Optimization of Protection in Digital radiography - CT
aspects
وبینار حفاظت در برابر اشعه ویژه مراکز پزشکی دانشگاه علوم پزشکی و خدمات بهداشتی درمانی بیرجند
دانشکده پیراپزشکی و بهداشت فردوس
1399/09/18
Mohammad Reza Deevband, Ph.D.
Medical engineering and medical physics section
Shahid Beheshti Medical Science University
3
• Regulatory aspects of occupational protection
• Basic methods for radiation protection
• Factors affecting patient and staff dose in CR & DR
• Factors affecting patient in CT
• Practical rules
• Protection devices
• Individual dose monitoring
• Health surveillance
Key topics
4
Regulatory basis of radiation protection
Recommendations of the
International Commission of Radiological Protection (ICRP)
General – in 1990 and last in 2007
BSS= “International Basic Safety Standards for
Protection against Ionizing Radiation and for the Safety
of Radiation Sources, ” IAEA, Vienna 2011 (interim edition)
National regulations
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BSS - Responsibilities of employers
“Registrants, licensees and employers of workers
are responsible for ensuring that exposures are
limited that protection and safety is optimized, and
that appropriate radiological protection programmes
are set up and implemented”
6
BSS - Dose limits
For effective dose:
For equivalent dose:
*BSS interim edition
“The occupational exposure of any worker shall be so controlled that the following limits be not exceeded:
20 mSv per year averaged over five consecutive years and 50 mSv
in any single year;
to the lens of the eye of 20 mSv* in a year; averaged over 5 years;
not exceeding 50 mSv in any single year.
Dose limit for the extremities (hands and feet) or the skin
of 500 mSv in a year.
7
Workers shall:
• follow any applicable rules and procedures for protection and safety specified by the employer;
• use properly the monitoring devices and the protective equipment and clothing;
• co-operate with the employer with respect to the operation of radiological health surveillance and dose assessment programmes;
• abstain from any wilful action that could put themselves or others in situations that contravene the requirements of the Standards;
• accept such information, instruction and training concerning protection and safety
BSS - Responsibility of workers
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• Regulatory aspects of occupational protection
• Basic methods for radiation protection
• Factors affecting staff doses in fluoroscopy
• Factors affecting patient in CT
• Practical rules
• Protection devices
• Individual dose monitoring
• Health surveillance
Key topics
9
Basic Radiation Protection
“Golden rules” :
• Time – minimize exposure time
• Distance – increasing distance
• Shielding –Lead or non-lead equivalent apron is MUST inside
the room with X ray machine
• fixed, portable and pull- down shields as appropriate;
• Personal protective devices
• Technique factors e.g. collimation, pulse fluoroscopy,
magnification, filters, grids etc.
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Minimize Exposure Time
• Everything you do to minimize
exposure time reduces radiation dose!!
Minimize fluoro and cine times
Whenever possible, step out of room
Use pulsed fluoroscopy– minimizes time x-ray tube is
producing x rays
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Maximize Distance – Inverse Square Law
Helps Protect You
“Inverse Square Law” - radiation dose varies inversely with the square of the distance
• The patient is the main source of scattered radiation!!
0.5 m 1 m 1.5 m
dose rate 100 units
25 units
11 units
distance
• Move from 0.5 m to 1 m (doubling the distance) dose
rate decreases 4 times or to 25%!!
patient
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Inverse Square Law Helps Protect You
Stay as far away as possible when radiation
is ON, use extension tubing, remote injector,
longer instruments, etc.
Practical rule
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• Regulatory aspects of occupational protection
• Basic methods for radiation protection
• Factors affecting patient and staff dose in CR &
DR
• Factors affecting patient in CT
• Practical rules
• Protection devices
• Individual dose monitoring
• Health surveillance and records
Key topics
14
Optimisation includes …
• All activities that ensure consistent, maximum
performance from physician and imaging facility1
• “A distinct series of technical procedures which
ensure the production of a satisfactory product”
• Four steps …
• Acceptance Testing (AT)
• Establishment of baseline performance
• Diagnosis of changes in performance
• Verification of correction of deterioration
1National Council on Radiation Protection and Measurements. (1988) Quality Assurance for Diagnostic Imaging, NCRP Report No. 99, Bethesda, MD;
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Optimisation includes both personnel
and equipment
• Identifying aspects of facility operation that require
decisions or actions
• Establishing policies with respect to these
• Encouraging compliance through education and
recognition
• Analyzing records at regular intervals
• Dose optimisation
• Image quality optimisation
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“What’s my motivation?”
• Regulatory Compliance • International BSS
• National Regulations
• Standards of Care • Standards established by professional
societies
• Providing the highest quality medical care
• MANAGING RADIATION DOSE!!!
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Factors that affect image quality and patient
dose Factor Contrast Resolution Noise Patient Dose
Focal spot size X
Off-focus
radiation
x (x) x
Beam filtration x X
Voltage
waveform
(x) x x
kVp X (x) X
mA (x)
S X
mAs (x) X X
SID X X
Field size X X
Scatter rejection X X
Wolbarst (1993) Table 19-1
X: very important
connection
x: sometimes
significant
(x): sometimes
noticeable
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Quantifiable Consequences of Degraded
Performance
• Loss of Contrast Sensitivity
• Loss of Sharpness/Spatial Resolution
• Loss of Dynamic Range
• Increase in Noise
• Decrease in System Speed
• Geometric Distortion
• artefacts
• Decrease in diagnostic accuracy
• Increase in observer time/fatigue
• Delay of diagnosis
• Increase in patient radiation dose
• Decrease in efficiency of imaging operation
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Reasons for differences between CR
and DR optimisation • CR cassette-based vs. integrated
receptor DR
• Cleaning
• Physical defects
• Erasure
• Mis-identified patient, view, orientation
• Need adequate knowledge of radiographic technique
• Separation between image acquisition and development
• Time
• Geographic (PACS)
• Distinctions are blurring
• Poorly integrated DR
• Integrated CR
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3. Verify
exam with
physician
5."Arrive"
patient in RIS
6. Escort patient
to exam room
7. Explain exam
to patient
8. Select and ID
cassettes
9. Position patient,
cassette, x-ray tube
10. Perform exam
11. Scan cassette
14. Review
images at QC
15. Repeat
necessary?
17. Complete exam
in RIS
END
4. Schedule exam in
RIS
12. Preview images
13. Repeat
necessary?
18. Release patient
1. Patient arrives in
imaging department
Y
Y
N
N
START
2. Is exam
scheduled?
N
Y
16. Release images
to PACS
QC?
QC?
QC?
QC?
QC?
QC?
QC?
QC?
Process map
• Flowchart of steps
• Identify potential QC control points • actions to be taken
• Identify “work-arounds” • Example: What if RIS is
out-of-service? • How to continue
operations?
• Don’t forget actions on restoration of service
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Step 1. Patient reports for an examination.
• The technologist verifies: • the patient is the person identified in the exam request • the anatomy to be examined matches the exam request • other information about the patient, such as
• Pregnancy
• Restricted motion
• Allergies
• Appliances
• QC accomplished by training or checklist
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Step 2. Technologist identifies the patient
and exam to the imaging system
• Usually occurs before, but sometimes after the exam is performed
• Misidentification has consequences • incorrect information can cause image
unavailability • incorrect exam info can affect image
development • mis-association complicates error
detection • proliferation of digital images
complicates correction
• Automation of association = imperfect QC! • New classes of errors
23
The best image, improperly identified, is
useless. • Consequences of
misidentification:
• Broken studies
• Orphans
• Exceptions
• Penalty Box
• Automation of association: • RIS interfaces
• Bar code scanner augmentation
• DICOM Modality Worklist Management (MWL)
• unscheduled exams
• resource re-allocation
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Step 3. Technologist positions the patient in the
radiation field and performs the examination
• Potential errors • mispositioning • patient motion • incorrect radiographic technique selection • poor inspiration • improper collimation • incorrect alignment of x-ray beam and grid • wrong exam performed • double exposure
• QC accomplished at acquisition station? • Image processing inadequate to correct • Correction requires repeated exam (s)
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Results:
Rejects during one month
Re a so n Numb e r %
mispositioned 240 53.3%
artifacts 40 8.9%
test images 22 4.9%
nondiagnostic 20 4.4%
patient motion 14 3.1%
misplaced marker 10 2.2%
no marker 6 1.3%
under-exposed 5 1.1%
inadequate contrast 4 0.9%
over-exposed 2 0.4%
wrong exam 2 0.4%
wrong patient 2 0.4%
T o ta l 450 100.0%
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Step 4. Image receptor captures the
radiographic projection
• Potential errors • Inadequate erasure, lag, ghosting • Improper compensation for non-uniform gain • Incorrect gain adjustment • Incorrect exposure factor selection • artefacts
• Interference with the projected beam
• Receptor defects
