposed to ionizing
radiation
• Not considered a “legal” record
• Low accuracy (+/- 20%)
• Physical impacts can affect radiation dose
readings

30. Solid State
• Provides instantaneous
information regarding dose
accumulation
• Simple to use
• Not a “legal” record
• Dose range device dependent

31. Wearing Radiation Badges
 In general, badges should be worn
 between the hips and shoulders
 outside of any clothing
 on the portion of the body nearest the radiation source
 with the window facing outward
 Do not attach tape or other substances to the dosimeter
(except in the designated spot)

32. Moonlighting
 Individuals who incur additional radiation
exposure from off-duty employment must
provide records of any doses received to the
Radiation Safety Office.

34. Individual Monitoring
When A Lead Apron Is Used (II)
• When expected doses are high, two dosimeters are required:
• 1 under the apron at waist level
• 1 over the apron at collar level
– The effective dose E is given by:
E = 0.5 Hw + 0.025 Hn
where:
– Hw : dose at waist level under the apron
– Hn : dose recorded by a dosimeter worn at neck level over the apron
– Note: The thyroid shielding allows 50% reduction of the E
• The dosimeter worn over the apron at collar level gives also an estimation
of thyroid and eye lens doses

35. Special Aspects Of Individual Monitoring
• In case of loss of a dosimeter, the dose estimation may be
carried out from:
– recent dose history,
– co-workers dose
– or, workplace dosimetry
• Individual monitoring devices should be calibrated
• Laboratory performing personnel dosimetry should be approved
by the regulatory authority

36. Individual Monitoring And Exposure
Assessment
• In some facilities and for some individuals with a low level of exposure
(e.g.: general dental practitioners), area dosimetry to estimate the level
of dose per procedure can be an acceptable alternative.
• Some X Ray systems for dental radiography, or others used in surgical
theatres which use X Rays on a limited number of occasions a month
may not require individual dosimetry for all staff involved although
fluoroscopy in surgical theatres may lead to high dose in short time if
not properly conducted
• In these cases, area dosimetry or some other individual dose
evaluation per procedure could allow the RPO to estimate the typical
level of risk

37. Individual Monitoring
When A Lead Apron Is Used
• The dosimeter should be worn under the apron for estimating
the effective dose
• The other body areas not protected by the apron will receive
higher dose
• One dosimeter worn under the apron will yield a reasonable
estimate of effective dose for most instances
• In case of high workload (interventional radiology) an
additional dosimeter outside the apron should be considered by
the RPO

38. Where Do You Wear A Personal Dosimeter?
• When you wear a lead apron, you can wear your Personal
dosimeter in one of the following three way;
1. Under the apron
2. Outside the apron
3. Wear two dosimeter; one out side the apron and the other under the
apron

39. Wearing Personal Dosimeter Under Lead
Apron
• If you wear your personal dosimeter under the apron you will be
able to measure the radiation penetrated the apron to your body.
• This way of using personal dosimeter is recommended if you
wear thyroid collar and lead google.
• To estimate the radiation dose delivered to the uncovered parts of
the body such as arms and legs you can multiply the measured
dose by (100/5) because a 0.5 mm lead equivalent apron absorbs
95% of radiation and only 5% penetrate to the body.
• In our Hospital we recommended to use this way of wearing
dosimeters.

40. Wearing Personal Dosimeter Outside Lead
Apron
• If you wear your personal dosimeter outside the apron will be
able to measure the radiation delivered to the uncovered parts
of the body.
• This way of using personal dosimeter is recommended if you
do not wear thyroid collar and lead google.
• To estimate the radiation dose delivered to the the body under
the apron multiply the measured dose by (5/100) because a 0.5
mm lead equivalent apron absorbs 95% of radiation and only
5% penetrate to the body.

41. Wearing Two Personal Dosimeter
• Wearing two personal dosimeter will allow you to measure
radiation exposure to both covered and uncovered parts of the
body

42. Recommendation
• We recommend to wear personal
dosimeters under the apron and
to wear thyroid collar because all
sensitive organs will by covered.

43. Monitoring Of The Workplace
• Annual area surveys should be performed
• All radiation monitors shall be calibrated, and their warning
devices and operability should be checked prior to each day of
use.

44. Monitoring Of The Workplace
• Registrant and licensees shall develop programmes for
monitoring of the workplace:
– All survey meters used for workplace monitoring shall be calibrated
and this calibration shall be traceable to a standards dosimetry
laboratory
– Initial monitoring should be conducted immediately after the
installation of new radiology equipment and shall include
measurements of radiation leakage from equipment, and area
monitoring of useable space around radiology rooms

45. Area Survey
• Area Surveys are used to measure:
– radiation level
– contamination level

47. Area Survey
• Area Surveys should be conducted:
– Daily whenever radionuclides are used
– Monthly even if no experiments
• Keep record of all surveys conducted

50. 6. Records

51. 6. Records
Among the records that shall be available to the
Radiation Safety Office are:
1. Dose equivalent data for all exposed personnel;
2. Training program description and attendance;
3. Environmental monitoring data;
4. Safety reviews of facility designs and operations;
5. Unusual occurrences of operational failures;
6. Quality assurance data;
7. Minutes of the RSC (including all approvals);
8. Survey meters and radiation alarm detectors calibration;
9. Radiation safety guideline

52. 7. Risk Assessments

53. Risk
• The statistical probability that personal injury
will result from some action
– smoking, speeding, extreme sports, ect.
– ionizing radiation exposure

54. 7.1 Risk Assessments Involving
Machine Sources
• When equipment is first installed it is the responsibility of the
installer to ensure that a critical examination is undertaken.
• This should ensure that all safety features and warning
indicators are functioning correctly and that dose-rates
associated with use of the equipment are within design
specifications so that adequate protection is provided from
ionizing radiations for both staff and members of the public.
• A survey will also need to be carried out whenever a machine
is relocated.

55. 7.2. Risk Assessments And Emergency
Procedures
• An important part of the risk assessment is to evaluate accident
scenarios and consider the actions to be taken in emergency
situations.

56. 7.3. Recording The Results Of The Risk
Assessments
• All risk assessments should be recorded.
• All risk assessments should also be reviewed periodically and
the results of such reviews recorded.

57. 8. Facility Design

58. 8.1. Site Selection
• The Radiation Safety Officer must participate
in the planning and design stages of new or
modified radiation facilities to ensure
incorporation of proper radiation safety
features.
• The layout must also consider the movement
of personnel into and out of the facility.

59. 8.2. Controlled Areas
• High radiation areas and each radiation area
where the possibility presents of approaching
10% of the occupational dose limit shall be
treated as controlled areas.

60. 8.2. Controlled Areas
The specific requirements are:
1. The area must be secured when it is not occupied by responsible
personnel.
2. The area must be posted with proper signs indicating the radiation
zone(s) and the sources which is present.
3. Personnel monitoring must be provided where appropriate, as
determined by the Radiation Safety Office.
4. Surveys must be performed to maintain surveillance on the hazards
which might be present, and records kept.
5. Personnel must receive written instructions as to the hazards present
in the area.

61. 9. Radiation Protection Surveys

62. Survey Report
The survey report must include at least the following:
1. sketch of the facility, showing the locations of the x-ray
equipment and control booth within the facility as well as the
nature and occupancy of the areas adjoining the facility;
2. identification of the x-ray equipment (i.e., name of the
manufacturer, model designation and serial number of the
generator, control, x-ray tube assembly, x-ray table, etc., as
applicable). The date, or at least approximate date, of
manufacture should be included;
3. the method of support of the x-ray tube assembly (i.e., floor-to
ceiling tube stand, ceiling suspended over-table tube, etc.);

63. Survey Report
4. observations on the operational condition (both electrical and
mechanical) of the x-ray equipment at the time of the survey.
Particular attention should be drawn to any conditions which could
lead to future malfunctioning of the equipment;
5. the actual or estimated total workload of the facility, as well as the
workload apportioned into the various useful beam directions and
procedures used, etc.;
6. results of radiation measurements carried out both inside and
outside the controlled area under “typical” and “worst case”
operating conditions. The locations at which the measurements
have been made must be indicated on the sketch of the facility;

64. Survey Report
7. an assessment of the condition of lead aprons, gloves, gonad
shields, mobile lead screens and other protective devices;
8. an estimate of potential exposures to personnel working in or
around the facility;
9. an assessment of radiological techniques from the point of view
of radiation safety. Attention must be drawn to any practices
which are or could be detrimental to the patient or to personnel
working in the facility. Recommendations of improved or safer
techniques should be made in such cases;
10.a summary of typical technique factors used and a measurement
of the total filtration in the useful beam;

65. Survey Report
11.recommendations regarding the need for a follow-up survey.
The survey report should also include the results of
investigations of any unusually high exposures from previous
personnel dosimetry reports and recommend whether other
persons should be included in the personnel dosimetry service.