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Background: Radiobiological and physical examinations suggest clinical advantages of heavy ion irradiation. We report the results of 23 women and 22 men (median age 48 years) with skull base tumors irradiated with carbon ion beams at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt, from December 1997 until September 1999.Patients and Methods: The study included patients with chordomas (17), chondrosarcomas (10) and other skull base tumors (Table 1). It is the first time that the intensity-controlled rasterscan-technique and the application of positron-emission tomography (PET) for quality assurance was used. All patients had computed tomography for three-dimensional-treatment planning (Figure 1). Patients with chordomas and chondrosarcomas underwent fractionated carbon ion irradiation in 20 consecutive days (median total dose 60 GyE). Other histologies were treated with a carbon ion boost of 15 to 18 GyE delivered to the macroscopic tumor after fractionated stereotactic radiotherapy (median total dose 63 GyE).Results: Mean follow-up was 9 months. Irradiation was well tolerated by all patients. Partial tumor remission was seen in 7 patients (15.5%) (Figure 2). One-year local control rate was 94%. One patient (2.2%) deceased. No severe toxicity and no local recurrence within the treated volume were observed.Conclusion: Clinical effectiveness and technical feasibility of this therapy modality could clearly be demonstrated in our study. To evaluate the clinical relevance of the different beam modalities studies with larger patient numbers are necessary. To continue our project a new heavy ion accelerator exclusively for clinical use is planned to be constructed in Heidelberg. [ABSTRACT FROM AUTHOR]

Background: In clinical practice it sometimes happens that with currently available conformal radiotherapy techniques no satisfactory dose distribution can be achieved. In these cases inverse radiotherapy planning and intensity modulated radiotherapy may give better solutions.Method: Inverse planning is a technique using a computer program to automatically achieve a treatment plan which has an optimal merit. This merit may either depend on dose or dose-volume constraints like minimum and maximum doses in the target region or critical organs, respectively, or biological indices like the complication free tumor control rate. As the result of inverse planning the inhomogeneous intensity fluence of the beams is calculated. These fluence distributions may be generated by beam compensators or multi-leaf collimation.Results: Clinical studies to prove the advantage of inverse planning are already on the way. It has been shown that this technology is safe and that the dose distributions which can be achieved are superior to conventional methods.Conclusions: Inverse treatment planning and intensity modulated radiation therapy will almost certainly come to be the technique of choice for selected clinical cases. [ABSTRACT FROM AUTHOR]

Background: Stereotaxy is a method to determine a point in the patient's body by an external coordinate system which is attached to the patient. Radiosurgery uses this method for precise delivery of a high single radiation dose to the patient. The aim is to destroy the tissue in the target and to spare surrounding unaffected normal tissue by a steep dose gradient.Methods: Three techniques of percutaneous radiosurgery are available: radiosurgery with ion beams with a cyclotron, spherical arrangement of cobalt-60 sources, the so-called gamma knife, and an adapted linear accelerator. The availability and the good clinical experience lead to a wide spread use of linear accelerator for radiosurgery in recent years. A subsequent development is fractionated stereotactic radiotherapy which combines the precision of radiosurgery with the radiobiological advantage of fractionation.Results: Only a few indications for radiosurgery are proven by statistically valid studies. One of these is the treatment of small arteriovenous malformation, where obliteration rates of 80% to 100% are reported with only minor toxicity. However, the obliteration rate is reduced significantly in large arteriovenous malformations. A local control rate of 90% is obtained after radiosurgery of brain metastases which is comparable to the results of microsurgical resection followed by adjuvant whole brain radiotherapy. An ongoing EORTC study evaluates the role of adjuvant whole brain radiotherapy after radiosurgery. The survival of the patients with brain metastases is limited by the existence of progressive extracerebral disease. The role of radiosurgery in the treatment of benign tumors is currently evaluated in clinical studies which include: vestibular schwannomas, meningiomas, chordomas and chondrosarcomas and pituitary adenomas. Most of the published studies include only small tumors because radiosurgery is limited by the risk of radionecrosis of adjacent normal tissue, which shows a steep dose volume response relationship. Recent developments of stereotactic radiotherapy include the use of mini-multileaf-collimators and clinical studies on stereotactic radiotherapy of extracranial targets.Conclusions: Stereotactic irradiation is a well established treatment technique for intracranial tumors and arteriovenous malformations. Methods are available that allow optimization of dose distributions to irregularly shaped tumors for single dose as well as fractionated stereotactic irradiations by linear accelerator. Therefore the therapeutic potential of this technique has increased and enables also the extracerebral application in controlled clinical studies. [ABSTRACT FROM AUTHOR]

