[ RadSafe ] Blood Irradiation

[NIXON, Grant]

Dear Dr. Faermann:

I've been involved with the dosimetry of blood irradiation for over 7
years now, my company for over 30 years. There are many recommendations
out there. Most people that irradiate blood use dedicated blood
irradiators (e.g. self-contained irradiators using Cs-137 or X-rays like
the Gammacell 3000 or the Raycell, respectively). With dedicated units,
geometry issues are less of a problem because the mating of the
dedicated canister with the turntable. Also, water/blood-equivalent
phantoms are used which completely fill the canister during dose mapping
studies. Such a geometry is well-suited to validate a given process as
far as establishing the minimum dose rate during irradiation. One tries
to restrict the irradiation volume in order to ensure that the maximum
dose is not exceeded for partially-filled canister geometries.

Appropriate dosimeters of high metrological quality are, e.g., Fricke
and alanine. These can be used for dose mapping studies.
Electrometers/ion chambers can also be used. TLD's can be used but are
far less accurate (+/- 10%).

There are also dose indicators on the market (e.g., RadTAG that are
typically used for QA purposes (although  not as dosimeters) once a
process has been validated. They visibly change colour at specified
doses (e.g., 15 Gy and 50 Gy). These can be placed inside each blood
bag.

Feel free to contact me for further discussion.

Best regards,

Grant

Grant I. Nixon, Ph. D., P. Phys.
Radiation Physicist
Engineering
MDS Nordion
Tel: (613) 592 3400 ext. 2869
Fax:( 613) 592 7423


-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
Behalf Of Dr. Sergio Faermann
Sent: Sunday, March 05, 2006 5:18 AM
To: radsafe at radlab.nl
Subject: [ RadSafe ] Blood Irradiation

In our medical center blood irradiation ( to avoid Host VersusG raft
Disease) is performed with our medical linacs, according to the geometry
and MU's calculated by the physicists( we irradiate with 2500cgy)
 
I would like to know if there are specific recommendations for QA of
irrediated blood: I mean frequent checks of the right geometry of
irradiation performed by the technicians, check of the real dose
received by the blood , etc. 
 
Are the physicists responsible for blood irradiation as part of their
duties? What detector for high doses is recommended?
 
Thanking you in advance
 
Sergio Faermann,Ph.D.
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