Cs Implantation Research Articles

Recommendations for permanent prostate brachytherapy with 131Cs: A consensus report from the Cesium Advisory Group

Purpose Published clinical information on the safety and efficacy of 131Cs implants is limited. We provide consensus recommendations for 131Cs prostate brachytherapy based on experience to date. Methods and Materials The Cesium Advisory Group (CAG) consists of experienced 131Cs users. Recommendations are based on three clinical trials, one of which has completed accrual and has been published in the peer reviewed literature, and combined CAG experience of more than 1200 131Cs implants. Results We recommend using 1.059 cGy h −1 U −1 as the dose rate constant for the IsoRay source. The prescription for monotherapy implants is 115 Gy and when combined with 45–50 Gy external beam it is 85 Gy. Suggested individual source strength ranges from 1.6 to 2.2 U. The release criterion for 131Cs implants is 6 mR h −1 at 1 m. 131Cs brachytherapy should be performed differently from 125I and 103Pd brachytherapy: source placement is further from the urethra and rectum; the prostate V 150 should be ≤45%; sufficient margins may be obtained while limiting source placement to the capsule or close to the capsule. The increased dose rate may cause degradation of postimplant quantifiers due to edema. However, large variability in the magnitude and rate of resolution of edema make determination of the most representative postoperative imaging time impossible. The CAG recommends postimplant imaging on the day of the implant. Recommended postimplant evaluation goals include prostate D 90 greater than the prescription dose; maintaining D u ,30 < 140% of the prescription dose and keeping V r ,100 < 0.5 cm 3. Conclusion It was the consensus of the CAG that optimal 131Cs implants should be performed differently from those performed with 125I or 103Pd. Guidelines have been established to allow for safe and effective delivery of 131Cs prostate brachytherapy.

Depth distribution of Cs implanted into Si at steady-state during dual beam ToF-SIMS profiling

The steady-state depth distributions of Cs atoms implanted into a H-terminated Si surface at different energies (250 eV to 2 keV, 45° incidence angle) were studied. In situ ToF-SIMS depth profiles of the Si surface preloaded with Cs were obtained immediately after the Cs implantation using low energy Xe + (350 eV, 45°) and O 2 + (500 eV, 45°) sputter beams and a Ga + analysis beam (15 keV, 45°). The crater depth was measured ex situ by a profilometer to calibrate the depth scale. All the Cs profiles exhibited a surface peak attributed to segregation and a maximum under the surface for both Xe + and O 2 + sputtering beams. The relative height of the surface segregation peak, the position of the maximum and the width of the Cs profiles depend on the energy of the Cs primaries. Depth profiles of adsorbed/sputter deposited Cs obtained next to the implantation craters exhibited no surface peak. A dynamic TRIM code was used to obtain the depth distribution of the implanted Cs at steady-state. The results of the simulations were compared to those obtained experimentally.

Higher incidence and serum levels of minor cardiac biomarker elevation in sirolimus-eluting stent (Cypher) than bare metal stent implantations

Minor cardiac biomarker elevation after percutaneous coronary intervention has long-term prognostic significance. The sirolimus-eluting stent (Cypher) has been reported to require high postinflation pressure for optimal implantation. We examined the incidence of minor cardiac biomarker elevation induced by Cypher implantation. We measured the serum concentration of cardiac troponin-I (cTnI) 24 h after stenting and those of creatine kinase isoenzyme MB and creatine kinase before, immediately after, and 6, 12 and 24 h after implantation in patients who underwent Cypher stent (CS group; n=53) or bare metal stent (BMS group; n=57) implantation. No significant difference in clinical background was observed between the two groups. When a cutoff cTnI value of 0.50 ng/ml was used, the CS group showed a significantly higher incidence of cTnI elevation (35.8%, 19/53) than the BMS group (14.0%, 8/57) (P<0.05). Similarly, the incidence of cTnI > or = 0.03 ng/ml tended to be higher in the CS group (88.7%, 47/53) than in the BMS group (73.7%, 42/57: 0.05<P<0.10). Furthermore, the CS group showed significantly higher cTnI levels than the BMS group (1.32+/-2.38 vs. 0.34+/-0.91 ng/ml. P<0.001). Essentially, similar results were obtained for serum creatine kinase isoenzyme MB and creatine kinase. Among clinical, lesion and procedural characteristics, postinflation pressure for stenting was significantly higher only in the CS group (18.2+/-2.8 atm) than in the BMS group (14.0+/-2.7 atm) (P<0.001). The results demonstrated that CS implantation increases the incidence of minor cardiac biomarker elevation compared with BMS. The difference in postinflation pressure could account for the results.

