Extraction spectrophotometry using a lithium-ion selective metallacrown: temperature effect on extraction reaction and application to determination of lithium in serum and seawater.

A metallacrown-type ionophore, 2,3-pyridinediolate-bridged (3,5-dimethylanisole)ruthenium trinuclear complex, has a high extraction selectivity for Li+, but the extraction reaction is very slow. To solve this problem, the effect of temperature on the rapidity and equilibrium of the extraction of Li+ and Na+ as picrates from water to toluene with the metallacrown was investigated in this study. While the extraction of Li+ requires 6 h of shaking for equilibration at 25 °C, the distribution ratio becomes nearly constant after 4 h and 2 h of shaking at 37 °C and 50 °C, respectively. The extraction equilibrium constants (Kex) and associated thermodynamic parameters determined for Li+ and Na+ indicate that the extraction reactions are exothermic and enthalpy-driven: ΔH° = - 53 kJ/mol, ΔS° = - 0.03 kJ/(mol K) for Li+; ΔH° = - 28 kJ/mol, ΔS° = - 0.03 kJ/(mol K) for Na+. Although the extraction ability for Li+ and selectivity for Li+/Na+ decrease with increasing temperature, the values of Kex and Kex(Li+)/Kex(Na+) are 1.0 × 107 and 1.3 × 104, respectively, even at 50 °C, indicating that both are sufficiently high. In the determination of Li+ by extraction spectrophotometry using this metallacrown, extraction at 50 °C for 2 h was employed to speed up the analysis. The method was applied to seawater and serum samples containing a large amount of coexisting ions such as Na+ and Mg2+, and trace amounts (10-6-10-5 mol/L order) of Li+ in microvolume samples (sub-mL order) could be successfully determined.

Use of ionic liquids for extraction separation and concentration of iodide ions in brine samples.

Iodine in natural salt waters such as iodine-rich underground brine generally exists as iodide ions, and to extract iodide ions, it is necessary to oxidize them to nonpolar iodine molecules. In this study, we report that iodide ions in natural brine containing high concentrations of chloride ions can be quantitatively extracted without oxidation by extraction using ionic liquids. Extraction with the ionic liquids trihexyltetradecylphosphonium chloride and trioctyl ammonium chloride was found to be able to enrich trace amounts of iodide in brine samples up to 40- and 100-fold, respectively. The selectivity coefficients for I- over Cl- determined in this study clearly show that the ionic liquids have much higher I-/Cl- selectivity than typical strongly basic anion exchangers. Extraction with trihexyltetradecylphosphonium chloride was applicable as a preconcentration method for iodine determination by XRF analysis. Iodide ions extracted with trioctyl ammonium chloride were quantitatively stripped with an aqueous alkaline solution. These results indicate that ionic liquid extraction is useful for the separation and concentration of iodide from brines.

Planning study: prone versus supine position for stereotactic body radiotherapy in prostate by CyberKnife.

This study aimed to clarify the differences in radiotherapy dose characteristics and delivery efficiency between the supine and prone positions in patients with prostate cancer using the CyberKnife. The planning computed tomography (CT) and delineations of the prone position were obtained by rotating the supine CT images with delineations of 180° using image processing software. The optimization parameters for planning target volume (PTV) and organs at risk (OARs) were based on the prone position. The optimization parameters determined for the prone position were applied to the supine position for optimization and dose calculation. The dosimetric characteristics of the PTV and OARs, and delivery efficiency were compared between the two different patient positions. The plans in the prone position resulted in better PTV conformity index (nCI), rectum V90%, V80%, V75%, V50% and bladder V50%. A significant difference was observed in treatment time and depth along the central axis (dCAX) between the two plans. The mean treatment time per fraction and dCAX for the supine and prone positions were 20.9 ± 1.7 min versus 19.8 ± 1.3 min (P = 0.019) and 151.1 ± 33.6 mm versus 233.2 ± 8.8 mm (P < 0.001), respectively. In this study the prone position was found to improve dosimetric characteristics and delivery efficiency compared with the supine position during prostate cancer treatment with the CyberKnife.

