Two-dimensional square and hexagonal oxide quasicrystal approximants in SrTiO3 films grown on Pt(111)/Al2O3(0001).

The formation of two-dimensional oxide dodecagonal quasicrystals as well as related complex approximant phases was recently reported in thin films derived from BaTiO3 or SrTiO3 perovskites deposited on (111)-oriented Pt single crystals. Here, we use an all-thin-film approach in which the single crystal is replaced by a 10 nm thick Pt(111) buffer layer grown by molecular beam epitaxy on an Al2O3(0001) substrate. An ultra-thin film of SrTiO3 was subsequently deposited by pulsed laser deposition. The film stacking and structure are fully characterized by diffraction and microscopy techniques. We report the discovery of two new complex phases obtained by reduction of this system through high temperature annealing under ultrahigh vacuum conditions. The formation of a new large square approximant with a lattice parameter equal to 44.4 Å is evidenced by low-energy electron diffraction and scanning tunneling microscopy (STM). Additionally, a new 2D hexagonal approximant phase with a lattice parameter of 28 Å has been observed depending on the preparation conditions. Both phases can be described by two different tilings constructed with the same basic square, triangle and rhombus tiles possessing a common edge length of about 6.7 Å. Using the tiling built from high resolution STM images, we propose an atomic model for each approximant which accounts for the experimental observations. Indeed, the STM images simulated using these models are found to be in excellent agreement with the experimental ones, the bright protrusions being attributed to the topmost Sr atoms. In addition our theoretical approach shows that the adhesion of the oxide layer is rather strong (-0.30 eV Å-2). This is attributed to charge transfer, from the most electropositive elements (Sr and Ti) to the most electronegative ones (Pt and O), and to hybridization with Pt-states. Density of states calculations indicate differences in the electronic structure of the two approximants, suggesting different chemical and physical properties. This all-thin-film approach may be useful to explore the formation of complex two-dimensional oxide phases in other metal-oxide combinations.

[The effect of the application technic on the formal success of large-field radiotherapies]. / Zum Einfluss der Applikationstechnik auf den formalen Erfolg von Grossfeldstrahlentherapien.

198 patients suffering from Hodgkin's disease or non-Hodgkin's lymphomas were irradiated with large-field techniques from 1979 to 1988. 129 of these were treated with common block techniques whereas the field-integrated dose modification (FIDM) was applied to 69 patients. Retrospective analysis shows that FIDM decreases acute toxicity. This was also evident in those patients who were irradiated by accelerated hyperfractionation. Although single doses were higher in patients treated with FIDM treatment had to be interrupted or abandoned less often than in those treated with conventional block techniques. Even high-risk patients could be irradiated more consequently.

Individual skull model fabrication for craniofacial surgery.

The purpose of this report is to describe a milling procedure for the fabrication of skull models from 3-D CT data. Data from computer tomographic cuts are transferred to a computer and stored. Model fabrication takes place using high quality styrodur that is shaped with a high speed milling device. This allows the modeling of an individual life size skull in its skeletal as well as in its soft tissue contours. Smaller bone pieces and areas can be enlarged separately up to eight times normal size for better visualization. Planning and simulation of craniofacial surgery in three dimensions is possible, and bone implants or alloplastic biomaterials can be modeled for implantation.

[Practical application of digital therapy verification]. / Zur Praxis der digitalen Therapieverifikation.

The following describes the technical details which are of importance preparing portal radiographs using digital luminescence radiography. There are some advantages to this method: In comparison with the conventional portal radiographs using a low speed film, the new doses is ten to thirty times less than generally required. Double exposure techniques can be more easily applied than with conventional portal films. The contrast may be subsequently manipulated. In addition the dynamic range of the radiation detector is automatically adjusted to the exposure range. These facts may improve the verification quality. However, there are also some disadvantages: You need more apparatus, and the whole procedure is more time-consuming. Using typical examples we shall compare the procedure of digital portal radiographs and its results to traditional techniques.

[Ultrasound, computerized and nuclear magnetic resonance tomography of soft tissue processes of the head and neck]. / Sonographie, Computer- und Kernspintomographie bei Weichteilprozessen im Kopf-Hals-Bereich.

