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Biomedical subjects

K Faulkner

Publications and source records attributed to K Faulkner.

At least 109 records · Page 6Linked to original sources
PubMed1991

Patient dose and associated risk due to radiological investigation of the internal auditory meatus.

The radiation doses and associated somatic risks due to four radiological examinations for acoustic neuromata (AN) have been investigated. These examinations were (1) plain film radiography of the internal auditory meatus (IAM), (2) computed tomography (CT) of the IAM, (3) CT of the posterior fossa and (4) CT of the IAM with air contrast. Organ dose measurements were performed using lithium fluoride thermoluminescent dosemeters loaded in a patient equivalent phantom. Dose equivalents to various organs are presented, together with the effective dose equivalent and collective effective dose equivalent for each examination. Hypothetical fatal somatic risks for each examination studied here have been estimated from the effective dose equivalents. The estimated number of hypothetical fatal cancers induced by radiological examinations for AN is between approximately 110 and 820 times lower than the number of detected AN, depending on the method of assessing the radiation dose to the remainder organs. It is concluded that in this particular study the radiological examinations are of net benefit to this group of patients.

Brain↗
PubMed1991

A phantom for the measurement of contrast detail performance in film-screen mammography.

A National Breast Cancer Screening Programme, based on X-ray mammography, has been introduced in the UK. The success of this screening programme is dependent on the production of high quality radiographs. There are various methods of assessing imaging performance in mammography, but contrast detail detectability measurements have an advantage in that the observation of radiographs is taken into consideration. The design and construction of a contrast detail phantom for the assessment of image quality in mammography is described. This phantom can be used to assess the imaging performance of mammographic film-screen combinations. The results of some measurements to verify the accuracy of the contrast predictions are presented together with some initial results of an investigation into the contrast detail performance of film-screen combinations used in mammography.

Breast Neoplasms↗
PubMed1991

Osteoporosis. Current techniques and recent developments in quantitative bone densitometry.

Knowledge about the proper use and interpretation of bone densitometry studies and an understanding of appropriate medical interventions are not universal among physicians, nor are instrumentation and technical performance of bone density studies of uniformly high quality. Indeed, this deficiency of medical and technical expertise is the principal deterrent to widespread implementation of our recommended clinical applications at this time. Nonetheless, given the current impetus to disseminate information about osteoporosis, to make newer instrumentation more readily available, and to limit the cost of these techniques, we anticipate that our recommendations may soon become standard medical practice.

Absorptiometry, Photon↗
PubMed1990

Pressure measurements during automatic breast compression in mammography.

Breast compression during X-ray mammography results in improved image quality at a lower radiation dose to the patient, and, as a consequence, the Department of Health recommends that automatic breast compression devices are fitted to mammographic X-ray units. However, the degree of breast compression is not standardized and can vary depending on the size of the patient, the particular mammography X-ray unit and the conditions of its use. A pressure measuring system was used to determine accurately the pressure on the breast. This system takes the form of a fluid-filled neonatal cuff connected to a pressure transducer by a fluid line. The pressure measuring system was calibrated and tested, first without and then with the patients, to assess its practical feasibility. The elements of the pressure measuring system, the techniques involved in its calibration and its use on patients in the clinical environment are described here. The system has proved to be a quick and simple method of relating the pressure on the breast to the pressure reading of the mammography X-ray unit.

Automation↗
PubMed1990

Automated quality assurance and patient dosimetry in diagnostic radiology.

It has been generally considered that improved methods of quality assurance would reduce the population dose from diagnostic radiology. This paper describes the development of a computerized method of automatically monitoring tube and generator parameters to perform on-line quality assurance, whilst undertaking various patient dosimetry measurements and calculations for each exposure. The method involves interfacing a microcomputer to a microprocessor controlled X-ray generator. Details of the various interfacing methods and modifications to the X-ray unit are given. The instrument enables quality assurance to be performed for every exposure by comparing tube and generator parameters against nominal settings. The software automatically warns the operator of any deviations from accepted limiting values. When a patient is examined, details of the examination and projection are entered into a database. The exposure area product and field size are monitored for each exposure. This data, together with information on tube potential and examination/projection is used to deduce patient entrance skin dose and energy imparted. Doses to individual organs are estimated using normalized organ dose data and a knowledge of tube potential and field size.

Equipment Design↗
PubMed1990

An investigation into the performance of an automated quality assurance and dosimetry system in diagnostic radiology.

A system has been developed to undertake automatic quality assurance and dosimetry for diagnostic radiology examinations. The accuracy and reproducibility of the measurements and calculations made by the system have been investigated in a laboratory study and compared with concurrent measurements of exposure parameters made using standard techniques. In a later set of experiments, doses measured using a RANDO phantom and thermoluminescent dosimeters were compared with those calculated by the automated system. Assessment was carried out over a wide range of exposure factors and for a number of different radiological examinations. It is deduced from the results that exposure parameters can be measured with comparable accuracy to standard techniques, and that the automated system is suitable for performing on-line dosimetry.

Humans↗
PubMed1989

Measurement of x-ray tube potential in the mammographic region.

