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PubMed1992

Pterygium treated with excision and postoperative beta irradiation.

A retrospective study was done of 338 patients with pterygia treated between October 1974 and May 1990. These patients resided in the desert of the southwestern United States, where the hot, dry, dusty climate is thought to predispose to pterygium formation and subsequent recurrence. The pterygia were excised, and the administration of beta irradiation was initiated within 24 hr of surgery. Sixteen percent of the pterygia were recurrent. Ninety-five percent of the beta irradiation prescriptions consisted of 3 weekly 800 cGy fractions. For patients with a minimum of 6 months follow-up, the crude local control rate was 225/258 (88%). The Kaplan-Meier estimate of the 5-year local control rate was 84% (95% confidence interval: 79-89%). Ten of 33 recurrences were diagnosed within 6 months, and 32/33 recurrences were diagnosed within 5 years of treatment. Previously untreated pterygia were controlled more easily than were recurrent pterygia (p = 0.005). In 86% of the cases, patients judged the cosmetic results to be satisfactory. No severe complications developed. This study and others, when compared with studies involving excision alone, suggest that postoperative beta irradiation reduces the likelihood for pterygium recurrence. When the beta irradiation is fractionated, satisfactory cosmetic results can be achieved with low morbidity.

Adult↗
PubMed1992

Beta irradiation of recurrent ptergia: results and complications.

Although postoperative beta irradiation for prevention of pterygium recurrence is widely used, its complication rate has not been widely appreciated. Thirty-six patients underwent pterygium excision followed by irradiation with 90Sr to between 1600 and 5300 cGy (median 2400) in two to four fractions over 7 to 27 days. A median of three fields were used in each treatment course (range two to 10). Most patients had undergone previous treatment for their pterygia, including surgery alone (25 patients), or both surgery and irradiation (5 patients). Overall, recurrences developed in 10 eyes (28%). Recurrence occurred in one eye after re-irradiation (20%), compared to 9 of 31 (29%) previously non-irradiated eyes (p greater than 0.1). There was no association with number of excisions and recurrences, although all but 6 patients had undergone more than one excision. Thirteen patients (36%) developed complications including: epithelial defect or corneal thinning (3), symblepharon (5), cataract (4) and corneal ulceration (1). Complications developed in 4 of the 5 (80%) re-irradiated eyes compared to 9 of 31 (29%) previously non-irradiated eyes (p less than 0.05). The power of the statistical analysis was limited by sample size, but no significant association was observed between the development of complications or recurrences and total dose, number of abutting fields, number of previous surgical excisions or patient age, even when re-irradiated patients were excluded. Recently described calibration uncertainties with the 90Sr applicator may explain in part these complications. Alternatively, technical factors such as the number of fields or volume treated may play a role. Excessive complications and recurrences with the use of postoperative beta irradiation in this series emphasize the danger of re-treatment and the need for alternative safe and effective therapies.

Adolescent↗
PubMed1994

Amelioration of both early and late radiation-induced damage to pig skin by essential fatty acids.

PURPOSE: To evaluate the possible role of essential fatty acids, specifically gamma-linolenic and eicosapentaenoic acid, in the amelioration of early and late radiation damage to the skin. METHODS AND MATERIALS: Skin sites on the flank of 22-25 kg female large white pigs were irradiated with either single or fractionated doses (20 F/28 days) of beta-rays from 22.5 mm diameter 90Sr/90Y plaques at a dose rate of approximately 3 Gy/min. Essential fatty acids were administered orally in the form of two 'active' oils, So-1100 and So-5407, which contained gamma-linolenic acid and a mixture of that oil with eicosapentaenoic acid, respectively. Oils (1.5-6.0 ml) were given daily for 4 weeks prior, both 4 weeks prior and 10-16 weeks after, or in the case of one single dose study, just for 10 weeks after irradiation. Control animals received a 'placebo' oil, So-1129, containing no gamma linolenic acid or eicosapentaenoic acid over similar time scales before and after irradiation. Acute and late skin reactions were assessed visually and the dose-related incidence of a specific reaction used to compare the effects of different treatment schedules. RESULTS: A reduction in the severity of both the early and late radiation reactions in the skin was only observed when 'active' oils were given over the time course of the expression of radiation damage. Prior treatment with oils did not modify the radiation reaction. A 3.0 ml daily dose of either So-1100 or So-5407 given prior to, but also after irradiation with single and fractionated doses of beta-rays produced the most significant modification to the radiation reactions, effects consistent with dose modification factors between 1.06-1.24 for the acute reactions of bright red erythema and/or moist desquamation, and of 1.14-1.35 for the late reactions of dusky/mauve erythema and dermal necrosis. There was the strong suggestion of an effect produced by the 'placebo' oil, So-1129, after higher daily doses of oil. CONCLUSIONS: Essential fatty acids can modulate normal tissue reactions when given over the time when radiation damage is normally expressed. Dose modification factors suggest that a > or = 10% higher dose is required to produce the same level of normal tissue injury. Clinical application of selected essential fatty acids at appropriate doses may lead to a significant increase in the therapeutic gain in patients treated for cancer by radiotherapy.