Separation of Light and Middle Lanthanides Using Multistage Extraction with Diglycolamide Extractant.

We investigated the chemical behavior of lanthanides (Ln) by multistage extraction. Using 10 aqueous phases with Ln and 3 organic phases, we drew the breakthrough curves for light and middle Ln. Our study reveals that the limit of metal extraction depends on their D values and the metal concentration employed in experiments. From the multistage extractions of 15 stage aqueous phases and 15 stage organic phases, three curves (extraction curves, back-extraction curves, and separation curves) were obtained. Setting appropriate conditions, adequate separation of light Ln from middle ones can be achieved. As an example, under the condition of the separation curve experiment (aqueous phase: 0.5 M HNO3, organic phase: 0.1 M TDDGA (N,N,N',N'-tetradecyl-diglycolamide) in n-dodecane), the recovery of more than 99% of Sm in the organic phase with less than 1% of Nd can be obtained, even in the case of two metals adjacent to each other in the Ln series.

Performance of a newly designed end-to-end phantom compatible with magnetic resonance-guided radiotherapy systems.

PURPOSE: In this study, we report on our proposed phantom based on the new end-to-end (E2E) methodology and its results. In addition, we verify whether the proposed phantom can replace conventional phantoms. METHODS: The hexagonal-shaped newly designed phantom has pockets on each side for a film dosimeter of size 80 × 90 mm2 , which is easily removable, considering the 60 Co penumbra. The new phantom comprises water, shell, and auxiliary shell phantoms. The shell and auxiliary shell materials are Solid Water HE. A mock tumor (aluminum oxide) was attached by a single prop in the water phantom and placed at the center of the new phantom. The results of a conventional E2E test were compared with those of the novel E2E test using the newly designed phantom. The irradiated film dosimeter in the novel E2E test was scanned in a flatbed scanner and analyzed using an in-house software developed with MATLAB. The irradiated field center, laser center, and mock tumor center were calculated. In the novel image-matching E2E (IM-E2E) test, image matching is performed by aligning the laser center with ruled lines. In the novel irradiation-field E2E (IF-E2E) test, the displacement of the irradiation-field center was defined as its distance from the laser center. In the composite E2E test, the overall displacement, which included the accuracy of the irradiated field and image matching, was defined as the distance between the irradiated field center and mock tumor center. In addition, using the newly designed phantom, the overall irradiation accuracy of the machine was evaluated by calculating the three-dimensional (3D) center of the irradiated field, phantom, and laser. The composite E2E test could be performed using the newly designed phantom only. RESULTS: In the IM-E2E test, the results of the conventional and novel IM-E2E tests were significantly different in each direction (left-right direction: p-value < < 0.05, anterior-posterior direction: p-value = 0.002, and superior-inferior direction: p-value = 0.002). The displacement directions were the same in both the conventional and novel IM-E2E tests. In the analysis of the IF-E2E test, no significant difference was evident between the results in each direction. Moreover, the displacement directions were the same in the conventional and novel IF-E2E tests, except for the left-right lateral direction of head three. In addition, the 3D analysis results of the novel IF-E2E test were less than 1 mm in all directions. In the analysis of the composite E2E test, the maximum displacement was 1.4 mm in all directions. In addition, almost all results of 3D analysis for the composite E2E test were less than 1 mm in all directions. CONCLUSION: The newly designed E2E phantom simplifies the E2E test for MRIdian, and is a possible alternative to the conventional E2E test. Furthermore, we can perform the previously unfeasible composite E2E tests that include the entire treatment process.

An Ionic Liquid-based Microextraction Method for Ultra-High Preconcentration of Paraquat Traces in Water Samples Prior to HPLC Determination.