In mammography it is important to be able to measure x-ray tube potential with an accuracy of +/- 1 kV or better. Mammography x-ray sets generally use molybdenum for both target and filter. Consequently, a high proportion of the x-ray spectrum consists of characteristic radiation from the target. Devices for estimating tube potential such as penetrameters and digital kV meters, which depend on the relation between tube potential and the filtered x-ray spectrum, could be affected in their performance unless calibrated on similar x-ray sets. This paper reports tube potential measurements on a Mo/Mo x-ray set from 25 to 37 kV using the fluorescence technique, a manufacturer's potential divider, two penetrameters of different design and two digital meters of a single design. Agreement between all four techniques was good, being within the various combined experimental errors associated with each, from 37 down to 28 kV, below which the results diverged only slightly.

Calibration↗
PubMed1989

An instrument for monitoring the force applied by breast compression devices on mammography x-ray sets.

Automatic breast compression devices are commonly fitted to mammographic x-ray sets. The force exerted by these compression devices should be limited and periodically checked. This article describes the design and construction of an instrument for the routine assessment of the force applied by breast compression devices on mammography x-ray sets. Results obtained on four different mammography x-ray units are presented. In addition, data on the effect of compression plate design on compression force is given for one unit. The instrument has proved to be a simple and quick method of monitoring the force applied by the compression plates on mammographic x-ray units.

Female↗
PubMed1989

Evaluation of a maternity cushion (Ozzlo pillow) for backache and insomnia in late pregnancy.

The effect of a wedge-shaped pillow (Ozzlo pillow) was compared with a standard hospital pillow, used to support the abdomen of a pregnant woman while lying on her side, in preventing or alleviating backache and backache-related insomnia; 92 women at 36 weeks' gestation completed the study. Backache was found to be very common (87%), the onset of pain occurring before 29 weeks in 59%. Age, parity, previous backache and type of bed used did not correlate with the backache scores during the period of study. Lower scores for backache were recorded by women in the week they used the Ozzlo pillow compared with the week they used the standard pillow. Sleeping was deemed better by the patient with the Ozzlo pillow, though actual sleeping scores did not corroborate this. While significantly more felt the Ozzlo pillow was superior to a standard pillow for backache and sleeping, some found both methods helpful. The simple measure of supporting the abdomen with a pillow when in lateral recumbency is likely to benefit many women in late pregnancy. A wedge-shaped pillow of the Ozzlo type, conforming to the shape of the abdomen and supporting it more closely, may be of greater help than a standard cushion or pillow.

Back Pain↗
PubMed1989

Radiation dose to neonates on a Special Care Baby Unit.

Neonates on a Special Care Baby Unit often require radiography to monitor the progress of their treatment and as a result can have a large number of radiographs taken during their stay in hospital. The skin entrance dose was estimated from a knowledge of the technique factors, X-ray tube output and backscatter factors. Normalized organ dose data were employed to estimate the radiation dose to a number of critical organs. A number of methods of reducing the radiation dose to neonates were investigated. Initially, this involved changing the radiographic technique factors and introducing a lead rubber adjustable collimator, placed on top of the incubator, in addition to the light beam diaphragms on the X-ray tube. It was deduced from the results of calculations that these modifications to the radiographic examination technique had reduced the average entrance dose per radiograph from 92 mu Gy to 58 mu Gy, a reduction of 37%. Later, a rare-earth film-screen combination was introduced to replace the existing fast calcium tungstate screens. This enabled the average entrance dose per radiograph to be reduced to 39 mu Gy, a further reduction of 33%. The mean radiation dose to a neonate is mainly determined by the number of radiographs taken and this is dependent on the clinical symptoms.

Humans↗
PubMed1988

Estimation of effective dose equivalent to staff in diagnostic radiology.

The irradiation of staff in diagnostic radiology was simulated for conditions commonly encountered in fluoroscopy. Scattered radiation distributions were produced from diagnostic x-ray beams generated at tube potentials in the range 60-120 kVp, using the abdomen sections of a Rando phantom. Doses to a number of organs in the head and neck were measured using a Rando phantom loaded with lithium fluoride thermoluminescent dosemeters. The torso sections were placed on a water phantom on top of a stand, with film badge dosemeters positioned on the surface of the phantom at the forehead, neck, chest and waist, and the phantom was placed in the radiation field. Doses to organs in the torso were calculated from the waist-level film badge dosemeter reading using normalised organ dose data. Radiation doses to organs below a lead apron, when worn, were estimated from the unshielded dose values using a transmission factor appropriate to the quality of the scattered radiation. The effective dose equivalent (EDE) to the phantom was calculated for various x-ray beam qualities and lead apron thicknesses and compared with the film badge doses. The results indicate that a dosemeter worn at the waist/chest level under a lead apron generally underestimates the EDE. Conversely, dosemeters worn at the forehead/neck tend to overestimate the EDE. It is recommended that a dosemeter is positioned under a lead apron, if worn.

Female↗
PubMed1987

Fluoroscopic peroperative cholangiography: technique and associated radiation hazards.

The techniques specific to peroperative fluorocholangiography are discussed based on an experience of 632 cholangiograms and an estimation has been made of the associated radiation doses to staff and patients. Rapid and accurate information can be obtained during fluorocholangiography using appropriate techniques with acceptably low radiation hazards.

Bile Duct Diseases↗