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Biomedical subjects

S C Bushong

Publications and source records attributed to S C Bushong.

At least 19 recordsLinked to original sources
PubMed1995

History of standards, certification, and licensure in medical health physics.

Immediately following the discovery of x rays they were applied to medical diagnosis and therapy. These early medical applications were soon shown to be accompanied by rather severe biologic responses and injuries. This resulted in the development of standards. Radiation standards were developed to properly control the application of x rays in medicine by controlling equipment and how it was used. Control of personnel occurred later with first certification and then licensure.

Health Physics↗
PubMed1994

Exposure rates during special procedures with C-arm type fluoroscopic systems.

PURPOSE: To test for regulatory compliance of free-in-air entrance air kerma rates (EAKR) in C-arm type fluoroscopic equipment, measurements are frequently made under minimum source-to-image receptor distance (SID) and at 300 mm from the image intensifier. However, this is not representative of normal patient geometry, and the automatic brightness controls on these units frequently increase tube output as SID increases. This study investigated effects of these circumstances on actual EAKRs. MATERIALS AND METHODS: Typical patient geometries were observed and recorded for 23 consecutive body vascular procedures. EAKRs were measured under compliance and normal patient geometries with use of five modern C-arm type systems for special procedures. RESULTS: SIDs of 1 m were typical when rapid film changers were employed and the patient's entrance skin surface was typically 500 mm from the image receptor. Actual EAKRs were found to be up to 2.5 times those measured under compliance geometry. CONCLUSION: Actual patient geometries should be used to ensure correct estimates of EAKRs.

Fluoroscopy↗
PubMed1987

Patient and personnel exposure during extracorporeal lithotripsy.

Extracorporeal shock wave lithotripsy (ESWL) has provided a nonsurgical approach to treatment of renal stones. The Dornier lithotripter uses dual image intensified x-ray systems to center the stone before treatment. Three imaging modes are offered: a fluoroscopic mode and two video spot filming modes. The average entrance exposure to the stone side of the typical patient at our facility is 2.6 X 10(-3) C kg-1 (10 R) [range: 0.5-7.7 X 10(-3) C kg-1 (2-30 R)] which is comparable and often much less than that reported for percutaneous lithotripsy. Recommendations are made for minimizing patient exposure. Scattered radiation levels in the lithotripter room are presented. We have determined that Pb protective apparel is not required during this procedure provided x-ray operation is temporarily halted should personnel be required to lean directly over the tub to attend to the patient. If the walls of the ESWL room are greater than 1.83 m (6 feet) from the tub, shielding in addition to conventional construction is not required.

Humans↗
PubMed1987

Effects of MR imaging on murine natural killer cell cytotoxicity.

To determine the effect of MR imaging on the immune system, 21 male C57BL/6 X DBA/2 F1 mice were exposed to MR imaging at a field strength of 0.15 T for 2 hr. Another nine mice (controls) were sham exposed for the same amount of time. Mice were sacrificed and their spleens removed 24, 72, and 144 hr after the exposure (MR or sham). Spleen cell suspensions were passed over nylon wool columns and then used as effector cells in a short-term natural killer cell cytotoxicity assay with 51Cr-labeled YAC-1 cells as target cells. The results showed no evidence of decreased cytotoxicity due to exposure to MR. On the contrary, at all three times after exposure and for all target-to-effector cell ratios, mean cytotoxicity was greater for MR-exposed groups than for sham-exposed groups. The results show that MR exposure has no adverse effect on the immune system, as evidenced by natural killer cell activity.

Animals↗
PubMed1984

Effect of nuclear magnetic resonance on chromosomes of mouse bone marrow cells.

Three groups of six male Balb/c mice, subjected to 30 MHz continuous wave NMR exposure in a static magnetic field of 7.05 K Gauss for one hour, were each compared to another group of ten unexposed mice with respect to chromatid and chromosomal aberrations. The exposed groups were sacrificed at two hours, 24 hours and 48 hours following NMR exposure respectively. Control mice were sacrificed 24 hours after sham-exposure. All groups had approximately 0.02 apparent aberrations per cell. These apparent aberrations were in the form of metacentric chromosomes, possibly resulting from a union of chromosomes at their centromeres or possibly simply chromosomes in association. The results are consistent with earlier in vitro findings that NMR exposure causes no adverse cytogenetic effects.

Animals↗
PubMed1984

Defects in new protective aprons.

Upon careful examination, several defects have been detected in new protective aprons . The nature of the defects is identified and described. Although the occurrence of such defects has not exceeded 5%, they are significant enough to warrant return of the lead apron to the supplier. It is recommended that the integrity of all new protective aprons be verified upon receipt as well as at yearly intervals.

Fluoroscopy↗
PubMed1983

Radiographic workload and use factors for orthopedic facilities.