An ionic liquid (IL)-based microextraction method was developed for the preconcentration of paraquat traces in water samples prior to HPLC determination. On the basis of the relationship between the aqueous solubility and the extractability of known ILs, 1-ethyl-3-methylimidazolium bis(nonafluorobutanesulfonyl)amide ([EMIm][NNf2]) was selected as the extractant for paraquat. The distribution ratio of paraquat dication in the [EMIm][NNf2]/water biphasic system was theoretically estimated to be nearly 108 at its maximum level, indicating that [EMIm][NNf2] was suitable for the ultra-high preconcentration (a maximum of 106-fold concentration) of paraquat with a quantitative recovery (more than 99%). The extraction procedure could be performed easily and quickly following the in situ solvent formation microextraction technique, and the paraquat traces in the IL phase could be determined by hydrophilic interaction chromatography with good detection limits and linearity ranges (0.16 and 1 - 50 ng mL-1 for paraquat, respectively). The combined method was successfully applied to four real environmental water samples spiked with paraquat and its analog, diquat at 5.0 ng mL-1.

Application of a Lithium-ion Selective Metallacrown to Extraction-Spectrophotometric Determination of Lithium in Saline Water.

The solvent-extraction behavior of Li+ and Na+ with a Li+ selective metallacrown, [{Ru(η6-3,5-dimethylanisole)(2,3-pyridinediolate)}3], was investigated in the presence of organic dye anions, 3',3″,5',5″-tetrabromophenolphthalein ethyl ester ([TBPE]-), 2,6-dichloroindophenolate, and picrate ([pic]-). Each alkali metal ion was extracted as a 1:1:1 ternary complex of the metal ion, metallacrown, and anion. The Li+/Na+ extraction selectivity is anion dependent and highest with [pic]-. Therefore, we devised an extraction-spectrophotometric determination method for Li+ in saline water based on the extraction of Li+ using the metallacrown and [pic]- for high selectivity and subsequent replacement of [pic]- in the extracted species with [TBPE]- for high sensitivity. When applying this to artificial seawater samples containing known concentrations of Li+, a linear relationship was observed between the absorbance at 571 nm of the organic phase and the Li+ concentration in the samples. By this method, the determination of Li+ at the sub-ppm level in natural seawater is possible.

The laws governing ionic liquid extraction of cations: partition of 1-ethylpyridinium monocation and paraquat dication in ionic liquid/water biphasic systems.

To find the laws governing the extraction of cations from aqueous solutions into hydrophobic ionic liquids (ILs), we investigated the partition of 1-ethylpyridinium monocation and paraquat (1,1'-dimethyl-4,4'-bipyridinium) dication in various IL/water biphasic systems. Ten different ILs of 1-butyl-3-methylimidazolium-based or bis(trifluoromethanesulfonyl)amide-based salts were used. The distribution ratio of the target cations (T(n+)) was dependent on the initial concentration in the aqueous phase and also very sensitive to the kind of IL. The behavior was quantitatively explained on the basis of a model in which the extraction goes through both the ion exchange and ion pair transfer processes, while keeping the product of the aqueous concentrations of the IL constituent ions a constant value (solubility product, Ksp). The distribution ratio of T(n+) is expressed as a function of the difference between the initial and equilibrium concentrations of T(n+) in the aqueous phase (Δ[T(n+)]W), the aqueous solubility of IL (Ksp(1/2)), and the cation valence n. The distribution ratio is a nearly constant value (D0) when Δ[T(n+)]W ≪ Ksp(1/2)/n and decreases inversely proportional to the nth power of Δ[T(n+)]W when Δ[T(n+)]W ≫ Ksp(1/2)/n. The log D0 versus log Ksp(1/2) plot gives a linear relationship with a slope of +n for the ILs with the same anion but different cations and that with a slope of nearly -n for the ILs with the same cation but different anions. This means that the extractability dependence on the kinds of IL constituent ions is greater for the divalent cation than for the monovalent one.

Adsorption behavior of beryllium(II) on copper-oxide nanoparticles dispersed in water: A model for (7)Be colloid formation in the cooling water for electromagnets at high-energy accelerator facilities.

