Recent epidemiological studies suggest a rather low dose threshold (below 0.5 Gy) for the induction of a cataract of the eye lens. Some other studies even assume that there is no threshold at all. Therefore, protection measures have to be optimized and current dose limits for the eye lens may be reduced in the future. Two questions arise from this situation: first, which dose quantity is related to the risk of developing a cataract, and second, which personal dose equivalent quantity is appropriate for monitoring this dose quantity. While the dose equivalent quantity H(p)(0.07) has often been seen as being sufficiently accurate for monitoring the dose to the lens of the eye, this would be questionable in the case when the dose limits were reduced and, thus, it may be necessary to generally use the dose equivalent quantity H(p)(3) for this purpose. The basis for a decision, however, must be the knowledge of accurate conversion coefficients from fluence to equivalent dose to the lens. This is especially important for low-penetrating radiation, for example, electrons. Formerly published values of conversion coefficients are based on quite simple models of the eye. In this paper, quite a sophisticated model of the eye including the inner structure of the lens was used for the calculations and precise conversion coefficients for electrons with energies between 0.2 MeV and 12 MeV, and for angles of radiation incidence between 0 degrees and 45 degrees are presented. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are up to 1000 times smaller for electron energies below 1 MeV, nearly equal at 1 MeV and above 4 MeV, and by a factor of 1.5 larger at about 1.5 MeV electron energy.

We demonstrate a novel method to monitor the total angular distribution of the spectrum of hard x-ray emission from a plasma generated with femtosecond laser pulses with an intensity of 5 x 10(18) W/cm2 on a solid target. Measured and calculated angular distributions of x rays show a pronounced anisotropy for MeV photon energies. We complemented the spectral information by demonstrating a (gamma,n) nuclear reaction with a tabletop laser system.

In recent years, several papers dealing with the eye lens dose have been published, because epidemiological studies implied that the induction of cataracts occurs even at eye lens doses of less than 500 mGy. Different questions were addressed: Which personal dose equivalent quantity is appropriate for monitoring the dose to the eye lens? Is a new definition of the dose quantity H(p)(3) based on a cylinder phantom to represent the human head necessary? Are current conversion coefficients from fluence to equivalent dose to the lens sufficiently accurate? To investigate the latter question, a realistic model of the eye including the inner structure of the lens was developed. Using this eye model, conversion coefficients for electrons have already been presented. In this paper, the same eye model-with the addition of the whole body-was used to calculate conversion coefficients from fluence (and air kerma) to equivalent dose to the lens for photon radiation from 5 keV to 10 MeV. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are similar between 40 keV and 1 MeV and lower by up to a factor of 5 and 7 for photon energies at about 10 keV and 10 MeV, respectively. Above 1 MeV, the new values (calculated without kerma approximation) should be applied in pure photon radiation fields, while the values adopted by the ICRP in 1996 (calculated with kerma approximation) should be applied in case a significant contribution from secondary electrons originating outside the body is present.

Since several years, the irradiation facility for beta radiation, the Beta Secondary Standard BSS 2 developed at PTB, is in worldwide use to irradiate devices with calibrated beta sources. In this work the electron and photon particle spectra of the BSS 2 radiation fields are made available as data files, in addition angular distributions and the depth dose profiles are given. The spectra were determined using the Monte Carlo particle transport code BEAMnrc and are provided as electronic files. In order to verify the simulations, from the same simulations the depth dose curves in a phantom were deduced and compared with corresponding measurements -the agreement is quite good -proving the correctness of the particle spectra.

Due to two errors in the geometry module of the EGSnrc C++ class library egs++ (EGSpp), several data presented in the original work are not correct. The following figures and tables present the correct values of the dose conversion coefficients for electron exposure of the human eye lens.The corrected values deviate at most by about 25% and 50% for 0 • and 45 • angles of incidence, respectively, from the ones presented originally.The conclusions given in sections 4 and 5 of the original paper are, however, still valid. Nevertheless, the text has to be slightly modified: the last sentence in the abstract must be changed to 'Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP) the new values are up to 20 000 times smaller for electron energies below 1 MeV, nearly equal at 1 MeV and above 2 MeV, and by a factor of 1.3 larger at about 1.5 MeV electron energy'. In section 3.2, line one, the words 'near 2 MeV' must be changed to 'below 2 MeV'. In the same section, third bullet point, line five, the words 'from side to top to bottom' must be changed to 'from side to bottom to top'. In section 3.3, line five, the words 'a significant impact' must be changed to 'no significant impact'; the rest of that sentence must be deleted.The first error in EGS++ was corrected by Ernesto Mainegra from the National Research Council of Canada (NRC). A short description of what has to be done to remove the error is given as follows.

