Large scale accelerator production of 225Ac: Effective cross sections for 78-192MeV protons incident on 232Th targets.

Actinium-225 and 213Bi have been used successfully in targeted alpha therapy (TAT) in preclinical and clinical research. This paper is a continuation of research activities aiming to expand the availability of 225Ac. The high-energy proton spallation reaction on natural thorium metal targets has been utilized to produce millicurie quantities of 225Ac. The results of sixteen irradiation experiments of thorium metal at beam energies between 78 and 192MeV are summarized in this work. Irradiations have been conducted at Brookhaven National Laboratory (BNL) and Los Alamos National Laboratory (LANL), while target dissolution and processing was carried out at Oak Ridge National Laboratory (ORNL). Excitation functions for actinium and thorium isotopes, as well as for some of the fission products, are presented. The cross sections for production of 225Ac range from 3.6 to 16.7mb in the incident proton energy range of 78-192MeV. Based on these data, production of curie quantities of 225Ac is possible by irradiating a 5.0gcm-2 232Th target for 10 days in either BNL or LANL proton irradiation facilities.

Placental weights of normal and aneuploid early human fetuses.

Placental and body weights were plotted for 252 normal human fetuses less than 600 gm and mean regressions and 95% prediction intervals were calculated. Placentas from 62 aneuploid fetuses were compared to these standards. Placenta to body weight ratios from 34 trisomy-21 fetuses were not reduced but those from 15 trisomy-18 fetuses were generally decreased. One of 5 trisomy-13 ratios was below the prediction interval. Among 7 triploid fetuses the ratios were above the normal interval in 3 and below normal in 4. Three of the triploids that were below were associated with a karyotype of 69,XXX and did not have hydatidiform degeneration. All 4 placentas with hydatidiform changes were abnormally large. All of the 7 triploids had 3-4 syndactyly and 3 had hydrocephalus.

Placenta previa percreta with fetal survival.

A case of placenta previa percreta accompanied by massive hemorrhage is described. Both the mother and fetus survived. Anticipation of this rare obstetric condition is both possible and essential for optimum management.