Search PubMed⌕ Search

Biomedical subjects

L K Harding

Publications and source records attributed to L K Harding.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1985

Dose rates from patients having nuclear medicine investigations.

Dose rates have been measured at 0.1 m, 0.5 m and 1.0 m from patients in a Nuclear Medicine Department. Data are presented for a variety of Nuclear Medicine procedures using doses of radiopharmaceuticals within the recommendations of the administration of Radioactive Substances Advisory Committee (ARSAC). The corresponding figures when the patient left the department, and the time average dose rate over the next 8 h were calculated. At 1.0 m the dose rates do not exceed 7.5 microSv h-1, and at 0.5 m the time average dose rate does not exceed 60 microSv h-1. Assuming that the nurse is as close to the patient as 0.1 m for 20 min in a working day, the accumulated dose over a working day would not exceed 60 microSv.

Hospital Departments↗
PubMed1985

The value of syringe shields in a nuclear medicine department.

The radiation dose to the pulp of both index fingers has been measured in a radiopharmacy supplying 11 000 patient doses a year, in a hospital dispensary (4500 doses a year) and in its injection area. Tungsten syringe shields were used for one week and not used during the other week. In the radiopharmacy and the dispensary the highest finger dose recorded was 6.8 mSv, which corresponds to an annual figure of 330 mSv. Syringe shields gave a protection factor of less than two, and the dose to the left hand was approximately half that to the right. When giving injections the corresponding weekly and annual doses were 4.6 and 220 mSv respectively. If all injections had been given by a single person the corresponding annual dose would have been 430 mSv. Using syringe shields this could be reduced by factors of at least eight for the right hand but only 1.3 for the left hand. Dose rates for unshielded syringes expressed per 10 GBq handled are similar to other data in the literature. However, syringe shields reduce the dose rates less than anticipated. Tungsten 1.94 to 3.05 mm thick would be expected to give an attenuation factor of 27 to 178.

Body Burden↗
PubMed1984

Gastric histology and its relationship to entero-gastric reflux after duodenal ulcer surgery.

Thirty-six volunteers, asymptomatic 7 to 22 years after various operations for duodenal ulcer, were screened for enterogastric reflux by external scanning following injection of 99mTc HIDA; they also had endoscopy for measurement of the fasting juice pH, and multiple biopsies. In patients with a pH above 4 there was an association between a positive bile reflux test and the presence of pre-malignant changes in the gastric mucosa. Carcinoembryonic antigen in the gastric mucosa was found in all patients and was not, therefore, a useful screening test for stump cancer. Blind examination of two sets of endoscopic biopsies obtained 6 weeks apart in symptomatic patients with post-operative reflux gastritis showed that histological assessment remained reproducible. Gastric biopsies obtained from 16 patients before, and a year after, Roux-en-Y gastro-jejunostomy demonstrated that foveolar hyperplasia tended to regress after bile diversion.

Biopsy↗
PubMed1984

The incidence of duodenogastric reflux in peptic ulcer disease.

Using 99mTc diethyl HIDA, a gamma camera was used to assess duodenogastric reflux of bile in the supine position in control patients and patients with active duodenal ulceration. Cholecystokinin was injected intravenously during the test to contract the gall bladder. Patients with benign gastric ulcers, and a group of age matched controls, were investigated for duodenogastric bile reflux in the sitting position by a nasogastric aspiration technique after a 10% dextrose meal. Of 60 patients with duodenal ulceration 32 (53%) were reflux positive, and of 13 control patients 6 (46%) were positive. Of 30 patients with gastric ulceration 17 (53%) were reflux positive, and 8 out of 15 (53%) control subjects were positive. The incidence of duodenogastric reflux assessed supine in the fasting state, and seated after a liquid meal, was similar in patients with peptic ulceration and in normal controls.

Cholecystokinin↗
PubMed1984

Bile reflux after duodenal ulcer surgery. A study of 114 asymptomatic and symptomatic patients.

The hypothesis has been examined that the quantity of enteral contents refluxing into the stomach affects the severity of symptoms after peptic ulcer surgery. 99mTc HIDA scintigraphy was used to investigate the incidence and quantity of reflux in 20 normal subjects, in 94 symptomatic or asymptomatic patients after traditional operations for duodenal ulcer, and after revision of surgery for bile reflux gastritis. The percentage of the injected dose of 99mTc HIDA (PID) counted in the stomach area was used as an index of the quantity of refluxed bile. After duodenal ulcer surgery, symptomatic patients had a PID (6.2%) not significantly different (4.5%) from that of asymptomatic patients but higher than (2.1%) that of normals (p less than 0.05). After operations for reflux gastritis, 10 symptom free patients had no reflux, whereas 3 of 8 patients who remained symptomatic and had a short Roux-en-Y gastrojejunostomy, had persistent reflux.

Bile Reflux↗
PubMed1984

Does duodenogastric reflux affect the rate of gastric emptying?

The gastric emptying of a liquid meal (10% dextrose solution) and a semi-solid meal (minced meat, peas, potatoes and milk) was measured in the sitting position; both meals were 400 ml. Duodenogastric reflux was assessed supine after intravenous injection of 75 MBq of 99 mTc HIDA and cholecystokinin. Patients were ajudged reflux positive (R+), or reflux negative (R-) by looking at gamma camera pictures. Thirty-two duodenal ulcer patients (DU), 22 patients after truncal vagotomy and pyloroplasty (TV+P) and 21 after proximal gastric vagotomy (PGV) were studied. In DU sufferers the mean volume of early liquid emptying in R+ patients (74 ml) was similar to R- patients (78 ml). After TV+P early liquid emptying was greatly increased (mean 176 ml) but no difference was found between R+ and R- patients. After PGV excessive early emptying was less common but emptying was significantly greater in R+ patients (R+ mean = 132 ml, SD = 48 n = 8; R- mean = 63 ml, SD = 21, N = 13: t = 4.2 p less than 0.001). There was no difference in solid meal emptying between R+ and R- patients in any group.