Animals↗
PubMed1994

Genotoxicity of tritiated water in human lymphocytes.

The present study was carried out to evaluate the genotoxicity of tritium, administered as tritiated water, in peripheral blood human lymphocyte cultures. Sister-chromatid exchanges (SCE) and chromosome aberrations (CA) were scored as genetic endpoints. From our results we can conclude that beta-radiation from low concentrations of tritium was able to induce a significant increase in the frequency of CA, although it was ineffective in increasing the frequency of SCE.

Beta Particles↗
PubMed1987

Beta spectroscopy with liquid scintillation systems: applications in dosimetry of 90Sr and 90Y.

We have demonstrated that commercially available liquid scintillation counters are adequate for obtaining useful information about the variation of beta spectral shapes as a function of attenuation. A gel scintillation system that permitted the approximation of point source geometry worked well. The spectral shapes predicted by the Fermi equations were reasonably matched with experimental spectra of sources with geometry close to a point source. For energies in the range of 50-2300 keV, we found sufficient linearity of the energy scale and uniformity of detection limits for the direct output of the instrument to be experimentally useful. The gel scintillation system has been used to directly measure the energy distribution of the beta flux coming out of bone samples and incident on the soft tissue of dogs fed 90Sr-90Y from in utero to 540 days of age.

Animals↗
PubMed1988

Cholesterol in the plasma very low density lipoprotein fraction in patients with type III hyperlipoproteinemia: analysis of factors which modulate its concentration.

Anthropometric data, plasma lipoprotein lipid levels, and post-heparin lipoprotein lipase (PHLPL) activity were measured in nine patients with type III hyperlipoproteinemia (HLP) and two hypocholesterolemic subjects with the apo-E2/2 phenotype. Five type III HLP patients were treated with clofibrate. Log PHLPL activity was inversely correlated (r = -0.667, p less than 0.05) and age was positively correlated (r = 0.706, p less than 0.05) with cholesterol levels in the VLDL fraction of plasma from type III HLP patients. The correlation between log PHLPL and VLDL cholesterol levels remained significant when age was held constant in partial correlation analysis. Together age and log PHLPL activity accounted for 77% of individual variation in VLDL cholesterol levels in the type III patients. Clofibrate treatment raised PHLPL activity (+48%, p less than 0.05) and reduced the levels of VLDL cholesterol (-67%, P less than 0.05), VLDL triglycerides (-40%, P less than 0.02), and the ratio cholesterol/triglyceride in VLDL (-50%, P less than 0.05) in five type III HLP patients. Mean PHLPL activity was higher in the hypocholesterolemic subjects with the apo-E2/2 phenotype compared to the type III HLP patients. These results suggest that lipoprotein lipase activity and factors associated with age modulate the levels of abnormal and atherogenic remnant particles (beta-VLDL) in the VLDL plasma fraction of type III HLP patients.

Adult↗
PubMed1991

Receptor-based assays.

Receptor-based assays have benefitted from the newest advances in biotechnology and electronics in three main ways: genetically engineered cells expressing single receptor subtypes have been developed for many natural and synthetic ligands; assays have been designed which take advantage of a variety of signals triggered in cells by binding, or inhibition of binding, of ligands to surface-bound receptors; and radiolabelled ligand assays have been considerably improved and simplified by novel electronic devices.