To analyze the repositioning accuracy in female patients with breast carcinoma, two different setups of an image-subtraction system (Positioning System FIVE) were devised using different numbers and alignments of lasers. The applicability of the system was tested for repositioning of the breast in normal volunteers. Horizontal translations as well as breathing-related movements in the vertical direction were measured. The mean repositioning accuracy was found to be 2.9 mm for the first setup and 1.5 mm for a second, optimized setup. For this second setup, a gating function was implemented which evaluates the position of the breast twelve times per second. The simulation of a gated treatment showed that the breathing-related displacement of the breast can be reduced to 45-70% of the displacement without gating. This implies a significant improvement of the positioning accuracy.

Complex dose-delivery techniques, as currently applied in intensity-modulated radiation therapy (IMRT), require a highly efficient treatment-verification process. The present paper deals with the problem of the scatter correction for therapy verification by use of portal images obtained by an electronic portal imaging device (EPID) based on amorphous silicon. It also presents an iterative method for the scatter correction of portal images based on Monte Carlo-generated scatter kernels. First applications of this iterative scatter-correction method for the verification of intensity-modulated treatments are discussed on the basis of MVCT- and dose reconstruction. Several experiments with homogeneous and anthropomorphic phantoms were performed in order to validate the scatter correction method and to investigate the precision and relevance in view of its clinical applicability. It is shown that the devised concept of scatter correction significantly improves the results of MVCT- and dose reconstruction models, which is in turn essential for an exact online IMRT verification.

The present paper describes a method for the individual dosimetric verification of IMRT treatment plans. The German Cancer Research Center (Deutsches Krebsforschungszentrum; DKFZ) has implemented the intensity modulated radiotherapy (IMRT) since 1997. So far, 246 patients with head and neck cancer, cancer of the prostate, breast, and vertebral column, as well as mesothelioma of the pleura have been treated. Every IMRT plan is transferred into a special IMRT verification phantom, recalculated, and dosimetrically verified. Absolute dose distributions are measured with Kodak EDR films and compared with the results of the dose calculation. After correction of the optical density in relationship to the dose, EDR films are able to measure the absolute dose with an accuracy of +/- 2% compared to an ionization chamber. A visual C++ software tool has been developed to correlate and evaluate the film dose distributions with the corresponding slices of the 3D dose cube. Beside the overlay of absolute or relative isodoses and dose profiles, the median dose within correlated regions of interest (ROIs) is also included in the quantitative dose evaluation. The deviation between EDR film dosimetry and dose calculation is delta D = -0.3% +/- 2.3%. After introduction of the verification software, the total verification time (including handling, correlation, evaluation, and documentation of the data), could be reduced to less than 2 hours.

Background: Radiobiological and physical examinations suggest clinical advantages of heavy ion irradiation. We report the results of 23 women and 22 men (median age 48 years) with skull base tumors irradiated with carbon ion beams at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt, from December 1997 until September 1999., Patients and Methods: The study included patients with chordomas (17), chondrosarcomas (10) and other skull base tumors (Table 1). It is the first time that the intensity-controlled rasterscan-technique and the application of positron-emission tomography (PET) for quality assurance was used. All patients had computed tomography for three-dimensional-treatment planning (Figure 1). Patients with chordomas and chondrosarcomas underwent fractionated carbon ion irradiation in 20 consecutive days (median total dose 60 GyE). Other histologies were treated with a carbon ion boost of 15 to 18 GyE delivered to the macroscopic tumor after fractionated stereotactic radiotherapy (median total dose 63 GyE)., Results: Mean follow-up was 9 months. Irradiation was well tolerated by all patients. Partial tumor remission was seen in 7 patients (15.5%) (Figure 2). One-year local control rate was 94%. One patient (2.2%) deceased. No severe toxicity and no local recurrence within the treated volume were observed., Conclusion: Clinical effectiveness and technical feasibility of this therapy modality could clearly be demonstrated in our study. To evaluate the clinical relevance of the different beam modalities studies with larger patient numbers are necessary. To continue our project a new heavy ion accelerator exclusively for clinical use is planned to be constructed in Heidelberg.

