For stable-xenon computed tomography (CT), an X-ray examination for measurement of cerebral blood circulation in the brain, the radiation exposure of the patient was determined in order to estimate the risk of inducing cancer. Organ doses of brain, eyelenses, thyroid and gonads have been calculated using the measured air kerma free-in-air on the axis of rotation and organ-specific conversion factors calculated with the Monte Carlo method. Dose measurements with TLD-100 rods using a humanoid Alderson phantom were carried out for verification of the calculated organ doses. In the case of brain partially located in the region of primary radiation a mean organ dose of 39 mSv was calculated. The dose measurements showed dose equivalents between 6 and 68 mSv in different regions of the brain and consequently an inhomogeneous dose distribution. From an estimation of the radiation-induced risk using the effective dose of 1.6 mSv it follows that one additional fatal cancer per 12,500 stable-xenon CT examinations has to be expected. The organ doses of eyelenses and thyroid located in the region of scattered radiation are so low that biological effects are hardly to be expected. The calculated dose equivalents of 6.5 mSv and 0.5 mSv, respectively, are in good agreement with measurements. The organ dose of gonads amounted to less than 0.07 mSv.

When using defaecography as a radiological tool for diagnosing the anorectal function in female patients, the ovaries are inevitably directly exposed. With the aim of minimising the ovarian dose applied both the area-dose product and the surface dose above the ovaries were measured during investigations of female patients with a digital C-arm unit. These values were converted into ovarian doses using tissue-air ratios. From the surface dose measured with TLD-100 a mean ovarian dose of 15.6 +/- 8.6 mGy was derived. The contributions of screening and film exposures were similar. A reduction of screening time by 10 seconds or omission of 60 film exposures results in a decrease of ovarian dose by values between 0.7 and 2 mGy. Employing a greater focus-skin distance during defaecography, however, made it possible to reduce the ovarian dose by 26%.

To get a general idea of the actual staffing situation in medical radiation physics, all active members of the German Society of Medical Physics (DGMP) were surveyed by the task force "staff requirements" ("Personalbedarf") of the DGMP in 1999. Of the 322 forms sent out, 173 could be evaluated. The staff requirements in medical radiation physics were calculated from the major elements of the radiology equipment and from the staff responsibilities as defined in the DGMP Reports 8 and 10, and compared with the actual number of staff members. The data of this spot check were then extrapolated for the entire Federal Republic of Germany. The calculation revealed a deficit of 89% for the entire staff in diagnostic radiology and of 84% for physicists. Considering the age distribution of the DGMP members, a training capacity of about 100 medical physicists per year is needed to eliminate the calculated deficit within the next 10 years.

The recently published guide-lines for quality assurance in x-ray diagnostics issued by the German Federal Board of Physicians recommend using speed class 400 SFS. Since in that case an approximately halved radiation dose is necessary, dose reduction is hardly to be expected with DLR.

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