A. Hermanne

Vascular imaging of solid tumors in rats with a radioactive arsenic-labeled antibody that binds exposed phosphatidylserine.

Purpose: We recently reported that anionic phospholipids, principally phosphatidylserine, become exposed on the external surface of vascular endothelial cells in tumors, probably in response to oxidative stresses present in the tumor microenvironment. In the present study, we tested the hypothesis that a chimeric monoclonal antibody that binds phosphatidylserine could be labeled with radioactive arsenic isotopes and used for molecular imaging of solid tumors in rats. Experimental Design: Bavituximab was labeled with 74As (β+, T1/2 17.8 days) or 77As (β−, T1/2 1.6 days) using a novel procedure. The radionuclides of arsenic were selected because their long half-lives are consistent with the long biological half lives of antibodies in vivo and because their chemistry permits stable attachment to antibodies. The radiolabeled antibodies were tested for the ability to image subcutaneous Dunning prostate R3227-AT1 tumors in rats. Results: Clear images of the tumors were obtained using planar γ-scintigraphy and positron emission tomography. Biodistribution studies confirmed the specific localization of bavituximab to the tumors. The tumor-to-liver ratio 72 h after injection was 22 for bavituximab compared with 1.5 for an isotype-matched control chimeric antibody of irrelevant specificity. Immunohistochemical studies showed that the bavituximab was labeling the tumor vascular endothelium. Conclusions: These results show that radioarsenic-labeled bavituximab has potential as a new tool for imaging the vasculature of solid tumors.

New cross-sections and intercomparison of deuteron monitor reactions on Al, Ti, Fe, Ni and Cu

Abstract The 27Al(d,x)22,24Na reactions are frequently used to monitor deuteron beams above 20 MeV. To extend possible monitoring energy region toward lower energies, new monitor reactions are proposed and experimental cross-sections are measured for the processes 27Al(d,x)22,24Na, natTi(d,x)48V, natFe(d,x)56Co, natNi(d,x)61Cu and natCu(d,x)65Zn. The excitation functions were studied using the activation method on stacks of thin metallic foil targets with natural isotopic composition. The data sets of the six processes were cross-checked with each other to provide reliable numerical cross-sections. Detailed literature compilation and critical comparison were made on the available data sets for the studied reactions. Predictions of model calculations were compared with the new experimental data. After establishing selection criteria, consistent data sets were chosen for each of the processes, which were then fitted with a spline or Pade method to provide recommended cross-sections.

Determination of the external beam energy of a variable energy. Multiparticle cyclotron

Abstract Optimization of commercial production of GBq batches of radioisotopes by threshold nuclear reactions needs an accurate knowledge of the particle beam energy. We present three independent techniques allowing energy determination with 2% accuracy for external beams of a multiparticle cyclotron with a positionable deflector used in isotope production. Stopping power analysis, activation analysis followed by comparison with monitor reaction cross-sections and direct time-of-flight (ToF) study of the particle velocity using a double beam pick-up set up allows us to conclude that only at the high energy end a discrepancy exists between real and calculated energy (maximal 4.5% for α-particles).

Investigation of the natMo(p,x)96mgTc nuclear reaction to monitor proton beams: New measurements and consequences on the earlier reported data

Abstract The excitation function of the natMo(p,x) 96 mg Tc monitor reaction has been measured up to 38 MeV to verify published experimental cross-section data sets measured earlier by using this monitor reaction. The activation method and the stacked foil technique using high-resolution HpGe gamma spectrometry were applied to determine the excitation function. Reliable data sets were produced with the help of simultaneous measurement of the excitation functions of natTi(p,x)48V, natNi(p,x)57Ni, natCu(p,x)62Zn, natCu(p,x)63Zn and natCu(p,x)65Zn monitor reactions in the whole investigated energy range. The new cross-section values indicate the necessity of normalisation the excitation functions of about 250 of proton induced nuclear reactions by a factor of 0.8 measured earlier by Levkovski using the natMo(p,x)96mgTc process as monitor reaction.

New cross-sections and intercomparison of proton monitor reactions on Ti, Ni and Cu

Abstract The excitation functions of proton induced reactions on Ti, Ni and Cu were studied using activation method on stacks made of thin metallic foil targets with natural isotopic composition. Since titanium, nickel and copper are ideal target material with respect to their availability, physical, mechanical and chemical properties the use of the nat Ti(p,x) 48 V, nat Ni(p,x) 57 Ni, nat Cu(p,x) 62 Zn, nat Cu(p,x) 63 Zn and nat Cu(p,x) 65 Zn processes are suitable for monitoring the intensity and/or energy of charged particle beams. These processes are recommended under 40 MeV bombarding proton energy as monitor reaction. The new data sets of these five processes were cross-checked with each other to provide reliable consistent numerical cross-sections. Results were compared to the recommended cross-section values reported recently by the International Atomic Energy Agency [IAEA TECDOC-1211, 2001].

