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Biomedical subjects

W H Thomson

Publications and source records attributed to W H Thomson.

At least 55 records · Page 3Linked to original sources
PubMed1991

Radiation dose rates from paediatric patients undergoing 99Tcm investigations.

Infants or children undergoing nuclear medicine investigations may subsequently come into close contact with nurses or parents responsible for their care. In order to estimate the radiation dose to these individuals, and to formulate appropriate recommendations, dose rates were measured at distances of 0.1, 0.5 and 1.0 m from 148 paediatric patients who had undergone one of 12 99Tcm studies. The maximum dose rates of 70, 14 and 5 microSv h-1 at these distances were not greater than the corresponding maximum values found in an earlier study of adult patients. However, the maximum dose rates per unit activity of 0.5, 0.2 and 0.1 microSv h-1 MBq-1 were greater than the corresponding maximum 99Tcm adult values, consistent with a general increase of dose rate per unit activity with decrease of body weight observed in the paediatric measurements. A parent caring for and feeding a young infant is most unlikely to receive a dose equivalent of 1 mSv, and a nurse attending to one young radioactive patient is most unlikely to receive a dose equivalent in a working day of 60 microSv. The data obtained should allow radiation doses to be estimated and appropriate recommendations to be formulated for other circumstances, including any future legislative changes in dose limits or derived levels.

Adolescent↗
PubMed1990

The radiation dose to accompanying nurses, relatives and other patients in a nuclear medicine department waiting room.

The radiation dose to accompanying nurses, relatives and other patients in a nuclear medicine department waiting room was assessed at 5 min intervals by observing the seating arrangement. The total radiation dose to each person was calculated, using fixed values of dose rate per 100 MBq activity for radionuclides, and applying the inverse square law. Radioactive decay and attenuation effects due to intervening persons were also taken into account. The median radiation doses to accompanying nurses, relatives and other patients were 2.3, 2.0 and 0.2 microSv with maximum values of 17, 33 and 5 microSv respectively. In all cases, the radiation dose received by patients was less than 0.2% of the radiation dose resulting from their own investigation. Also, the maximum radiation dose received by an accompanying nurse or friend was less than 1% of their appropriate annual dose limit. Similar values were obtained with calculations based on a 15 min time interval. The radiation doses received by those in a nuclear medicine department waiting room are small, and separate waiting room facilities for radioactive patients are unnecessary.

Family↗
PubMed1990

Staff radiation doses associated with nuclear medicine procedures--a review of some recent measurements.

Despite publication of the Approved Code of Practice and the Notes for Guidance, implementation of the UK Ionising Radiation Regulations has required local interpretation by nuclear medicine departments. One problem has been the lack of data upon which decisions can be based. In the last five years we and others have made a number of measurements of radiation doses to staff relating to nuclear medicine practice. This paper collates, summarizes and comments on this information. Where possible, results have been expressed in relation to the workload of an average nuclear medicine department.

Environmental Exposure↗
PubMed1989

A multiple regression analysis for accurate background subtraction in 99Tcm-DTPA renography.

A technique for accurate background subtraction in 99Tcm-DTPA renography is described. The technique is based on a multiple regression analysis of the renal curves and separate heart and soft tissue curves which together represent background activity. It is compared, in over 100 renograms, with a previously described linear regression technique. Results show that the method provides accurate background subtraction, even in very poorly functioning kidneys, thus enabling relative renal filtration and excretion to be accurately estimated.

Humans↗
PubMed1987

Mathematical prediction of ileal pouch capacity.

Restorative proctocolectomy is an operation still in the stage of development. Three main types of ileal pouch construction are used, but the advocacy of each probably arises more from familiarity and convenience than from scientific considerations. Since, other things being equal, pouch capacity can be expected to affect stool frequency, it seemed reasonable to examine calculable pouch capacity geometrically for different methods of construction. A mathematical model was therefore used to compare the double loop ('J') type with the quadruple loop ('W') construction. The W was estimated to have a capacity more than half as great again as the J. Similarly anastomotic methods which encroach on the ileal circumference by creating an inverted edge can be expected to reduce resultant capacity by 10 per cent or more.

Colectomy↗
PubMed1987

Identifying and circumventing the defect in Duchenne muscular dystrophy: clinical and biochemical restoration after practical intervention.

