Additionally, the international transportation of isotopes involves radiation protection issues that complicate the process ( 5 5. However, recently, it has become increasingly difficult to purchase such irradiators because their manufacturing was interrupted. The most common irradiators used are the gamma-ray irradiators that employ radioactive isotopes such as cobalt-60 or cesium-137. Delineating set-up protocols with the equipment (linear accelerators) used clinically for patient treatments is a slow process, and using these irradiators for cells and small animal experiments in the preliminary stages of research would save time. PedersenKH, KunugiKA, HammerCG, CulbersonWS, DeWerdLA.

Dosimetric characterization of an image-guided stereotactic small animal irradiator.Phys Med Biol2011 56: 2585., 4 4. PidikitiR, StojadinovicS, SpeiserM, SongKH, HagerF, SahaD, et al. There are specific small animal irradiators designed especially for preclinical studies, used to evaluate and optimize new treatment modalities ( 3 3. They assist with the understanding of ionizing radiation interactions with tissues and cells, which is crucial for translational research of new effective radiotherapy techniques.

SU-GG-T-150: Commissioning and validation of a novel measurement based IMRT QA method, incorporating dose recalculation on patient CT data.Med Phys2008 35: 2760, doi: 10.1118/1.2961901. McCurdyB, MuellerL, BackmanE, VenkataramanS, FlemingE, AsuniG, et al. Pre-clinical research in small animals using radiotherapy technology - a bidirectional translational approach.Z FГјr Med Phys2014 24: 335вЂ“351, doi: 10.1016/j.zemedi.2014.07.004. TillnerF, ThuteP, BГјtofR, KrauseM, EnghardtW. Studies using small animals and cell experiments have become indispensable for cancer research before clinical implementation of a new therapy ( 1 1. X-ray irradiator Dosimetric characterization Radiotherapy Dosimetry Radiochromic film The irradiator characterization enables us to perform radiobiological experiments, and assists or even replaces traditional therapy equipment (e.g., linear accelerators) for cells and small animal irradiation, especially in early research stages. There was no observed mechanical failure during evaluation of the irradiator safety devices and the radiometric survey obtained a maximum ambient equivalent dose rate of 0.26 mSv/h, which exempts it from the radiological protection requirements of the International Atomic Energy Agency. The dose rate dependence with tube voltage and current presented a quadratic and linear relationship, respectively. The mean dose rate inside the cell plates was 0.92вђ.19 Gy/min. The mean dose rate inside the animal cages was 1.27вђ.06 Gy/min with a uniform beam of 95.40% (above the minimum threshold guaranteed by the manufacturer). Tests showed that the dose rate was linear overtime (R 2=1) and remained stable for long (constant) and short (repeatability) intervals between readings. The irradiator default setting was established as 160 kV and 25 mA. In addition, we evaluated the performance of the X-ray tube (voltage and tube operating current), the radiometric survey (leakage radiation) and safety devices. We evaluated the linearity, consistency, repeatability, and dose distribution in the positions in which the animals or cells are placed during irradiation. This study presents the characterization of an X-ray irradiator through dosimetric tests, which confirms the actual dose rate that small animals and cells will be exposed to during radiobiological experiments.

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