Cholecystokinin↗
PubMed1984

The pharmacokinetics of 99mTc HIDA in man and its relationship to intra-gastric bile acids.

We have examined the pharmacokinetics of 99mTc diethyl HIDA in five patients with a T-tube inserted into their common bile duct after choledocotomy. Blood clearance was rapid with 27.5% of the injected dose in the circulation at 2.5 min and 5% at 30 min. The peak bile excretion of 15.4% occurred between 45 and 60 min after injection of the HIDA. By 2 h 69% of the dose was excreted in the bile and 14% in the urine. In a second group of 33 patients a naso-gastric tube was passed after injection of HIDA. The patients drank 400 ml of 10% dextrose and aliquots of the stomach contents were aspirated every 10 min for an hour. In specimens with a pH greater than 4, the amount of HIDA correlated well (p less than 0.01) with the amount of bile acid determined by an enzymatic method.

Adult↗
PubMed1984

Sensitivity and reproducibility of a bile reflux test using 99mTc HIDA.

We have studied the sensitivity and reproducibility of entero-gastric bile reflux measurements using a gamma camera. Aspiration of the stomach at the end of the study in a group of 14 patients showed that less than 1% of the administered HIDA was present in 7 patients who were judged reflux negative. In all 7 patients considered reflux positive, there was more than 1% of the dose in the stomach (median 8.2%, p less than 0.01 Mann-Whitney). The second group of 20 patients was studied twice in the same week with a 48 h interval between the tests. The results were reproduced in 15 patients (75%). Finally, the gamma camera technique was compared with nasogastric aspiration on a separate occasion. There was agreement in 16 patients out of 19(84%). These results suggest that the test is sensitive, and the lack of reproducibility is compatible with day to day variation in entero-gastric reflux.

Bile Reflux↗
PubMed1984

Quantitation and the elimination of errors in bile reflux tests using a gamma camera.

Entero-gastric reflux may be assessed quantitatively using 99mTc HIDA and a gamma camera. We have devised a computer program which applies corrections for several sources of error. The technique was validated using naso-gastric aspiration and phantom experiments. In 23 patient studies, 13 patients considered not to show reflux by visual assessment had a mean percentage injected dose (PID) in the stomach of 1.9% before correction and less than 1% after correction. The 10 patients with reflux showed a fall of PID from 5.8% to 1.7% as a result of the correction. In 14 patients the mean PID in the stomach after computer correction (3%) was not significantly different from that (3.5%) measured by aspiration. Computer correction of bile reflux data is essential when attempting to quantify the amount of entero-gastric reflux using a gamma camera.

Bile Reflux↗
PubMed1984

Does gastric entubation cause entero-gastric reflux?

Using 99mTc diethyl HIDA, we have examined patients with duodenal and gastric ulceration for the effect of naso-gastric intubation on bile reflux. Fourteen patients with duodenal ulceration were studied supine under a gamma camera. Activity from the stomach area showed no significant change before and after naso-gastric intubation (Mann-Whitney U = 0.18). Nineteen patients with gastric ulceration were investigated for bile reflux using two techniques. One method used the gamma camera but without naso-gastric intubation. The other method involved passing a naso-gastric tube and aspirating aliquots of a liquid meal which were analysed for 99mTc HIDA content. The incidence of bile reflux in patients with gastric ulceration was the same when the results of the two methods were compared. We conclude that investigation of groups of patients for duodeno-gastric reflux by naso-gastric aspiration of gastric contents is a valid technique.

Duodenal Ulcer↗
PubMed1984

Quantitative lung scintigrams and lung function in the selection of patients for pneumonectomy.

A method for predicting postoperative respiratory function following lung resection has been used in 11 patients with both histologically proven bronchial carcinoma and chronic obstructive airways disease, in order to assess their fitness for surgical treatment. Quantitative ventilation and perfusion scintigrams were used to measure the amount of functioning tissue in each lung. These data were used in conjunction with spirometric measurements to calculate the likely functional effect of pneumonectomy. There was a high degree of correlation (r) between predicted and measured lung function for both FEV1 (r = 0.75, P less than 0.01) and FVC (r = 0.88, P less than 0.01). The postoperative FEV1 was within 150 ml of the predicted value in 45% of the patients. In the remaining patients the actual volumes were greater than predicted by 210-540 ml. For FVC the results were within 150 ml of predicted in 45% of patients and in the remainder actual volumes were greater by 160-650 ml. Both sets of calculations underestimated lung volumes by an average of 200 ml. The method is shown to be accurate, simple, non-invasive, and readily available and brings a degree of objectivity to an important decision that is often based mainly on clinical assessment.

Aged↗
PubMed1983

Regional distribution of ventilation and perfusion in patients with obstructive pulmonary disease and alpha 1-antitrypsin deficiency.

Regional distribution of pulmonary ventilation and perfusion has been determined of 13 patients with chronic obstructive pulmonary disease (COPD). Eight patients had alpha 1-antitrypsin deficiency (alpha 1 ATD). Ventilation studies were carried out using xenon-133 (133Xe) and krypton-81m (81mKr) gases. Trapping indices were determined from the wash-out part of the xenon ventilation studies. Results obtained from patients were compared with those of normal controls. Ventilation studies with 81mKr showed pulmonary changes more clearly than did 133Xe studies and the trapping of radio-xenon was more extensive in lung bases than in apices whether or not the patients had alpha 1 ATD. The distribution of perfusion followed a pattern similar to that of ventilation, but did not differ statistically from that of the normal controls.

Humans↗