The adsorption behavior of Be(II) on CuO nanoparticles dispersed in water was studied as a model for colloid formation of radioactive (7)Be nuclides in the cooling water used for electromagnets at high-energy proton accelerator facilities. An aqueous Be(II) solution and commercially available CuO nanoparticles were mixed, and the adsorption of Be(II) on CuO was quantitatively examined. From a detailed analysis of the adsorption data measured as a function of the pH, it was confirmed that Be(II) is adsorbed on the CuO nanoparticles by complex formation with the hydroxyl groups on the CuO surface (>S-OH) according to the following equation: n > S-OH + Be(2+) ⇔ (>S-O)n Be((2-n)+) + nH(+) (n = 2, 3) S : solid surface. The surface-complexation constants corresponding to the above equilibrium, ß(s,2) and ß(s,3), were determined for four types of CuO nanoparticles. The ß(s,2) value was almost independent of the type of nanoparticle, whereas the ß(s,3) values varied with the particle size. These complexation constants successfully explain (7)Be colloid formation in the cooling water used for electromagnets at the 12-GeV proton accelerator facility.

Extraction of gallium(III) from hydrochloric acid solutions by trioctylammonium-based mixed ionic liquids.

The extractabilities of aluminium(III), gallium(III), and indium(III) from hydrochloric acid solutions were investigated using a mixture of two protic ionic liquids, trioctylammonium bis(trifluoromethanesulfonyl)amide ([TOAH][NTf(2)]) and trioctylammonium nitrate ([TOAH][NO(3)]). At a HCl concentration of 4 mol L(-1) or more, gallium(III) was nearly quantitatively extracted and the extractability order was Ga > Al >> In. The extractability of gallium(III) increased with increasing [TOAH][NO(3)] content in the mixed ionic liquid. The extracted gallium(III) was quantitatively stripped with aqueous nitric acid solutions. The separation and recovery of gallium(III) from hydrochloric acid solutions containing excess indium(III) was demonstrated using the mixed ionic liquid.

Mechanisms and rules of anion partition into ionic liquids: phenolate ions in ionic liquid/water biphasic systems.

It is important to understand the mechanisms and general rules of ion partitioning in hydrophobic ionic liquid (IL)/water biphasic systems in order to predict the extractability of an ionic species with various ILs. In this study, we have investigated the partition of picrate ion (target anion, T(-)) from aqueous sodium picrate solutions into several ILs and the accompanying changes in aqueous concentrations of the IL component cation (C(+)) and anion (A(-)) at 298.2 K. The main ILs examined are 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-methyl-3-octylimidazolium bis(trifluoromethanesulfonyl)amide. The aqueous concentrations of C(+) and A(-) decreased and increased, respectively, with the extraction of T(-) into the IL phase. From the standpoint of equilibrium, the partition behavior of T(-) can be explained both by the anion exchange with A(-) in the IL phase and by the ion pair extraction with C(+) in the aqueous phase. The aqueous concentrations of C(+) and A(-) are governed by the solubility product of the IL (K(sp)). The distribution ratio of T(-) is expressed as a function of Δ[T(-)](W), namely, the difference between the initial and equilibrium concentrations of T(-) in the aqueous phase; the distribution ratio of T(-) is nearly constant when Δ[T(-)](W) << K(sp)(1/2), but decreases with increasing Δ[T(-)](W) in the larger Δ[T(-)](W) region. The equilibrium constants of the ion pair extraction and the ion exchange extraction have been determined for picrate and other phenolate ions whose partition data were previously reported. The dependences of the extraction constants and extractability on the kinds of IL component ions can be quantitatively explained on the basis of the variations of K(sp).

Ion-pair formation between Cd(II), Na(I), and Ag(I) complex ions with 18-crown-6 ether derivatives and various pairing anions in water: an understanding of the ion-pair formation based on the HSAB principle.

