Biomedical subjects
Publications and source records attributed to H Gremmel.
Presentation of causes, clinical- and radiographic findings and therapy of chylothorax, along with a review of the anatomy of the thoracic duct. Radiographic demonstration of the thoracic duct by lymphography is necessary prior to surgery in order to demonstrate the site of the lesion to assure reasonable ligation.
Fifty-four usual cases of radiation therapy were evaluated, comparing the effective surface doses in sound tissues for different irradiation techniques. Irradiation of the esophagus, mediastinum, lung and bladder was calculated for the cross-fire method, 3-field therapy, and monaxial or biaxial pendulum technique. Pendulum irradiation proved superior to multiple-field techniques in all cases. The number of free parameters in computer-assisted relative optimization of dose distributions can be reduced by means of the determination of the irradiation technique.
By means of deconvolution, which can be preformed simply with a minicomputer, a new function is derived from the circulation activity time function and the renal activity time function. This function describes the impulse response of the system "Kidney". The activity time functions are determined with a four-probe counter. The impulse response allows statements about the time during which the activity remains in the kidney, the relative blood flow of both kidneys and a so-called passage time distribution. It was also attempted to substitute the circulation activity time function by a derivative of the bladder activity time function.
Computational methods for the determination of normal tissue tolerance under various modes of dose fractionation are applied at many radiation therapy installations. The methods differ in details, but most are based on the Ellis-formula. A survey of the relevant quantities and relations is given in order to facilitate comparison of the various methods. The established equations which are applicable to regular fractionation are related to the generalization of the Ellis-formula which is also applicable to irregular fractionation modes.
A general formula for consideration of the dependence of tolerance doses upon volume is obtained by mathematical evaluation of known skin tolerance doses. The validity for different organs is verified using available data of literature. It is recommended to introduce the volume dependence into the Ellis-formula for tolerance doses.
Malignant tumors of man have duplication times ranging between few days and several years. This fact allows to estimate the age of tumor and metastases. The decision whether a curative of a palliative irradiation is to be executed can be taken according to the development and the age of the tumor. The duplication time has an influence on the fractionation of the irradiations and the possible focal dose and also on the time after which check-up examinations are to be made. A method for the determination of the tumor volume by means of radiographs is described in the appendix.
The utilization of the Ellis-formula for the determination of the tolerance of normal connective tissue is described. Beyond this, the formula is adapted to so-called critical organs. The individual suppositions implicated by the Ellis-formula are commented. Because of the verifyable congruency of the Ellis-formula with data obtained in clinical practice also by other authors, this conception is presented for the provisional determination of the limits of tolerance of normal tissue together with a computerized programme elaborated for use in different therapeutic techniques.
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