Kenneth L. Miller

Unusual Aspects of Urine Ascites

Urine ascites usually presents at birth or shortly thereafter and is associated with a high overall mortality rate. Posterior urethral valves are the most common obstructive lesions. Prompt recognition is vital if the survival rate is to be improved. Two unusual cases of urine ascites are presented. A stillborn premature infant with imperforate anus and massive ascites showed radiologic evidence of peritoneal calcification. A prepartum diagnosis could have been made from the radiographs of the maternal abdomen. The second case is unique in the presentation of urine ascites caused by a presacral neuroblastoma that produced bladder outlet obstruction and perforation.

Plasma levels of free and acid-labile hydralazine: effects of multiple dosing and of procainamide.

The steady‐state plasma levels of unchanged free (H) and its ALC were measured in 6 normal volunteers—3 RA and 3 SA. All subjects received 25 mg H every 6 hr for a total of 12 doses; RA received an additional dose of 50 mg in a similar manner. Peak plasma levels offree H occurred at ½ to 1 hr following drug administration and declined with a t½ of 3.5 to 4.5 hr in both RA and SA. In contrast, ALC levels remained approximately constant over the 8‐hr sampling period. In the SA the mean steady‐state plasma concentration of ALC was 28% of the free H at the 25‐mg dose level. In the RA the percentages were 25 at the 25‐mg dose and 22 at the 50‐mg dose. These results indicate that under steady‐state conditions H is present predominantly in its free form. Administration of H (12 doses; 25 or 50 mg every 6 hr) with PA (every 3 or 4 hr) resulted in no alteration in the plasma levels of either H and its ALC or PA and its acetylated metabolite. This remained true when each phenotype was considered separately. The results from this portion of the study demonstrate that in normal subjects therapeutic plasma levels of neither PA nor H interfere with the acetylation of the other. Possible explanations for the lack of an interaction are presented.

Recent experiences with shielding a PET/CT facility.

Since the photon energy of positron emitting radionuclides is significantly higher than the maximum kVp of diagnostic x rays, designing a shielding plan for a PET/CT imaging facility requires careful consideration of future workloads and potential occupancy of surrounding spaces. The shielding calculations can be done by hand or with the aid of available software. In calculating the shielding, specific considerations arise. Some of these are presented as a checklist of things to consider when preparing to calculate the shielding required for a PET/CT facility.

Health physics considerations in medical radiation emergencies.

Preplanning and organization can facilitate the health physics response in the event of a medical radiation emergency. Anticipating the needs will allow for advanced assembly of needed information and supplies that would be useful in effectively responding to such events. Annual training of emergency care providers and an easy to read and understand poster will be of great benefit in guiding personnel until health physics arrives. Major events also need consideration, in advance, as they will place additional demands on health physics.

Some experiences with treating thyroid cancer patients.

U.S. NRC Regulatory Guide 8.39 provides for the release of patients treated with 131I provided that predetermined calculations indicate that no member of the public will receive a total dose equivalent in excess of 5 mSv (500 mrem). When this condition cannot be met or there are other reasons for keeping the patient hospitalized after treatment, control of contamination and exposure from the patient must be taken into consideration. If the patients are hospitalized following treatment, decontaminating the patients room after discharge and controlling the exposure potential from the patient are considerations for the hospital radiation safety staff. This paper reviews the experiences from fifty patients treated as inpatients over the past two years.

Potential dose to nuclear medicine technologists from 99mTc-DTPA aerosol lung studies.

Air sampling performed during 190 99mTc-labeled DTPA aerosol lung ventilation studies indicated that the maximum airborne concentration to which the nuclear medicine technologists might be exposed was 7.1 × 10−1 Bq mL−1 (1.9 × 10−5 μCi mL−1). If a single technologist performed ALL the aerosol studies, at this maximum airborne concentration, based on the Annual Limit on Intake (ALI), the resulting dose equivalents could be either 1 mSv (100 mrem) to the lungs or 0.1 mSv (10 mrem) to the total body. However, the procedures are shared by the technical staff, the times of exposure are represented by only a fraction of the overall procedure time, and the average airborne concentrations were found to be more than an order of magnitude lower than the maximum. This resulted in a projected average annual dose equivalent of 7.0 × 10−3 mSv (0.7 mrem) to the lungs or 7.0 × 10−4 mSv (0.07 mrem) to the whole body from the performance of these procedures.

Dynamic Radiography An Evaluation of Cardiac Motion by the Analysis of Scattered Radiation During Fluoroscopy

A non-invasive technique, utilizing scattered radiation, has been developed to monitor and measure the motion of the epicardial surface during fluoroscopy. A number of dogs were studied using a monitoring device which consists of an X-Ray beam collimator, collimated sodium iodide dectetors and their associated electronics. The detector signals are computer processed to obtain frequency fingerprints of epicardial motion that may, in the future, indicate the condition of the myocardium.

Dynamic Radiography: Analysis of Dynamics Using Secondary Radiation

Dynamic radiography is a high resolution technique using finely collimated radiation detectors to analyze the scattered component of penetrating radiation (e.g. x-rays, gamma rays, and neutrons). Inherent or induced periodic motions (vibrations) within a subject produce a complex modulation pattern in the scattered radiation field. This modulation can be detected and used to locate the site of the perturbation, the amplitude of the motion, and the frequency components generated. Completed initial experiments demonstrate a resolution capability in the sub-millimeter range accompanied by detailed frequency information in a 0 to 100 hertz spectrum.

Legal liability and the health physicist.

While Ken Miller was preparing several talks on medical management of radiation accident victims for the Health Physics Society’s Midyear Meeting in San Antonio the question arose as to “Who is responsible for decontamination of radioactivity from an individual, the health physicist (HP) or the physician?” Another way to ask this same question might be “Does contamination of an individual classify that individual as a ‘patient?’” The standard of practice seems to be that decontamination, when physical injury is absent, is a health physics function. Medical consultation is usually not sought by the health physicist, unless there is obvious physical injury in addition to the contamination or unless the contamination results in exposure to the contaminated individual above some predescribed guideline such as the occupational dose limits. Miller wondered if there are legal liabilities that a health physicist should be concerned about regarding decontamination or exposure of an individual. To obtain authoritative answers to the questions, Miller contacted Charles Rysavy, Esq., a member of the Health Physics Society and a Partner in the Products Liability, Pharmaceuticals and Toxic Tort Litigation Group at the law firm of McCarter & English, LLP, in Newark, New Jersey. After posing the questions and hearing the answers, it was mutually agreed that this discussion might be of interest and benefit to the readers of Operational Radiation Safety. The questions by Miller and the answers by Rysavy follow: