Breast dose variability in a bi-racial population undergoing screening mammography.

This study evaluated individual and population dose variability during screening mammography, among 570 white and black women in South Carolina, USA. Aspects of dosimetry that were considered include compressed breast thickness (CBT), number of films per screening session, and dose in previous or subsequent sessions. Breast dose was log-normally distributed in the population, with a geometric mean of 6.6 mGy per session. Doses were significantly higher for black women, for women with high CBT or who receive more than two views per breast, and for the mediolateral oblique, compared to the craniocaudal, view. No relationship was observed between age and dose. Total dose per breast varied by a factor of 20 across the study population, but the individual's dose varied little among repeat screening sessions, especially after adjusting for the number of films received per session. These results may inform assessments of the projected risks of inducing breast cancer from screening mammography.

Mammography dose in relation to body mass index, race, and menopausal status.

Mammography dose increases with compressed breast thickness (CBT), but few studies have examined other correlates of dose. The purpose of this study was to evaluate the relation between factors such as race, age, body mass index (BMI), CBT, and menopausal status and mammography screening dose, measured for 509 women in a US population. A multiple linear regression model was developed for dose, based on consideration of these factors as well as examination characteristics. BMI and number of films during examination were positively related to dose. After adjusting for these factors, high CBT also leads to higher dose. Whites receive lower doses than black women but differences are slight after controlling for the effects of CBT and BMI, which were significantly higher among black women. Pre-menopausal women receive higher doses, after adjusting for all other factors, than post-menopausal women. Jointly, these factors account for approximately 75% to 80% of the variability in dose among this study population. Because rates of overweight are increasing in the US, average doses from mammography may be increasing as well.

Health physics consequences of out-patient treatment of non-Hodgkin's lymphoma with 131I-radiolabeled anti-B1 antibody.

The Medical University of South Carolina is currently participating in clinical trials of 131I radiolabeled Anti-B1 antibody for treatment of Non-Hodgkin's lymphoma. Under current South Carolina Department of Health and Environmental Control regulatory guidelines,; these patients are required to be admitted to the hospital and to remain as inpatients until the whole body burden is <30 mCi or the exposure rate measured 1 m from the patient is <5 mR h(-1). We demonstrate that these patients can be released in accordance with the new recommended guidelines of the Nuclear Regulatory Commission for the release of patients containing radioactive materials in compliance with all radioactive material and public dose standards. This benefits these patients by reducing their risk of infection and other hospital insults and by reducing the length of hospitalizations. Further, unnecessary hospital admissions are decreased, and the overall cost of healthcare delivery for these patients is significantly reduced.

Teleradiology: technology and practice.

Teleradiology increases the ability of radiologists to provide service to remote and underserved locations as well as coverage at times when direct reading of images is not possible. Good practices for teleradiology are described in the American College of Radiology (ACR) teleradiology standard. Teleradiology equipment is converging with picture archiving and communications systems (PACS) equipment so that diagnostic interpretation from remote locations is possible. Image capture can be directly from digital modalities or by film scanner. Transmission speed is still an issue. High transmission speeds were difficult to achieve but recent improvements may increase speeds and decrease costs.

Quantitative mammography contrast threshold test tool.

Mammographic contrast is commonly evaluated by visualizing small objects of varying size or mass divided by projected area. These qualitative contrast determinations are commonly performed by imaging a phantom like the American College of Radiology accreditation phantom at clinical mammographic settings. However, this contrast assessment does not take into account the kVp of the machine. This work describes a quantitative mammography contrast threshold test tool which examines light object contrast on a uniform background for a contrast range of 0.32% to 1.38% at 25 kVp. For this mammography contrast threshold test tool, contrast is defined by delta I/I = loge (psi O/ psi b), where psi O is the target energy flux, and psi b is the background energy flux. Contrast threshold is defined as the lowest contrast value for which the objects are visible. Unlike traditional assessments of mammographic contrast, this measurement of contrast threshold is kVp corrected. The mammography contrast threshold test tool is constructed out of common plastics and provides a quantitative means of assessing contrast threshold for individual mammographic units and total mammographic systems.

Diagnosis of adult respiratory distress syndrome with Tc-99m human serum albumin and portable probe.

A gamma-camera and computer were used to measure pulmonary accumulation of technetium-99m human serum albumin in 15 patients who met the criteria for adult respiratory distress syndrome (ARDS), and in ten asymptomatic patients. The ratio of lung to blood-pool activity increased in ARDS patients, but did not change in nonARDS patients. Lung to heart measurements by a portable probe with scaler correlated well with those obtained simultaneously with the gamma-camera and computer: probe measurements over 60 min increased significantly (p less than .0001) more in ten ARDS patients than in the nonARDS patients or in five postARDS patients, three with pneumonia and two with congestive heart failure. We conclude that the probe with scaler is sensitive enough to detect abnormal pulmonary accumulation of albumin in ARDS patients.

Quantitative analysis of the cervical spinal canal by computed tomography.

Computed tomography measurements of the AP diameter, width, and cross-sectional area of the bony cervical canal were derived from cervical spine examinations of fifty-two normal adults. These quantitative parameters were then used to evaluate 80 patients with various cervical abnormalities to determine the clinical usefulness of the measurements. With the exception of spinal stenosis, quantitative cervical canal analysis was found to be of limited usefulness since normal measurements frequently occurred in the presence of significant cervical pathology.

Liposomes as carriers of iodolipid radiocontrast agents for CT scanning of the liver.

We studied the potential of liposomes to deliver oil soluble radiocontrast agents to the liver and have developed a new preparation for CT liver scanning. The preparation consists of Ethiodol with a large amount of phospholipids. Nuclear magnetic resonance (NMR) spectroscopy was done for this lipid preparation, and the spectra show that the lipids are in the bilayer liposome configuration. Electron microscopy provides direct visualization of the liposomes. X-ray fluorescence measurements suggest that the Ethiodol is incorporated in the liposomes, and since no other particulate configurations are observed, we conclude that the Ethiodol is contained within the hydrophobic region of the liposomes. We used a GE CTT-8800 scanner and a rabbit model to study the liver uptake of the iodine from the Ethiodol. The iodine uptake in the liver was rapid and significant, and an increase in HU number of more than 40 was observed within 20 minutes after i.v. injection of 50 mg I/kg of body weight. Significant image enhancement was obtained. The iodine from the Ethiodol remained in the liver for several hours. Studies in rabbits with hepatic implants of the VX2-carcinoma show that while normal liver concentrates, areas of tumor do not concentrate the Ethiodol liposomes. Tumors not visible on ordinary scans become visible after administration of this combination. The advantages of this liposomal mode of radiocontrast agent administration are small particle size, rapid uptake in the liver, long retention times, a large increase in HU number and low iodine dose.

Computed tomography evaluation of pheochromocytoma in pregnancy.

Two cases representative of the spectrum of the problem of pheochromocytoma in pregnancy are presented. One patient was typical of many cases of pheochromocytoma not diagnosed until delivery, with resultant maternal and fetal death. Computed tomography accurately preoperatively localized a pheochromocytoma involving the organ of Zuckerkandl in the second patient, with subsequent uncomplicated removal of the tumor during a cesarean delivery. A discussion of pheochromocytomas in pregnancy and the relative risk and benefits of preoperative localization with computed tomography are presented.