• Interference with converting the captured projection into a digital image
• Detection possible at acquisition station? • Correction may require repeated exam • Can be averted by active QC
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Active QC countermeasures:
emphasize avoiding vs. correcting errors
• Prophylactic erasure at start of shift
• Periodic checks of non-uniformity corrections
• Periodic gain re-calibration
• Technique guide
• Periodic checks of Automatic Exposure Control (AEC) calibration
• Periodic cleaning of equipment and environment
• Thorough Acceptance Testing of new receptors • Also incidental to service events and software upgrades
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Step 5. Image receptor renders the
captured projection for viewing
• Potential errors • Incorrect Exposure Field recognition; incorrect
determination of values of interest (VOI)
• Incorrect histogram re-scaling
• Incorrect gray-scale rendition
• Incorrect edge restoration
• Inappropriate noise reduction
• Incorrect reorientation
• QC possible at acquisition station? • Correction usually possible without repeated exam
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Functions of the QC workstation:
sometimes integrated into acquisition station • Modify image processing
• Imprint demographic overlays
• Add annotations
• Apply borders or shadow masks
• Flip and rotate
• Increase magnification
• Conjoin images • Scoliosis
• Full leg
• Modify sequence of views
• Verify exposure indicator
• Select images for archive
• Delete images
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Step 6. Acquisition station transfers the
image to the archive
• Potential errors
• Transmission failure
• Image deletion from local cache
• Information omitted from transmitted image
• Exposure indicator
• Processing parameters
• Shutters
• Annotations
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Step 7. Digital image is displayed for
viewing by a physician
• Potential errors (hard or soft copy) • Incorrect GSDF calibration • Inadequate matrix
• Moire’ (interference) patterns
• Inadequate spatial resolution
• Incorrect or missing demographics or annotations • Inadequate viewing conditions • Errors not filtered by previous QC
• QC => Radiologist “Film” critique
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Task Allocation Matrix
Task Responsibility Frequency
Verify Patient ID and exam info Radiographer Each exam
Verify Patient Positioning Radiographer Each view
Verify Image Quality – release or repeat Lead Radiographer Each image
Verify exam in PACS Lead Radiographer Each exam
Reconcile patient data/image counts in PACS Medical Informatics Incidental
Report substandard images Radiologist Incidental
Erase cassette-based image receptors Radiographer Start-of-shift
Test image receptor uniformity Radiographer Weekly
Clean cassette-based image receptors Radiographer Monthly
Compile and review reject analysis data Lead Radiographer Monthly
Verify display calibrations Clinical Engineer Quarterly
Review QC indicators QA Committee Quarterly
Verify receptor calibrations Medical Physicist Semi-Annual
Verify x-ray generator functions Medical Physicist Annual
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Commitment to optimisation
• The optimisation effort is integral to how you organize and perform the work.
• The cost of optimisation is trivial compared to the cost of inefficiency: consider one bad patient outcome.
• Training for optimisation is professional development for hospital staff.
• Leverage local resources for optimisation expertise. • Biomedical engineering
• Medical informatics / Information services
• Medical Physicists
• Hospital QA personnel
34
Who is responsible for optimisation?
(“It takes a village …” )
• Physician responsible for clinical service is
ultimately responsible
• Medical Physicist oversees the program
• Radiographer makes day-to-day measurements,
verifies post-repair integrity
• Service engineer carries out repairs, PM,
calibrations
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Answer True or False
• Random error is a source of inherent
limitation of human operators
• It is the responsibility of the physician to
ensure appropriate delivery of all images to
PACS
• High doses can go undetected with the use of
DR or CR systems
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Answer True or False
• True. Every process that depends on a human
operator is a source of random errors and every
process that automation performs independently is
source of systematic errors.
• False. The technologist/supervisor is responsible
for appropriate delivery of all images to the PACS
• True. DR and CR have wide latitude and high
doses can go undetected. Optimised exposure
parameters should be used in digital systems.
