Sep 2, 2007 - protected by lead-apron. â relatively high exposure to unshielded parts of the body (extremities, eyes). Scatter radiation. â mainly from patient ...
Personal Dose Monitoring in Hospitals Global Assessment, Critical Applications, Future Needs Peter Covens Radiation Protection Office Academic Hospital – University of Brussels (AZ-VUB)
9-2-2007
Herhaling titel van presentatie
1
Contents Approach on personal dosimetry Exposure pathways Critical applications – interventional radiology – nuclear medicine
Conclusions / remarks Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Personal Dose Monitoring Objectives Demonstrate compliance with regulatory limits Identify new exposure pathways/risks Indicate good/bad radiation protection practice Implement ALARA policies
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Dosimetric Data Average: 0.19mSv/y all exposed workers Meaningless ! Average: 1.05mSv/y measurably exposed workers Meaningless ! Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
RADIOLOGY
NUCLEAR MEDICINE
RADIOTHERAPY
IN-VITRO APPLICATIONS/ RESEARCH Eurados Annual Meeting Madrid January 23, 2007
Dosimetric Data Practical Radiation Protection Occupational exposures in the medical field differ substantially! – distribution of yearly doses is important – how many people receive dose lower than X and higher than Y?
Order of magnitude of doses defined by – – – –
nature procedure? workload? level of radiation protection? methodology of the assessment?
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Departments Overlap
NUCLEAR MEDICINE
RADIOLOGY
RADIOTHERAPY
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
IN-VITRO APPLICATIONS/ RESEARCH
Eurados Annual Meeting Madrid January 23, 2007
Departments Overlap CONVENTIONAL RADIOLOGY CONVENTIONAL CT
RADIOLOGY
INTERVENTIONAL RADIOLOGY BONEDENSITO DENTAL
PET-CT
MAMMO
NUCLEAR SPECT MEDICINE RA DIO N TH UCL ER I AP DE Y
ING NN ING A L P TION SI PO
OTHER…
LABELLING
PET
IN-VITRO APPLICATIONS/ RESEARCH BIOMEDICAL RADIOIMMUNOASSAY
RESEARCH
RADIOTHERAPY
BRACHYTHERAPY
EXTERNAL BEAM THERAPY
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Interventional Radiology What? treatments or diagnoses, using imaging for guidance and where considerable amount of fluoroscopy is used
Not limited to radiology department Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Exposures during IR Staff is standing next to patient – protected by lead-apron – relatively high exposure to unshielded parts of the body (extremities, eyes)
Scatter radiation – mainly from patient and towards tube – not uniformly distributed – relatively low energies
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Routine Personal Dose Monitoring in IR How to assess E? – Hp(10) over and under apron will respectively overestimate and underestimate – many algorithms proposed in literature for lead apron workers (one or two dosemeters)
Extremities/eyes – technical problems eye-dose monitoring – routine extremity dose monitoring often encounters sterility problems Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Routine Personal Dose Monitoring in IR AZ-VUB 40 workers monitored with 2 to 3 dosemeters during IR-procedures – Hp(10),chest, under apron – Hp(10),chest, over apron (highest values ~140mSv/y) – Hp(0.07),wrist (highest values ~100mSv/y)
Present algorithm for assessment E – E= Hp(10),ch,u +0.05Hp(10),ch,o – combination “double dosimetry – wearing lead collar”: obligatory Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Multi-Centre Study Belgium
(AZ-VUB, SCK?CEN, FANC, CHU-Liège, CH-Jolimont, KU Leuven)
Algorithm for assessment of E – suitable for various exposure geometries and workloads – smallest overestimation, max 10% underestimation – use Hp(10) and two dosemeters
Assessment of extremity/eye doses – various exposure geometries – relation to workload (#procedures, DAP)? Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Multi-centre study Belgium Algorithms for E (MCNPX-Voxel) E (0.25/0.50mm wrap around apron)
Lead Collar (0.25mm)
Maximum overestimation of E
Geometry/ worker position
2.83 x Hp(10)thorax,u + 0.04 x Hp(10)neck,o
No
43%
2.74 x Hp(10)thorax,u + 0.01 x Hp(10)neck,o
