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Publications about radiation protection issues are not very frequent in the 100-year-old history of Strahlentherapie und Onkologie. While at the beginning of the last century the problems of radiation protection were determined by the technical development of radiation therapy, the importance of radiation protection measures and knowledge about radiation protection by the persons involved has clearly increased. A new challenge is treating patients according to radiation safety issues to avoid the risk of stochastic late effects, such as radiation-induced secondary tumors.

The structure and magnetism of several monolayer (ML) thick ferromagnetic nickel films evaporated on Cu(110) was studied in-situ under ultra- high-vacuum conditions. Optical-, magnetic- and structural properties of the layers are correlated using simultaneous Reflectance Anisotropy Spectroscopy (RAS) and Magneto Optical Kerr Effect Spectroscopy (MOKE-S) as well as STM at certain coverages. Using oxygen as a surfactant for the nickel/copper system, it is possible to obtain pseudomorphic layer growth up to 18 ML. These films turn out to be nearly single domain and show complete out-of-plane magnetization after a spin-reorientation transition from in-plane at 6 ML. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The surface optical and electronical properties of Cu(110) surfaces were studied by using reflectance anisotropy spectroscopy (RAS) together with angle-resolved photoemission spectroscopy (ARUPS). On the clean surface, a structure in the optical spectra at 2.1 eV is assigned to transitions between occupied p-type and unoccupied s-type surface states occurring at the $\overline{Y}$ point of the surface Brillouin zone. Another structure at 4.2 eV is associated with a transition at the $\overline{X}$ point between a surface resonance (occupied) split off from the bulk d bands and a p-derived surface state (unoccupied). The oxygen-induced $(2\ifmmode\times\else\texttimes\fi{}1)$ surface exhibits a double peak in the reflectance anisotropy which can be explained partly by transitions from oxygen induced d- to empty p-derived states. Surface modified bulk d-states are responsible for parts of the features around 2 eV and features at higher energies.

Structure and electronic properties of clean and hydrogen-terminated InP surfaces are studied by reflectance anisotropy spectroscopy (RAS), Auger electron spectroscopy (AES), high resolution energy electron loss spectroscopy (HREELS), low energy electron diffraction (LEED) and soft X-ray photoelectron spectroscopy (SXPS). Clean surfaces were prepared either by sputtering and annealing or decapping (As/P-cap). Both preparation methods lead to the same type of (2 × 4) surface structure with slightly different ratios of indium to phosphorus. The corresponding structural changes of the surface during hydrogen exposure are investigated by LEED, surface electronic modifications are observed by RAS. Medium exposures of atomic hydrogen break In bonds at the surface while high exposures lead to an In enrichment of the surface. With increasing hydrogen exposure the optical anisotropy is lifted.

Hintergrund Die CHART-Studie des Medical Research Council hat eine Verbesserung des Uberlebens von Patienten mit inoperablen nichtkleinzelligen Bronchialkarziomen (NSCLC) um 10% gegenuber einer konventionellen Bestrahlung bis 60 Gy ergeben. Derzeit ist ungeklart, ob dieser Vorteil auch im Vergleich zu hoheren Dosen einer konventionellen Therapie bestehenbleibt und ob das CHART-Schema durch das praktikablere CHARTWEL-Schema (CHART-weekend less) ersetzt werden kann.

Hintergrund Die akute Reaktion der Mundschleimhaut ist eine regelmasige Nebenwirkung der klinischen Strahlentherapie von Kopf-Hals-Tumoren, die in vielen Fallen eine Unterbrechung der Behandlung erzwingt. In den Behandlungspausen besteht gerade bei den im Kopf-Hals-Bereich haufigen Plattenepithelkarzinomen die Gefahr der verstarkten Proliferation von Tumorstammzellen, die in der Folge die Tumorheilungsaussichten drastisch verringern kann. Zudem fuhren uberschiesende Akutreaktionen in vielen Fallen zu einer Verstarkung von spaten Strahlenfolgen („consequential damage”). Die Verminderung der Schleimhautreaktion mit dem Ziel der Vermeidung von Bestrahlungspausen und der Verminderung von Spatschaden kann den therapeutischen Erfolg der Radiotherapie entscheidend verbessern.

