Investigation of activation cross-sections of deuteron induced reactions on ruthenium up to 50 MeV.

The activation cross sections of deuteron induced reactions on natural ruthenium have been measured up to 50 MeV for production of radioisotopes of rhodium (105Rh, 102mRh,102gRh,101mRh,101gRh, 100gRh, 99mRh, 99gRh), ruthenium (105Ru,103Ru (cum), 102Ru (cum), 97Ru (cum), 95Ru (cum)) and of technetium (99mTc, 96gTc (m+), 95mTc (cum), 95gTc (cum), 94gTc,93gTc (m+)). The results are compared with the predictions of the most common theoretical nuclear reaction model codes (ALICE-D, EMPIRE-D and TALYS (TENDL)). From the measured cross section physical yields have been calculated for all measured radioisotopes. The medically important radioisotopes are discussed from the point of view of production routes by charged particle methods and other alternatives.

Target development for diversified irradiations at a medical cyclotron.

The irradiation facility at an old medical cyclotron (Ep=17 MeV; Ed=10 MeV) was upgraded by extending the beam line and incorporation of solid state targetry. Tests performed to check the quality of the available beam are outlined. Results on nuclear data measurements and improvement of radiochemical separations are described. Using solid targets, with the proton beam falling at a slanting angle of 20°, a few radionuclides, e.g. (75)Se, (120)I, (124)I, etc. were produced with medium currents (up to 20 µA) in no-carrier-added form in quantities sufficient for local use. The extended irradiation facility has considerably enhanced the utility of the medical cyclotron.

Activation cross-sections of proton induced nuclear reactions on thulium in the 20-45 MeV energy range.

Cross-sections of proton induced nuclear reactions on (169)Tm were measured in the 20-45MeV energy range using the standard stacked-foil irradiation technique and high resolution gamma-ray spectroscopy. Experimental cross-sections and derived integral yields are reported for the production of (169,167,166)Yb and (168,167,166)Tm radioisotopes. The experimental data are analysed and compared to results of the earlier measurements and the theoretical model codes ALICE-IPPE, EMPIRE and TALYS. Application of the new cross-sections to the production of the (167)Tm medical radioisotope is discussed.

High yield production of the medical radioisotope 167Tm by the 167Er(d,2n) reaction.

As part of our systematic comparison of (p,n) and (d,2n) reactions, the excitation functions of the (167)Er(d,2n)(167)Tm production reaction and reactions leading to Tm radio-impurities were investigated up to 20 MeV. A stacked foil irradiation technique and γ-ray spectroscopy is used. The measured excitation functions are compared with results of ALICE-D, EMPIRE-D and TALYS reaction model codes and with data from our earlier investigations on natural Er. Thick target yields and contamination levels are discussed. A comparison with other charged particle production routes for (167)Tm shows that deuteron induced reactions are not competitive.

Experimental studies and nuclear model calculations on proton induced reactions on manganese up to 45 MeV with reference to production of (55)Fe, (54)Mn and (51)Cr.

Excitation functions of the reactions (55)Mn(p,n)(55)Fe, (55)Mn(p,x)(54)Mn and (55)Mn(p,x)(51)Cr were measured from their respective thresholds up to 18 MeV in the first case and up to 45 MeV in the latter two cases, using the conventional stacked-foil technique. The radioactivity of (55)Fe was determined via high resolution X-ray spectrometry and of other radionuclides via high resolution γ-ray spectrometry. Nuclear model calculations were performed using the codes ALICE-IPPE, EMPIRE and TALYS. In some cases, good agreement was found between the experimental and theoretical data while in others considerable deviations were observed. From the experimental data the expected integral yields of the three investigated radionuclides were calculated.

An Am/Be neutron source and its use in integral tests of differential neutron reaction cross-section data.

An Am/Be neutron source, installed recently at the Rajshahi University, is described. Neutron flux mapping was done using the nuclear reactions (197)Au(n,gamma)(198)Au, (113)In(n,gamma)(114m)In, (115)In(n,n'gamma)(115m)In and (58)Ni(n,p)(58)Co. An approximate validation of the neutron spectral shape was done using five neutron threshold detectors and the iterative unfolding code SULSA. Integral cross sections of the reactions (54)Fe(n,p)(54)Mn, (59)Co(n,p)(59)Fe and (92)Mo(n,p)(92m)Nb were measured with fast neutrons (E(n)>1.5MeV) and compared with data calculated using the neutron spectral distribution and the excitation function of each reaction given in data libraries: an agreement within +/-6% was found.