Yes
52%
fixed over-table tube geometry/ mixed worker positions
2.25 x Hp(10)thorax,u + 0.12 x Hp(10)neck,o
No
146%
2.25 x Hp(10)thorax,u + 0.10 x Hp(10)neck,o
Yes
235%
1.64 x Hp(10)thorax,u + 0.08 x Hp(10)neck,o
No
60%
1.64 x Hp(10)thorax,u + 0.06 x Hp(10)neck,o
Yes
105%
GENERAL ALGORITHM Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
under-table tube geometry/ mixed worker positions under-table tube geometry/ close to patient
PHYSICIAN ALGORITHM Eurados Annual Meeting Madrid January 23, 2007
Multi-centre study Belgium Assessment of E Calculated algorithms – strongly depend on practice – dosemeter positions strongly influence estimation – underestimation when distance worker-patient increases – large overestimation for general algorithm at positions close to patient (physician) – physician-algorithm? for higher exposures better estimation required! (ICRP) Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Multi-centre study Belgium Assessment of E Importance lead collar – min ~20% – less pronounced for under-table tube geometry
One dosemeter algorithm? – less accurate – under-apron dosemeter gives no information about eye dose (strong correlation found for Hp(0.07),collar – eye dose) Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Implementation of Double Dosimetry in Practice Algorithm – install safe algorithm – E= a X,under apron+ b Y,over apron shouldn’t we take a=“1” and X=Hp(10),chest?
Who? – all lead apron workers? – related to workload (#procedures, DAP)? – make double dosimetry and lead collar a conditio sine qua non Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Multi-centre study Belgium Extremity and Eye Dose Approach
apron
– 250 angiography / vascular surgery procedures over 17 centres – Recorded data – dose at legs, hands, forehead – DAP-value/procedure – position of staff members (physician, assistant, nurse) – exposed patient region – use of RP-devices ?
nurse
phys Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
assis
Eurados Annual Meeting Madrid January 23, 2007
Multi-centre study Belgium Extremity and Eye Dose Recorded doses show large differences between centres (same type procedures)! Retracting during acquisition of images (RP) is efficient Median Hp(0.07) (µSv/procedure)
200 180 160 140 120 100
Physicians - RP Physicians + RP Assistants - RP Assistants + RP Nursing Staff
80 60 40 20 0 Head
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Hand
Leg Eurados Annual Meeting Madrid January 23, 2007
Multi-centre study Belgium Extremity and Eye Dose Workload relation – moderate to strong correlation for physicians Hp(0.07),leg – DAP-value (no additional RP) – normalising the doses to procedure DAP-value (physicians) Staff dose(µSv/Gycm2) angiography centres
head patient exposed region
hand leg head
vascular surgery centres Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
patient exposed region
hand leg
Eurados Annual Meeting Madrid January 23, 2007
Multi-centre study Belgium Extremity and Eye Dose
Estimated Annual Hp(0.07)
700
90000 Head dose
600
80000
Hand dose
500
Leg dose
70000
Annual Cumulated DAP
60000
400
50000
300
40000 30000
200
20000 100
10000
0
Annual Cumulated DAP (Gycm2)
Extrapolation to annual dose based on 3rd quartile values DAPnormalised doses
0 Phys 1
Phys 2
Phys 3
Phys 4
angiography -RP Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Phys 5
Phys 6
vascular surgery
Phys 7
Phys 8
angiography +RP Eurados Annual Meeting Madrid January 23, 2007
Multi-centre study Belgium Extremity and Eye Dose Reason for higher dose/DAP in vascular surgery is unclear Varying radiation protection measures – retracting from patient during acquisition only in some centres – under-table lead curtain rarely used
Large observed differences emphasises routine extremity/eye dose monitoring Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Interventional Radiology Challenges / Future Needs Validation of multi-centre study! Practical routine dose monitoring double dosimetry, extremities, eyes
Trends – modern rooms: biplanar systems – interventional CT (CT-fluoroscopy) – increasing number of procedures (biopsies) – AZ-VUB: 700µSv/proc and 200µSv/proc for respectively hand and head!
