Shielding reproductive organs of orthopaedic patients during pelvic radiography.
(9/472)
The use of gonadal shielding has been advocated for patients undergoing pelvic radiography before and during the reproductive years. The aim of this study is to look at the adequacy of gonadal shielding used in a district general hospital for young patients having pelvic radiographs. A total of 200 radiographs were reviewed of 49 patients below the age of 45 years. Full coverage was achieved in only 36% of cases. Amongst females, only 22% received adequate shielding. None of the patients in their reproductive years (16-45 years) had gonad shields. The reasons for inadequate coverage were, in order of frequency: (i) no shielding was used; (ii) malposition of the shielding device; and (iii) the use of inappropriately shaped or sized devices. Suggestions for improvement are proposed. (+info)
Medical use of byproduct material; policy statement, revision. Nuclear Regulatory Commission. Final policy statement; revision.
(10/472)
The Nuclear Regulatory Commission (NRC) is revising its 1979 policy statement on the medical use of byproduct material. These revisions are one component of the Commission's overall program for revising its regulatory framework for medical use, including its regulations that govern the medical use of byproduct material. The overall goals of this program are to focus NRC regulation of medical use on those medical procedures that pose the highest risk and to structure its regulations to be risk-informed and more performance-based, consistent with NRC's "Strategic Plan for Fiscal Year 1997-Fiscal Year 2002." The policy informs NRC licensees, other Federal and State agencies, and the public of the Commission's general intentions in regulating the medical use of byproduct material. (+info)
Therapeutic 131I in outpatients: a simplified method conforming to the Code of Federal Regulations, title 10, part 35.75.
(11/472)
The Code of Federal Regulations, title 10, part 35.75 (10CFR35.75), provides greater latitude and flexibility in the dosing and management of outpatients treated with therapeutic 131I than did preceding regulations. Prescribing physicians should consider applying these new regulations to enhance patient convenience and lower the cost of managing appropriate outpatients. Managed care organizations and third-party payers may require that all eligible patients be treated as outpatients or that justification for hospital admission be specifically documented. To facilitate application of the code and guidelines, maximum 131I doses for patients undergoing thyroid remnant ablation, therapy for metastatic or recurrent thyroid cancer, or therapy for hyperthyroidism have been calculated and summarized in tables. METHODS: A model was developed that calculates the maximum dose of 131I that may be dispensed to an outpatient. This model complies with 10CFR35.75. The maximum dose is calculated as a function of 5 variables: the occupancy factors for 3 periods after dose administration, the fractional uptake of 131I by residual thyroid tissue or metastasis, and the duration of constrained activity. Occupancy factor, a key new concept in the regulatory guidelines, is a physician estimate of the time that a treated patient will be near the individual with whom the patient will spend the most time after treatment. The model also considers 3 constants: the effective half-life of 131I during the preequilibrium period, and the effective half-lives of 131I in both the thyroidal component and the extrathyroidal component during the equilibrium period. Tables for maximum allowable patient 131I doses were derived on the basis of this model. RESULTS: Through dosing charts, maximum 131I therapy doses may easily be calculated. Most outpatients undergoing thyroid remnant ablation, therapy for metastatic or recurrent thyroid cancer, or therapy for hyperthyroidism may be treated with 7400 MBq (200 mCi) 131I or more. CONCLUSION: If the prescribing physician understands the concept of occupancy factor and how to use the dosing charts, our model facilitates application of and adherence to 10CFR35.75. (+info)
The factors controlling stem cell recirculation. i. Migration of hemopoietic stem cells in adrenalectomized mice.
(12/472)
The influence of bilateral adrenalectomy on hemopoietic stem cell (CFU) migration in mice has been studied. Formation of endogenous spleen colonies in lethally irradiated, leg-shielded mice was sharply increased by prior adrenalectomy, and this increase was not dependent on the volume of shielded bone marrow. Adrenalectomy was shown to increase endogenous spleen colony formation in sublethally irradiated mice as well. However, it had no affect on formation of spleen colonies in lethally irradiated mice injected with syngeneic bone marrow. The CFU content of murine bone marrow decreased acutely after removal of the adrenals, and this decrease was accompanied by a concomitant increase in the peripheral blood and splenic CFU. Thus, adrenalectomy appeared to have no affect on the splenic plating efficiency or proliferative rate of hemopoietic stem cells, but it did result in increased migration of stem cells from the bone marrow to the blood, and thence to the spleen. It is concluded that the adrenal steroids may be of physiologic importance in the regulation of ehmopoietic stem cell migration. (+info)
Radiation safety precautions in the management of the hospitalized (131)I therapy patient.