Potential impact of prostate edema on the dosimetry of permanent seed implants using the new (model CS‐1) seeds

Our aim in this work was to study the potential dosimetric effect of prostate edema on the accuracy of conventional pre- and post-implant dosimetry for prostate seed implants using the newly introduced 131Cs seed, whose radioactive decay half-life (approximately 9.7 days) is directly comparable to the average edema resolution half-life (approximately 10 days) observed previously by Waterman et al. for 125I implants [Int. J. Radiat. Oncol. Biol. Phys. 41, 1069-1077 (1998)]. A systematic calculation of the relative dosimetry effect of prostate edema on the 131Cs implant was performed by using an analytic solution obtained previously [Int. J. Radiat. Oncol. Biol. Phys. 47, 1405-1419 (2000)]. It was found that conventional preimplant dosimetry always overestimates the true delivered dose as it ignores the temporary increase of the interseed distance caused by edema. The overestimation for 131Cs implants ranged from 1.2% (for a small edema with a magnitude of 10% and a half-life of 2 days) to approximately 45% (for larger degree edema with a magnitude of 100% and a half-life of 25 days). The magnitude of pre- and post-implant dosimetry error for 131Cs implants was found to be similar to that of 103Pd implants for typical edema characteristics (magnitude < 100%, and half-life <25 days); both of which are worse compared to 125I implants. The preimplant dosimetry error for 131Cs implants cannot be compensated effectively without knowing the edema characteristics before the seed implantation. On the other hand, the error resulted from a conventional post-implant dosimetry can be minimized (to within +/-6%) for 131Cs implants if the post-implant dosimetry is performed at 10+/-2 days post seed implantation. This "optimum" post-implant dosimetry time is shorter than those determined previously for the 103Pd and 125I implants at 16+/-4 days and 6+/-1 weeks, respectively.

High temperature behaviour of fission product analogues implanted into nuclear ceramics

The present article deals with the retention of fission products in nuclear ceramics considered as possible inert matrices for actinide transmutation. Various concentrations of a typical fission product (Cs) were introduced into yttria-stabilized zirconia and magnesium-aluminate spinel by ion implantation. The modifications of the Cs implantation profiles resulting from thermal treatments (annealing and/or irradiation at temperatures up to 900°C) were monitored by Rutherford backscattering spectrometry experiments. The results show the essential role played by the concentration of implanted species on their retention. A dramatic release of fission products was observed when the concentration exceeds a threshold of a few atomic per cent in both materials. Irradiation of implanted samples with medium-energy noble-gas ions leads to an enhancement of the Cs diffusion.

Effect of a Calcium Sulfate Implant With Calcium Sulfate Barrier on Periodontal Healing in 3‐Wall Intrabony Defects in Dogs

