Funding - Nucleus Documents/Radiation... · Funding. Monitoring the eye lens Dr. Rolf Behrens Physikalisch-Technische Bundesanstalt IAEA Oct. 2012 2 ... •April 2011: Limit of H

Physikalisch-Technische Bundesanstalt

TS7e.3

Monitoring the eye lens

Rolf Behrens

Funding


Dr. Rolf Behrens Physikalisch-Technische Bundesanstalt

IAEA

Oct. 2012

2

• Main question:

Which quantity / kind of dosemeter is suitable?

Hp(0.07), Hp(3) or Hp(10)?

• Method:

Compare indication of ideal dosemeters and Hlens,

i.e. compare conversion coefficients for Hp(d) and Hlens Only valid for dosemeters worn near the eye and

below eye protection equipment when used!

Introduction

• April 2011:

Limit of Hlens: 150 mSv 20 mSv per year

Protecting and monitoring may be necessary!

Hp(3) should work well, BUT:

not used in the past,

only few dosemeters available.



IAEA

Oct. 2012

3

Data base

Radiation Quantity Data source

Electrons

Hp(0.07)slab

Hp(3)slab

Hp(10)slab

Hp(3)cyl

ICRP74 + ICRU57

Ferarri and Gualdrini

Photons

Hp(0.07)slab

Hp(10)slab

Hp(0.07)rod

Hp(3)slab

Hp(3)cyl

ICRP74 + ICRU57

Grosswendt

Till et al.

Vanhavere et al.

)(lens Eh

Quantity Data source

Hlens

ICRP116 (Rev. ICRP74);

Behrens

Hlens

ICRP116 (Rev. ICRP74);

Behrens and Dietze

}

}

? > Organ dose to the lens

(Equivalent dose)

Operational quantity

(Dose equivalent)

? =

ORAMED ICRU / ISO

);(p Edh



IAEA

Oct. 2012

4

Data base

Biology Simulation

Organ dose to the lens

Complete lens: ICRP state of art



IAEA

Oct. 2012

5

Data base

Biology Simulation

R. Behrens et al. in Phys. Med. Biol. (PMB):

PMB 54 (2009) 4069 + PMB 55 (2010) 3937,

PMB 56 (2011) 415 and PMB 57 (2012) submitted


Sensitive cells: In ICRP discussion



IAEA

Oct. 2012

6

10 100 10000.6

0.8

1.0

1.2

1.4

10

60

Hp(3)

cyl/H

lens

Hp(0.07)

rod/H

lens

Hp(0.07)

slab/H

lens

Hp(3)

slab/H

lens

Hp(10)

slab/H

lens

keV

= 0°

Eph

Hp(d

) / H

len

s

Photon radiation: Hp(d) / Hlens (based on complete lens)

Conservative

------------------------

Not conservative

ICRP state of art

rod slab cyl

ORAMED ICRU / ISO

Lack of backscatter

Too much absorption

Only valid for dosemeters worn near the eye and below eye protection equipment when used!



IAEA

Oct. 2012

7

10 100 10000.6

0.8

1.0

1.2

1.4

10

60

Hp(d

) / H

len

s

Hp(3)

cyl/H

lens

Hp(0.07)

rod/H

lens

Hp(0.07)

slab/H

lens

Hp(3)

slab/H

lens

Hp(10)

slab/H

lens

keV

= 75°

Eph


Conservative

------------------------

Not conservative

ICRP state of art

rod slab cyl

ORAMED ICRU / ISO

Lack of backscatter

Too much absorption




IAEA

Oct. 2012

8

10 100 10000.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

10

60

Hp(d

) / H

len

s

Hp(0.07)

rod/H

lens

Hp(10)

slab/H

lens

Hp(3)

cyl/H

lens

Hp(0.07)

slab/H

lens

Hp(3)

slab/H

lens

keV

= 90°

Eph


Conservative

------------------------

Not conservative

ICRP state of art

rod slab cyl

ORAMED ICRU / ISO

Only cyl.-ph. suited

Absorption in edge

of slab phantom




IAEA

Oct. 2012

9

0.6 1 100.0

0.4

0.8

1.2

1.6

2.0

10

100

Hp(d

) / H

len

s

Hp(3)

cyl/H

lens

Hp(0.07)

slab/H

lens

Hp(3)

slab/H

lens

Hp(10)

slab/H

lens

MeV

= 0°

Eel

Electron radiation: Hp(d) / Hlens (based on complete lens)

