Transfusion of blood and blood components in patients with immunosuppression
and malignant diseases is life-saving; however, it
can result in some serious fatal side effects such as graft-versus-host
disease (GVHD). T-lymphocytes of the donor proliferate and damage
the recipient's target organs, especially the bone marrow, skin,
liver and the gastrointestinal system. In an effort to eliminate this
problem, blood and cellular blood components are exposed to ionizing
gamma radiation prior to transfusion. Irradiation of the blood
and its components with gamma radiation and X-rays in established
practices for the prevention of transfusion-associated (TA)-GVHD
is the only acceptable method. This process renders T-lymphocytes
incapable of proliferating due to the level of irradiation-induced
damage in the DNA. Most blood centers rely on a nominal dose of
25-30 Gy with no less than 15 Gy delivered to any area of the bag
to inactivate lymphocytes in cellular products for transfusion. Accordingly
to our survey, there are 24 Cesium-137 blood irradiators
throughout Turkey in University Medical Faculties, Health Ministry
Hospitals and Our Leukemia Children's Foundation for irradiation
of chemical material and only 1 unit for medical sterilization.
There are two types of blood irradiators in Turkey: a) CIS BIO
International France, IBL 437C type units and b) MSD Nordion
Canada Gammacell-3000 units. These two types are monitored by
an electronic controller and they cannot be activated without the
canister being in the irradiation chamber and fully self-protected
irradiation units. Radiation levels on the surface of the IBL 437C
are below 25 μSv/h (2.5 mR/h), in compliance with relevant international
regulations. All blood irradiators are radiation-emitting devices.
For these reasons, all physical and dosimetric measurements,
dose calculations, quality assurance, and control procedures must
be performed by Qualified Medical Radiation physicists in Turkey.
There are 24 irradiators licensed by TAEK (Turkey Atomic Energy
Authority) and 24 specialists, medical radiation oncology physicists
and radiation physicists; quality control should be done regularly.
Keywords: Dose measurements; blood irradiators; clinical indications; transfusion associated graft-versus-host disease
