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Biomedical subjects

A M Perry

Publications and source records attributed to A M Perry.

9 recordsLinked to original sources
PubMed1989

Stereotactic radiosurgery.

Stereotactic radiosurgery is the accurate focusing of ionising radiation onto an intracranial target, and was pioneered in Sweden in the early 1950's. It has proven effective in the treatment of arteriovenous malformations, acoustic tumours and many other small brain lesions. In the last decade the commercial availability of a gamma ray system has led to other centres following the work in Stockholm; more recently, various techniques utilising linear accelerators, (LINACs), have been developed. Both types of system necessitated special dosimetry and treatment planning methods for the small, high dose-gradient circular fields. Localization of the lesions requires angiography, computerised tomography (CT) or magnetic resonance imaging (MRI).

Brain Diseases↗
PubMed1982

Dose response experiments using the mouse tail model.

Radiation induced tail necrosis in BALB/c mice was used to investigate the effects of tissue temperature and local oxygenation on the radiation response. Single doses of 250 kV roentgen-rays were given over the temperature range 32.5 to 37 degrees C and dose response curves obtained. The temperature dependence of the response was shown to be consistent with changing hypoxic status by the derivation of a simple model; this has practical implications for the treatment of patients using simultaneously combined radiation therapy and hyperthermia.

Animals↗
PubMed1980

An investigation of the alternating fractionation formula of the Cumulative Radiation Effect.

The alternating fractionation formula of the Cumulative Radiation Effect (CRE) system was investigated using the mouse intestinal crypt system as a method of assessment of the amount of radiation damage in a normal tissue. The experimental results revealed that the formula is correct in predicting an increased effect with alternating large and small sized fractions, when compared with a standard schedule where the fraction size was kept constant but achieved the same total dose. However, the results also demonstrated that the order in which the alternate fractions were administered affected the amount of radiation damage produced in the tissue. This observation is in contradiction to another prediction of the formula, that the order in which equal numbers of fractions of different magnitudes are administered, will have no effect on the biological end point. The formula, therefore, is only an approximate model of radiation damage in normal tissue and much more information is required before it can be improved upon.

Animals↗
PubMed1979

Investigation of time-gap formulae on the CRE system using mouse tissue as a biological model.

The cumulative radiation effect (CRE) is one of several empirical scalar descriptions of biological effect which enable corrections to be made for gaps in radiotherapy treatment. Predictions of this theory were tested using mouse crypt regeneration and mouse skin as biological models. These experimental results are discussed in terms of the dependence of tissue regeneration potential during a gap on the biological effect achieved before the gap, and on gap length. A hypothesis is proposed to reconcile the apparent conflict between the two experiments. While the simple exponential gap formulation of the CRE is seen to be inadequate, insufficient data are available at present to modify it.

Animals↗
PubMed1977

An assessment of a non-invasive technique for measuring deep body temperature.

The assessment of a non-invasive technique for measuring deep body temperature is described. An experimental system, in which the insulating effect of subcutaneous fat thickness could be simulated, was designed to test the deep body thermometer (DBT). The assumption that the instrument produced zero temperature gradient was found to be incorrect, and a mathematical model was developed which showed that the cyclically varying output of the device is an inherent property of its design. The accuracy and response time were investigated as a function of tissue thickness to assess the instrument's clinical usefulness.

Adipose Tissue↗