Richard M. Lambrecht

211At radiocolloid therapy: Further observations and comparison with radiocolloids of 32P, 165Dy, and 90Y

We compared the therapeutic efficacy of alpha and beta emitting radiocolloids for the treatment of experimental malignant ascites. 211At is an almost pure alpha-emitter. As 211At-tellurium colloid, the dose survival curve is linear and extrapolates through the origin in a manner similar to other high linear energy transfer radiations. Doses of 25 microCi were curative. Less than curative doses showed a graded prolongation of median survival. In cured mice, long term histological changes were seen in thyroid tissue. Acute changes were seen in the gastrointestinal tract as early as 2 hr after radiocolloid administration; these changes reached a plateau at 6 hr and were essentially gone 36 hr later. By comparison, radiocolloids of the beta emitters 32P, 165Dy and 90Y were not curative, but relatively large doses did substantially prolong median survival. The doses for maximal effect were 150 microCi 32P-chromic phosphate, 8000 microCi ++165Dy-ferric hydroxide macroaggregates and 200 microCi 90Y-citrate. The most compelling reason for the increased therapeutic efficacy of 211At-tellurium colloid is the direct and densely ionizing character of the emitted alpha radiations.

Cyclotron Isotopes and Radiopharmaceuticals

Absolute cross sections fo r the production of oxygen-15 by the 1 5 N ( p , n) s 0 nuclear reaction were determined between 3.72 and 16.58 MeV with 99 .9% isotopically enriched 1 S N as N , . The consistencies and discrepancies with earlier cross section and thick target yield measurements are discussed.

Radiochemistry of germanium

Since the publication ofRadiochemistry of Germanium (NAS-NS-3043) in 1961, there have been significant developments on the subject. During the period from 1970 to 1980, the diagnostic utilization of the68Ge→68Ga generator system in nuclear medicine stimulated research in the field. In addition, over the past 30 years there have been many advances in the analytical chemistry of germanium (Ge), owing to the rapid increase in application of Ge in the electronics industry and, most recently, as an important component in infrared spectrometers.This fatest review has been completely rewritten. A literature search has been completed through December of 1990. Literature for selected topics has been surveyed through September 1993. The first section contains general information about germanium and its radioisotopes, and relevant nuclear data in tabulated form. In the second section, a general review of the inorganic and analytical chemistry of Ge is presented. Following these two introductory sections, subsequent sections deal with the production and preparation of germanium radioisotopes, separation and determination of Ge, of particular interest to the radiochemist, and selected procedures for its determination in or separation from various media. The section on separation chemistry has been greatly expanded.The review includes sections on hot-atom chemistry and the chemical behavior of carrier-free68Ge. A section entitled “Applied Radiochemistry of Germanium” deals specifically with68Ge→68Ga generator systems, the role of71Ge in the detection of solar netrinos, and the preparation of68Ge positron sources for studying dislocations in metallic lattices and calibration of Positron Emission Tomography (PET) cameras.Two other noteworthy points follow. Throughout the text, the oxidation state of a metal ion having only one stable state, such as germanium, is not explicitly indicated. Therefore, “Ge” typically represents Ge4+. Other ions such as arsenic and tin, however, are indicated with their appropriate oxidation states. The term “carrier-free” applies to radioactive preparations to which no isotopic carrier (stable isotopes) is intentionally added.

An improved tungsten-188/rhenium-188 gel generator based on zirconium tungstate

An improved188W-188Re gel generator based on Zr tungstate is described. The influence of synthesis parameters and pre-treatment conditions on188Re elution yields and the188W breakthrough was studied with 0.15M aqueous solution of NaCl at pH 5.3 to 7.3 as well as with some organic solvents. An elution efficiency of 80% was achieved during 3 month of explotation with 0.15M NaCl at pH=6.3. The188W breakthrough was 10−4 to 10−3%. The188W breakthrough may be decreased to 10−6% when converted into tandem generator with an alumina column. However,188Re yields are reduced by 8–12% with a tandem generator.

Target preparation and recovery of enriched isotopes for medical radionuclide production

A remotely-driven internal target system with an improved stationary target head and manually controlled target transfer assembly was constructed. Methodology and techniques for the preparation of targets utilized for the routine production of 67Ga, 111In, 123I, 124I, and 201Tl with a CS-30 cyclotron are described. Experiences in recovery of isotopically enriched target materials are detailed for plating, radiochemical separation, and target recovery for 21 cycles with 68Zn; 18 cycles with 112Cd; 40 cycles with 124Te; and 24 cycles with 203Tl. This represented 84, 72, 145, and 196 targets for 67Ga, 111In, 123I + 124I, and 201Tl, respectively. Data on target stability under routine production conditions at high currents are summarized.

In vivo evaluation of a lead-labeled monoclonal antibody using the DOTA ligand.

Abstract. The aim of this study was to assess the utility of a radioimmunoconjugate containing a lead radionuclide for therapy and scintigraphy applications. The radioimmunoconjugate evaluated consisted of a bifunctional DOTA ligand and monoclonal antibody (MAb) B72.3 using athymic mice bearing LS-174T tumors, human colon carcinoma xenografts. In the studies reported here, the lead-203-DOTA complex itself was first demonstrated to have in vivo stability. MAb B72.3 was then conjugated with the DOTA ligand and labeled with 203Pb, and the immunoreactivity of B72.3 was maintained. The localization of the radioimmunoconjugate to tumor tissue and other select organs paralleled that of DOTA-125I-B72.3, suggesting a similar metabolic pattern of the two radioimmunoconjugates. Thus, the DOTA-metal complex does not alter the behavior of the radioimmunoconjugate. Tumor localization of the 203Pb-DOTA-B72.3 conjugate was demonstrated with biodistribution studies as well as immunoscintigraphy studies. Such data highlight the stability of a lead radionuclide in the DOTA ligand. The suitability of this chelation chemistry for labeling radioimmunoconjugates with a lead radionuclide now makes its application in nuclear medicine a feasible proposition.

The 122 Te( 4 He,3n) 123 Xe ( +,EC-2.1 hr) 123 I generator.

The characteristics and applications of a

Localization of temporal lobe epileptic foci with iodine-123 iododexetimide cholinergic neuroreceptor single-photon emission computed tomography

{}^{122}{\rm Te}({}^{4}{\rm He},\ 3n){}^{123}{\rm Xe}@>\beta ^{+},\ {\rm EC}>>{}^{123}{\rm I}

Krypton-81m: a better radiopharmaceutical for assessment of regional lung function in children.

generator for producing123 I are described. A 46-MeV external4 He beam was used for irradiation. The rate of production of123 I (i.e., based on the continuous collection of

Is planar thallium-201/fluorine-18 fluorodeoxyglucose imaging a reasonable clinical alternative to positron emission tomographic myocardial viability scanning?

{}^{123}{\rm Xe}