The ion-pair formation constants (K(MLX)(0)/mol(-1) dm(3)) of CdL(2+) with Br(-) or NaL(+) with N,N-diethyldithiocarbamate ion (DDTC(-)) in water were determined potentiometrically at 25°C; ionic strength (I)→0: L denotes 18-crown-6 ether (18C6) and its mono-benzo derivative for the CdBr(2)-L system and 15-crown-5 ether and 18C6 for the NaDDTC-L one. The formation constant corresponding to the simple salt, NaDDTC, in water was also determined at I→0. Using the log K(CdLX)(0) values of CdLCl(+), CdLBr(+), CdLPic(+), and CdLSO(4), then CdL(2+) and picrate ion (Pic(-)) in water have been classified with the hard and soft acids and bases principle, where the values were available in the literature, except for CdLBr(+). The same classification was examined in NaX-L systems with X(-) = DDTC(-), trifluoroacetate ion, MnO(4)(-), ReO(4)(-), Pic(-), and BPh(4)(-) and the AgPic-L one. Consequently, CdL(2+), NaL(+), and AgL(+) were classified as the hard acids, while Pic(-) and BPh(4)(-) as the hard bases. These results reflected the reactivities of the complex ions in ion-pair formation with X(-) and SO(4)(2-) in water.

Extraction of some univalent salts into 1,2-dichloroethane and nitrobenzene: analysis of overall extraction equilibrium based on elucidating ion-pair formation and evaluation of standard potentials for ion transfers at the interfaces between their diluents and water.

Sodium permanganate, sodium picrate (NaPic), Bu(4)NPic, Me(4)NPic, and Et(4)NPic were extracted at an ionic strength of 2 × 10(-5) to 0.08 mol dm(-3) and 25°C from water (w)-phases into the organic (o)-ones, 1,2-dichloroethane (DCE) and nitrobenzene (NB). Thereby, apparent distribution constants (K(D,±)) of the anions (A(-)) or the cations (M(+)) and ion-pair formation ones (K(MA)(org)) of the univalent salts (MA) in the o-phases were determined at 25 °C, where K(D,±) = ([A(-)](o)[M(+)](o)/[A(-)][M(+)])(1/2) = (K(D,A)K(D,M))(1/2) and K(MA)(org) = [MA](o)/[M(+)](o)[A(-)](o). Also, the K(ex) and K(D,MA) values with A(-) = Pic(-), MnO(4)(-) were estimated from the relations K(ex) (= [MA](o)/[M(+)][A(-)]) = K(MA)(org)(K(D,±))(2) and = K(MA)K(D,MA), respectively. Standard potentials (Δψ(tr)(0)) for ion transfers at the w/DCE and w/NB interfaces were evaluated from the log K(D,A) or log K(D,M) values by assuming the relations K(D,Pic) = K(D,Et4N) and = K(D,Me4N), respectively. The thus-obtained Δψ(tr)(0) values, especially for the w/DCE system, were in good agreement with the values based on the extra-thermodynamic assumption for Ph(4)As(+) and BPh(4)(-) transfers at the interfaces. In the present extraction systems, the ion-pair formation of MA in the w- and o-phases was less effective in the determination of their distribution constants into the two o-phases.

New method for obtaining position and time structure of source in HDR remote afterloading brachytherapy unit utilizing light emission from scintillator.

When using a HDR remote afterloading brachytherapy unit, results of treatment can be greatly influenced by both source position and treatment time. The purpose of this study is to obtain information on the source of the HDR remote afterloading unit, such as its position and time structure, with the use of a simple system consisting of a plastic scintillator block and a charge-coupled device (CCD) camera. The CCD camera was used for recording images of scintillation luminescence at a fixed rate of 30 frames per second in real time. The source position and time structure were obtained by analyzing the recorded images. For a preset source-step-interval of 5 mm, the measured value of the source position was 5.0 +/- 1.0 mm with a pixel resolution of 0.07 mm in the recorded images. For a preset transit time of 30 s, the measured value was 30.0 +/- 0.6 s, when the time resolution of the CCD camera was 1/30 s. This system enables us to obtain the source dwell time and movement time. Therefore, parameters such as 192Ir source position, transit time, dwell time, and movement time at each dwell position can be determined quantitatively using this plastic scintillator-CCD camera system.

