Radiologia clinica最新文献

The initial shape of a cellular dose-survival curve is a factor of major importance in determining radiotherapy responses. It is probable that survival curves for mammalian cells exposed to X- and gamma-rays, as well as higher LET beams have an initial exponential region after which they bend downwards. The slope of this initial segment of the curve, and more importantly, the width of the shoulder before it bends significantly are the subject of the investigations to be reported. Because of the difficulty in measuring the biological effects of low doses of radiation--particularly in vivo--we have used multifraction experiments to determine the effects of the fractional doses. Such studies help determine the width of the shoulder and, with less precision, the slope of the initial part of the curve. The tissues we have studied include the bone marrow, testis, fibrovasculature, transplantable tumors, and the gastrointestinal tract. The results will be presented and some of the difficulties in their interpretation will be discussed.

This study presents an analysis of the nature and incidence of pulmonary complications in the first 110 patients to undergo renal transplantation in Nijmegen. The complications are divided into primary and secondary complications. An unmistakable relation to immunosuppressive medication was established in both groups. The radiological manifestations of the pulmonary lesions were atypical due to the use of large doses of immunosuppressive drugs. Pulmonary complications account for 45.1% of the total mortality after renal transplantation. Differential diagnosis from pulmonary oedema associated with rejection is exceedingly difficult, but of paramount importance.

Measurement of the spatial distribution of the clearance rate of xenon-133 from the kidney after its injection into the renal artery for estimating intrarenal blood flow can easily be combined with selective X-ray angiography as a routine method. Using a gamma camera as detection equipment anand applying a special computer analysis technique, 'functional images' can be obtained, by which the spatial distribution of the blood flow in the kidney is quantitatively mapped. Experiments with a rather heterogenous group of 12 patients suggest that in at least one type of renal pathology the xenon-133 flow study is more indicative for clinical evaluation than the X-ray angiography

2 cases of absent cervical pedicle are presented. It is important to be acquainted with this condition to be able to differentiate it from dumbbell tumour. Some other lesions which simulate it are briefly mentioned.

In 61 of the 110 patients with renal transplantation an angiography was performed. Besides the indication for angiography different pathological changes are illustrated: arterial stenosis, arteriovenous fistula, dissection of the arterial wall. Before angiography it is necessary to be informed about the operation technique. Sometimes different projections must be applied to get sufficient information about the arterial system of the transplant.

A computer-based data retrieval system for clinical research in oncology is described. The system has been designed to enable busy clinicians to retrieve and analyze data directly without major involvement of a computer specialist. The system uses texts similar to those in daily practice. In most situations no code is printed. The other important feature of the system is its ability to analyze clinical data in the form of tables, frequency distribution, etc. It may also furnish actuarial characteristics of the total population or subpopulations. Mathematical functions are calculated easily. Amendments and updating are simple enabling follow-up data to be incorporated. The system is under use for about 2 years and appears to be a versatile tool in the field of clinical research.

The experimental determination of the dose distribution in the body of patients treated with high-energy electrons is very difficult and inaccurate as, among other things, the body contours and the size of the patient's organs are seldom identical with those of a phantom. With the aid of the computer, it is possible to elaborate quickly for each treatment isodose plans sufficiently accurate for practical application. The dose distribution depends on the following factors: number of fields or rotation angle, size of the radiation fields, electron energy, curvature of the body surface and shape and composition of the organs. With the aid of the computer, which is capable of simulating a multiple-field or moving-beam irradiation by the summation of the dose values of two or more single fields, the above-mentioned parameters can be changed as required and thus various types of treatment plans can be prepared. Prior to the treatment, the radiotherapist can select the optimal plan for the case in question from a number of possibilities.