High dose rate dosimetry

There are uncertainties in the dosimetry we have used at the high dose rates, but as stated they are believed to be less 5%. Further the ratio of cyclohertene to bicyclohexyl does not depend on dosimetry. Another aspect of the comparison between low and high dose rates is the invariance of yields at the high dose rates up to 5 Mrads. 

A review is given on the experiences with the oxalic acid dosimeter. The system was first suggested by Draganic, who has carried out extensive investigations on the dosimetric properties. Further experiments have been carried out at various laboratories—e.g., in the United States, Japan, and Denmark. Although the system suffers from some systematic weaknesses, it can be applied successfully, when properly calibrated under the conditions where it is to be used. The present report describes its application for 60Co and high dose-rate electron dosimetry. 

The basic advantage of applying fluorimetry for dosimetry purposes is the high sensitivity of the method as compared to, e.g., spectrophotometry. Other advantages are the wide dynamic range, use for both passive and real-time dosimetry and for both low-and high-dose rates, variable geometries of the dosimeters (pellets, films, optical fibers, etc.), and inexpensive multiuse radiation detectors. 

To overcome these technical limitations of lORT we developed a technique for high-dose-rate (HDR) irradiation of liver metastases using an afterloading method with a iridium source sited using CT-guided percutaneous applicator placement with dosimetry using three-dimensional CT data sets. 

The dosimetry is usually made in 0.01 mol dm air- or oxygen-saturated solution. Since the (SCN)2 ions disappear in a fairly slow bimolecular reaction with a rate coefficient of 3 x 10 moH dm s, this system is applicable for measuring high-dose pulses. The dose can be calculated from the increase of absorbance at 475 nm, AA, using Gs = 2.6 X 10 m J (Buxton and Stuart 1995)... 

Glutamine has been found suitable for LL dosimetry. The glutamine system has been developed for high-dose dosimetry as routine dosimeter in radiation processing (Puite and Ettinger 1982 Temperton et al. 1984). The irradiation temperature coefficient for this dosimeter is about +0.35% (°C) in the temperature range of 10-40°C. Miller and Xie (1985) found no dose-rate dependence up to about 10 Gy s. ... 

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