Re: ICRP60 TISSUE WEIGHTING FACTORS : HOW CALCULATED?

[Quintino De Notariis <qdenotariis@novacon.it>]

John,

thank you for suggesting me to read Roger Clarke's explanation "1990

Recommandations of ICRP". Actually the consideration of "Lethality" and

"Loss of Life" in Table 1 made me realise that something else was to be

considered in determining the tissue risk factors than the probabilities

alone. So I looked over the ICRP 60 and found the table B-20 at page 136,

that solved my problem of understanding the origin of WT values.

Maybe someone could be interested, so I describe the simple procedure.



WT values come from the "Relative contributions" in column 6 of Table B-20.



                Relative

                contribution



Bone surfaces   0,009

skin            0,006



                These values are rounded to WT = 0,01



Bladder         0,040

Breast          0,050

Liver           0,022

Oesophagus      0,034

Thyroid         0,021

Remainders      0,081



                These values are all rounded to WT = 0,05



Colon           0,141

Lung            0,111

Bone marrow     0,143

Stomach         0,139



                These values are all rounded to WT = 0,12



Gonads          0,183



                rounded to WT = 0,20





Quintino











Il giorno 5-08-2002 16:28, John Johnson, idias@interchange.ubc.ca ha

scritto:



> Quintino

> 

> I understand your difficulty. I found that Roger Clarke's explanation "1990

> Recommendations of ICRP" in the Supplement to the Radiological Protection

> Bulletin, No 119, 1991 helped me understand ICRP's recommended risk/tissue

> weightng factors.

> 

> John

> _______________________

> John R Johnson, PhD

> idias@interchange.ubc.ca

> 

> 

> 

> 

> ----- Original Message -----

> From: "Quintino De Notariis" <qdenotariis@novacon.it>

> To: "'RadSafe'" <radsafe@list.vanderbilt.edu>

> Sent: Monday, August 05, 2002 4:39 AM

> Subject: ICRP60 TISSUE WEIGHTING FACTORS : HOW CALCULATED?

> 

> 

>> Recently Italian legislation adopted the criteria and terminology of

> ICRP60.

>> Could someone tell me how Tissue Weighting Factors WT in ICRP60 have been

>> calculated?

>> I mean, these factors in the old ICRP26 can be easily calculated from Risk

>> Factors per Sievert. For exemple, the Risk Factor fr Breast is 2.5E-3 and

>> the Total Risk Factor is 16.5E-3; so WT is :

>> 2.5/16.5 = 0,15

>> The same way you can proceed with Red Bone Marrow, whose Risk Factor per

>> Sievert is 2.0E-3 :

>> 2.0/16.5 = 0,12

>> I can't find a similar procedure for the new WT values in ICRP60.

>> I think we should use the values in Table 4, pag. 24 of the publication,

> but

>> there must be something else to consider that I don't know.

>> Could someone help me?

>> 

>> Quintino De Notariis

>> Health Physicist

>> Corso Vittorio Emanuele 45/E

>> 86039 Termoli

>> 

>> ************************************************************************

>> You are currently subscribed to the Radsafe mailing list. To unsubscribe,

>> send an e-mail to Majordomo@list.vanderbilt.edu  Put the text "unsubscribe

>> radsafe" (no quote marks) in the body of the e-mail, with no subject line.

>> You can view the Radsafe archives at http://www.vanderbilt.edu/radsafe/

>> 

> 



************************************************************************

You are currently subscribed to the Radsafe mailing list. To unsubscribe,

send an e-mail to Majordomo@list.vanderbilt.edu  Put the text "unsubscribe

radsafe" (no quote marks) in the body of the e-mail, with no subject line.

You can view the Radsafe archives at http://www.vanderbilt.edu/radsafe/