Evaluation of the hydrophilic properties of crown ether-ion-pair complexes with alkali metal picrates by their distribution into less-polar diluents.

Cohesive energy densities (C(w,MLA)/J cm(-3)) for ion-pair complexes (MLA: M(+) = Li(+) to Cs+; w: water) with six crown ethers (L), such as 18-crown-6 ether (18C6), benzo-18C6, and dibenzo-24-crown-8 one, and A(-) = picrate were calculated at 298 K by a procedure that uses either (i) an equation rearranged from that underlying log K(D,MLA)-vs.-log K(D,L) plots or (ii) intercepts of their plots and from both procedures. Here, K(D,MLA) and K(D,L) denote the distribution constants of MLA and L from w into a diluent, respectively. As additional MLA, Na(18C6)(2,4-dinitrophenolate) and Na(18C6)(2,6-dinitrophenolate) were employed for the present C(w,MLA) calculation. The C(w,MLA) values calculated from the two procedures agreed well, and they were proportional to the log(K(D,MLA))(-1) values. From the log K(D,MLA) values for dinitrophenolates and previously-reported values for Na(18C6)A, the hydrophobic property of some pairing anions, A(-), was ordered as F(3)CCO(2)(-) < ReO(4)(-) < MnO(4)(-) < 2,4-dinitrophenolate < 2,6-dinitrophenolate < picrate, and then discussed based on a relation with the log K(ex) values, where K(ex) shows the extraction constant (mol(-2) dm(6) unit) for Na(18C6)A into 1,2-dichloroethane.

Selective extraction of lithium with a macrocyclic trinuclear complex of (1,3,5-trimethylbenzene)ruthenium(II) bridged by 2,3-dioxopyridine.

A macrocyclic trinuclear complex of (1,3,5-trimethylbenzene)ruthenium(II) bridged by 2,3-dioxopyridine was synthesized, and the extraction properties for lithium and sodium picrates were investigated in a dichloromethane/water system at 25 degrees C. The complex was found to have extremely high extractability and selectivity for lithium picrate; the logarithmic values of the extraction constants are 5.86 and 2.63 for Li(+) and Na(+), respectively. By using this complex as an extractant, nearly quantitative extraction and separation of Li(+) from Na(+) could be achieved by a single extraction.

Distribution of 1-alkyl-3-methylimidazolium ions and their ion pairs between dichloromethane and water.

The distribution behavior of the salts of a series of 1-alkyl-3-methylimidazolium cations (RMeIm(+); R = butyl, hexyl, and octyl) with tetrafluoroborate (BF(4)(-)), hexafluorophosphate (PF(6)(-)), bis(trifluoromethanesulfonyl)amide (NTf(2)(-)), and 2,4,6-trinitrophenolate (Pic(-)) anions has been investigated in a dichloromethane-water system at 25 degrees C. The distribution constants (K(D)) of the ion pairs and the transfer activity coefficients ((o)gamma(w)) of the single ions were determined. For the ion pairs with a given anion, the log K(D) value increases linearly with the number of methylene groups (N(CH2)) in the cation, which can be explained by using the regular solution theory. A similar relationship was observed between log (o)gamma(w) and N(CH2) for the free RMeIm(+) ions, and the result was discussed by decomposing the transfer activity coefficient into the Born-type electrostatic contribution and the non-electrostatic one. For the free anions and their ion pairs with a given cation, the (o)gamma(w) and K(D) values increase with increasing molar volume of the anion: i.e., BF(4)(-) < PF(6)(-) < Pic(-) < NTf(2)(-). The features of the RMeIm(+) salts in the liquid-liquid distribution and the ion-pair formation in water are also discussed by comparing the present results with those of tetraalkylammonium salts previously reported.