37
• Regulatory aspects of occupational protection
• Basic methods for radiation protection
• Factors affecting patient and staff dose in CR &
DR
• Factors affecting patient in CT
• Practical rules
• Protection devices
• Individual dose monitoring
• Health surveillance
Key topics
38
Radiation protection of patients in CT
1. Perform scan only if it is indicated!
• It is estimated that a significant number of imaging
examinations are unnecessary
• Consultation between the referring physician and the
radiologist is recommended
39
Radiation protection of patients in CT
2. Encourage use of alternative non-ionizing imaging (MRI,US)
when appropriate especially in younger patients
3. Always check if patient may be pregnant
• Use special signs and informative material notifying patients that they
MUST disclose any possibility of pregnancy
4. High quality /Crisp images may look nice but they impart
higher radiation dose to patients
• Start using images with some noise without loss of diagnostic
information
40
Radiation protection of patients in CT
5. Use indication-specific CT protocols for each body region, e.g.
for lung nodule follow up or kidney stones, diagnostic images
can be obtained at 50-75% lower radiation dose compared to
routine or general use protocols
6. Multiple pass or phase CT should NOT be performed
routinely
• Multiphase CT can increase the dose by as much as 2-3 folds over
single phase CT
41
Radiation protection of patients in CT
7. Adjust exposure parameters according to patient
and body part
8. Know your equipment: Learn how to adjust the
parameters of the automatic exposure control (AEC)
system to fine tune radiation dose for different clinical
indications and body regions • Most body CT examinations should be performed with use of AEC
9. Good technique: Lower kVp, mAs,
Higher pitch
Restrict scan length to what is necessary
Always center the area of interest in isocenter of CT gantry
All CT protocols should state the start and end location for different clinical indications
Thin slices only when necessary
42
Radiation protection of patients in CT
10. Pay attention to radiation dose values and compare
with diagnostic reference levels (DRLs)
• Be aware of CT dose metrics and recommended dose levels
for different body regions
43
Radiation protection of patients in CT
44
• Regulatory aspects of occupational protection
• Basic methods for radiation protection
• Factors affecting patient and staff dose in CR & DR
• Factors affecting patient in CT
• Practical rules
• Protection devices
• Individual dose monitoring
• Health surveillance
Key topics
45
Whenever possible collimate the X-ray beam to
the area of interest
Practical rules
Collimation
•reduces staff dose
•reduces patient dose
•improves image quality
46
Staff and patient dose are partially linked
They are function of: available X-ray system
real conditions of the system
how the system is used
RP tools available and applicable
number and type of the procedures
staff skills
used operational protocols
Factors affecting staff doses
47
IF PATIENT SIZE
INCREASES
PATIENT SKIN DOSE
AND THE LEVEL OF
SCATTERED
RADIATION INCREASE
SUBSTANTIALLY
Factors affecting patient
and staff doses
48
Influence of patient thickness
Increase from 16 to 24 cm,
Scatter dose rate could increase by a
factor of 5 (10 mSv/hr x 5=50 mSv/hr)
Factors affecting patient
and staff doses
49
CHANGING
FROM NORMAL
FLUOROSCOPY
MODE TO THE
HIGH DOSE
RATE MODE
INCREASES
DOSE RATE BY A
FACTOR OF
2 OR MORE
Factors affecting patient
and staff doses
50
Practical advice
for staff protection
• Increase distance from the patient.
• Minimize the use of fluoroscopy and use low
dose rate fluoroscopy modes.
• Acquire only the necessary number of images per
series and limit the number of series.
• Collimate the X-ray beam to the area of interest.
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• Use under couch tube systems
• Consider the size of the patient and the position of
the X-ray tube (C-arm angulation).
• Stand on image intensifier side as far from patient
as possible
• Use suspended screen and other personal shielding
tools if available.
Practical advice
for staff protection
52
Optimization of
Radiation Protection
• Ensure adequate image quality by optimization of
dose rate
• Must optimize dose to patient and minimize dose to
staff
• Minimization of dose to patient and staff should not
be the goal.
If image quality is inadequate,
any radiation dose results in
needless radiation dose!
53
• Regulatory aspects of occupational protection
• Basic methods for radiation protection
• Factors affecting patient and staff dose in CR & DR
• Factors affecting patient in CT
• Practical rules
• Protection devices
• Individual dose monitoring
• Health surveillance and records
Key topics
54
Personal protective equipment
• Employer shall ensure that workers are provided with
suitable and adequate personal protective equipment
which meets any relevant regulations or standards (BSS).
But it is the responsibility of
workers to use this devices!
However, protective clothing must not be used as a
substitute for proper protective measures.
55
Protective clothing:
• Protective equipment includes lead aprons,
thyroid protectors, protective
eye-wear and gloves.
