Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Beta Particles”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,783 records · Page 99Linked to original sources
PubMed1994

Dosimetry and toxicity of samarium-153-EDTMP administered for bone pain due to skeletal metastases.

UNLABELLED: Palliation of bone pain in patients with cancer metastatic to bone is being evaluated in several cancer centers by the administration of the bone-seeking phosphonate ethylenediaminetetramethylenephosphonic acid (EDTMP) chelated with the beta particle-emitting radionuclide 153Sm. METHODS: In this study, 153Sm-EDTMP was intravenously injected into 19 patients over a 1-min period. Patients received up to four injections of 18.5 MBq (0.5 mCi) or 37 MBq (1.0 mCi) per kilogram of body weight. Skeletal retention was calculated from urinary excretion. RESULTS: No uptake of 153Sm-EDTMP in nonskeletal tissues was observed in whole-body gamma camera images. The mean skeletal uptake for all patients was 54% +/- 16% of the injected dose (%ID). This resulted in the bone marrow receiving 89 cGy/GBq +/- 27 cGy/GBq (3.28 cGy/mCi +/- 0.99 cGy/mCi), with calculated marrow doses ranging from 27 cGy to 338 cGy. For each patient, the estimated radiation absorbed dose to the marrow was correlated to the percent decrease in platelet number, ranging from 7.4% to 78.9%. CONCLUSION: Since the deviation of uptake between the four injections for a given patient (7.6% ID) was less than the deviation for all patients (16% ID), the initial dose may be used to estimate the skeletal uptake for the remaining doses. These radiation dose estimates permit patients at risk to be identified prior to reaching myelotoxicity and develop dose-response models. Thirteen patients (68%) reported significant pain relief from this radionuclide therapy. Bone pain appears to be alleviated by 153Sm-EDTMP with limited red marrow doses and no toxic effects in other organs.

Bone Marrow↗
PubMed1995

Fluorine-18-fluorodeoxyglucose-guided breast cancer surgery with a positron-sensitive probe: validation in preclinical studies.

UNLABELLED: In this study, the feasibility of utilizing 2-deoxy-2-fluoro-d-glucose (FDG) in conjunction with a positron-sensitive intraoperative probe to guide breast tumor excision was investigated. METHODS: The probe was constructed with a plastic scintillator tip coupled to a photomultiplier tube with fiber optic cable. Anticipated resolution degradation was evaluated by measurement of line spread functions in the presence of background radiation. Realistic photon background distributions were simulated with a human torso phantom and a cardiac insert. The relationship between resolution and energy threshold was measured to find the optimal discriminator settings. In addition, probe sensitivity as a function of energy threshold was determined for various size-simulated tumors. Finally, the ability to localize breast cancers in vivo was tested in a rodent model. Mammary rat tumors implanted in Lewis rats were examined after injection with FDG; these results were correlated with those of histologic analyses. RESULTS: Measurements of line spread functions indicated that resolution could be maximized in a realistic background photon environment by increasing the energy threshold to levels at or above the Compton continuum edge (340 keV). At this setting, the probe's sensitivity was determined to be 58 and 11 cps/muCi for 3.18- and 6.35-mm diameter simulated tumors, respectively. Probe readings correlated well with histologic results: the probe was generally able to discriminate between tumor and normal tissue. CONCLUSION: This study indicates that breast cancer surgery guided by a positron-sensitive probe warrants future evaluation in breast-conserving surgery of patients with breast cancer.

Animals↗
PubMed1995

Microchannel array detector for quantitative electronic radioautography.