Radiation protection training Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine CONVENTIONAL RADIOLOGY
RADIOLOGY
INTERVENTIONAL RADIOLOGY
PET-CT
MAMMO
BONEDENSITO DENTAL
NUCLEAR SPECT MEDICINE RA DIO N TH UCL ER I AP DE Y
ING NN ING A L P TION SI PO
OTHER…
LABELLING
PET
CONVENTIONAL CT
IN-VITRO APPLICATIONS/ RESEARCH BIOMEDICAL RADIOIMMUNOASSAY
RESEARCH
RADIOTHERAPY
BRACHYTHERAPY
EXTERNAL BEAM THERAPY
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine Procedures Diagnostic – > 95% – intravenous administration
Therapeutic Radiopharmaceuticals – 85% 99mTc-labelled – 10% PET (18FDG) – other… Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine Internal radiation exposures Contaminations (inhalation, ingestion, skin contamination) – safety procedures – hygienic measures
Traceability? – reporting problems (worker hesitation) – short half-life of applied radionuclides
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine External Radiation Exposures Effective dose – highest Hp(10) values ~ 5mSv/y – effect of PET-introduction hardly observable (10% workload, lower applied activities)
Extremity doses – close contact with sources – relatively high concentrations – more attention needed
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine Location Extremity Dosemeters wrist dosemeter ring dosemeter finger stall TLD-tape Convenience? (exposure time, contamination risk) Accuracy? (highest dose location, correction factor needed) Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine AZ-VUB Routine monitoring with ring dosemeters Case study: dose assessment at 36 locations for 5 different manipulations – location highest dose – order magnitude – correction factor after routine monitoring at position “R08” (location ring dosemeter)
L03
L04
L01
L02
L05
L06
L07
L10
R09 L12
L13 L08 L11
R12
R10
R06
R07
R13 R11 R08
L14
L15
R15
R14
L16
L17
R17
R16
L18
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
L09
R03
R04
R05
R01
R02
R18
Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine Manipulations kit preparation (labelling) 99mTc
syringe dispensing
Radiopharmacy staff
18F
administration to patient Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Nursing staff Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine Manipulations kit preparation (labelling)
Radiopharmacy staff
99mTc
syringe dispensing 18F
administration to patient Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Nursing staff
Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine Manipulations kit preparation (labelling) 99mTc
syringe dispensing
Nursing staff
18F
administration to patient Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Average Hp(0.07) per handled activity (µSv/GBq)
Nuclear Medicine Kit Preparation 99mTc 30
worker 1 worker 2
L03
L04
25 L01
20
L02
L05
L06
L07
L09 L10
R09 L12
L13 L08 L11
R12
R06
R10 R07
R13 R11 R08
L14
L15
R15
R14
L16
L17
R17
R16
R03
ring dosemeter location
R04 R05
R01
R02
15 L18
R18
10
5
0 L01 L02 L03 L04 L05 L06 L07 L08 L09 L10 L11 L12 L13 L14 L15 L16 L17 L18 R18 R17 R16 R15 R14 R13 R12 R11R10R09 R08 R07 R06 R05 R04 R03 R02 R01 Location
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Average Hp(0.07) per handled activity (µSv/GBq)
Nuclear Medicine Dispensing 99mTc 140
120
worker 1 worker 2
L03
L04
100
L01
L02
L05
L06
L07
L09 L10
R09 L12
L13 L08 L11
R12
R06
R10 R07
R13 R11 R08
L14
L15
R15
R14
L16
L17
R17
R16
R03
R04 R05
ring dosemeter location R01
R02
80
60 L18
R18
40
20
0 L01 L02 L03 L04 L05 L06 L07 L08 L09 L10 L11 L12 L13 L14 L15 L16 L17 L18 R18 R17 R16 R15 R14 R13 R12 R11R10 R09R08 R07 R06 R05 R04 R03 R02 R01 Location
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Average Hp(0.07) per handled activity (µSv/GBq)
Nuclear Medicine Dispensing 18FDG 900
800
worker 1 worker 2
L03
L04
700 L01
L05
L06
L07
L09 L10
R09 L12
L13 L08 L11
R12
R06
R10 R07
R13 R11 R08
R03
R04 R05
R01
600 L02
L14
L15
R15
R14
L16
L17