• Aprons should be equivalent to :
at least 0.25 mm Pb if the X-ray equipment
operates up to 100 kV and
0.35 mm Pb if it operates above 100 kV
• Aprons may be of the style which is open, or
contains less lead, at the back, due to the
extra weight of lead required - this assumes,
however, that the wearer is always facing
the radiation source
56
0.25 mm lead
60 kV; 100% 2 - 3 %
100 kV; 100% 8 - 15 %
Attenuation of lead
Courtesy of Prof. E. Vano
Personal protective equipment
Higher kV, lower protection
57
0.50 mm lead
60 kV; 100% < 1 %
100 kV; 100% 3 - 7 %
Personal protective equipment
Attenuation of lead
Courtesy of Prof. E. Vano Higher kV, lower protection
58
• Leaded shielding may reduce doses to 5% or
less(1-15%)
• Shielding must be between the patient and
the person to be protected.
If back is facing patient (radiation scatter
source), protection on back is essential
• Everyone in the procedure room
must wear a protective apron
Personal protective equipment
59
Vest-Skirt Combination distributing 70% of the total weight onto the
hips leaving only 30% of the total weight on the shoulders.
Option with light material reducing the weight by over 23% while still
providing 0.5 mm Pb protection at 120 kVp
Personal protective equipment
60
Personal protective equipment
Hang aprons! Do not fold them!
61
Expensive light protective apron sent to Laundry without
the appropriate instructions
Personal protective equipment
62
Expensive protective apron sent to Laundry
Before After cleaning
…$1000 loss!
Personal protective equipment
IAEA Training Course on Radiation Protection for Doctors (non-radiologists, non-cardiologists) using Fluoroscopy
L05. How do I reduce my radiation risk?
63
Thyroid protectors
Personal protective equipment
64
Protective goggles
Lead Equiv: 0.75mm front and
side shields leaded glass;
Weight: 80 grams
Personal protective equipment
DETERMINISTIC
LENS THRESHOLD
AS QUOTED BY
ICRP
OPACITIES
THRESHOLD
>0.1 Sv/year
CONTINUOUS
ANNUAL RATE
>0.15 Sv/year
CONTINUOUS
ANNUAL RATE
CATARACT
65
66
Gauntlets are heavy gloves. They
have limited value because they are
difficult to use and should therefore
only be used where appropriate
67
Protective Surgical Gloves
• Minimal effectiveness
• Transmission on the order of 40% to 50%, or more
• Costly ($40 US), not reusable
• Reduces tactile sensitivity
• Dose limit for extremities is 500 mSv
• Hands on side of patient opposite of x-ray tube so dose
rate is already low compared to entrance side
• Lead containing disposable products are environmental
pollutants
Radiation Protection of Hands
68
Radiation Protection of Hands
Best way to minimize dose to fingers and hand:
Keep your fingers out of the beam!!!
Dose rate outside of the beam and on side of patient opposite x-ray tube: Very low compared to in the beam!
69
Protective devices
• Additional protective devices should be available
in fluoroscopy and interventional rooms as
appropriate:
• Ceiling suspended protective screens.
• Protective lead curtains mounted on the patient table.
• Protective lead curtains for the operator if the
X-ray tube is placed in an over couch geometry and if
the radiologist must stand near the patient
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Ceiling suspended screen
Typically equivalent to 0.5 - 1mm
lead.
Very effective if well positioned.
Not available in all the rooms.
Not used by all the
interventionalists.
Not always used in the correct
position.
Not always used during the whole
procedure.
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Protective lead curtains and ceiling
suspended screens
72
Under-couch tube
Head level
Without
protection
With
protection Pb
Head level
Height from the floor
Protective lead curtains
Height from the floor
Over-couch tube
(GOOD Practice) (BAD Practice)
Image Intensifier close to
patient, X ray tube far from
patient
Image intensifier far from
patient, X ray tube close to
patient From: J American College of Cardiology 2004; 44(11): 2259-82
Entrance Dose to Patient vs. Imaging
Geometry
73
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• Regulatory aspects of occupational protection
• Basic methods for radiation protection
• Factors affecting patient and staff dose in CR & DR
• Factors affecting patient in CT
• Practical rules
• Protection devices
• Individual dose monitoring
• Health surveillance and records
Key topics
75
Individual dose monitoring
• Individual external doses should be determined by
using individual dosimeter
• Worn at breast level, between the shoulders and
the waist
76
Types of Personal Radiation Monitors
1. Film badges
Courtesy of J. Jankowsky
Metal filters
Open window
77
Types of Personal Radiation Monitors
2. Thermoluminescent dosimeters (TLDs)
79
Types of Personal Radiation Monitors
3. Optically stimulated luminescence (OSL)
dosimeters
Courtesy of M. Goodsitt
80
Personal dosimetry
ICRP report 85 (2001) states ...