Animals↗
PubMed1996

Depth-dose distribution in bricks determined by thermoluminescence and by Monte-Carlo calculation for external gamma-dose reconstruction.

The analysis of depth-dose distributions in bricks sampled from walls in areas with nuclear waste or accident contamination has the potential of providing information on the energy and source configuration of the gamma-radiation that had been incident on the brick. In this study, a brick from a mill facing a shallow water reservoir of the contaminated Techa river in the South Ural region is investigated. Thermoluminescence (TL) methods were used to measure the accumulated dose at several depths in the brick. The accidental external gamma-dose is obtained by subtracting the natural radiation background dose from the total accumulated dose. In the first segment of the brick, at a depth of about 1.5 cm, the accident dose was found to be roughly 3.5 Gy. Monte-Carlo simulations of the photon transport from the reservoir bed contaminated with 137Cs were calculated for different depths in the brick. The calculations were made assuming different attenuating water levels. It is found that the depth-dose distribution determined by measurements corresponds to a water level between 20 and 50 cm. The results indicate that TL measurements combined with Monte-Carlo modelling calculations are highly promising for external gamma-dose reconstruction applications.

Beta Particles↗
PubMed1996

Comparison of the targeting characteristics of various radioimmunoconjugates for radioimmunotherapy of neuroblastoma: dosimetry calculations incorporating cross-organ beta doses.

To optimize the efficacy of radioimmunotherapy (RIT), the ideal antibody-radioisotope combinations should be used to deliver the highest tumor and the lowest normal tissue doses. In a mouse model, tumor and critical organ-absorbed doses delivered by different radioimmunoconjugates were calculated and compared. We used a Medical Internal Radiation Dosimetry (MIRD)-style mouse dosimetry model that incorporates cross-organ beta doses to make refined estimates of the radiation absorbed dose to tissues. Biodistribution data from neuroblastoma xenografted nude mice were used to estimate tumor, organ and bone marrow absorbed dose values for 90Y-3F8, 131I-3F8 and 131I-F(ab')2 fragments. Immunoreactive fractions of the radiolabeled antibodies were comparable. Although tumor uptake of the radioiodinated and radiometal labeled 3F8 was much higher than that of the radioiodinated F(ab')2 fragments (maximum percent injected dose per gram values were 39.4, 33.2 and 20.1 for 131I-3F8, 90Y-3F8 and 131I-F(ab')2, respectively), tumor to nontumor ratios were higher for radioiodinated fragments (with the exception of tumor to kidney ratio). For the minimum tumor dose necessary for complete ablation, the bone marrow received 195, 278 and 401 cGy for 131I-F(ab')2, 131I-3F8 and 90Y-3F8, respectively. Tumor doses were 50.1, 232 and 992 cGy/MBq for 131I-F(ab')2, 131I-3F8 and 90Y-3F8, respectively. Tumor to bone marrow dose, which is defined as the therapeutic index, was 21.5, 14.7 and 10.4 for 131I-F(ab')2, 131I-3F8 and 90Y-3F8. 131I-F(ab')2 fragments produced the highest therapeutic index but also the lowest tumor dose for radioimmunotherapy. Radiometal conjugated IgG produced the highest tumor dose but also the lowest therapeutic index.

Animals↗
PubMed2005

Two-year clinical follow-up of 90Sr/90 Y beta-radiation versus placebo control for the treatment of in-stent restenosis.

BACKGROUND: It is an ongoing concern that intracoronary brachytherapy may possibly just delay the problem of in-stent restenosis ("late catch up"). For gamma-radiation, 3 placebo-controlled studies have shown the maintenance of the initially positive effect after 2 years, but similar data do not exist for beta-radiation. STents And Restenosis Trial (START) was the first placebo-controlled randomized trial for in-stent restenosis with beta-radiation; herein, we report the 2-year clinical follow-up. METHODS AND RESULTS: Two hundred and forty-four patients were randomized to active treatment, 232 patients to placebo (nonactive source train) treatment. The primary end point of efficacy was target vessel revascularization (TVR); primary safety end point was any major adverse cardiac event (MACE) at 8 months and 2 years. Two-year clinical outcome in patients receiving brachytherapy was based on 195 of 244 original patients (79.9%) and in the placebo arm on 183 of 232 original patients (78.9%). TVR was significantly reduced by 25%; from 36.6% (placebo) to 27.5% (brachytherapy) remained significant after 2 years (RR .7 [.57-.98], 95% CI -9.2 [-17.5-0.8]). The Kaplan-Meier analysis for TVR and MACE showed improvement beginning approximately 90 days after radiation and remained almost constant for the 2 following years. Freedom from TVR was significantly increased from 62.4% +/- 3.8% to 71.6% +/- 3.3% (P = .027) and freedom from MACE from 58.9% +/- 3.7% to 68.0% +/- 3.4% (P = .035). CONCLUSIONS: The START trial shows for the first time that the initial beneficial effects of intracoronary brachytherapy with beta-radiation using 90 Sr/ 90 Y are maintained at 2-year clinical follow-up period.

