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In 2013, a nationwide investigation was conducted in Switzerland to establish the population's exposure from medical X rays. A hybrid approach was used combining the Raddose database accessible on-line by the participating practices and the Swiss medical tariffication system for hospitals. This study revealed that the average annual number of examinations is 1.2 per inhabitant, and the associated annual effective dose is 1.4 mSv. It also showed that computed tomography is the most irradiating modality and that it delivers 70 % of the total dose. The annual effective dose per inhabitant registered a 17 % increase in 5 y and is comparable with what was recently reported in neighbouring countries.

Diagnostic reference levels (DRLs) were established for 21 indication-based CT examinations for adults in Switzerland. One hundred and seventy-nine of 225 computed tomography (CT) scanners operated in hospitals and private radiology institutes were audited on-site and patient doses were collected. For each CT scanner, a correction factor was calculated expressing the deviation of the measured weighted computed tomography dose index (CTDI) to the nominal weighted CTDI as displayed on the workstation. Patient doses were corrected by this factor providing a realistic basis for establishing national DRLs. Results showed large variations in doses between different radiology departments in Switzerland, especially for examinations of the petrous bone, pelvis, lower limbs and heart. This indicates that the concept of DRLs has not yet been correctly applied for CT examinations in clinical routine. A close collaboration of all stakeholders is mandatory to assure an effective radiation protection of patients. On-site audits will be intensified to further establish the concept of DRLs in Switzerland.

[Abstract] A patient-oriented survey was conducted in Switzerland with the aim to establishing the distribution of medical X-ray examinations among the population. A sample of 1235 people aged between 15 and 74 y (589 males and 637 females) was contacted. The participants were asked to give the number of medical X-ray examinations performed during the previous 12 months. Three-fourths of the sample did not undergo any medical X-ray examination during a 12 month-period, and 10% of the population underwent more than 1 medical X-ray examination in a year. These results were independent of the geographic region. The age distributions of the participants who did not undergo any medical X-ray examination and those who underwent one medical X-ray examination were similar. On the other hand, the age distribution of the participants who underwent more than one medical X-ray examination was characterised by a higher contribution from the elderly. [authors]

The response functions of four widely used Bonner sphere spectrometers (BSS) with an Lil scintillator and different 3 He detectors were calculated by means of the three-dimensional Monte Carlo neutron transport code, MCNP, taking into consideration a detailed description of the detector set-up; they were then compared with experimental calibration data. The calculated response functions reproduce the calibration data in shape. A common adjustment factor is only needed to take into account the neutron detection efficiency of the central detector. An interpolation method proposed to correct the BSS response functions to another polyethylene density was verified.

Several experiments at CERN using high energy, high intensity beams of lead ions search for evidence of a quark-gluon plasma. The ions pass through an accelerating chain which supplies an energy up to 160 GeV per nucleon, 35 TeV in total. When these lead ions collide with targets or are lost due to unintentional imperfections in the transfer lines they interact with materials and produce stray radiation fields. The spectrometric and microdosimetric results are presented of the first measurements in such stray fields made at CERN, on top of a concrete shielding surrounding a lead ion beam which collided with a lead target. They are compared with the results obtained with a high energy proton beam operated in a similar configuration.

A modification of the Bonner spheres neutron spectrometer is proposed in order to improve its energy resolution at low and intermediate energies. The small diameter polyethylene spheres are surrounded by layers of neutron absorbers with suitable composition and thickness. The system design is based on response function calculations with the neutron transport code ANISN. Several absorbers were investigated and, eventually, boron with natural isotopic composition has been retained. The optimal set of detectors consists of the 2 and 3 spheres surrounded by boron layers of 0.0628, 0.837 and 2.76 g.cm -2 . Narrower response functions have been obtained with one maximum per decade in the energy range 1 eV-100 keV. An experimental calibration has been performed with neutron beams of 0.186, 2, 24 and 144 keV. The computed response functions have been adjusted to the calibration points. Simulations with numeric neutron spectra confirmed the improved energy resolution of the new system.

Measurements have been made with different active dosimetric systems in four Swiss nuclear power plants (2 BWR and 2 PWR) to characterise the mixed n-γ fields. They were performed in 22 positions covering a wide variety of situations inside the containments, in a fuel storage facility and around spent fuel transport flasks. The spectrometric and dosimetric results are presented, discussed and compared. A classification of the neutron spectra in four categories according to their hardness is proposed. The spectra inside the containments are rather soft; they are much harder in the fuel storage facilities and around spent fuel transport flasks. Neutron dose equivalent rates in free access areas are low compared to those due to gammas, whereas in some limited access areas the neutron contribution to the dose equivalent may be appreciable

ICRP considers that a dose limit of 2 mSv close to the body surface of a pregnant woman will ensure a dose limit of 1 mSv to the foetus. This assumption depends on the energy spectrum and composition of the radiation fields, especially those containing high energy particles such as are found around particle accelerators or in aircraft. In this work the response of a tissue-equivalent proportional counter in radiation fields of different composition and energy was measured as a function of depth in cylindrical phantoms. The decrease in dose and dose equivalent at a phantom depth equivalent to that of a foetus was 10% in a typical high energy stray radiation field and 30% for neutrons from a Pu-Be source. It is concluded that it would be prudent in these cases to limit the exposure of a pregnant woman to I mSv in order to ensure that the dose to the foetus stays below the same limit.

A number of parameters use to quantify the neutron spectrum hardness are evaluate for 43 different neutron spectra encountered in radiation protection, in nuclear power plants and around neutron sources. They include different integral quantities derived from the fluence neutron spectrum established by multisphere spectrometry, as well as other spectrum hardness quantifiers directly given by some measuring devices such as the 9″ to 3″ ratio or the neutron quality factor displayed by the Dineutron type monitor. The range of the various quantities in different spectrum categories is discussed and mean values for each category are given