Early Behavioral Analysis of Low-Dose-Rate, High-Dose Gamma-Irradiation Effects

1964 ◽  
Vol 22 (2) ◽  
pp. 398
Author(s):  
Gilbert W. Meier
Keyword(s):  
Gamma Irradiation ◽  
Dose Rate ◽  
Low Dose ◽  
Behavioral Analysis ◽  
High Dose ◽  
Irradiation Effects ◽  
Low Dose Rate

LOW-DOSE-RATE OR HIGH-DOSE-RATE BRACHYTHERAPY IN COMBINATION WITH EXTERNAL BEAM RADIOTHERAPY FOR INTERMEDIATE AND HIGH-RISK PROSTATE CANCER

2018 ◽  
Vol 64 (1) ◽  
pp. 79-83
Author(s):  
Vladimir Solodkiy ◽  
Andrey Pavlov ◽  
Aleksey Tsybulskiy ◽  
Anton Ivashin
Keyword(s):  
Prostate Cancer ◽  
High Risk ◽  
Dose Rate ◽  
Low Dose ◽  
External Beam Radiotherapy ◽  
Combined Treatment ◽  
High Dose ◽  
External Beam ◽  
Low Dose Rate ◽  
Risk Of Progression

Introduction. One of the main problems of modem on-courology is treatment for prostate cancer of intermediate and high risk of progression. Modern radiotherapy in this category of patients has an advantage over surgical methods of treatment. One way to improve the effectiveness of radiotherapy is to escalate the dose in the prostate gland. For this purpose a combination of brachytherapy and remote radiotherapy is used. This combination allows increasing the dose of radiation, thereby providing better local control, reducing complications from neighboring organs. Purpose of the study. To conduct a comparative analysis of efficacy and safety of radical treatment of patients with prostate cancer at medium and high risk of progression using a combination of high and low dose rate brachytherapy with external beam radiotherapy. Materials and methods. 107 patients with prostate cancer of the group of medium and high risk of progression combined treatment (brachytherapy with external beam radiotherapy) was conducted. 53 patients underwent combined treatment (HDR-brachytherapy and external beam radiotherapy). 54 patients underwent combined treatment (LDR-brachytherapy and external beam radiotherapy). The observation period was 5 years. Conclusion. In a comparative analysis in groups of combined radiotherapy with the use of high-dose and low-dose-rate brachytherapy, the same effectiveness of immediate and long-term results of treatment was demonstrated. A significant reduction in early and late toxic reactions in patients with high-power brachytherapy has been demonstrated.

A study of the effect of X-rays on the electrical properties of mammalian nerve and muscle

1963 ◽  
Vol 157 (969) ◽  
pp. 536-561 ◽  
Keyword(s):  
Dose Rate ◽  
Action Potentials ◽  
Time Course ◽  
Low Dose ◽  
High Dose ◽  
X Rays ◽  
Low Dose Rate ◽  
End Plate ◽  
Small Doses ◽  
Motor End Plate

Resting potentials, action potentials, and miniature end-plate potentials have been re­corded from isolated phrenic-diaphragm preparations of the rat during and after irradiation with X-rays. Relatively small doses of a few thousand roentgens have no obvious effect on the preparation for many hours but larger doses, of the order of 70 to 150 kr irreversibly block neuromuscular transmission. The block is not accompanied by any change in the size of action potentials, resting potentials, membrane constants or miniature potentials recorded in the muscle with intracellular electrodes, or in the size of action potentials recorded in the nerve. Records made at the motor end-plate show that the cause of the block is a ‘pre-synaptic ’ failure of impulse propagation in the intramuscular part of the nerve. The time course of the failure depends largely on the rate at which X-rays are delivered to the pre­paration: at a high dose-rate (70kr/min) the block develops rapidly and is accompanied by an increase in the frequency of miniature potentials; at a low dose-rate (7 kr/min) larger doses are required, the latency is longer and the miniature potentials continue at a normal frequency. The sequence in which different parts of the muscle become blocked, the abrupt nature of the failure at an individual motor end-plate, and the increase in frequency of the miniature potentials together suggest that the action of X-rays is to block conduction in the nerve near its terminals, possibly by depolarizing points where the axons branch and the safety factor for the propagation of impulses is low. The results reported in this paper do not support the hypotheses that small doses of X-rays at a high or a low dose-rate lead to an initial 'enhancement' of function or that they produce immediate and reversible changes in the permeability of excitable membranes to ions.

Sign in / Sign up

Export Citation Format

Share Document