(13/472)
OBJECTIVES: The patient who has been dosed with therapeutic activities of (131)I for thyroid carcinoma poses a unique set of problems for nuclear medicine technologists in their efforts to reduce personnel exposure and control contamination spread. It is the objective of this article to: (a) review practical radiation safety concerns associated with hospitalized (131)I therapy patients; (b) propose preventative measures that can be taken to minimize potential exposure and contamination problems; and (c) review pertinent federal regulations that apply to patients containing therapeutic levels of radionuclides. (+info)
Cosmic radiation protection dosimetry using an Electronic personal Dosemeter (Siemens EPD) on selected international flights.
(14/472)
The effectiveness of an Electronic Personal Dosemeter (Siemens EPD) for cosmic-radiation dosimetry at aviation altitudes was examined on eight international flights between March and September, 1998. The EPD values (Hepd) of the dose equivalent from penetrating radiation, Hp(10), were assumed to be almost the same as the electron absorbed doses during those flights. Based on the compositions of cosmic radiation in the atmosphere and the 1977 ICRP recommendation, an empirical equation to conservatively estimate the personal dose equivalent (Hp77) at a depth of 5 cm was derived as Hp77 = 3.1 x Hepd. The personal dose equivalent (Hp90) based on the 1990 ICRP recommendation was given by Hp90 = 4.6 x Hepd; the conservative feature of Hp90 was confirmed in a comparison with the calculated effective doses by means of the CARI-6 code. It is thus expected that the EPD will be effectively used for radiation protection dosimetry on selected international flights. (+info)
Keratinocyte apoptosis induced by ultraviolet B radiation and CD95 ligation -- differential protection through epidermal growth factor receptor activation and Bcl-x(L) expression.
(15/472)
Previous work has shown that activation of the epidermal growth factor receptor by endogenous or exogenous signals markedly enhances survival of cultured keratinocytes upon cellular stress such as passaging. This is due, in part, to epidermal-growth-factor-receptor-dependent expression of Bcl-x(L), an antiapoptotic Bcl-2 homolog. In this study we tested whether epidermal-growth-factor-receptor-dependent signal transduction and attendant Bcl-x(L) expression affected survival of human keratinocytes upon exposure to a frequently encountered apoptotic stimulus, radiation with ultraviolet B. We describe that blocking epidermal-growth-factor-receptor-dependent signal transduction sensitized normal keratinocytes to undergo apoptosis upon ultraviolet B radiation with solar light characteristics. Forced expression of Bcl-x(L) partially but significantly inhibited ultraviolet-B-induced apoptosis of immortalized keratinocytes (HaCaT). Bcl-x(L) overexpression afforded no protection to HaCaT cells against apoptosis induced by binding of an agonist antibody to the death receptor CD95, however. CD95 activation has previously been shown to functionally contribute to apoptosis in ultraviolet-irradiated keratinocytes. These results indicate that epidermal growth factor receptor activation and attendant Bcl-x(L) expression provided a physiologically relevant protective pathway of keratinocytes against ultraviolet-induced but not CD95-dependent apoptosis. (+info)
Radioprotection to the eye during CT scanning.
(16/472)
BACKGROUND AND PURPOSE: The lens of the eye is sensitive to radiation. Children undergoing CT of the head and patients undergoing repeated CT scanning of the head are vulnerable to this complication. The purpose of this study was to test the ability of a heavy metal, bismuth, in reducing radiation to the lens of the eye during routine cranial CT. METHODS: Both phantom and human studies were done. Using a standard head-attenuating phantom, scanning was performed with detectors placed over the eye, first without the protectors, and then with shielding by one (1T), two (2T), or three thickness (3T) of bismuth-coated latex. The patient study included 30 patients randomized into one of three groups with eye protection provided by 1T, 2T, or 3T of the bismuth-coated latex. Control measurements were done using thermoluminescent dosimeters over the forehead above each eye. Image artifact from the bismuth shields was assessed. RESULTS: The phantom study demonstrated that the use of bismuth-coated shielding over the eyes decreased radiation dosage by 48.5%, 59.8%, and 65.4% using 1T, 2T, and 3T, respectively. The effect of eye shielding in decreasing radiation dosage to the eye was highly significant for all three thicknesses (P = 2.9 x 10(-81) to 1.9 x 10(-89)). In the patient study, the use of 1T, 2T, and 3T of bismuth-coated latex saved an average radiation dose of 39.6%, 43.5%, and 52.8%, respectively. While the use of shielding was statistically significant in saving radiation for all thicknesses (P = 2.2 x 10(-10) to 1.4 x 10(-21)), there was no statistical difference between 1T, 2T, and 3T of bismuth-coated latex shielding found in patients. However, the trend was for increased radiation savings to the eye with increased thickness of shielding used. A review of all 30 studies showed no significant artifact caused by the eye shielding, regardless of thickness. CONCLUSION: Bismuth-coated latex shielding of the eye during cranial CT is simple to apply, inexpensive, and causes up to a 50% reduction in radiation to the lens of the eye. (+info)