Experimental study of the excitation functions of proton induced nuclear reactions on (167)Er for production of medically relevant (167)Tm.

(167)Tm (T(1/2)=9.25d) is a candidate radioisotope for medical therapy and diagnostics due to its Auger-electron and low-energy X- and gamma-ray emission. Excitation functions of the (167)Er(p,n)(167)Tm reaction and (168)Er(p,n)(168)Tm, (167)Er(p,2n)(166)Tm, (166)Er(p,2n)(165)Tm disturbing reactions were measured up to 15MeV by using the stacked foil irradiation technique and gamma-ray spectroscopy. The measured excitation functions agree well with the results of ALICE-IPPE, EMPIRE-II and TALYS nuclear reaction model codes. The thick target yield of (167)Tm in the 15-8MeV energy range is 6.9MBq/microAh. A short comparison of charged particle production routes of (167)Tm is given.

Excitation functions of natGe(p,xn)71,72,73,74 As reactions up to 100 MeV with a focus on the production of 72 As for medical and 73 As for environmental studies.

Excitation functions for the formation of the arsenic radionuclides (71)As, (72)As, (73)As and (74)As in the interaction of protons with (nat)Ge were measured from the respective threshold energy up to 100 MeV. The conventional stacked-foil technique was used and the needed thin samples were prepared by sedimentation. Irradiations were done at three cyclotrons: CV 28 and injector of COSY at Forschungszentrum Jülich, and Separate Sector Cyclotron at iThemba LABS, Somerset West. The radioactivity was measured via high-resolution gamma-ray spectrometry. The measured cross section data were compared with the literature data as well as with the nuclear model calculations. In both cases, the results generally agree but there are discrepancies in some areas, the results of nuclear model calculation and some of the literature data being somewhat higher than our data. The integral yields of the four radionuclides were calculated from the measured excitation functions. The beta(+) emitting nuclide (72)As (T(1/2)=26.01 h) can be produced with reasonable radionuclidic purity ((71)As impurity: <10%) over the energy range E(p) = 18-->8 MeV; the yield of 93 MBq/microAh is, however, low. The radionuclide (73)As (T(1/2)=80.30 d), a potentially useful indicator in environmental studies, could be produced with good radionuclidic purity ((74)As impurity: <11%) over the energy range E(p) = 30 --> 18 MeV, provided, a decay time of about 60 days is allowed. Its yield would then correspond to 2.4 MBq/microAh, and GBq amounts could be produced when using a high current target.

Activation cross sections of the 169Tm(d,2n) reaction for production of the therapeutic radionuclide 169Yb.

Activation cross sections of deuteron induced nuclear reactions on (169)Tm were measured up to 20 MeV by using the stacked-foil technique. Special emphasis was on production of the internal radiotherapy related radionuclide (169)Yb. No earlier experimental cross-section data on deuteron induced reactions on (169)Tm were found in the literature. The experimental data were compared with the results of the nuclear model codes ALICE-IPPE and EMPIRE-II. The integral yield of the (169)Tm(d,2n)(169)Yb reaction was deduced over the optimum energy range Ed = 20-->9 MeV. At 3.8 MBq/microA.h the yield is lower than that available from the commonly used (168)Yb(n,gamma) (169)Yb reactor method but on the other hand, it is higher than the yields from the earlier investigated (169)Tm(p,n)(169)Yb and (nat)Er(alpha,x) (169)Yb reactions.

Excitation functions of (alpha,xn) reactions on (nat)Rb and (nat)Sr from threshold up to 26 MeV: possibility of production of (87)Y, (88)Y and (89)Zr.