Excitation functions of deuteron induced nuclear reactions on natural zinc up to 50 MeV

Excitation functions were measured for production of 66,67Ga, 62,65,69mZn, 61,64,67Cu and 58Co radioisotopes in deuteron induced reactions on natural Zn up to 50 MeV by activation using stacked foil techniques. Detailed compilations were made of the earlier reported experimental cross-section and integral yield data. They are compared with the new values and theoretical calculations. The use of the measured formation cross-section for production of practically important radioisotopes of gallium and copper is discussed as well as the application of cross-section data of 65Zn in the field of wear monitoring by the thin layer activation method.

Two-dimensional plastic microlens arrays by deep lithography with protons: fabrication and characterization

We present a quantitative study of the fabrication process of two-dimensional plastic microlens arrays fabricated using deep lithography with protons. Our process involves the proton irradiation of a PMMA (poly(methyl methacrylate)) sample in regions with a circular footprint followed by a diffusion of MMA vapour into the bombarded zones to cause a lens-shaped volume expansion. In the first part of this paper we give a detailed description of our fabrication technique and of the calibration procedure that goes with it. We demonstrate the flexibility of our approach with the fabrication of different types of array: highly uniform microlens arrays and arrays of microlenses with varying sags (maximum height of the spherical lenscap) and pitches. All lenses under test feature diameters of 200 ± 2µm, root-mean-square (RMS) roughnesses on the top of the lenses of λ/30 @ 632 nm and lens sags ranging from 10 to 70 µm. We also present the optical performances and the aberrations of the microlenses, measured using a dedicated transmission Mach–Zehnder interferometer. The focal lengths of the lenses under study range from 166 to 1444 µm, corresponding to a range of sags between 9.77 and 69.73 µm and to focal numbers between 0.83 and 7.22. Typical values for the RMS and peak-to-valley aberrations of 0.209λ and 1.057λ respectively were observed. To conclude, we analyse and discuss the strengths and weaknesses of this fabrication method.

Study on production of 103Pd and characterisation of possible contaminants in the proton irradiation of 103Rh up to 28 Mev

Abstract Excitation functions for the proton-induced reactions on 103 Rh of importance in the production of the medically used 103 Pd were studied by the stacked foil technique. Several experiments at incident energies between 14.7 and 29.4 MeV allowed reliable determination of the cross-sections for 101 Pd, 103 Pd, 101m,101g Rh and 102m,102g Rh. Measurements for 103 Pd were done in the X-line region as well as for γ-lines and show 25% difference. The new experimental values are compared to the available literature values and show mostly higher values. Thick target yields were calculated that are in good agreement with earlier published values. Practical upper limit of incident energy to be used in production runs is derived.

New cross section data on68Zn(p, 2n)67Ga andnatZn(p,xn)67Ga nuclear reactions for the development of a reference data base

Excitation functions were measured by stacked-foil technique for the68Zn(p, 2n)67Ga,68Zn(p,3n)66Ga,natCu(p,xn)62Zn,natZn(p,xn)67Ga,natZn(p,xn)66Ga,natZn(p,px)62Zn andnatZn(p,αx)61Cu nuclear reactions in the energy range from 15–35 MeV. The experimental excitation functions were compared with published data. Our present measurements not only increase the number of available cross section data points for the above reactions, but for some reactions (and in some energy regions) values are presented for the first time.

Deep proton writing: a rapid prototyping polymer micro-fabrication tool for micro-optical modules

One of the important challenges to deploying the emerging breed of nanotechnology components is interfacing them with the external world, preferably accomplished with low-cost micro-optical devices. In our labs at the Vrije Universiteit Brussel (VUB), we are therefore focusing on the continuous development of a rapid prototyping technology for the fabrication of micro-optical modules. In this technology, which we call deep proton writing (DPW), we bombard polymer samples with swift protons, which will result after chemical processing steps in high quality micro-optical components. The strength of the DPW micro-machining technology is the ability to fabricate monolithic building blocks that include micro-optical and mechanical functionalities which can be precisely integrated into more complex photonic systems. The DPW technology is furthermore compatible with low-cost mass-replication techniques such as micro-injection moulding and hot embossing. In this paper we give an overview of the process steps of the technology and the characteristic qualities we can expect from the components made by DPW. The general overview of the technology is followed by three case studies of different micro-optical components that were fabricated at our labs: (i) two-dimensional fibre connectors, (ii) out-of-plane couplers for optical waveguides embedded in printed circuit boards (PCBs), (iii) intra multi-chip-module (MCM) level optical interconnection via free space optical modules.