The microchannel array detector provides direct electronic detection and real time imaging of radioactive tracers in samples that traditionally have been imaged by film radioautography. The technology of the detector is described, and the main benefits of this new technology, speed and precise quantitation, are illustrated with practical results. The instrument response to a 14C dilution series (range of 10(5)) was linear over the whole range. Results from the microchannel array detector are compared to results obtained with liquid scintillation counting (LSC) and densitometry of film radioautographs. Because the instrument response is linear and consistent from day to day, it is not necessary to routinely include calibration standards as is required for film. The 14C counting efficiency was found to be essentially constant for different tissues in a whole body microtome section. As with LSC, results reported as counts per min. (CPM) are independent of counting time. Quantitative results were obtained with assays for chloramphenicol acetyl transferase in two min. and little as 0.2 DPM/mm2 of 32P was detected in seven min.

Animals↗
PubMed1995

Apolipoprotein E isoforms and rare mutations: parallel reduction in binding to cells and to heparin reflects severity of associated type III hyperlipoproteinemia.

The LDL receptor-independent binding of human apolipoprotein E isoforms and rare apoE mutations were studied on LDL receptor-deficient human fibroblasts using chemical cross-linking and cell binding studies. The cross-linking experiments demonstrated that all apoE variants bind to the low density lipoprotein receptor-related protein, a potential receptor for remnant lipoproteins. In cell binding studies, the effect of the apoE variants on binding of beta-VLDL was investigated. Addition of normal apoE-3 to the binding assay resulted in a 12-fold increase of beta-VLDL particle binding, whereas this effect was reduced in the clinically defective variants: apoE-2, (Arg158-->Cys), 24.4% of apoE-3; apoE-1, (Gly127-->Asp, Arg158-->Cys), 49.2% of apoE-3; apoE-1(Lys146-->Glu), 18.2% of apoE-3. Heparin binding studies with the same variants showed a parallel reduction in proteoglycan binding (apoE-2(158), 58.2% of apoE-3; apoE-1(127,158), 37.9%; apoE-1(146), 20.6%). We conclude that LDL receptor-independent mechanisms contribute to remnant clearance. The functionally dominant mutation apoE-1(146) was most defective in heparin binding studies in vitro. In cell binding studies, apoE-1(146) did mediate lipoprotein binding only 18% compared to apoE-3. This indicates the important role of the apoE interaction with proteoglycans in vivo and could explain the development of type III hyperlipoproteinemia in patients with such apoE variants.

Animals↗
PubMed1994

Development of a ceramic matrix system for continuous delivery of azidothymidine.

A beta-tricalcium phosphate (TCP) ceramic system was designed to deliver azidothymidine (AZT) in an aqueous medium (phosphate buffered saline pH 7.4) at 37 degrees C. Since AZT is an analog of thymidine, initial studies were conducted with thymidine. Ceramic capsules were made by pressing one gram of < 38 microns beta-TCP particles with or without the desired amount of thymidine or azidothymidine in a 10 mm die at a load of 4000 lbs in an electric hydraulic press. The amount thymidine released from TCP ceramic capsules was directly dependent on the amount of the drug loaded in the ceramic. Treatment of TCP ceramic particles with either sesame seed oil or wheat germ oil (vitamin E) delayed the release of thymidine and azidothymidine from TCP ceramic capsules. Incorporation of thymidine or azidothymidine in the form of a compressed pellet (5/16" diameter at a load of 4000 lbs) further inhibited the release of thymidine and azidothymidine from TCP ceramic capsules fabricated with oil-treated ceramic particles. Thus, ceramic drug delivery systems can be designed to deliver continuously desired therapeutic levels of AZT in AIDS patients.

Calcium Phosphates↗
PubMed1994

Bremsstrahlung radiation dose in yttrium-90 therapy applications.

UNLABELLED: The bremsstrahlung component of the decay scheme of beta emitters has been traditionally ignored in internal dosimetry calculations. METHODS: We have estimated the radiation dose from the bremsstrahlung component of the decay scheme of 90Y as a function of distance from a point source in a liquid medium and to body organs from distributed sources of 90Y in the liver and spleen. RESULTS: These estimates agree with measurements of bremsstrahlung dose measured in a Rando phantom, and give an estimate of the importance of this contribution to the overall dosimetry. CONCLUSIONS: The bremsstrahlung radiation absorbed dose contribution from an organ to itself is very small compared to that from the beta dose, but the contribution to other organs is not always negligible, especially when large amounts of 90Y may be involved, as in therapy applications.