Background: In clinical practice it sometimes happens that with currently available conformal radiotherapy techniques no satisfactory dose distribution can be achieved. In these cases inverse radiotherapy planning and intensity modulated radiotherapy may give better solutions., Method: Inverse planning is a technique using a computer program to automatically achieve a treatment plan which has an optimal merit. This merit may either depend on dose or dose-volume constraints like minimum and maximum doses in the target region or critical organs, respectively, or biological indices like the complication free tumor control rate. As the result of inverse planning the inhomogeneous intensity fluence of the beams is calculated. These fluence distributions may be generated by beam compensators or multi-leaf collimation., Results: Clinical studies to prove the advantage of inverse planning are already on the way. It has been shown that this technology is safe and that the dose distributions which can be achieved are superior to conventional methods., Conclusions: Inverse treatment planning and intensity modulated radiation therapy will almost certainly come to be the technique of choice for selected clinical cases.

Background: Stereotaxy is a method to determine a point in the patient's body by an external coordinate system which is attached to the patient. Radiosurgery uses this method for precise delivery of a high single radiation dose to the patient. The aim is to destroy the tissue in the target and to spare surrounding unaffected normal tissue by a steep dose gradient., Methods: Three techniques of percutaneous radiosurgery are available: radiosurgery with ion beams with a cyclotron, spherical arrangement of cobalt-60 sources, the so-called gamma knife, and an adapted linear accelerator. The availability and the good clinical experience lead to a wide spread use of linear accelerator for radiosurgery in recent years. A subsequent development is fractionated stereotactic radiotherapy which combines the precision of radiosurgery with the radiobiological advantage of fractionation., Results: Only a few indications for radiosurgery are proven by statistically valid studies. One of these is the treatment of small arteriovenous malformation, where obliteration rates of 80% to 100% are reported with only minor toxicity. However, the obliteration rate is reduced significantly in large arteriovenous malformations. A local control rate of 90% is obtained after radiosurgery of brain metastases which is comparable to the results of microsurgical resection followed by adjuvant whole brain radiotherapy. An ongoing EORTC study evaluates the role of adjuvant whole brain radiotherapy after radiosurgery. The survival of the patients with brain metastases is limited by the existence of progressive extracerebral disease. The role of radiosurgery in the treatment of benign tumors is currently evaluated in clinical studies which include: vestibular schwannomas, meningiomas, chordomas and chondrosarcomas and pituitary adenomas. Most of the published studies include only small tumors because radiosurgery is limited by the risk of radionecrosis of adjacent normal tissue, which shows a steep dose volume response relationship. Recent developments of stereotactic radiotherapy include the use of mini-multileaf-collimators and clinical studies on stereotactic radiotherapy of extracranial targets., Conclusions: Stereotactic irradiation is a well established treatment technique for intracranial tumors and arteriovenous malformations. Methods are available that allow optimization of dose distributions to irregularly shaped tumors for single dose as well as fractionated stereotactic irradiations by linear accelerator. Therefore the therapeutic potential of this technique has increased and enables also the extracerebral application in controlled clinical studies.

Substantial improvement in conformal radiotherapy is possible using modulated irradiation fields. Such modulated fields may be generated even with conventional accelerators by means of individual metal compensators or with the recently available dynamic multileaf collimators (MLC). For treatment planning a new kind of planning program is required that can calculate the 2 D-intensity matrices for each photon field. At the German Cancer Research Center (Deutsches Krebsforschungszentrum) such a program has been developed under the name of "KonRad" (Conformal Radiotherapy). Although it is an independent application, it is proposed for clinical usage to supplement a planning system that is already present. So-called inverse planning differs from conventional 3 D planning, as the trial-and-error approach for finding good field parameters is nearly completely avoided. Instead, the radio-oncologist is given the chance directly to specify medically oriented criteria like the prescription dose in the target volume, maximal tolerance dose values for each organ at risk and their weighting factors. In addition, the so-called DVH optimization allows aimed, partial overdosage, especially in parallelly structured organs in order to obtain better overall planning results. Because of very fast dose calculation in connection with rapidly converging gradient optimization and an intuitive use interface, the planning is done in a comfortable and interactive manner. Using a workstation or a PC, a typical plan can be created within a few minutes.