In interventional procedures:
• In addition, it is possible to combine the two
dosimeter readings to provide an improved
estimate of effective dose (NCRP-122; 1995).
81
Additional:
outside and above the
apron at the neck
•Better estimation of effective
dose
•gives also an estimation of
thyroid and eye lens doses
Individual dose monitoring
with two dosimeters
The main:
under the lead apron
at the breast level
For accurate dose estimation
83
The use of electronic
dosimeters to measure
occupational dose per
procedure helps in the
optimization
84
Individual dose monitoring
• The monitoring period shall not exceed three months,
preferably one month.
• The exchange of dosimeters and report receipt should not
exceed three months
• It is important that workers return dosimeters on time for
processing
• Delays in the evaluation of a dosimeter can result in the
loss of the stored information
• Employer should make every effort to recover any
missing dosimeters
85
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
86
• Monthly individual effective dose or equivalent
dose higher than those specified by national
regulations should be evaluated as a part of the
regulatory compliance.
Special aspects of
individual monitoring
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 Radiation Protection Officer
• Extra dosimeters (when available):
• At neck or eye level for estimation of eye lens dose
• Finger ring dosimeter for estimation of finger dose
87
Individual monitoring
when a lead apron is used
• 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 additional 50% reduction of the E
• The dosimeter worn over the apron at collar level gives also an estimation of thyroid and eye lens doses
88
89
• Regulatory aspects of occupational protection
• Basic methods for radiation protection
• Factors affecting patient and staff dose in CR & DR
• Factors affecting patient in CT
• Practical rules
• Protection devices
• Individual dose monitoring
• Health surveillance and records
Key topics
90
Health surveillance
• Primary purpose is to assess the initial and
continuing fitness of employees for their intended
tasks
• Medical surveillance (medical examinations) to
workers as specified by the Regulatory Authority.
• Counselling should be provided for women who are
or may be pregnant
This is especially relevant
in interventional radiology.
91
Protection of the
embryo or foetus
• The female worker should, on becoming aware that she is
pregnant, notify the employer in order that her working
conditions may be modified if necessary.
• The pregnancy shall not be considered as a reason to
exclude a female worker from work,
• But it is the responsibility of the employer to adapt the
working conditions in respect of occupational exposure so
as to ensure that the embryo or foetus is afforded the same
broad level of protection as required for members of the
public (< 1 mSv equivalent dose to the foetus to the end of
the pregnancy period”
92
X-RAY TUBE POSITION
RELATIVE POSITION WITH
RESPECT TO THE PATIENT
IRRADIATED PATIENT VOLUME (FIELD SIZE)
kV, mA and time (NUMBER AND
CHARACTERISTICS OF PULSES)
EFFECTIVE USE OF ARTICULATED
SHIELDING AND/OR PROTECTION
GOGGLES
Factors affecting staff doses
93
A final general recommendation
Be aware of the radiological protection of your
patient and you will also be improving your
own occupational protection
94
Where to Get More Information
• ICRP publication 103. http://www.icrp.org/
• Radiological Protection for Medical Exposure to
Ionizing Radiation. http://www-
pub.iaea.org/MTCD/publications/PDF/Pub1117_scr.pdf
• International Basic Safety Standards for Protection
Against Ionizing Radiation and for the Safety of
Radiation Sources. 115, Safety Standards. IAEA, 2011
(Interim Edition).
• International Atomic Energy Agency. Occupational
Radiation Protection. Safety Guide RS-G-1.1
95
Where to Get More Information
• ICRP Report 85 (2001): Avoidance of Radiation Injuries from Interventional Procedures
• Education and Training in Radiological Protection for Diagnostic and Interventional Procedures
• ICRP Publication 113
• Ann. ICRP 39 (5), 2009 E. Vaño, M. Rosenstein, J. Liniecki, M. Rehani, C.J. Martin, R.J. Vetter
•http://rpop.iaea.org
Thank you
96