ABSTRACT
We present dose calculations to the basal cell layer of the epidermis resulting from skin contamination by radionuclides used in nuclear medicine. Dose calculations were made using the computer code VARSKIN, as modified by us to include these radionuclides and to account for their monoenergetic electron emissions. Results indicate that basal skin doses (taken to be at a depth of 0.007 cm) are approximately 1 cGy h-1 per 3.7 X 10(-4) Bq cm-2 (1 rad h-1 per muCi cm-2) from 99mTc, 111In and 201Tl, implying that established limits may be approached under certain circumstances. The implication of these results for small areas of contamination is also discussed.
Subject(s)
Accidents, Occupational , Hand , Nuclear Medicine , Radioisotopes , Skin , Beta Particles , Electrons , Humans , Radiation Dosage , Technetium , Thallium RadioisotopesABSTRACT
We have analyzed 60 cases of intra-axial brain tumors associated with antecedent radiation therapy. These include four new cases. The patients had originally received radiation therapy for three reasons: (a) cranial irradiation for acute lymphoblastic leukemia (ALL), (b) definitive treatment of CNS neoplasia, and (c) treatment of benign disease (mostly cutaneous infections). The number of cases reported during the past decade has greatly increased as compared to previous years. Forty-six of the 60 intra-axial tumors have been reported since 1978. The relative risk of induction of an intra-axial brain tumor by radiation therapy is estimated to be more than 100, as compared to individuals who have not had head irradiation.
Subject(s)
Brain Neoplasms/etiology , Neoplasms, Radiation-Induced , Radiotherapy/adverse effects , Adult , Animals , Brain Neoplasms/radiotherapy , Child, Preschool , Female , Humans , Infant , Macaca mulatta , Male , Meningeal Neoplasms/prevention & control , Meta-Analysis as Topic , Neoplasms, Experimental/etiology , Precursor Cell Lymphoblastic Leukemia-Lymphoma/radiotherapy , Radiotherapy Dosage , Tinea Capitis/radiotherapyABSTRACT
This paper discusses a methodology which uses a specially developed computer program that enables estimation of output parameters of an x-ray machine from a single test exposure. Exposure at skin entrance values can be estimated, as well as using the data from the program for organ dose estimates. To perform the estimation procedure, curves and analytical expressions for the curves are presented for conversion of half-value layers to total filtration and for conventional mR/mAs output curves. Results are given showing that the estimation procedure is reasonably accurate.
Subject(s)
Radiation Dosage , Radiation Protection , Radiography , Humans , SoftwareABSTRACT
Methods and results are given to enable the computation of radiation dose as a function of depth in the wall of a suprasellar cyst containing radioactivity. Both beta- and gamma-emitting nuclides are considered. The methodology considers distribution of the radioactivity on the cyst wall (spherical shell geometry) and distribution uniformly in the fluid (volume geometry).
Subject(s)
Brachytherapy/methods , Craniopharyngioma/radiotherapy , Models, Biological , Pituitary Neoplasms/radiotherapy , Radiotherapy Dosage , Beta Particles/therapeutic use , Gamma Rays/therapeutic use , HumansABSTRACT
The nuclear medicine bleeding scan is frequently insufficient to locate sites of bleeding precisely, in spite of its great sensitivity. A small, hand-held Geiger-Müller counter, placed directly on exposed intestine in the operating room, enables precise location of the probable bleeding site. In three patients, the technique allowed a minimal amount of intestine to be resected, distinguished between large- and small-intestinal hemorrhage, and eliminated other foci as sites of bleeding.
Subject(s)
Gastrointestinal Hemorrhage/diagnostic imaging , Radiometry , Humans , Intraoperative Care , Radionuclide ImagingABSTRACT
This paper presents a method for performing diagnostic x-ray shielding calculations which is somewhat different than that given in NCRP Report No. 49. The method computes exposure at the location to be shielded from multiple sources of radiation in the room and accounts for differences in transmission characteristics of leakage and primary/scatter radiation. Also discussed in the paper is a method for determining shielding credit for existing common structural materials. Methods and results derived in the paper are then discussed and compared with NCRP Report No. 49.
Subject(s)
Radiation Protection , Radiography , Technology, RadiologicABSTRACT
Personnel monitoring data reported in the literature at selected monitoring sites for personnel working in fluoroscopic X-ray facilities are analyzed. The results are used to attempt to more realistically estimate the potential organ doses for X-ray personnel wearing protective devices such as lead aprons and protective eyeglasses when these personnel wear only one dosimeter positioned outside the apron at the collar. The applicability of these results to current U.S. dose standards and the ICRP weighted dose equivalent concept is discussed.