Modern imaging techniques are a substantial part of treatment planning for minimally invasive radiotherapeutic procedures. The aim is three-dimensional assessment of the target volume and adjacent critical structures. In this paper, we report on our clinical experience with a precise system for stereotactic image correlation. Hereby, the advantages of each imaging modality can be combined. Precise immobilization of the patient is a prerequisite. The immobilization method has an accuracy of less than 1 mm. This method was evaluated in a clinical study in which a tumor control rate of 93% was achieved in patients with brain metastases after stereotactic single high dose radiotherapy. This indicated the excellent reliability of this treatment planning method. The integration of functional image information, such as blood flow or activation of cerebral cortical areas, will be evaluated in the future.

A treatment planning system for stereotactical neurosurgery has been developed. A modular system has been designed which is readily extendable. Different modalities of tomography (CT, MRI) can be correlated and presented simultaneously in transverse, frontal and sagittal reconstructions. The volumes of interest are segmented with respect to the different modalities, and the positions of the catheters are defined. The calculation of dose must be adapted to the physical requirements of the therapy and is designed as an independent process. The calculated data are shown in various presentations. The treatment planning system is applied to intratumoral chemotherapy. The drug is encapsulated in small carriers for prolonged release and injected via catheters directly into the tumor interstitium, bypassing the blood-brain barrier. The dose is calculated using the time-dependent, three-dimensional finite elements method. To achieve homogeneous temporal and spatial drug distribution it is necessary to use a great number of catheters due to the limited diffusion of drug, which is not practical in neurosurgery. Therefore this therapy concept is useful for small volumes only. Interstitial hyperthermia and brachytherapy, in contrast to intratumoral chemotherapy, show successful clinical results.

Unlabelled: The aim of 3D radiotherapy treatment planning is to match the dose as closely as possible to the target volume, thus avoiding side effects in healthy tissue and radiosensitive organs at risk. A virtual radiotherapy simulator designed for the definition of treatment parameters and the analysis of precalculated dose distributions enables iterative optimization of treatment plans., Methods: VOXELPLAN is a software package for 3D radiotherapy treatment planning developed at the German Cancer Research Center; it consists of user interfaces for image segmentation, virtual therapy simulation, dose calculation, plan evaluation and patient documentation. It is written in C and FORTRAN and runs on VAXstation 4000, IBM RS/6000 and DEC ALPHA hardware., Results: Since 1990 a pilot installation of VOXELPLAN has been applied in clinical routine at the Center and at the University Clinic for Radiology, Heidelberg. Treatment for more than 1500 patients has been planned and carried out using the system, proving its technical and organizational applicability., Conclusions: We expect better acceptance and further dissemination of the techniques described, conformation therapy as well as (after its technical realization) inverse planning, from continuous optimization of the planning process.

Purpose: Since 1991 the use of three-dimensional planned radiation therapy for rectal cancer was evaluated as a part of a clinical project funded by the Deutsche Krebshilfe at the Radiological Department of the University of Heidelberg. First clinical experiences are reported., Patients and Methods: 32 patients who were irradiated loco-regional for rectal cancer were analysed retrospectively. Radiation therapy techniques: patient's position was prone by the use of a belly board. Three-dimensional treatment (3D) planning system was voxelplan. The radiation therapy was started using a 3-field-box technique modified by 3D-technique after 22 to 42 Gy, depending on therapeutic concept., Results: On average 92% of the planning target volume were encompassed with the 80% isodose. The average maximum dose was 108% (isocenter = 100%), of the small bowel volume received less than 34% of the dose, 70% of the bladder volume less than 40% respectively. Total average dose was 52.4% Gy. Irregular fields were used in all patients, a non-coplanar field was used to optimize dose-distribution in 41% of the patients, 21 patients received chemotherapy simultaneously. Acute side effects according to gastrointestinal tract reached grade 1 (WHO) in 9 patients, grade 2 in 2 patients. Side effects according to bladder reached grade 1 in 5 patients grade 2 in 1 patient respectively. In 4 patients suffered from acute side effects concerning the bladder. In one patient acute side effects grade 1 concerning gastrointestinal tract was observed. Portal films were analysed to evaluate precision of radiation therapy. On average the error was 3.1/4.5/4.0 mm in the x/y/z direction respectively. The standard deviation was 4.4/6.8/6.3 mm for x/y/z respectively. A median time of 2 hours was necessary for all planning procedures., Conclusions: Three-dimensional treatment planning optimizes dose-distribution in a relevant number of patients. Its clinical use for treatment of large targets or in order to applicate high doses is justified. Planning target volume should cover the clinical target volume with a margin of 1.5 cm.