The present retrospective study was initiated to characterize the effect of oncological treatments in children and adolescents on bone and soft tissues, and to assess their dependence on radiation dose and age at exposure. The study included 146 patients treated between 1970 and 1997. All patients received external beam radiotherapy to the trunk or extremities, but no cranial irradiation. Median age at treatment was 8.8 years. Patients were screened at 18 years (median time interval since treatment 9.2 years, range 0.9–17.7 years) for pathological changes in the skeletal system and soft tissues (scoliosis, kyphosis, bony hypoplasia, soft tissue defects, asymmetries), which were classified as minor/moderate (grade 1) or substantial (grade 2). Pathological findings were recorded in 75/146 patients (51 %). These were scored as minor in 44 (59 %) and substantial in 31 patients (41 %). Most pathological changes occurred in children treated under the age of 6 years. At 6 years and older, only doses > 35 Gy caused an effect, and no substantial changes were seen for treatment ages exceeding 12 years. Significant effects of radiation dose and age at exposure were observed for kyphoscoliosis (with vertebral body dose gradients

The effect of local conditioning of human oral mucosa by silver nitrate solution (3%) on epithelial proliferation rates was tested in 11 healthy volunteers by in vitro labelling of biopsies with tritiated thymidine. Compared to control biopsies from 13 volunteers, stimulation over 3 days, 3 times per day, yielded a significant ( p = 0.006) increase in the epithelial labelling index (LI) from 4.75 ± 0.32% to 6.85 ± 0.65%, i.e., by 44%. The increase in the absolute number of labelled cells per mm epithelial length was dependent on the overall cell density at the various intraoral sites and varied between 45% in the maxillary vestibule and 91% at the floor of the mouth. In an analysis of variance, stimulation turned out to be the most important source causing the effect ( p = 0.011 for LI and 0.015 for labelled cells per mm). In a radiotherapy trial with conventional postoperative treatment with 5 × 2 Gy/week to a total dose of 60 Gy in 6 weeks, the left buccal mucosa in 10 patients with squamous cell carcinomas of the head and neck was conditioned (3% silver nitrate, 3 times per day, 5 days before and the first 2 days of radiotherapy) while the contralateral mucosa, receiving an identical dose, served as individual control. Mucositis scores according to the EORTC/RTOG or the Dische system showed that the time course and severity of the mucosal response was almost identical in both cheeks, which is in clear contrast to a previous clinical study (Maciejewski et al. Radiother. Oncol. 22, 7–11, 1991). Differences in radiation dose intensity, i.e., weekly dose, in these studies are discussed as a tentative explanation for the different clinical findings.

We report on a cw mode-locked non-critically phase matched KTP optical parametric oscillator synchronously pumped by a picosecond Ti:Sapphire laser. High average signal output power of up to 950 mW over a large tuning range has been achieved. For this OPO the influence of resonator-length detuning on the output power, pulse duration and spectral bandwidth has been investigated. The measured data are in good agreement with the results of a numerical simulation using a split-step Fourier method which considers the group-velocity mismatch, the group-velocity dispersion and the self-phase modulation. The numerical simulation also describes the measured strong pump depletion and its influence on the OPO output and efficiency.

Publications about radiation protection issues are not very frequent in the 100-year-old history of Strahlentherapie und Onkologie. While at the beginning of the last century the problems of radiation protection were determined by the technical development of radiation therapy, the importance of radiation protection measures and knowledge about radiation protection by the persons involved has clearly increased. A new challenge is treating patients according to radiation safety issues to avoid the risk of stochastic late effects, such as radiation-induced secondary tumors.