Aged↗
PubMed2005

Sirolimus-eluting stent implantation and beta-irradiation for the treatment of in-stent restenotic lesions: comparison of underlying mechanisms of acute gain and late loss as assessed by volumetric intravascular ultrasound.

BACKGROUND: The aim of the study was to compare the angioplasty mechanisms of drug (sirolimus)-eluting stent (DES) implantation and vascular brachytherapy (VBT) for the treatment of in-stent restenosis (ISR) as assessed by intravascular ultrasound (IVUS). METHODS: We performed IVUS in 53 patients (28 DES, 25 VBT) before and after angioplasty of ISR and at 6-month follow-up. Cross-sectional areas of the external elastic membrane, the stent, and the lumen were measured. Plaque + media, peristent plaque, and intimal hyperplasia areas were calculated, respectively. RESULTS: Clinical and IVUS baseline characteristics did not differ between groups at baseline. After the index procedure, the lumen at the stent site was smaller in the DES group (DES 6.7 +/- 2.0 mm2 vs VBT 7.5 +/- 2.2 mm2, P = .042). Because of less intimal hyperplasia (DES 0.2 +/- 0.5 mm2 vs VBT 0.7 +/- 0.7 mm2, P = .043), the lumen dimensions revealed no difference between groups at follow-up (DES 6.5 +/- 2.3 mm2 vs VBT 6.8 +/- 2.2 mm2, P = .374). At the reference site, the index procedure led to a similar increase of plaque + media (DES 0.9 +/- 0.9 mm2 vs VBT 0.6 +/- 1.2 mm2, P = .150). At follow-up, the plaque + media was significantly smaller in the DES group (DES 8.0 +/- 6.6 mm2 vs VBT 9.9 +/- 7.8 mm2, P = .013). CONCLUSIONS: Drug-eluting stent for the treatment of ISR more effectively inhibits neointima formation when compared with VBT. Yet insufficient stent expansion might be a reason for device failure and should be avoided. At the reference site, lumen loss by an increased plaque burden, as has been well recognized following VBT, is not present with DES.

Aged↗
PubMed2006

Comparison between drug-eluting stents and beta-radiation for the treatment of diffuse in-stent restenosis: clinical and angiographic outcomes.

BACKGROUND: Initial reports on drug-eluting stents (DES) for the treatment for in-stent restenosis (ISR) show very good outcomes. Nevertheless, few data are available on direct comparison with intracoronary brachytherapy (IBT). The aim of this study was to compare brachytherapy and DES in treatment of diffuse ISR. METHODS: One hundred forty-one consecutive patients with diffuse ISR were treated with IBT (68 patients; beta (90Sr/90Y) emitters) or with DES (73 patients; 32 with sirolimus-eluting and 41 with paclitaxel-eluting stents). Angiographic and clinical follow-up was scheduled within 9 months. RESULTS: The first 74 lesions were treated with IBT (group 1) and the latter 74 with DES (group 2). The two groups were well matched for clinical/angiographic characteristics. At follow-up, restenosis rates were 37.8% (28/74) in IBT group and 14.9% (11/74) in DES group (P = .0028). A diffuse pattern of recurrence was more frequent after IBT (20/74 vs 6/74, P = .005). A worse outcome after IBT was associated with the "edge effect," accounting for most failures. Recurrence within the original restenotic stent was similar in both groups (12.9% vs 14.9% in groups 1 and 2 respectively, P = .8). CONCLUSIONS: Drug-eluting stents are more effective than IBT with beta-irradiation in reducing recurrence rates after treatment of diffuse ISR. In case of failure, the pattern of restenosis is more benign after treatment with DES.

