[ RadSafe ] Fw: dose-rates in the design of linear accelerator rooms

[kali1 at zahav.net.il]

----- Original Message ----- 
From: "Yehoshua Kalish" <kali1 at zahav.net.il>
To: <MEDPHYS at LISTS.WAYNE.EDU>
Sent: Tuesday, May 24, 2005 2:51 PM
Subject: dose-rates in the design of linear accelerator rooms


Dear friends,

According to British guidelines, as outlined in "Medical and Dental Guidance 
Notes, a Good Practice Guide on all Aspects of Radiation Protection in 
Clinical Environment, Table 1.2, p. 9, 2002" in the design of a linear 
accelerator room, one is to consider not only the annual integral dose but 
also is limited by Time Averaged Dose Rate (TADR). The value of TADR for 
unsupervised public areas -- estimated over 8 hours, taking in account use 
and workload for the typical worst day case scenario (an occupancy factor of 
one is assumed)  --  is less than 0.5 microsievert per hour (0.05 mrem per 
hour).

I would appreciate answers to two questions:

1.   How do British radsafers explain and justify bothering as to dose-rates 
where negligible doses are involved.

2.   Why the above TADR value is not applied in the design of aeroplanes, 
where the TADR is some 10 times higher (Well, I don't really reccommend the 
use of 10 cm thick lead ceilings in planes; I would rather stop bothering as 
to dose-rates in the design of linear accelerator rooms}.

Yehoshua Kalish
Consultant, Hod-Hasharon, Israel

  ----- Original Message ----- 
  From: ROBBARISH at aol.com
  To: radsafe at list.vanderbilt.edu
  Sent: Friday, February 04, 2005 9:54 AM
  Subject: Solar particle event


  Dear friends at RADSAFE:

  For those who are interested, I have posted on my website a plot of the 
radiation dose rate at altitude during the large solar flare that occurred 
on 20 January. At its peak, the dose rate in a commercial airliner at 40,000 
feet was 100 microsievert (10 mrem) per hour.

  You may see the data at:

  http://robbarish.tripod.com/events/

  I am grateful to Dr. Wallace Friedberg of the FAA for supplying the 
information.

  Robert Barish, Ph.D., CHP
  robbarish at aol.com








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