icru report 95 - nucleus-new.iaea.org
TRANSCRIPT
![Page 1: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/1.jpg)
ICRU Report 95: Operational quantities for External
Radiation Exposure
What changes for Radiation Protection ?
Thomas Otto, ICRU and CERN
IAEA ORPAS Meeting, 17. 9. 2021
![Page 2: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/2.jpg)
ICRU Report 95 (2020)Operational Quantities for External Radiation Exposure
• Previous quantities
(ICRU 39 and 51)
• Operational Quantities
for external exposure
• Conversion Coefficients
• Practical Consequences
• Appendices
• Values of Conversion
coefficients
• Computer Codes
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 2
![Page 3: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/3.jpg)
• Short excursion to quantity definition
• What changes ?
• Effect on dose values in radiation fields
• Effect on instrument calibration
• Summary
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 3
![Page 4: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/4.jpg)
Protection vs. Operational Quantities
• ICRP defines protection quantity Effective Dose based on absorbed dose to express risk, constraints and limits
• Protection quantity defined over the volume of a body,not measurable
• ICRU proposes operational quantities, defined in a point and measurable
X
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 4
![Page 5: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/5.jpg)
Relation of QuantitiesPhysical Quantities
F, Ka, D
Protection Quantity Operational Quantities
MeasurementInstrument response R (E,W)
Calculation
With
Phantoms
Calculation
With
Phantoms
Numerical value for
specified radiation field
Numerical value for
specified radiation field ?
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 5
![Page 6: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/6.jpg)
Today
Physical Quantities
F, Ka, D
Protection QuantityEffective dose E
Operational QuantitiesAmbient dose equivalent H*(10)Personal dose equivalent Hp(10)
MeasurementInstrument response R (E,W)
≠
For photons in kerma approximation
𝐸 = න𝑑𝐸p 𝛷𝐸pℎ𝐸(𝐸p, inc∗)
* incident directions: AP, PA, LLAT, RLAT, ROT, ISO
Calculation:
Anthropomorphic
Phantoms
Calculation:
Geometric
Phantoms
𝐻𝑝 𝑑, Ω = ඵ𝑑𝐸p𝑑𝜴 𝛷𝐸pℎ𝑝 𝑑,𝐸p, 𝜴
𝐻∗ 𝑑, Ω = ඵ𝑑𝐸p𝑑𝜴 𝛷𝐸pℎ∗ 𝑑,𝐸p,𝜴
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 6
![Page 7: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/7.jpg)
What changes ?
• Operational quantities from present to future:
• Change to anthropomorphic phantoms
• Better approximation of E by definition
• Also:
• Definition of quantities to limit tissue effects (local dose to skin and to eye lens) as absorbed dose
• More radiation types, e.g. positrons, protons, pions…
• Much wider energy range
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 7
![Page 8: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/8.jpg)
ICRU Report 95
Physical Quantities
F, Ka, D
Protection QuantityEffective dose E
Operational QuantitiesAmbient dose H*Personal dose Hp
MeasurementInstrument response R (E,W)
𝐸 = න𝑑𝐸p 𝛷𝐸pℎ𝐸(𝐸p, inc∗)
* incident directions: AP, PA, LLAT, RLAT, ROT, ISO
Calculation:
Anthropomorphic
Phantoms
𝐻∗ = න𝑑𝐸p 𝛷𝐸p ⋅ ℎ𝐸max(𝐸𝑝)
𝐻p = 𝑑𝛺 𝑑𝐸p𝛷𝐸p ⋅ ℎp (𝐸p,𝒂)
Calculation:
Anthropomorphic
Phantoms
≜
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 8
![Page 9: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/9.jpg)
What changes – Photons
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021
Effective dose E vs.
Personal Dose equivalent Hp(10)
Effective dose E vs.
Personal Dose Hp
9
![Page 10: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/10.jpg)
What changes – Neutrons
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021
0.1
1
10
100
1000
1.00E-09 1.00E-07 1.00E-05 1.00E-03 1.00E-01 1.00E+01 1.00E+03
hE(
W),
h*(
10
)
(pSv
cm2 )
Neutron Energy (MeV)
AP
PA
LLAT
RLAT
ISO
ROT
H*(10)
0.1
1
10
100
1000
1.0E-09 1.0E-07 1.0E-05 1.0E-03 1.0E-01 1.0E+01 1.0E+03
hE(
W),
h*
(p
Sv c
m2 )
Neutron Energy (MeV)
AP
PA
LLAT
RLAT
ISO
ROT
H*
Effective dose E vs.
Ambient Dose equivalent H*(10) Effective dose E vs.