Aged↗
PubMed2004

Survival, anatomic, and functional long-term results in choroidal and ciliary body melanoma after ruthenium brachytherapy (15 years' experience with beta-rays).

PURPOSE: To analyze survival, radiation-related complications, local recurrence, enucleation, and visual acuity after ruthenium-106 irradiation of malignant uveal melanoma. DESIGN: Retrospective study. METHODS: A total of 213 patients treated with ruthenium-106 brachytherapy between 1983 and 1995. End point rates were estimated by life tables, and prognostic factors by Cox proportional hazards regression. Main outcome measures were survival rate, radiation-related maculopathy, radiation-related vascular occlusion, local tumor recurrence, enucleation, and visual acuity (<20/100 at 3 years). RESULTS: At 5 and 10 years, survival was 82% (standard error [SE] 2.7%) and 72% (SE 3.4%), local recurrence 21.7% (SE 3.0%) and 24.3% (SE 3.2%), and enucleation 18.0% (SE 2.7%) and 19.2% (SE 2.8%), respectively. Sixty-one patients showed maculopathy (29%), 36 retinal vascular occlusion (17%), in 33 local recurrence (16%), and 38 enucleation (18%). Age and large tumor diameter were independently associated with survival (P <.0001 and P <.0075, respectively). Age below 40 and melanoma located posteriorly were significant risk factors for maculopathy (P <.0085 and P <.0004, respectively) and vascular occlusion (P <.0415 and P <.0114, respectively). Diameter and Bruch membrane rupture were significant predictors (P <.0032 and P <.0390, respectively) of local recurrence. Visual acuity <20/100 was observed in only 26 of 97 (27%) cases of anterior but 34 of 42 (81%) of posterior tumor (P <.001). CONCLUSION: Although percentage tumor recurrence was high, survival was comparable to series using other treatments. Radiation-related complication rates were acceptable, especially for anterior tumors. Ruthenium therapy can, therefore, be recommended for small and medium-sized tumors with anterior location.

Adult↗
PubMed2003

Comparison of the angiographic outcomes after beta versus gamma vascular brachytherapy for treatment of in-stent restenosis.

This study was designed to compare the angiographic outcomes of beta versus gamma vascular brachytherapy (VBT). We reviewed the angiographic results of 636 lesions (212 that underwent beta and 212 that underwent gamma VBT, and 212 that received placebo) with native coronary in-stent restenosis matched for lesion length, vessel size, preprocedure minimum lumen diameter (MLD), and time to angiographic follow-up in the various randomized clinical trials and studies. Baseline lesion complexity was similar in these 3 groups. Final MLD was smaller in the beta VBT group than in the gamma VBT or placebo group. At follow-up, beta and gamma VBT significantly reduced both angiographic restenosis (34.4% for beta VBT, 26.4% for gamma VBT, and 50.9% in the placebo group; p <0.0001) and recurrent lesion length (9.2 mm for beta VBT, 8.4 mm for gamma VBT, and 15.5 mm placebo, p <0.0001) compared with placebo. Gamma VBT was associated with a greater reduction in restenosis outside the stent than beta VBT. By multivariable analysis, independent angiographic predictors of treated segment restenosis included beta or gamma VBT, lesion length, and vessel size. In matched lesions, beta and gamma VBT achieved similar reductions in treated segment restenosis and recurrent lesion length compared with placebo.

Adult↗
PubMed2004

Angiographic and three-dimensional intravascular ultrasound analysis of combined intracoronary beta radiation and self-expanding stent implantation in human coronary arteries.