We have offered the so-called "triple-marker screening" since May 1991 to all patients who came for prenatal care and did not select an invasive procedure primarily. First evaluation of 5210 cases revealed that 3.7% were test-positive for neural tube defects, 13.8% for Down's syndrome and 0.5% for both at the same time. The explanation for the comparatively high "test-positive" rate of 13.5% is the maternal age distribution with the median at 31.4 years. The highest number of women selecting triple-marker determinations was in the age group of 35 years. We detected 16 cases of Down's syndrome and in this group the majority of women was below 35 years. The decision of women to have an invasive procedure was obviously very much influenced by the actual risk assessment, because amniocentesis was chosen by 72/85 (84.8%) of women with a risk of more than 1:50, 192/290 (66.2%) of women in the risk category of 1:51 to 1:200 and 182/333 (54.6%) in the risk category of 1:201 to 1:400. The follow-up is not yet complete, but there is already good evidence for the efficiency of the screening program. Triple-marker screening also proved predictive in 10 cases of trisomy 18 and 8 cases of triploidy in this series. As a cut-off value we chose the risk of 1:386 which is equivalent to the odds of a 35 year old to have a child with Down's syndrome at birth.(ABSTRACT TRUNCATED AT 250 WORDS)

Biochemical markers of bone metabolism are not well established as diagnostic tools. Recently, a new radioimmunoassay has been described, that specifically detects the carboxyterminal telopeptide of type I collagen (ICTP). We have used this method in our studies. Ten menopausal women, age 49-64, received 1.25 mg conjugated estrogens (Presomen) within three cycles of 20 days and 8 days pause. Before and under therapy following parameters have been estimated: cholesterol, LDL, HDL, triglycerides, estradiol, FSH, prolactin, thromboxane B2- 6-ketoprostaglandin F1 alpha, ICTP, and the carboxyterminal propeptide of type I procollagen (PICP). Administration of Presomen resulted in significantly increased levels of HDL. Hormonal replacement therapy (HRT) also resulted in significantly decreased levels of cholesterol, LDL, triglycerides, FSH, prolactin, ICTP, and thromboxane B2. PICP and 6-ketoprostaglandin F1 alpha were uneffected by HRT. Our studies confirm the favorable effects of HRT on lipoprotein metabolism. In addition to these findings we noted a beneficial effect on the arachidonic acid metabolism and on the bone resorption, this requires confirmation in clinical trials.

The routine use of three-dimensional treatment planning was evaluated in a clinical project funded by the German Krebshilfe at the Radiological Department of the University of Heidelberg. 166 patients entered the prospective study within 14 months, 155 of them were treated according to the 3D-plans. More than 50% of the patients had thoracic tumors, followed by pelvic tumors. One medicine physicist and one specially trained technician performed the treatment planning. The target volumes were contoured in the CT slices at the planning computer by the responsible radiotherapists. A mean of 6.5 hours per patient was necessary for all planning procedures, however, this time consumption shows a trend toward less time of only four hours including about ten optimization steps. Meanwhile approximately 20 to 30% of all computer assisted planning are performed in 3D, corresponding to about one plan per day. The achieved time consumption is a clinically accepted quantity, that allows the introduction of 3D-planning into clinical routine.

In the Department for Gynecology and the Department for Gynecologic Radiology, University of Heidelberg, breast conserving therapy was carried out in 1,330 patients with breast cancer between 1975 and 1990. The tumor size was up to 3 cm, 28% showed positive nodes. The medium age was 47.6 years, segmental resection was the standard operation, whole breast irradiation with 50 Gy and an additional boost of 10 Gy was standard irradiation schedule. After five years (n = 307) the following results were observed: local failure 6.8%, regional lymph node recurrence 2.1%, overall survival 88.3%, disease-free survival 81.2%. Five out of 36 of the death-cases died without recurrence. Significant factors for local failure were following: 1. lymphangiosis of more than 1 cm in size around the tumor (p = 0.03); 2. intra-ductal non-invasive cancer of more than 1 cm in size around the primary (p = 0.01); 3. intra-ductal non-invasive cancer reaches the margin of resection (p less than 0.00001). With segmental resection (2 cm margin macroscopically free of tumor) showed in 19% histologically tumor beyond the margins so-called residuals. In the other three quadrants additional second primaries of (multicentric cancers) macroscopical size could be confirmed in an additional study. In case of high risk for local failure more radicality in operation as well as in irradiation is recommended.