Conservative

------------------------

Not conservative

ICRP state of art

Lack of dose build-up

Too much absorption




IAEA

Oct. 2012

10


Conservative

------------------------

Not conservative

ICRP state of art

0.6 1 100.0

0.4

0.8

1.2

1.6

2.0

10

100

Hp(d

) / H

len

s

Hp(3)

cyl/H

lens

Hp(0.07)

slab/H

lens

Hp(3)

slab/H

lens

Hp(10)

slab/H

lens

MeV

= 60°

Eel

Too much absorption




IAEA

Oct. 2012

11

0.6 1 100.0

0.4

0.8

1.2

1.6

2.0

10

100

Hp(d

) / H

len

s

Hp(3)

cyl/H

lens

Hp(0.07)

slab/H

lens

Hp(3)

slab/H

lens

Hp(10)

slab/H

lens

MeV

= 75°

Eel

ICRP state of art


Conservative

------------------------

Not conservative

Too much absorption

Too much absorption




IAEA

Oct. 2012

12

0.6 1 100.0

0.4

0.8

1.2

1.6

2.0

10

100

Hp(d

) / H

len

s,s

Hp(3)

cyl/H

lens,s

Hp(0.07)

slab/H

lens,s

Hp(3)

slab/H

lens,s

Hp(10)

slab/H

lens,s

MeV

= 0°

Eel

In ICRP discussion

Electron radiation: Hp(d) / Hlens,s (based on sensitive cells)

Conservative

------------------------

Not conservative

Lack of dose build-up

Too much absorption




IAEA

Oct. 2012

13

In ICRP discussion

Electron radiation: Hp(d) / Hlens,s (based on sensitive cells)

Conservative

------------------------

Not conservative

0.6 1 100.0

0.4

0.8

1.2

1.6

2.0

10

100

Hp(d

) / H

len

s,s

Hp(3)

cyl/H

lens,s

Hp(0.07)

slab/H

lens,s

Hp(3)

slab/H

lens,s

Hp(10)

slab/H

lens,s

MeV

= 60°

Eel

Too much absorption

Too much absorption




IAEA

Oct. 2012

14

0.6 1 100.0

0.4

0.8

1.2

1.6

2.0

10

100

Hp(d

) / H

len

s,s

Hp(3)

cyl/H

lens,s

Hp(0.07)

slab/H

lens,s

Hp(3)

slab/H

lens,s

Hp(10)

slab/H

lens,s

MeV

= 75°

Eel

In ICRP discussion

Electron radiation: Hp(d) / Hlens,s (based on sensitive part)

Conservative

------------------------

Not conservative

Too much absorption

Too much absorption




IAEA

Oct. 2012

15

ORAMED ICRU / ISO

Conclusions

Radiation Quantity Good to estimate Hlens? Good to estimate Hlens,s?

Photons

Hp(0.07)rod

Hp(10)slab

Hp(0.07)slab

Hp(3)slab

Hp(3)cyl

Underestimating

Underest. up to 40 keV

Up to 75° appropriate


As for Hlens

Electrons

Hp(0.07)slab

Hp(3)slab

Hp(3)cyl

Hp(10)slab

Extrem. overestimating


Underestimating

Extremely overestimating

Underestimating,

Hp(d<3) necessary?

Underestimating

? >


(Equivalent dose)

Operational quantity

(Dose equivalent)

}

? =

– equal for realistic radiation fields

ICRP state of art: Complete lens:

Hlens

In ICRP discussion: Sensitive cells :

Hlens,s

}



IAEA

Oct. 2012

16

Radiation field Hp(0.07)rod /

Hlens

Hp(0.07)slab /

Hlens

Hp(3)slab /

Hlens

Hp(10)slab /

Hlens

Photons < 30 keV 0.9 – 5 1.1 – 5 0.6 – 1 0.01 – 0.9

Photons > 30 keV 0.8 – 0.9 ≈ 1.1 1 – 1.2 0.9 – 1.2

Electrons < 0.6 MeV

and photons

1 – 100 1 – 100 ≈ 1 see above

Electrons < 0.6 MeV

and photon

1 – 500 1 – 500 ≈ 1 2x10-4

– 1

Hp(10) for e- &

Eph ≤ 40 keV

NOT adequate!

Hp(0.07)slab is ONLY

adequate for

photon radiation.

Hp(3) is

NECESSARY for

beta radiation.

Hp(0.07)rod, i.e. ring dosemeters worn near the eye, suitable for photons?

Same conclusions for realistic radiation fields

R. Behrens and G. Dietze:

Phys. Med. Biol. 55 (2010) 4047-4062 and

Phys. Med. Biol. 56 (2011) 511



IAEA

Oct. 2012

17

Extremity dosemeters suitable for the eye lens?

Are extremity dosemeters (for Hp(0.07)) appropriate?

Is a calibration on a rod phantom (as usual) appropriate?