The International Organization for Standardization (ISO) has issued a standard series on photon reference radiation qualities (ISO 4037). In this series, no conversion coefficients are contained for the quantity personal dose equivalent at a 3 mm depth, H(p)(3). In the past, for this quantity, a slab phantom was recommended as a calibration phantom; however, a cylinder phantom much better approximates the shape of a human head than a slab phantom. Therefore, in this work, the conversion coefficients from air kerma to H(p)(3) for the cylinder phantom are supplied for X- and gamma radiation qualities defined in ISO 4037.

Several correction factors for two new reference beta-particle radiation fields complementing ISO 6980 have been measured and calculated for both primary beta dosimetry and the operational quantities in radiation protection. The following correction factors for primary beta dosimetry for the determination of the absorbed dose to tissue, D t, have been determined by calculations: k ba for backscatter from the collecting electrode, k pe for perturbation by the chamber’s side walls, k ih for inhomogeneity inside the collecting volume, k Sta for the stopping power ratio at different phantom depths, and k SA for the use of the Spencer-Attix theory, while the following have been measured: k br for the effect of bremsstrahlung and k abs for variations in the attenuation and scattering of beta particles between the source and the collecting volume due to variations from reference conditions and for differences of the entrance window to a tissue-equivalent thickness of 0.07 mm. Furthermore, calculations were undertaken to determine the following correction factors to assess the operational quantities H p(0.07), H p(3), H′(0.07), and H′(3): k rod(0.07) for the rod instead of the slab phantom, k cyl(3) for the cylinder instead of the slab phantom, as well as k′(0.07) and k′(3) for the ICRU sphere instead of the slab phantom, while the correction factor for oblique radiation incidence has been measured. The newly determined correction factors were determined in the same way as those for several well-established beta-particle radiation fields described in two earlier publications by the author. Furthermore, they are ready to be implemented in an updated version of the ISO 6980 series and in the software of the Beta Secondary Standard BSS 2.

Since several years, the irradiation facility for beta radiation, the Beta Secondary Standard BSS 2 developed at PTB, has been in worldwide use for the performance of irradiations with calibrated beta sources. Due to recent developments in eye tumor therapy, in eye lens dosimetry, and in soft-and hardware technology, several extensions have been added to the BSS 2.These extensions are described in this paper:1. The possibility of using a 106 Ru/ 106 Rh beta source was added as this radionuclide is often used in tumor therapy. 2. The (small) contribution due to photon radiation was included in the dose (rate) reported by the BSS 2, as this was missing in the past. 3. The quantity personal dose equivalent at a depth of 3 mm, H p (3), was implemented due to recent findings on the radio sensitivity of the eye lens regarding cataract induction and the subsequent lowering of the dose limit from 150 mSv down to 20 mSv per year; 4. The correction for ambient conditions (air temperature, pressure, and relative humidity) was improved in order to adequately handle the quantity H p (3) and in order to extend the range of use beyond 25 • C. 5. A checksum test was added to the software to secure the calibration data against (un)intended changes. 6. The connection of the PC and the BSS 2 has been changed to a network interface (TCP/IP) in order to be able to use up-to-date computers not containing a parallel and a serial port. 7. A rod phantom was added in order to make sure the mechanical set-up is of high quality.All these extensions have been implemented in the PTB's BSS 2 model. The routine implementation of extension 1 is still under investigation by the manufacturer. The commercially available BSS 2 will contain extensions 2 to 6 starting approximately in 2012, while extension 7 has already been incorporated since 2011. Extensions 2 to 4 will also be available for old BSS 2 versions via a software update, starting approximately at the beginning of 2012. Extension 6 will be available via hardware change by the manufacturer.