Ambient Dose H*
10
![Page 11: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/11.jpg)
Personal dose – photonsConversion coefficients from kerma Ka to operational quantity
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021
𝐻p ≈1
5𝐻p(10)
𝐻p ≈ 0.86 𝐻p(10)
At energies typical for radioisotopes, Hp = 0.86 * Hp(10)
At low-energy x-ray (backscatter from patient) Hp = 0.2 * Hp(10)
11
![Page 12: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/12.jpg)
Activation products
Activation with 3.5 GeV proton beam
Photon and electron spectra (1h decay)
H*(10) and H* overlay
Ratio H* / H*(10)
• Photons dominate
• H* < H*(10) by 15 %
• Typical for radionuclides
• Attention for pure b-emitters
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021
photons
electrons
12
![Page 13: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/13.jpg)
Low-energy x-ray spectra
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021
High-dose rate spectrum, 20 kV
tube voltage
Fluence spectrum
H*(10)-weigthed spectrum
H*-weighted spectrum
Diagnostic x-ray calibration
spectra
Upper curve: H*(10)
Lower curve: H*
Influence on dose of medical personnel during interventional radiology under study
13
![Page 14: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/14.jpg)
Prompt radiation at a particle accelerator (160 MeV protons)
• Behind the dump: high-energy particles, H* ≥ H*(10)
• In Front: multiple scattered neutrons: H* < H*(10)
• Analogue results for proton therapy accelerators
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 14
![Page 15: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/15.jpg)
Consequences for Dose Registers
• Dose registers (should) record effective dose E
• New quantities: closer approximation to E
• For most workers, where monthly dose is (close
to) zero, no difference
• Measurement uncertainty at low dose (trumpet
curve) !
• Recorded value for workers with significant dose
will be slightly lower
• Case of medical staff in Interventional Radiology
needs to be studied in more detail
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 15
![Page 16: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/16.jpg)
ICRU 95 – Consequences for Photon Dosimeters
Area monitoring
instruments with energy
cut-off > 50 keV nearly
unaffected
Simple recalibration of
sensitivity
Today’s personal
dosimeters would show
overresponse at low
photon energies
Redesign of filter required
(or algorithm for multi-
detector types)
T. Otto 2019 JINST 14 P01010
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021
(ICRU95)
16
![Page 17: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/17.jpg)
ICRU 95 – Consequences for Neutron Monitors
J S Eakins et al 2018 J. Radiol. Prot. 38 688
Black lines: IEC 61005 Ed. 3.0 b:2014
recommended response interval
Re-assessment of IEC acceptance
regions required
As previously, standard Rem-counter
response in mono-energetic fields within a
large factor
No significant change for use at Ekin < 20 MeV
Field calibration may be necessary
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 17
![Page 18: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/18.jpg)
ICRU 95 – Conclusion
• New operational quantities are defined in a consistent manner to the protection quantities
• Numerical values and their trends with energy are coherent with protection quantities
• System of quantities is easier to understand
• Adaptation of certain dosimeter types required: • Personal dosimeters for g and b radiation at low
energy
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 18
![Page 19: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/19.jpg)
Thank you for your Attention
![Page 20: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/20.jpg)
Spare slides
![Page 21: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/21.jpg)
Response of dosimeters
• Response: 𝑅 =𝐺
𝐶
• Dose Indication G /Conventional true value C
• Change of quantity: Cold →Cnew
• Dose indication remains the same: G →G
• Response of dosimeter in the new quantity:
𝑅new =𝐺
𝐶old
𝐶old𝐶new
= 𝑅𝑜𝑙𝑑𝐶old𝐶new
= 𝑅𝑜𝑙𝑑ℎoldℎnew
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 21
![Page 22: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/22.jpg)
Response of Survey instrument
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021
Recalibration at
reference point
22
![Page 23: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/23.jpg)
Response of Ionisation chamber
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 23
![Page 24: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/24.jpg)
Response of personal dosimeter 1
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 24
![Page 25: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/25.jpg)
Response of personal dosimeter 2
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 25
![Page 26: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/26.jpg)
Personal dose to local skin
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021
← Region of practical interest →
Due to similar phantom Hp(0.07) and Dlocal skin are numerically similar.
26
![Page 27: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/27.jpg)
Response of “skin” dosimeters
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021
• Similar calculation
phantoms for the
conversion coefficients to
Dlocal skin and Hp(0.07)
• Existing dosimeter
elements for Hp(0.07) will
give very good reading of
Dlocal skin
27
![Page 28: ICRU Report 95 - nucleus-new.iaea.org](https://reader030.vdocuments.site/reader030/viewer/2022012809/61bf79c8955a0c4d6159b5cd/html5/thumbnails/28.jpg)
Dosimeter Response - Findings• Survey monitors can be re-calibrated in ambient
dose H* without loss of measuring capability• Reason: sensitivity cutoff at Ep < 50 keV
• Survey meters for low energy photons must be investigated separately
• Personal dosimeters show overresponse to personal dose Hp at low photon energies• Reason: Hp(10) > E ≈ Hp
• Possible solutions:• Multi-detector dosimeters: change of algorithm
• Single detector dosimeters: reconstruct holder
• For more details: arxiv:1809.08680v2 [physics.ins-det]
Th. Otto - ICRU Report 95 - IAEA ORPAS - 17. 9. 2021 28