3D Reconstructions from tomographic images are used in the planning of radiation therapy to study important anatomical structures such as the body surface, target volumes, and organs at risk. The reconstructed anatomical models are used to define the geometry of the radiation beams. In addition, 3D voxel models are used for the calculation of the 3D dose distributions with an accuracy, previously impossible to achieve. Further uses of 3D reconstructions are in the display and evaluation of 3D therapy plans, and in the transfer of treatment planning parameters to the irradiation situation with the help of digitally reconstructed radiographs. 3D tomographic imaging with subsequent 3D reconstruction must be regarded as a completely new basis for the planning of radiation therapy, enabling tumor-tailored radiation therapy of localized target volumes with increased radiation doses and improved sparing of organs at risk. 3D treatment planning is currently being evaluated in clinical trials in connection with the new treatment techniques of conformation radiotherapy. Early experience with 3D treatment planning shows that its clinical importance in radiotherapy is growing, but will only become a standard radiotherapy tool when volumetric CT scanning, reliable and user-friendly treatment planning software, and faster and cheaper PACS-integrated medical work stations are accessible to radiotherapists.

Gonadal function was evaluated in 25 boys treated for Hodgkin's disease according to the DAL-HD-85 protocol with OPA- or OPA/COMP-chemotherapy (vincristine-prednisone-adriamycine/cyclophosphamide-vincristine-m ethotrexate- prednisone). All boys were in first continuous complete remission for 6 to 45 months at chronological ages varying from 14.0 to 18.9 years. Testosterone, basal and GnRH-stimulated LH- and FSH-levels were measured. Gonadal function was normal in 16 patients treated with 2 cycles of OPA-chemotherapy in Hodgkin stages I-IIA. 9 patients were treated with 2 OPA- and 2 or 4 COMP-cycles of chemotherapy and had received mean cyclophosphamide doses ranging from 2004 to 3722 mg/m2. Again, no major testicular damage was noted, though some patients had increased stimulated LH-levels possibly indicating compensated Leydig cell-insufficiency. Our results demonstrate, that testicular function is not severely affected when patients are treated for Hodgkin's disease without procarbazine even if cyclophosphamide is given in cumulative doses below 3800 mg/m2. The previously documented severe testicular damage in boys treated according to the DAL-studies HD-78 and HD-82 is thus a result of the gonadotoxic action of procarbazine.

Compared with conventional radiation treatment techniques, quality assurance for dynamic techniques has to consider additionally the variability of the movement parameters of the treatment unit. In this context the exactness and the reliability of the computer control are of special interest. In this paper the results of quality assurance for dynamic treatment techniques are reported. At first investigations concerning the reproducibility are carried out. Another test is the simulation of conventional moving beam techniques by external computer control. Further the differences between measured dose distributions of dynamic techniques and the distributions resulting from the sequence of fixed fields approximating these techniques are determined. Finally we compared measured and calculated dose distributions. The results of the investigations justify the introduction of dynamic radiation treatment techniques into clinical use.

Four experimental series were applied to 342 prepuberal young sows to establish ovulation developments. Different periods of time were allowed to elapse between injection and slaughter. Injected were 400 IU PMS/200 IU HCG or 500 IU PMS/250 IU HCG. Onsets of ovulation were found to be highly differentiated and variable. Some of the animals had completed ovulation 72 hours after application of gonadotrophin, whereas in others had not even started 168 hours after such application. In the majority of all sows involved in the experiments ovulation occurred 96--144 hours from application of the gonadotrophis hormone. In other words, fertile semen should be present in the genital tract of sows in that period of time, if the concept of deadlineoriented insemination is followed.

A further specific, reproducible radioimmunoassay of cholecystokinin-pancreozymin was developed. 125J-labelled 39-CCK was used as tracer. The limit of detection for CCK in serum was 40 pg/ml. Basal levels for CCK have been found to be 222 pg/ml, being increased after food ingestin. No crossreactivity with gastronintestinal hormones could be observed. Somatostatin was inhibiting the stimulated CCK-release. Histochemical and radioimmunological determinations localized CCK-containing cells in duodenal tissue of humans. Physiological and pathological processes in which CCK is involved have to be studied to evaluate its role in the gastrointestinal tract.

Cryosurgery of the prostate should be performed only in high risk patients on which other conventional methods of treatment cannot be applied. 82% of the patients could void after cryosurgery without indwelling catheter. Cryosurgery of the prostate became one of the routine procedures in the treatment of the prostatic diseases.