Excitation functions were measured by the stacked-foil technique for (nat)Rb(alpha,xn)(87m,87m+g,88)Y and (nat)Sr(alpha,xn)(86,88,89)Zr reactions from their respective thresholds up to 26 MeV. The samples for irradiation were prepared by sedimentation and pellet pressing techniques. The measured data were compared with those available in the literature. From the excitation functions, integral yields of the products were calculated. The suitable energy ranges for the production of (87)Y and (88)Y via (nat)Rb(alpha,xn) processes and of (89)Zr via the (nat)Sr(alpha,xn) process are E(alpha)=26-->20 MeV, E(alpha)=26-->5 MeV and E(alpha)=20-->8.5 MeV, respectively. The respective yields amount to 8.2, 0.08 and 0.9 MBq/microA h. Production of (88)Y is feasible if a waiting time of about 2 months is allowed to let the impurities decay out. Also, (87)Y can be produced with a relatively low impurity of (88)Y. The yields of both (88)Y and (87)Y via the present routes are, however, appreciably lower than those via the (nat)Sr(p,xn) processes. There is a possibility to produce (89)Zr via the alpha-particle irradiation of (nat)Sr. The yield is rather low but would be considerably increased if enriched (86)Sr would be used as target material. The radionuclidic impurity levels in all the three products are discussed.

Yield and purity of 82Sr produced via the natRb(p,xn) 82Sr process.

The recently reported cross-section data for the production of 82Sr via the natRb(p,xn) 82Sr process were evaluated. For the natRb(p,xn) 85Sr process, cross-sections were measured experimentally over the proton energy range of 25-45 MeV, a region where very few data existed. An evaluation of the recently published data on the formation of 85Sr was then also performed. From the recommended data curves, the integral yields of the desired radionuclide 82Sr and the impurity 85Sr were calculated. Yields were also determined experimentally over several energy ranges using thick natRbCl targets. The experimental and calculated yields were found to be in agreement within 15%. These integral tests add confidence to the evaluated cross-section data. For the production of 82Sr, an incident proton energy of 60 MeV or above is recommended; the 85Sr impurity then corresponds to <20%.

Nuclear data for production of the therapeutic radionuclides 32P, 64Cu, 67Cu, 89Sr, 90Y and 153Sm via the (n,p) reaction: evaluation of excitation function and its validation via integral cross-section measurement using a 14 MeV d(Be) neutron source.

Nuclear data for production of the therapeutic radionuclides 32P, 64Cu, 67Cu, 89Sr, 90Y and 153Sm via (n,p) reactions on the target nuclei 32S, 64Zn, 67Zn, 89Y, (90)Zr and 153Eu, respectively, are discussed. The available information on each excitation function was analysed. From the recommended data set for each reaction the average integrated cross section for a standard 14 MeV d(Be) neutron field was deduced. The spectrum-averaged cross section was also measured experimentally. A comparison of the integrated value with the integral measurement served to validate the excitation function within about 15%. A fast neutron source appears to be much more effective than a fission reactor for production of the above-mentioned radionuclides in a no-carrier-added form via the (n,p) process. In particular, the possibility of production of high specific activity 153Sm is discussed.

Cross-section measurement of the 169 Tm p,n reaction for the production of the therapeutic radionuclide 169 Yb and comparison with its reactor-based generation.

The radionuclide (169)Yb (T(1/2)=32.0 d) is potentially important for internal radiotherapy. It is generally produced using a nuclear reactor. In this work the possibility of its production at a cyclotron was investigated. A detailed determination of the excitation function of the (169)Tm(p,n)(169)Yb reaction was done over the proton energy range up to 45 MeV using the stacked-foil technique and high-resolution gamma-ray spectrometry. The integral yield of (169)Yb was calculated. Over the optimum energy range E(P)=16-->7 MeV the yield amounts to 1.5 MBq/micro Ah and is thus rather low. A comparison of this production route with the established (168)Yb(n,gamma)(169)Yb reaction at a nuclear reactor is given. The (169)Yb yield via the reactor route is by several orders of magnitude higher than by the cyclotron method. The latter procedure, however, leads to "no-carrier-added" product.

Probenecid-induced changes in the clearance of carprofen enantiomers: a preliminary study.

Probenecid inhibits the elimination of several acidic drugs. In this study, the influence of probenecid on the pharmacokinetics of carprofen was investigated in three healthy volunteers after single peroral administration of 150 mg of RS-(+/-)-carprofen. Carprofen enantiomers and their glucuronides (after cleavage with sodium hydroxide) were measured by use of a stereospecific procedure. The plasma concentrations of S-(+)-carprofen were higher than those of R-(-)-carprofen at most of the sampling points. Probenecid reduced apparent total and renal clearances for both enantiomers. It also reduced the clearances of the carprofen enantiomers to their glucuronides and the renal clearances of the glucuronides. The differences caused by probenecid were significant, but few stereoselective effects were observed.