The aim of the present study was to analyze in detail the time course of the incidence of radiation-induced late effects. For this purpose, unpublished data of patients treated by radiation therapy in Hamburg in the late 1980s were analyzed. Relatively large volumes were exposed to comparatively high doses, thus leading to a high rate of treatment-related side effects.A total of 180 consecutive patients received radiotherapy for prostate cancer. The median age was 66 years (range 41-88 years). The median of the maximum dose was 77.5 Gy (range 56.3-95 Gy) and overall treatment time was 51 days (range 28-128 days). Endpoints analyzed were late complications of grade 3 or higher, overall and disease-free survival, local tumor control, and distant metastases. Data analysis was actuarial and the log-rank test was used to compare the various subgroups.After 2 years, 80.5 ± 3.2% of the patients were without any complications of grade 3 or higher, and after 5 years a constant level of 70.3 ± 4.0% was approached. When multiple lesions occurred per patient, the later events were disregarded. A total of 66 complications occurred in 42 patients. The percentage of patients being free from late complications, plotted as a function of time after start of radiation therapy, was adequately described by an exponential function and a constant fraction. Complications approached a constant level of 70.3% at a rate of 5.3% per month. This means that patients who will develop a complication do so at exponential kinetics and at a relatively high rate, whereas about 70% of the patients will never experience a late effect even over long observation periods. After subdividing the maximum dose into three equal dose groups of 55 patients each ( 73.3 Gy, 73.3-80 Gy, 80 Gy), the constant fraction decreased from 85.7 to 72.8% and 52.2%, whereas the incidence rate was 4.3%, 7.7%, and 5.6% per month and, thus, almost independent of radiation dose.For a given group of patients, the rate of the incidence of late complications appears to be independent of radiation dose and (from analyzing data in the literature) independent of the grade of lesions, whereas the fraction of patients without late effects depends on both parameters.

Background Continuous hyperfractionated accelerated radiotherapy (CHART) counteracts repopulation and may significantly improve outcome of patients with non-small-cell lung cancer (NSCLC). Nevertheless high local failure rates call for radiation dose escalation. We report here the final results of the multicentric CHARTWEL trial (CHART weekend less, ARO 97-1). Patients and methods Four hundred and six patients with NSCLC were stratified according to stage, histology, neoadjuvant chemotherapy and centre and were randomized to receive 3D-planned radiotherapy to 60Gy/40 fractions/2.5weeks (CHARTWEL) or 66Gy/33 fractions/6.5weeks (conventional fractionation, CF). Results Overall survival (OS, primary endpoint) at 2, 3 and 5yr was not significantly different after CHARTWEL (31%, 22% and 11%) versus CF (32%, 18% and 7%; HR 0.92, 95% CI 0.75–1.13, p =0.43). Also local tumour control rates and distant metastases did not significantly differ. Acute dysphagia and radiological pneumonitis were more pronounced after CHARTWEL, without differences in clinical signs of pneumopathy. Exploratory analysis revealed a significant trend for improved LC after CHARTWEL versus CF with increasing UICC, T or N stage ( p =0.006–0.025) and after neoadjuvant chemotherapy (HR 0.48, 0.26–0.89, p =0.019). Conclusions Overall, outcome after CHARTWEL or CF was not different. The lower total dose in the CHARTWEL arm was compensated by the shorter overall treatment time, confirming a time factor for NSCLC. The higher efficacy of CHARTWEL versus CF in advanced stages and after chemotherapy provides a basis for further trials on treatment intensification for locally advanced NSCLC.

For about 200 years surface shape specification for optical components always had one goal only, to make an individual optical component comparable with other pieces of the same type. If the specification is met, the component should fulfill the requested behavior in the related optical system. Nomenclature of specification did not differ in dependence on the components different position in the system or on different used beam diameters vs. components clear aperture. With increasing performance of designed optical systems, surface shape tolerances of components became tighter more and more. Such requirements either lead to inadequate expenses or to the absence of equipment to manufacture and test them in a controlled process. But in reality, only a small part of optical system components are used as they are measured - within full clear aperture. Moreover, the light beam has a significant smaller diameter than the clear aperture has. Typically, this kind of components we find in scanning systems and lenses with large Field of View (FOV). As far as designed surface shape tolerances are derived from maximal acceptable wave front deviation for individual light beams passing through the system, the related method for optical components acceptance test procedures is to analyze wave front deviation in sub apertures caused by surface shape deviation. In this case designed values and manufactured results are comparable to each other. To get the comparable values, surface shape analysis must be done in a gliding sub-aperture area instead of analysing full clear aperture. We show how sophisticated optical systems components may be specified, manufactured and tested in gliding subaperture areas for any term described in normative papers, such as ISO 10110-Part 5 "Surface Form Tolerances", to assure the final function in system. The chosen examples correspond with "classic specified" optical component surface shapes down to 3/ - (0.02)@546nm.

The (110) surface of an Ag crystal was investigated by reflectance anisotropy spectroscopy and angle-resolved photoemission spectroscopy. A strong resonance in the optical spectra of the clean surface is assigned to a surface-state transition at the $\overline{Y}$ point of the surface Brillouin zone. This resonance is absent on the oxygen-covered surface. The accompanying photoemission spectra show the corresponding occupied surface state on the clean surface as well as its disappearance with oxygen coverage.

