A survey of radiation dose and compressed breast thickness was conducted in samples of women undergoing mammography in the United Kingdom National Health Service breast screening programme. The aims were to determine the average value and distribution of dose and thickness, and to identify technical difficulties in carrying out such a survey. Values of breast thickness and mean glandular dose, calculated from exposure factors and measured X-ray beam parameters, were collected for 4633 women in 92 screening units in 1994 and 1995. The median (lower quartile, upper quartile) dose per film was 1.7 (1.2, 2.4) mGy for the mediolateral oblique view (mean thickness 57 mm) and 1.4 (1.1, 2.0) mGy for the craniocaudal view (mean thickness 52 mm). The median dose per woman was 1.8 (1.3, 2.5) mGy for a one-view examination and 3.3 (2.3, 4.6) mGy for a two-view examination. The dose per film showed an exponential relationship to breast thickness, but no relationship was found between median dose and median breast thickness in the different screening units, possibly because of errors in breast thickness measurement. The values of breast thickness and dose were generally consistent with those in other published surveys, allowing for differences in radiographic technique. No relationship between breast dose and standard optical density was demonstrated. Some recommendations for the conduct of future surveys of breast dose in the UK are proposed.

SUMMARY Fibreoptic endoscopes exposed to x-radiation showed increased optical density of the fibre bundles with a reduction in light transmission. The length irradiated was important as well as the total dose, and there was a linear relationship between the dose/length product (Rm) and the loss of light transmission. The minimum light transmission acceptable for performing ERCP was found to be 57 % of that through an unused fibre bundle, and this degree of damage occurred after a total dose of 33.9 Rm. The radiation dose to the duodenoscope during ERCP examinations was measured. The endoscope sheath was shown to have screening properties, with a transmission factor of about 30% for the Olympus JFB-1 and about 11 00 for the JFB-2 and JFB-3 instruments. The actual dose received by the fibre bundle of an Olympus JFB-2 duodenoscope was 0-084 R per ERCP and the mean dose-length product to the fibre bundle was calculated as 0.028 Rm per ERCP. Some degree of recovery of light transmission occurred while a duodenoscope was 'resting'. The expected life of a duodenoscope was estimated to be about 1200 examinations, but might be much less than this in units where greater radiation doses and longer exposures were used, and the endoscope was in constant use. Ways of minimising the radiation exposure during ERCP and prolonging the useful life of the duodenoscope are outlined.Fibreoptic endoscopes are being used increasingly for diagnostic and therapeutic procedures which involve exposure of the instrument to irradiation. Endoscopic retrograde cholangiopancreatography (ERCP) requires x-ray screening and exposure of static x-ray films, and therapeutic procedures such as papillotomy, retrieval of retained stones, dilatation of oesophageal strictures, and placing of indwelling tubes for inoperable carcinoma of the oesophagus are all associated with the use of x-rays. Exposure of an endoscope to x-irradiation shortens the life of the fibreoptic bundles, and this is of economic importance because replacing a damaged fibrebundle is an expensive repair. Two aspects of this problem have been investigated, the effect of radiation on a fibreoptic bundle, and the radiation dose received by the fibre bundle within the endoscope during ERCP. The investigations were carried out using Olympus JFB duodenoscopes and components.

X-ray machines used for mammography have, until recently, almost exclusively employed molybdenum (Mo) as anode material and filtration. In the UK, the RMI model 232 kVp meter is used extensively for the measurement of kilovoltage on such equipment. This unit is provided with switchable internal calibration only for molybdenum and molybdenum, or tungsten and aluminium, as anode and filtration, respectively. However, rhodium (Rh) has recently been introduced for filtration with either a molybdenum or rhodium anode in mammography equipment but, as yet, calibration facilities are not available for rhodium spectra. In this work, appropriate corrections for readings obtained with the RMI 232 kVp meter are derived for use with rhodium as filtration material with either molybdenum or rhodium anode material. An intercomparison between measurements made with four RMI model 232 kVp meters and nine IGE DMR X-ray sets was undertaken. The reproducibility of the instruments was confirmed and measurements of tube potential made on each of the X-ray sets pooled. Measurements were made from a nominal 25-35 kVp using Mo/Mo, Mo/Rh and Rh/Rh target/filter combinations. Corrections for readings obtained with Mo/Rh and Rh/Rh were produced by comparison with readings obtained with Mo/Mo, assuming stability of tube potential between anodes. The results are compared with data recently produced by the manufacturer of the meter.

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Quality control techniques are increasingly being applied in general radiography and particularly in mammography. A densitometer is an important basic tool for quality control measurements, and may be used for checking film processor performance (in conjunction with a sensitometer) and for measuring optical densities at test points on a radiograph of an image quality phantom (BIR, 1988; IPSM, 1989). Incorrect calibration or drift of such an instrument could give a misleading impression of the performance of the imaging system when performing comparisons with colleagues. The purpose of the present work was to establish whether differences between instruments are likely to be a significant source of error. In a quality control programme, all measuring equipment should be calibrated at a frequency that may be advised by the manufacturer; in the absence of such advice, this would typically be on an annual basis. The densitometers discussed here were not calibrated especially for the study, except where this was a part of the routine method of use. A test strip was produced, having a range of optical densities, for circulation to the authors. The strip was produced by exposing a Kodak MinRE mammography film to a nine-step optical sensitometer (“QA Sensi-Densitometer” Model SDM, MIC Medical Ltd). This resulted in nine areas of the film, each roughly 1 cm square, with various densities in the range approximately 0.2–3.3.