This study tested the combination of vascular brachytherapy (VBT) and self-expanding Wallstent implantation in coronary lesions of patients at high risk for restenosis as assessed angiographically by quantitative coronary analysis and by 3-dimensional intravascular ultrasound analysis. Twenty-nine "de novo" lesions were managed with a self-expanding stent alone (n = 19) or with a self-expanding stent after beta-VBT (n = 10) in 27 patients who had been identified by high levels of plasma angiotensin-converting enzyme as being prone to myointimal growth after stent implantation. At 6 months, the increase in stent strut diameter was similar in the 2 groups by quantitative coronary analysis and 3-dimensional intravascular ultrasound (Delta mean stent strut diameter -0.33 +/- 0.3 vs -0.40 +/- 0.3 mm, p = 0.5; Delta stent area -11.8 +/- 6.1 vs -12.0 +/- 6.1 mm(2), p = 0.9; Delta stent volume -96.9 +/- 112 vs -83.5 +/- 73 mm(3), p = 0.7; for groups treated with VBT and self-expanding stents and only self-expanding stents, respectively). In-stent neointimal proliferation was decreased in the group treated with VBT and self-expanding stents (minimal luminal diameter 2.5 +/- 0.8 vs 1.88 +/- 0.8 mm, p = 0.04) by quantitative coronary analysis (minimal luminal area 6.7 +/- 2.5 vs 4.1 +/- 1.9 mm(2), p = 0.01), by intravascular ultrasound, and proliferation volume (84.6 +/- 66.4 vs 159.2 +/- 103.5 mm(3), p = 0.05) by 3-dimensional intravascular ultrasound. Positive vessel and luminal remodelings were observed in 50% of the group treated with VBT and self-expanding stents and in 11% of the group treated only with self-expanding stents (p = 0.02). The combined use of VBT and self-expanding stents is a novel approach that enlarges vascular lumen by preventing vessel constriction and neointimal proliferation. The feasibility and good results of this experimental approach suggest that the simultaneous use of these 2 technologies may be an interesting alternative for difficult vascular districts with high restenosis rates, such as peripheral circulation in the lower limbs.

Angioplasty, Balloon↗
PubMedDate not supplied

Reusability of plastic scintillators used in beta emitter activity determination.

The use of plastic scintillation in the measurement of beta emitter activity is a suitable alternative to classical detection techniques in spite of the high cost and potential memory effects. Reuse of the plastic scintillator beads after a cleanup procedure would overcome both drawbacks. In the present paper, we tested several cleaning solutions (water, HCl 0.1M, commercial soap, EDTA 0.01 M pH=3, citric acid 0.1 M pH=3). The recommended procedure consists of the immersion of the beads in three consecutive citric acid baths for 24 h. If this protocol is followed, plastic beads contaminated with 90Sr/90Y, 14C, and 3H recover their initial condition, and can be used in successive determinations.

Beta Particles↗
PubMed2004

Self-absorption correction for beta radioactivity measurements in water samples.

Two methods were used to apply self-absorption corrections for the determination of beta radioactivity in water samples (either for an identified radionuclide or for monitoring trends). One method was performed by estimating the absorption coefficient by assuming an exponential behaviour of absorption using external absorbers, while the other method was performed by preparing empirical curves using standards of different mass. In the first method, a relationship between absorption coefficient and maximum beta energy was also derived. In the second method, self-absorption curves for 90Sr/90Y standard were prepared with several sodium salts (carbonate, nitrate and sulphate salts) and, for 40K standard using a potassium salt. Both beta emitters are usually necessary to calibrate detectors for beta radioactivity measurements. This study showed that, for 90Sr/90Y, results using standards of different mass were more accurate than using external absorbers. Furthermore, it is highly recommended to melt sodium nitrate salts in order to perform a self-absorption curve for 90Sr/90Y because standards were stable in time and homogeneously distributed. For 40K, a self-absorption curve may be easily derived using paper absorbers of different thickness, instead of performing a time consuming self-absorption curve using a set of varying thickness of 40K standards. In order to test the two methods, the gross beta activity of several environmental water samples was analysed.

Absorption↗
PubMedDate not supplied

Standardization of 67Ga by 4pigamma (NaI) and 4pibeta-gamma coincidence methods.

The nuclide 67Ga is widely used in nuclear medicine for diagnostic purposes. It decays with a half-life of 3.259 days to 67Zn, a stable nuclide. The decay mode is electron capture with several branches followed by gamma-de-excitation. One of the excited levels of 67Zn with energy 93 keV has a half-life of 9.1 micros, which makes its absolute standardization by coincidence methods difficult. Two methods were used to standardize a solution of this nuclide: (a) 4pi-EC(PPC)-gamma(NaI) coincidence counting with efficiency extrapolation to infinite dead time and (b) high-efficiency 4pigamma counting with a well-type NaI detector.

Algorithms↗