Observations of technique factors at 9 radiographic installations dedicated to orthopedic radiography have been made. Monthly area radiation measurements with thermoluminescent dosimeters were made at three of these facilities. The results of these observations and measurements suggest that current NCRP recommended assumptions utilized in protective barrier computations result in considerably more shielding than is necessary. We observed an average workload of 224 mA min/wk and a maximum weekly average of 670 mA min/wk. The use factor for the chest wall averaged 5%. That for all other vertical barriers was less than 1%. The average operating potential was 75 kVp. Room radiation measurements confirm the suggestion that at least two of the walls and the control booth barrier in an orthopedic radiographic facility may be considered secondary barriers.

Ambulatory Care Facilities↗
PubMed1983

Diagnostic X-ray shielding design based on an empirical model of photon attenuation.

A series of nomograms that simplify determination of diagnostic X-ray shielding requirements with lead are presented. All recommendations of the NCRP, except that to "add one half value layer" in determining secondary barriers, were followed in the production of these curves. For secondary barriers, the shielding required to reduce the weekly exposure to the applicable MPD has been determined. This eliminates the over-shielding inherent in the "add one HVL" approximation and allows a variety of more cost effective materials to be considered for secondary barriers.

Hospital Departments↗
PubMed1982

A computer-assisted procedure for estimating patient exposure and fetal dose in radiographic examinations.

A computer program for calculating patient entrance exposure and fetal dose for 11 common radiographic examinations was developed. The output intensity measured at 70 kVp and a 30-inch (76-cm) source-to-skin distance was entered into the program. The change in output intensity with changing kVp was examined for 17 single-phase and 12 three-phase x-ray units. The relationships obtained from a least squares regression analysis of the data, along with the technique factors for each examination, were used to calculate patient exposure. Fetal dose was estimated using published fetal dose in mrad (10(-5) Gy) per 1,000 mR (258 microC/kg) entrance exposure values. The computations are fully automated and individualized to each radiographic unit. The information provides a ready reference in large institutions and is particularly useful at smaller facilities that do not have available physicians who can make the calculations immediately.

Body Burden↗
PubMed1980

Effect of dimethyl sulfoxide on hematopoietic stem cells in mice.

The effects of dimethyl sulfoxide (DMSO) were studied in irradiated BALB/c mice to see if DMSO has a stimulatory effect on hematopoietic stem cells. The spleen colony forming technique was employed. DMSO given after a lethal dose of radiation enhanced post-irradiation recovery and survival. The erythroid to granuloid spleen colony ratio was higher in the DMSO treated group compared to the controls. There was some evidence of an increase in the endogenous formation of erythroid colonies after DMSO treatment (0.38%). However, DMSO had no effect on exogenous erythroid colony formation; rather, it inhibited granuloid differentiation.

Animals↗
PubMed1979

Patient radiation dose in conventional and xerographic cephalography.

A comparison of the radiation doses for xeroradiographic and conventional film screen cephalography was made. Alderson tissue-equivalent phantoms were used for patient stimulation. An optimum technique in terms of patient dose and imaqe quality was established for the xeroradhe data indicated that the dose for the Xerox process ranged from five to eleven times greater than that for the conventional process for entrance and exit exposures, respectively. The most commonly reported dose, the entrance dose, was found to be 206 mrad, which is five Imes that for the conventional cephalogram. This dose, however, falls within an acceptable range for other dental and medical radiation doses. It is recommended that conventional cephalography be used for routine purposes and that xeroradiography be reserved for situations requiring the increased image quality that the process affords.

Cephalometry↗
PubMed1979

Bone marrow dose in chest radiography: the posteroanterior vs. anteroposterior projection.

The dose to active bone marrow resulting from anteroposterior (AP) and posteroanterior (PA) chest examinations was estimated using an Alderson Rando phantom and extruded lithium fluoride dosimeters. The AP projections resulted in a mean marrow dose range of 1.9-2.6 mrad (0.019-0.026 mGy) as compared to doses for PA projections of 3.4-3.8 mrad (0.034-0.038 mGy) for optimally diagnostic exposure taken at 70, 90, and 120 kVp.

Bone Marrow↗
PubMed1977

Effect of irradiation on electrophoretic properties of enzymes in haemopoietic cells of opossum.

5-month-old male opossums were exposed to 5000 rads whole body 60Co radiation and sacrificed at 16, 40 and 90 h following irradiation. Stract gel electrophoretic studies of dehydrogenases of lactate, malate, 6-phospho-gluconate and glucose-6-phosphate and alpha-esterases and acid phosphatase were conducted on the homogenates of spleen and bone marrow cells. Expressions of LDH and G6PD were affected by irradiation in bone marrow and spleen cells.

Animals↗