Rod phantom Slab phantom

R. Behrens et al.:

Rad. Prot. Dosim. 148 (2012) 139-142



IAEA

Oct. 2012

18


R. Behrens et al.:

Rad. Prot. Dosim. 148 (2012) 139-142



IAEA

Oct. 2012

19

R. Behrens et al.:

Rad. Prot. Dosim. 148 (2012) 139-142

10 100 1000 20000.85

0.90

0.95

1.00

1.05

1.10

1.15

Rro

d /

Rsl

ab

Energy / keV

MPA-TKD-01 LPS-TLD-TK 03 LPS-TLD-TK 07

LPS-TLD-TK 08 GSF-TL-TD-60 GSF-TL-TD-70

BE-TLD-TD-PHOTONEN 01 BE-TLD-TD-Brille

Extremity dosemeters (for Hp(0.07)) estimate

the lens dose in pure photon radiation fields!




IAEA

Oct. 2012

20

Photon ring dosemeters for Hp(0.07) are available as eye lens dosemeters in Germany:

MPA-TKD-01

with headband

LPS TLD-TK 07

GSF-TL-TD-60

also with

headband

BE-TLD-TD-Brille



IAEA

Oct. 2012

21

Practice: Choice of dosemeters Whole body dosemeters measure Hp(10):

- must be worn on the trunk (far from the eyes);

- underestimate at Eph<40 keV (too thick cover)

- under the lead apron if in use;

danger for the eyes!

Extremity dosemeters measure Hp(0.07):

- must be worn “facing” the beam / source;

- can be worn near the eye, then it

- correctly estimate the lens dose in photon fields but

- overestimates the lens dose in beta fields (too thin cover)

work may be changed although not necessary!

Eye dosemeters measure Hp(3):

- must be worn “facing” the beam / source;

- must be worn near the eye;

- is the only type of dosemeter that correctly esti-

mate Hlens (not Hlens,s) in beta and photon fields! Only valid for dosemeters worn near the eye and below eye protection equipment when used!


Funding

TS7e.3


Rolf Behrens


Some additional material…

for IAEA meeting: October 2-4, 2012

Rolf Behrens



IAEA

Oct. 2012

24

IEC standard (draft) on Protective Eyewear: (only for IAEA purposes on the basis of the liaison of IAEA and IEC TC62 / SC62B)



IAEA

Oct. 2012

25

Irradiations and type tests in Hp(3) • Conversion coefficients for Ka Hp(3)slab:

Rad. Prot. Dosim. 147, 373 (2011)

• Conversion coefficients for Ka Hp(3)cyl: Rad. Prot. Dosim. doi:10.1093/rpd/ncs032 (2012)

Photon spectra:

Beta radiation: • Extension to the Beta Secondary Standard BSS 2:

Incl. conversion factors for Hp(0.07) Hp(3): J. Instrum. 6, P11007 (2011)

• Available for old instruments via SW update

Details: Poster P02.247

ICE 62387: • Passive dosimetry systems (Final draft FIDS 2012)

Hp(3) implemented for both photons and betas



IAEA

Oct. 2012

26

Early draft of ISO standard on lens, skin, extr. dosimetry:

May be significantly changed in future versions! (only for IAEA purposes on the basis of the liaison of IAEA and ISO TC85 / SC2)

From the contents:

From draft ISO 15382

Current target date: 2015



IAEA

Oct. 2012

27



From the contents:

No conversion coefficients from

Ka to H (́3) available!




IAEA

Oct. 2012

28



From the contents: From draft ISO 15382



IAEA

Oct. 2012

29



From the contents: From draft ISO 15382



IAEA

Oct. 2012

30



From the contents:

- for photons and betas

- for Hp(0.07), Hp(3) and

Hp(10) - for photons and betas

- for Hp(0.07) and Hp(10)

but NOT yet for Hp(3)




IAEA

Oct. 2012

31

Literature • Monitoring the eye lens: Which dose quantity is adequate?

Phys. Med. Biol. 55, 4047 (2010) and Phys. Med. Biol. 56, 511 (2011)

• Conversion coefficients for mono-energetic electrons: Heye:

Phys. Med. Biol. 54, 4069 (2009) and Phys. Med. Biol. 55, 3937 (2010)

and J. Rad. Prot., to be published (including a whole body phantom)

• Conversion coefficients for mono-energetic photons: Heye:

Phys. Med. Biol. 56, 415 (2011) (including a whole body phantom)

• Conversion coefficients for photon spectra: Ka Hp(3)slab:

Rad. Prot. Dosim. 147, 373 (2011)

• Conversion coefficients for photon spectra: Ka Hp(3)cyl:

Rad. Prot. Dosim. doi:10.1093/rpd/ncs032 (2012)

• Hp(0.07) photon dosemeters: Calibration on a rod vs. a slab phantom:

Rad. Prot. Dosim. 148 (2012) 139-142

• Extensions to the Beta Secondary Standard BSS 2:

J. Instrum. 6, P11007 (2011) and Erratum and Addendum


Rolf Behrens