R17
R16
R02
500
ring dosemeter location
400 L18
R18
300
200
100
0 L01 L02 L03 L04 L05 L06 L07 L08 L09 L10 L11 L12 L13 L14 L15 L16 L17 L18 R18 R17R16 R15 R14 R13 R12 R11R10 R09R08 R07R06 R05R04 R03 R02 R01 Location
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Average Hp(0.07) per handled activity (µSv/GBq)
Nuclear Medicine Administration 99mTc 70
60
50
worker 3 worker 4
L03
worker 5
L04
worker 6 worker 7
L01
L02
L05
L06
L07
L09 L10
R09 L12
L13 L08 L11
R12
R06
R10 R07
R13 R11 R08
L14
L15
R15
R14
L16
L17
R17
R16
R03
R04 R05
R01
R02
40
30
L18
ring dosemeter location
R18
20
10
0 L01 L02 L03 L04 L05 L06 L07 L08 L09 L10 L11 L12 L13 L14 L15 L16 L17 L18 R18 R17 R16 R15 R14R13 R12 R11R10R09R08 R07 R06 R05 R04R03 R02 R01 Location
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Average Hp(0.07) per handled activity (µSv/GBq)
Nuclear Medicine Administration 18FDG 600
worker 3 worker 4 500
L03
worker 5 worker 6 worker 7
L04
L01
L05
L06
L07
L09 L10
R09 L12
L13 L08 L11
R12
R06
R10 R07
R13 R11 R08
R03
R04 R05
R01
400 L02
300
L14
L15
R15
R14
L16
L17
R17
R16
R02
ring dosemeter location L18
R18
200
100
0 L01 L02 L03 L04 L05 L06 L07 L08 L09 L10 L11 L12 L13 L14 L15 L16 L17 L18 R18R17 R16 R15R14 R13R12 R11R10R09 R08 R07R06 R05R04 R03 R02 R01 Location
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine Extrapolation of Results Extremity dose / handled activity, manipulation, worker at 36 locations Monthly handled activity / manipulation, worker Monthly extremity dose / worker at 36 locations
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Highest dose: order of magnitude, location Overall ratio “highest dose/R08-dose” (ring dosemeter) Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine Monthly Extremity Dose 50 Highest Hp(0.07) (mSv/month)
6
Ratio Highest dose / R08 dose Administration 18FDG Administration Tc-99m Dispensing 18FDG Dispensing syringes Tc-99m Kit preparation Tc-99m
40
5
4
30
3
20
2
10
1
0
0 L01 worker 1
L09 worker 2
L03 worker 3
L01 worker 4
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
L01 worker 5
L01 worker 6
Ratio Highest dose/R08-dose
60
L03 worker 7 Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine Routine Extremity Dose monitoring Dosemeter location – highest dose location not necessarily on “dominant” hand – use practical location and implementation correction factor
Order of magnitude of extremity doses – probably underestimation (contaminations) – accuracy 18F – is there a contribution of β+ ? – do we measure this contribution (physical thickness detector, detectorholder)? Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine Radiation Protection Measures Syringe shields – – – –
rarely used during dispensing (poor visibility) sometimes less efficient poor protection for 18FDG always removed for activity calibration
Automated dispensing/administration – more and more commercially available – rather expensive
Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Nuclear Medicine Challenges / Future Needs PET-radionuclides – introduction of β/γ-emitters: 124 I,…
60/61/62 Cu, 68Ga, 94Tc,
– relatively high β+ energies (>1MeV) – relatively high γ energies (>1MeV)
– increasing exposure (whole body, extremities)
Therapy with β- radionuclides – monitored extremity doses > 100mSv (Barth et al) – evaluation of β-response for extremity dosemeters needed Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
Conclusion Routine personal dose monitoring in hospitals – some technical / accuracy problems – no consensus interpretation of results
Increasing number applications – workload needs to be considered – radiation protection measures
Increasing diversity asks continuously for characterisation studies Personal Dose Monitoring in Hospitals Global assessment, Critical Applications, Future Needs Peter Covens, Academic Hospital University of Brussels (AZ-VUB)
Eurados Annual Meeting Madrid January 23, 2007