Received 28 March 2006; revised manuscript received 3 October 2006; published 27 November 2006Reflectance anisotropy spectra RAS , extended into the near infrared spectral region, of anisotropic metalislands, metal surfaces, and atomic nanowires are analyzed with respect to anisotropies in the optical responseof the free-electron gas of such low dimensional metal structures. In order to distinguish conductivity andmorphology effects, both a phenomenological anisotropic Drude model and an effective medium model usingellipsoidal metal inclusions are used to model the spectra. In some cases metal islands the RAS response isdominated by the free-electron contribution, while this contribution is significantly smaller for the metalsurfaces and nanowires in the accessible spectral range.DOI: 10.1103/PhysRevB.74.195432 PACS number s : 73.50. h, 73.20.At, 73.63.Nm, 73.25. i

We investigate the growth mode and the magnetism of Ni on $\mathrm{Cu}(110)$ substrates using oxygen as a surfactant. Layer by layer growth on oxidized $\mathrm{Cu}(110)$ is obtained, in contrast to the island growth found on clean $\mathrm{Cu}(110)$ substrates. The main emphasis of our work addresses the potential of optical spectroscopy for analyzing structure and magnetism. For that purpose we use a spectrometer which allows us to record reflectance anisotropy (RAS) and magneto-optic Kerr (MOKE) spectra simultaneously and in situ during film growth, in the spectral range from 0.72 to $6.5\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. We show that RAS is very useful for monitoring the growth of Ni on $\mathrm{Cu}(110)$, since it reveals information on the atomic surface structure and on the strain evolution during the growth process. MOKE, on the other hand, is sensitive to the magnetic properties of the epitaxial Ni film. Combining RAS and MOKE thus allows us to directly relate growth mode and magnetic properties and to identify correlations in between. As such, an out-of-plane magnetization for Ni films between 7.5 and 35 ML thickness is observed, correlated with a flat layer morphology, i.e., two-dimensional growth mode of the Ni film. Above 35 ML roughening sets in and the magnetization direction rotates towards in-plane orientation again. Well below 35 ML, between 14 ML and 18 ML of Ni, the strain due to pseudomorphic growth is relaxed, correlated with a strong increase in coercivity due to dislocation formation. Mandatory for a meaningful analysis of the Voigt parameter of Ni is the sophisticated optical modeling of the layer system. Doing so, we prove that a modification of electronic properties ($d$-band narrowing) of the Ni film in the pseudomorphic growth regime does not occur, in contrast to expectations.

Summary:PET/CT imaging is most likely to be of use in radiation oncology with patients who have poorly defined target volume areas, e.g. brain tumours, bronchogenic carcinoma, and cases of miscellaneous geographical miss. Other tumours that call for dose escalated radiotherapy, such as head and neck tumours, bronchogenic carcinoma, and prostate carcinomas may further benefit from an accurate delineation of the metabolically active tumour volume and its differentiation from surrounding healthy tissue, or tumour atelectasis.

The electronic structure of a clean (110) surface of crystalline aluminum is investigated experimentally by measuring the angle-resolved ultraviolet photoemission spectra at high-symmetry points of the surface Brillouin zone for photon energies in the range $10--29\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. The binding energies and dispersions of several features in the experimental spectra are determined. The experimental data are interpreted by means of an ab initio full-potential linear-augmented plane-wave calculation of the surface electronic structure based on density functional theory. Two of the features in the spectra are identified as being due to emission from previously unobserved surface states and surface resonances. The effects of surface relaxation on the surface electronic structure are discussed.

This article deals with a high power, high repetition-rate picosecond regenerative amplifier based on Nd:YVO/sub 4/. Using novel electro-optic modulators (EOM), the system generates average powers well above 10 Watt at repetition-rates up to 100 kHz. The combination of good beam quality, high power and high repetition rate qualifies this laser system as a valuable tool for micro-machining. In particular, metallic materials like steel can be processed with a high speed of operation.