14 patients with a space-occupying growth in the head and neck region were examined via sonography, CT and MR to explore and demonstrate by means of a prospective comparative study the possibilities offered by these three imaging methods. Stages are best diagnosed by means of sonography; the leading role of this method is undisputed. To clarify sonographically unclear findings and especially in pre-surgery planning, MR offers advantages over CT on account of the high soft-part contrast and multiplanar visualisation. However, it is impossible or very difficult to differentiate abscesses and lymphadenitides from malignant growths with these three methods solely on the basis of image-morphological criteria.

[Posterior uveitis caused by highly malignant B cell lymphoma]. / Hintere Uveitis durch hochmaligne B-Zell-Lymphome.

A diagnostic vitrectomy was performed on three patients with posterior uveitis of unknown origin and whose vitrous body was markedly affected. In all cases, cells of high-grade B-cell lymphoma (earlier referred to as reticulum cell sarcoma) were identified by cytological analysis of the specimen. In addition to the ocular findings, one of the three patients showed clinical and radiological evidence of a tumorous mass in the area of the right thalamus at the time of diagnosis. This was interpreted as a cerebral manifestation of the lymphoma. Initially, the other two patients did not show any cerebral involvement. One of them, however, developed clinical symptoms 9 months after diagnosis, which were radiologically verified as tumor infiltration of the cerebellum and the diencephalon. Under radiation therapy, the ocular findings disappeared within a few weeks.

Planning orthognathic surgery with three-dimensional models.

Computerized imaging to provide the perspective of the third dimension is helpful for preoperative evaluation and has been introduced for a variety of indications. Calculated from original computerized tomographic scans, deformities in skeletal and soft tissue profiles can be visualized on a television monitor. A method of fabricating three-dimensional skeletal models that can be used for planning orthognathic surgery has been developed. Mandibular and maxillary surgical movements can be simulated exactly, and osteosynthesis materials can be chosen, adapted, and prepared to save time intraoperatively.

Fractionated total body irradiation and high-dose VP 16-213 followed by allogeneic bone marrow transplantation in advanced leukemias.

Thirty-eight patients (median age, 21 years) with acute nonlymphoblastic leukemia (ANLL) (17 patients), acute lymphoblastic leukemia/lymphoma (ALL) (18 patients), chronic myelogenous leukemia (two patients), and refractory anemia received allogeneic bone marrow transplants from HLA-identical sibling donors or a one-antigen-mismatched brother (one patient) after a preparatory regimen consisting of fractionated total body irradiation and high-dose VP 16-213 (60 to 70 mg/kg body weight). Of the 33 patients with acute leukemia who received grafts from HLA-identical donors, three patients with ANLL received transplants in first remission and one patient with standard-risk ALL received a graft while in second remission. All other patients were in more advanced stages of their disease or exhibited other high-risk features. At the time of analysis, 20 of the 33 patients were alive, with 19 of them remaining in continued complete remission for 6 to 35 months (median, 18 months). The 3-year actuarial disease-free survival rate of 56.6% +/- 9.7% (SE) and the actuarial relapse rate of 11.9% +/- 6.8% (SE) demonstrate that the combination of fractionated total body irradiation and high-dose VP 16 is an effective mode of therapy in patients with advanced leukemias. Preliminary experience cautions against the use of VP 16 instead of cyclophosphamide in any clinical situation carrying an increased risk of graft rejection because the immunosuppressive potency of VP 16 is largely untested but may be inferior to that of cyclophosphamide.

[Optimization of combined brachy-teletherapy by the modification technic]. / Zur Optimierung der kombinierten Brachy-/Teletherapie mit Hilfe der Modifikationstechnik.

A method is presented for combined brachy-teletherapy by which the dose distribution of percutaneous irradiation is adapted to the distribution of short-distance irradiation with 192iridium by means of the so-called "field integrated dose modification". Insufficient or excessive doses within the area of superposition of both therapy modalities can so be avoided. Moreover, the therapist can define zones of deviation from the reference dose, if such a dose heterogeneity seems desirable in the individual case. The combined irradiation of prostata and cervix is given as an example to describe in detail the technical, clinical, and radiobiological aspects of this method.

The field integrated dose modification (FIDM): three typical clinical applications of a new irradiation technique.