Beta Particles↗
PubMed1994

Planar gamma camera imaging and quantitation of yttrium-90 bremsstrahlung.

UNLABELLED: Yttrium-90 is a promising radionuclide for radioimmunotherapy of cancer because of its energetic beta emissions. Therapeutic management requires quantitative imaging to assess the pharmacokinetics and radiation dosimetry of the 90Y-labeled antibody. Conventional gamma photon imaging methods cannot be easily applied to imaging of 90Y-bremsstrahlung because of its continuous energy spectrum. METHODS: The sensitivity, resolution and source-to-background signal ratio (S/B) of the detector system for 90Y-bremsstrahlung were investigated for various collimators and energy windows in order to determine optimum conditions for quantitative imaging. After these conditions were determined, the accuracy of quantitation of 90Y activity in an Alderson abdominal phantom was examined. RESULTS: When the energy-window width was increased, the benefit of increased sensitivity outweighed degradation in resolution and S/B ratio until the manufacturer's energy specifications for the collimator were exceeded. Using the same energy window, we improved resolution and S/B for the medium-energy (ME) collimator when compared to the low-energy, all-purpose (LEAP) collimator, and there was little additional improvement using the high-energy (HE) collimator. Camera sensitivity under tissue equivalent conditions was 4.2 times greater for the LEAP and 1.7 times greater for the ME collimators when compared to the HE collimator. Thus, the best, most practical selections were found to be the ME collimator and an energy window of 55-285 keV. When we used these optimal conditions for image acquisition, the estimation of 90Y activity in organs and tumors was within 15% of the true activities. CONCLUSIONS: The results of this study suggest that reasonable accuracy can be achieved in clinical radioimmunotherapy using 90Y-bremsstrahlung quantitation.

Beta Particles↗
PubMed1994

[Watermarks of ancient drawings and betaradiographic findings].

Betaradiography, an identification process which satisfies the current requirements for the study of watermarks was systematically investigated in the Graphic Arts Department of the Louvre museum. The curves obtained in this context allowing the evaluation of the weight of sheets using the C-14 plate used for betaradiography and those allowing evaluation of the exposure time as a function of the weight and the choice of films were found to be essential tools for the rational use of this method. Lastly, a filming apparatus adapted to drawings has been developed allowing the first perfectly conclusive betagraphic films in the Drawing Collection.

Beta Particles↗
PubMed1993

Aggravation of experimental allergic conjunctivitis by environmental chemical and physical factors.

The effects of trichlorfon (DEP, Dipterex, anticholinesterase pesticide) and paraquat dichloride (Gramoxon, inhibitor of superoxide dismutase) on passive anaphylactic reaction in guinea pig conjunctiva using Japanese cedar pollen were quantitatively studied. For estimation of allergic conjunctivitis, Evans blue after i.v. injection was extracted from conjunctiva and measured spectrophotometrically. Allergic conjunctivitis was apparently aggravated by extremely low dosages of organophosphorus pesticide (10(-5) mg/kg) and organochlorine herbicide (10(-4) mg/kg). The aggravation of allergic conjunctivitis was also observed after exposure to cathode ray tubes used in commercial television, possibly due to electromagnetic waves. IgE-mediated allergic reaction could be non-specifically potentiated by such environmental factors.

Allergens↗
PubMed1994

[Results of treatment of malignant melanoma of the choroid using local beta-irradiation (Ru106/Rh106) from 1988 to 1992].