This controlled, split-mouth, preclinical study was designed to evaluate outcome following surgical implantation of an allogeneic, freeze-dried demineralized bone matrix-calcium sulfate (DBM+CS) composite with a CS barrier in 3-wall intrabony periodontal defects in 4 dogs. Control conditions included surgical implantation of DBM or CS and gingival flap surgery (GFS) alone. Three-wall intrabony defects (4x4x4 mm) were surgically created at the mesial and distal aspect of the maxillary and mandibular first and third premolars, respectively. Maxillary and mandibular defects each received 1 of the 4 experimental conditions. Experimental conditions were rotated between defect sites in subsequent animals. Block sections of the defects were collected at sacrifice 8 weeks postsurgery and processed for histometric analysis. Histometric defect height (means +/- SD) for the DBM+CS, DBM, CS, and GFS groups amounted to 4.2 +/- 0.5, 4.3 +/- 0.7, 4.0 +/- 0.2, and 4.1 +/- 0.2 mm, respectively. Connective tissue adhesion (connective tissue contact to the root without apparent cementum formation) amounted to 0.4 +/- 0.3, 0.4 +/- 0.3, 0.5 +/- 0.2, and 1.6 +/- 0.5 mm for the DBM+CS, DBM, CS, and GFS groups, respectively; the DBM+CS, DBM, and CS groups being significantly different from the GFS group (P < 0.05). Cementum regeneration amounted to 3.0 +/- 0.3, 3.1 +/- 0.4, 2.5 +/- 0.4, and 1.6 +/- 0.3 mm for the DBM+CS, DBM, CS, and GFS groups, respectively; the DBM+CS, DBM, and CS groups being significantly different from the GFS group (P < 0.05). Alveolar bone regeneration amounted to 2.7 +/- 0.4, 2.7 +/- 0.3, 1.8 +/- 0.5, and 0.7 +/- 0.1 mm for the DBM+CS, DBM, CS, and GFS groups, respectively; the DBM+CS, DBM, and CS groups being different from the GFS group (P < 0.05), and the DBM+CS and DBM groups being different from the CS group (P < 0.05). None of the DBM-containing implants provided evidence of bone metabolic activity. In summary, surgical implantation of DBM and CS, alone or in combination, may result in significantly improved regeneration of alveolar bone and cementum in this preclinical model. Observed regeneration is likely unrelated to a biologic activity inherent in DBM. Rather it appears that space-providing properties of the implants supported observed regeneration.

Behaviour of CS and I In Zirconia Based Fuel

AbstractA zirconia based ceramic is foreseen as an inert matrix fuel for burning excess plutonium in light water nuclear reactors. For reactor safety reasons the behaviour of volatile fission products such as cesium and iodine must be studied since a retention of fission products is favourable for licensing the studied inert matrix fuel. In this study, implantation of Cs and I was performed into polycrystalline (Zr0.85, Y0.15)O1.925 samples. The implantation depth was selected on the basis of the ability to observe by Rutherford backscattering spectroscopy (RBS) the behaviour of Cs and I after treatment. With a 1 MeV incident energy, the ions are implanted at a depth of 200 nm as predicted by TRIM. After implantations full quantification of I and Cs concentration profiles was performed by RBS. The implantation profiles are measured as a function of sample temperature during stepwise heating programs. It is interesting to observe retention of Cs and I at relatively high temperature (e.g. for 2 h, below 900 K for Cs and below 1400 K for I). This behaviour is likely to be due to the size and interactions of these species in the zirconia solid solution.

Occupational Skin Doses in Manual Implantation of Cs and Ir Sources

Occupational Skin Doses in Manual Implantation of Cs and Ir Sources

Occupational Skin Doses in Manual Implantation of Cs and Ir Sources

Occupational Skin Doses in Manual Implantation of Cs and Ir Sources

Dependence of the Flatband Voltage of Si‐MOS on Distribution of Cesium in SiO2: Comparison of Two Implantation Methods

Correlation between measured shifts in the flatband voltage, , of Si‐MOS structure and physical distribution of cesium ions in as measured by secondary ion mass spectrometry has been investigated. Direct implantation of Cs into and into Si with the subsequent oxide growth results in different profiles that depend on thermal processing. Corresponding negative are increasing with the amount of Cs in in the first case and in the latter case depend also on the height of cesium peak at interface. The change in the interface state density due to Cs is small.