The reflectance anisotropy of a clean Al(110)-vacuum interface has been measured experimentally, and compared with the results of an ab-initio self-consistent full-potential linear augmented plane-wave calculation. Good agreement is found in the interband regime, while a discrepancy in the Drude regime is consistent with anisotropy in the intraband contribution. The calculated surface dielectric anisotropy and reflectance anisotropy of Al(110) are not significantly affected by surface relaxation, suggesting that optical transitions between surface states and surface resonances make only a minor contribution to the surface dielectric response. The measured reflectance anisotropy of Al(110) is found to be only weakly affected by oxidation and by the deposition of Ni overlayers, providing further evidence in support of this conclusion.

We report on the efficient operation of cw mode-locked singly resonant ps and fs optical parametric oscillators of noncritically and quasi noncritically phase-matched KTiOPO4 (KTP). The OPOs are synchronously pumped either by self-mode-locked ps/fs-Ti:sapphire laser or by a cw mode-locked Nd:YLF laser for the generation of powerful ultrashort pulses from the near to the mid-IR up to 3.3 μm.

Summary from only given. We report on the generation of powerful picosecond laser pulses in the red (671 nm) and blue (447 nm) spectral range by second and third harmonic generation of a mode-locked Nd:YVO/sub 4/-laser operating at 1342 nm. The nonlinear crystals used for both the second and third harmonic are periodically poled quasi-phase-matched KTP-crystals (pp-KTP).

Visible and UV light spectra display striking differences in optical reflectivity for the two types of monatomic steps on copper (111) surfaces. Electronic structure calculations trace these differences to the specific contributions of p(axially) and p(radially) local densities of states, parallel and perpendicular to the steps, of the distinctly coordinated corner atoms. The local origin of the spectral reflectance anisotropy is further corroborated by experiments on Cu(111) surfaces with varying step densities. Site specificity of the electronic structure of atoms in low coordinated sites on Cu(111) vicinals is thus revealed by reflectance anisotropy spectroscopy which can thereby detect step atom densities down to 10(13) atoms/cm(2).

Powerful solid state laser sources which generate red (R), green (G) and blue (B) radiation are of interest for many applications which include optical printing and large frame optical displays.

The optical properties of copper and silver bulk crystals with atomically clean surfaces have been determined experimentally and interpreted in terms of ab initio band structure calculations. The dielectric functions are evaluated from spectroscopic ellipsometry data taken in ultrahigh vacuum (UHV) in the spectral range of 2.5--9.0 eV (at room temperature). The data are corrected for surface roughness using results from ex situ atomic force microscopy (AFM). Significant differences of detail in the amplitudes and line shape are attributed to the better surface quality of our samples. Density functional calculations of the dielectric functions of copper and silver are carried out, based on models of the valence bands deduced by fitting to experimental Fermi surface and quasiparticle mass data. Small energy shifts, which take into account many-body effects in the final states of the optical transitions in an extended scissors approximation, are needed to bring the calculated dielectric functions into good agreement with the experimental data. The interband transitions associated with individual features in the dielectric function are identified by comparing the energy derivatives of the measured and calculated dielectric functions.

Mitarbeiterorientierung bei der Reorganisation von Geschaftsprozessen druckt sich unter anderem durch die Beteiligung von Mitarbeitern aus.

Zur Einfuhrung von Workflow-Management-Systemen (WMS) gehort die Erhebung und Modellierung von Geschaftsprozessen. Dazu werden spezielle abteilungsubergreifende Vorgehensweisen und besondere Methoden benotigt, die in diesem Beitrag vorgestellt werden.

Because of the large single-fraction dose in stereotactic radiosurgery it is important to guarantee a high geometric and dosimetric accuracy. The paper represent the quality assurance program for the Gamma Knife unit at the University Clinic of Neurosurgery in Graz. The program includes the following procedures: timer control, mechanical radiation isocenter coincidence, trunnion centricity, helmet microswitches test, radiation output and relative helmet factors, dose profile verification, safety interlocks checks and software quality assurance. In summary, the mechanical accuracy and reproducibility of the Gamma Knife unit are < 1 mm. The geometric failure in stereotactic Gamma Knife treatment is limited by the human error in setting the clinical target volume and the spatial accuracy of dose delivery to the patient is limited by the accuracy of modern target localization procedures.

