Abstract:
:Ultrasoft x-rays of 0.3-5 keV have provided a unique tool for the investigation of intracellular mechanisms of radiation action in biological organisms, including mammalian cells. However, their use presents unique practical problems in dosimetry and experimental design. Detailed interpretation of the biological results requires reliable dosimetry and well characterised monoenergetic beams. This paper presents a comparison between two fundamentally different dosimetric techniques, namely the ionisation current in an extrapolation chamber and photon counts in a proportional counter. Agreement within 7% was obtained when these two methods were applied to an Al K x-ray beam (1.5 keV) from an MRC cold-cathode transmission target discharge tube as previously used in many biological experiments. Photographic film was calibrated as a relative dosimetric technique and used for investigation of the intensity uniformity of the radiation field. These techniques provide a comprehensive characterisation of the beam in the position of the biological cells, including photon flux (or absorbed dose rate), spectral purity (showing much less than 1% bremsstrahlung relative to characteristic Al x-rays) and uniformity over the irradiation area (within about 5% for mammalian cell irradiations).
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Hoshi M,Goodhead DT,Brenner DJ,Bance DA,Chmielewski JJ,Paciotti MA,Bradbury JNdoi
10.1088/0031-9155/30/10/002subject
Has Abstractpub_date
1985-10-01 00:00:00pages
1029-41issue
10eissn
0031-9155issn
1361-6560journal_volume
30pub_type
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