In addition to an earlier developed "compensator integrated modification technique", a method is derived which uses as basic principle the "field integrated dose modification" (FIDM) without need for computer tomographic data. The method enables the radiotherapist to introduce one or more volumes within which doses can be delivered which are different from the one in the main irradiation volume. The steps of practical preparation and clinical application are described in detail. The radiobiological aspects of FIDM, especially those in case of acceleration and hyperfractionation, are elucidated by discussing three typical examples.

[Various rib anomalies]. / Uber verschiedene Rippenanomalien.

Three patients are presented who were suffering from different anomalies of the ribs: There was one each plus and minus variant and a female patient with Gorlin-Goltz syndrome (basal cell nevus syndrome) demonstrating several changes in the ribs as an expression of a genetically determined segmentation disturbance. These presentations are followed by a detailed discussion on the types and causes of such anomalies.

[Field-integrated dosage modification (FIDM). 2. The physical principles of the procedure]. / Die feldintegrierte Dosismodifikation (FIDM). 2. Mitteilung: Physikalische Grundlagen des Verfahrens.

A method is suggested and described which allows to introduce areas of different sizes, shapes, sites, and doses into a photon irradiation field. The bases for calculation and manufacturing of such irregular field stops containing integrated dose modification blocks are, according to precision requirements and data acquisition possibilities, either information provided by computed tomography or conventional planning radiographs. The following standard parameters are required as input data: sizes, shapes, and positions of the partial fields within the total irradiation field, depth of the reference plane, absorption coefficient of the modification material used, proportions of the planned dose modification, radiation quality, and other radiation field parameters. For the calculation of the dose distributions within the generally irregularly shaped irradiation volumes, an iterative algorithm has been formulated following the differential sector addition method and an equivalent TAR scheme. The quality of such a modifier can be checked by standard dosimetric methods. Deviations from the planned dose modification can be defined as sigma = +/- 5% for the radiation qualities employed (60Co gamma radiation and 15 MeV bremsstrahlung of a linear accelerator).

[Prenatal sonography and computed tomography of fetal cerebral malformations]. / Pränatale Sonographie und Computertomographie zerebraler Missbildungen des Feten.

In three pregnant women, sonography and amniocentesis suggested cranial abnormalities of the foetuses. In view of the far-reaching consequences of such a diagnosis, CT was carried out to confirm the diagnosis. It was possible to show the intra-uterine abnormalities and the type of malformation in considerable detail. In one case an encephalocele was demonstrated, in the two others, an anencephalic foetus was shown.

[Field-integrated dose modification. 1: Clinical significance of the procedure]. / Die feldintegrierte Dosismodifikation (FIDM). 1. Mitteilung: Klinische Bedeutung des Verfahrens.

A method is derived from a previously published compensator-integrated modification proceeding which maintains the principle of a field-integrated dose modification without needing CT input data. Three typical clinical examples are presented in order to describe this considerably simplified technique thus suited for everyday practice. The authors discuss the interesting radiobiological aspects involved.

[Presentation of a new partial-field blocker for breast-preserving therapy of breast carcinoma]. / Vorstellung eines neuen Teilfeldblockers für die brusterhaltende Therapie des Mammakarzinoms.

A combination of conservative surgery and locoregional radiotherapy is a promising conception for conservative treatment of the so-called little mammary carcinoma. As a further increase of the longterm healing rate is probably almost impossible to achieve, changes of the irradiation technique aim at present only to improve the irradiation quality. With this background, the authors have developed a partial field blocker considering the anatomic and topographic radiophysical features of this therapy method and making possible furthermore various individual treatment modalities. The construction, function and clinical importance of this partial field blocker are described in detail and the physical parameters changing with respect to open field irradiation are discussed.

[Clinically-oriented hints for the technic of integrated dosage modification in a partial irradiation field]. / Praxisorientierte Hinweise zur Technik der integrierten Dosismodifikation in einem Teilbereich des Bestrahlungsfeldes.

The authors present a method allowing the application of doses differing from the reference dose in partial zones of an irradiation volume. The compensator-integrated modification is performed by a simultaneous dose harmonization in the reference plane. Three methods are described by which a topographic and anatomic assignment of field and partial field is possible on the basis of the irradiation features. The optimum application of each method in the individual irradiation schemes is discussed.