TURKISH JOURNAL OF ONCOLOGY 2009 , Vol 24 , Num 3
Clinical indications, physical structures, radiation doses and dosimetric measurements of irradiators used in blood and blood components in the prevention of transfusion-associated graft-versus-host disease
Seyfettin KUTER,1 Sezer SAĞLAM2
1Bizim Lösemili Çocuklar Vakfı Kan ve Kan Bileşenleri Işınlama Ünitesi, Tıbbi Radyasyon Fizikçisi, İstanbul
2İstanbul Üniversitesi Onkoloji Enstitüsü, Medikal Onkoloji Bölümü, İstanbul
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