Both direct and indirect experimental evidence independently confirms that inadequate muscle purine biosynthesis is the basic lesion in Duchenne muscular dystrophy (DMD), and indicates the presence of a partial defect at adenylosuccinate synthetase. Purine conservation by oral allopurinol gives only limited improvement, but continuous infusion of adenylosuccinate causes an immediate and lasting increase in physical strength, with restoration to normal of the abnormal serum enzyme elevations, creatine/creatinine metabolism, heart rate and ECG. Mass screening of male infants by a blood-spot test is proposed for early detection and treatment of all DMD cases, including the mutant one third with no family history. Prospects of the eventual disappearance of clinical DMD now appear possible.

Adenosine Monophosphate↗
PubMed1986

On-table lavage to achieve safe restorative rectal and emergency left colonic resection without covering colostomy.

On table orthograde colonic lavage has been used in a nearly consecutive series of 122 cases of restorative rectal resection (16 for acutely obstructing rectosigmoid lesions), and in a further 4 cases of acutely obstructing left colonic carcinoma, with the aim of both achieving safer anastomoses in these adverse circumstances and avoiding a covering colostomy. The technique was found to be safe and to be effective, only five temporary colostomies being required for management of anastomotic leakage. The incidence of clinical anastomotic leakage was 4.8 per cent.

Adult↗
PubMed1986

Implications of the ionizing radiations regulations for typical nuclear medicine departments.

The application of the 1985 Ionizing Radiations Regulations and Approved Code of Practice to a typical Nuclear Medicine Department has been considered. References to the Regulations are given so that their implications in a given department may be examined. The radiopharmacy, radioisotope dispensary and injection room will need to be Controlled Areas. It will also be necessary to designate Controlled Areas if radiopharmaceuticals are injected in imaging rooms or on wards. Waiting rooms will need to be Controlled Areas. The area around individual patients will, however, not need to be Controlled except for some patients receiving therapeutic doses of 131I for thyrotoxicosis. It should not generally be necessary to designate employees as Classified persons. Major problems in implementing the Regulations are not envisaged in situations where the previous Code of Practice has been followed.

England↗
PubMed1986

Exercise training effects on serum lipids of prepubescent boys and adult men.

The effects of 10 wk of exercise training at low (40% VO2max) or high (75% VO2max) intensity on serum lipids and lipoproteins were compared in prepubescent boys and adult men. The final sample size consisted of: 8 boys (mean +/- SE age = 8.5 +/- 1.96 yr) and 8 men (36.6 +/- 3.18 yr) in low; 12 boys (8.0 +/- 1.40 yr) and 12 men (36.6 +/- 4.09 yr) in high; and 10 boys (9.0 +/- 2.08 yr) and 10 men (36.7 +/- 4.82 yr) in control. Training involved walking/jogging/running 3 d X wk-1 at a distance which progressed from 2.4 km X d-1 in the first week to 4.8 km X d-1 from the fifth week. Fasting blood samples, collected on 2 d during both pre- and post-training, were assayed for triglycerides, total cholesterol (CHOL), and high density lipoprotein cholesterol (HDL-C). Maximum aerobic power (VO2max) was determined from a treadmill test. Additionally, dietary intake was assessed from a 3-d dietary record and body composition from the sum of 6 skinfolds. The only statistically significant (P less than 0.05) changes occurred in HDL-C and CHOL for the high groups. HDL-C decreased following training. CHOL was lower for high than the other groups for the first day post-training only. There were no differences in the changes in HDL-C/CHOL ratio among the groups. VO2max only increased in the high groups. Dietary intake and body weight did not change. Further statistical adjustment in lipids for changes in sum of 6 skinfolds did not alter the results.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Clinical trials of allopurinol in Duchenne muscular dystrophy.

A wide range of different disturbances characteristic of Duchenne muscular dystrophy (DMD) can be attributed to a fundamental chronic shortage of intracellular adenosine 5'-triphosphate (ATP), in turn arising from a basic lack of total adenylate. Purine conservation by the hypoxanthine isomer allopurinol, which promotes salvage and inhibits catabolism, greatly increases muscle ATP and total adenylate, with corresponding clinical benefit. Among subsequent confirmatory clinical trials some gave positive results, while others provided no information. Reasons given why these latter proved uninformative include asking questions either irrelevant and/or incapable of being answered, not least in older boys with too much shrinking fibrous tissue infiltrating too little remaining muscle. Informative results from any metabolic intervention can be expected only where sufficient muscle is left to respond, and this age-linked effect is everywhere evident in the positive trials. Thus, if an effect of allopurinol now seems apparent, and since it is extremely safe and does not enter the genetic material, it is suggested that it be administered shortly after birth before irreversible pathological changes occur. This implies neo-natal male mass screening, easily accomplished by a simple dried-blood spot test, and already carried out successfully elsewhere.

Adenosine Triphosphate↗