Evaluation of the hydrophilic property of sodium ion-pair complexes with 3m-crown-m ethers (m = 5, 6) and their benzo-derivatives by solvent extraction.

The ion-pair formation constants {K(j)(0): j = MA (metal salt), MLA} of NaO(2)CCF(3) (Na(+)tfa(-)) and its ion-pair complexes (MLA) in water (w) were determined potentiometrically at 25 degrees C and an ionic strength (I) of zero. 15-Crown-5 (15C5), 18-crown-6 ethers (18C6), and their mono-benzo derivatives were used as crown ethers (L). The extraction of Natfa by these four L from w into 1,2-dichloroethane was done at 25 degrees C, and then the extraction constants (K(ex)) for NaLtfa were calculated by using the K(j) values, which were estimated from the corresponding K(j)(0) ones at I of the w-phases, and other equilibrium constants. Also, the distribution constants (K(D,MLA)) of NaLtfa between the two phases were obtained from a thermodynamic cycle expressing K(ex). An interaction of w-molecules with NaLA was considered using a relation of log K(D,MLA) with log K(D,L), derived from the Scatchard-Hildebrand equation, where K(D,L) denotes the distribution constant of L between the two phases. The interaction increased in the order of NaL (picrate) < free L

Hydration effect on the ion-pair extraction of lithium picrate by hydrophobic benzo-15-crown-5 ether into various less-polar diluents.

The ion-pair formation constant (K(MLA)(0) in mol(-1) dm(3)) for Li(B15C5)(+) with a picrate ion (Pic(-)) in water was determined by potentiometry with a K(+)-selective electrode at 25 degrees C and an ionic strength of 0, where B15C5 denotes benzo-15-crown-5 ether. Using the concentration equilibrium constants, K(MLA), estimated from this value, the extraction constants (mol(-2) dm(6) unit) of about ten diluents were re-calculated from previously reported extraction data. Also, the distribution constants of an ion-pair complex, Li(B15C5)Pic, between water and the diluents were re-estimated. A disagreement in the determined K(MLA) value between a solvent-extraction method and potentiometry was explained in terms of the Scatchard-Hildebrand equation; it came from the fact that the hydration of Li(I) in Li(B15C5)Pic was larger than that of free B15C5 in water. Then, the previously determined value by the former method was re-estimated using the potentiometric K(MLA) value.

Proton-beam therapy for olfactory neuroblastoma.

PURPOSE: To analyze the feasibility and efficacy of proton-beam therapy (PBT) for olfactory neuroblastoma (ONB) as a definitive treatment, by reviewing our preliminary experience. Olfactory neuroblastoma is a rare disease, and a standard treatment strategy has not been established. Radiation therapy for ONB is challenging because of the proximity of ONBs to critical organs. Proton-beam therapy can provide better dose distribution compared with X-ray irradiation because of its physical characteristics, and is deemed to be a feasible treatment modality. METHODS AND MATERIALS: A retrospective review was performed on 14 patients who underwent PBT for ONB as definitive treatment at the National Cancer Center Hospital East (Kashiwa, Chiba, Japan) from November 1999 to February 2005. A total dose of PBT was 65 cobalt Gray equivalents (Gy(E)), with 2.5-Gy(E) once-daily fractionations. RESULTS: The median follow-up period for surviving patients was 40 months. One patient died from disseminated disease. There were two persistent diseases, one of which was successfully salvaged with surgery. The 5-year overall survival rate was 93%, the 5-year local progression-free survival rate was 84%, and the 5-year relapse-free survival rate was 71%. Liquorrhea was observed in one patient with Kadish's stage C disease (widely destroying the skull base). Most patients experienced Grade 1 to 2 dermatitis in the acute phase. No other adverse events of Grade 3 or greater were observed according to the RTOG/EORTC acute and late morbidity scoring system. CONCLUSIONS: Our preliminary results of PBT for ONB achieved excellent local control and survival outcomes without serious adverse effects. Proton-beam therapy is considered a safe and effective modality that warrants further study.