In the work results of focused, local therapy of the MMU (localised at choroidea) in the years 1988-92, with episclerally fixed applicators of the beta-emittors Ru106/Rh106 are presented. After this, so called "brachytherapy" (without enucleation), the group of 17 eyes (treated 18 times) was evaluated 18-54 months after therapy. Favourable results of treatment of the MMU at choroidea (small and localised) with episcleral, focused beta-radiation are emphasised. Up to December 31, 1992 at the group of 17 eyes healed MMU of the choroidea showed 58.8% of treated patients. Effective visual acuity (between 0.4-1.0) was preserved in 66.6% of the eyes. Exitus due to metastases occurred in 5 patients (24-48 month after therapy) showing the mortality rate 29.4%. These results are comparable with published statistics.

Beta Particles↗
PubMed1993

Absorbed dose calculations in Haversian canals for several beta-emitting radionuclides.

A mathematical model of a Haversian canal was used to calculate absorbed dose factors for 90Sr, 90Y, 45Ca, 89Sr, 32P, 131I and 153Sm. The regions of interest considered in this study were the blood canal, the wall or bone surface and the bone matrix. The source regions were the blood canal and the bone surface. Absorbed dose calculations were performed with the EGS4-PRESTA Monte Carlo transport code. Dose factors were calculated for Haversian canals of 5-microns to 50-microns radius. These data are also tabulated so that dose factors can be evaluated for other radii. An example is given in which these data are used along with a biokinetic model of a radioactive material in bone to assess doses from diagnostic and radiotherapy procedures.

Beta Particles↗
PubMed1993

[Radionuclide therapy of thyroid disease--radioactive iodine therapy].

Radioiodine, 131I, has been used for treatment of hyperthyroidism and metastases of well differentiated thyroid carcinoma since 1942. The use of 131I to treat hyperthyroidism and metastatic foci of thyroid cancer is one of the least invasive and most effective methods since the ionization produced by beta rays of 131I and it's high target-to-nontarget ratio are suitable. The feature of therapy with 131I on hyperthyroidism has a slow improvement of symptom, a high incidence of hypothyroidism, and an exact therapeutic effect. And, there is no significant difference between the patients with late-onset hypothyroidism and euthyroidism after 131I-therapy in the pretreatment factors, such as thyroid hormone levels, thyroid weight, 131I administration dose, and absorbed dose and also in the course of follow-up studies. On the treatment of metastases of thyroid cancer with 131I, it is very effective for the patients with fine or occult type of pulmonary metastases on chest XP, who are younger than 40 years old. On the other hand, the response to bone metastases of 131I therapy is limited to only a part of tumors and/or temporally in most cases though high grade of 131I accumulation is seen on scintigram. Both surgery and a curative dose of external irradiation should be combined with radioisotope therapy for the patients of bone metastases.

Adult↗
PubMedDate not supplied

[The ultrastructural organization of pine needles after radiation exposure].

Pine assimilative tissue was studied in the region of Chernobyl Power Plant accident the 1986-1988. With radiation doses of 8-11 Gy pine needle was viable inspite of the significant structural changes in cell organelles. With doses of 20-25 Gy the inner structure of mesophyll cells was impaired. High radiosensitivity was displayed by mitochondria and chloroplasts where irreversible destruction of membrane systems occurred.

Accidents↗
PubMed1993

Zero tumor incidence in mice after repeated lifetime exposures to 0.5 Gy of beta radiation.

A final series of experiments on tumor induction by repeating 90Sr-90Y beta irradiation of the back of ICR mice three times weekly throughout the life span showed no tumor incidence with repeated doses of 0.5 Gy per exposure. The whole dose-response relationship for repeated irradiation with 0.5 to 11.8 Gy per exposure, summarized along with data obtained previously, showed a unique nonlinear dose response with saturation of tumor incidence at doses of over 2.5 Gy per exposure and a threshold-like value around 1.5 Gy per exposure.

Animals↗
PubMed1993

Beta zoomies.

Explore the source record for details and available documents.

Beta Particles↗