We combine reflectance anisotropy spectroscopy (RAS) with low energy electron diffraction, Auger electron spectroscopy, and soft x-ray photoemission spectra to analyze the surface optical anisotropy of ZnSe(001). Clean surfaces were prepared by thermal desorption of a protective Se cap from ZnSe layers of different thicknesses grown by molecular beam epitaxy on GaAs(001). Two surface reconstructions have been prepared by subsequent annealing, the Se-rich (2×1) reconstruction and the Zn-rich c(2×2) reconstruction. By modifying the surfaces either through submonolayer deposition of Sb or a short exposure to atmosphere it was possible to distinguish between surface and bulk/interface contributions to the optical anisotropy. Only on disordered, very Se-rich ZnSe(001) surfaces prepared at low annealing temperatures RAS features possibly related to electronic surface states are found. RAS spectra of the (2×1) and the c(2×2) surfaces are correlated with surface morphology and ordering rather than surface reconst...

Structural and electronic properties of the clean InP(001) surface and the CdS/InP(001) interface were investigated by soft x-ray photoemission and reflectance anisotropy spectroscopy (RAS). Clean InP(001) (2×4) surfaces were prepared by desorption of a protective arsenic/phosphorus double capping layer, thereafter, CdS deposited by single source molecular beam epitaxy at a substrate temperature of 200 °C. Core-level and valence-band photoemission spectra, as well as the RAS data, were taken in situ. Core-level spectra show a disappearance of In 4d and P 2p surface core-level shifts and a chemical reaction between indium and sulphur upon CdS deposition. From valence-band spectra, a total valence-band offset of ΔEV=(0.75±0.10) eV is derived, which corresponds to previous results of the CdS/InP(110) interface. After deposition of thin CdS layers, RAS spectra show strong features close to interband critical points of bulk InP due to surface roughening induced by the interface reaction. A feature around 5.3 e...

The speaker can encode one and the same object S in variable ways in order to enable a listener to identify this particular object. It can be demonstrated that, among other things, the labeling of S depends on the context objects SC that are presented with S, and with which S may be confused. Generally, speakers label the one feature of S which, within a given context, exclusively refers to S and not to any other object SC. If there are several features coinciding with this condition (multiple codability), (1) the labeling covaries with the discriminability of S: the feature which is labeled is that which permits the best subjective discrimination of S as opposed to SC; (2) the labeling covaries with the dimensional preference of the speaker in case the best discrimination proves impossible: the feature of S which is labeled is that which the speaker prefers as a result of his learning history. These theoretical assumptions listed above are investigated in two independent experiments (subjects: N=110 children; experimental material: geometric figures). The results largely confirm the theoretical considerations.

Summary Irradiations of the right lung with 6.2 MeV neutrons (38 test animals) and 60 Co photons (34 test animals) were made using young pigs. Twenty animals were used as controls. Five fractions were administered in an overall treatment time of 5 or 35 days. The radiogenic pneumopathy was monitored with clinical, radiological and histological investigations, and by determining the hydroxyproline content in the lung tissue. The pneumopathy in pigs given neutrons, developed after a shorter latency period and followed a more rapid and serious course than that in animals, given gamma rays. While after photons the extension of the overall treatment time from 5 to 35 days led to a measurable but low increase of the ED 50 this was not true for neutrons. The relative biological effectiveness (RBE) for the 6.2 MeV neutrons compared with 60 Co photons was 4.0 for an overall treatment time of 5 days and 4.1 for 35 days.

The dose-time relationship of radiogenic pneumopathy was studied in 68 young pigs. The right lungs of the animals were irradiated by means of a telecobalt unit. Dose distribution calculations and the preparation and execution of irradiation were chosen to largely parallel the treatment of patients. The radiation response of the lungs was quantified by chest-X-rays, functional studies and histological and biochemical investigations of the autopsy specimens. The dose which produced unambiguous signs of radiation pneumopathy in at least 50% of the individuals (ED50), was used to draw an iso-effect plot. A steep slope of the iso-effect line was found when the number of fractions was increased from 5 to 15. In contrast, the iso-effect line showed only a small slope when the influence of overall time was investigated. Significant differences between doses for early and late reactions of the lungs could not be detected. The radiogenic lung reaction in pigs is adequately described by the relation D approximately N0.32 X T0.05 and an alpha/beta value of 3.7 Gy. These results are in a good agreement with those derived for mice by other investigators. The good comparability of the biological findings obtained with pigs to man points to the application of this dose-time relation in radiotherapeutical practice.