Current status of clinical particle radiotherapy at Lawrence Berkeley Laboratory

Clinical experience with charged particle irradiation of human cancers has been underway at the University of California Lawrence Berkeley Laboratory. Over 150 patients have been irradiated with heavy charged particle beams including helium, carbon, neon, and argon ions. Pilot studies have included such tumor sites as glioma of the brain, carcinoma of the esophagus, carcinoma of the pancreas, carcinoma of the stomach, ocular melanoma, and carcinoma of the uterine cervix. Prospective studies are planned to investigate the improved dose localization potential (helium) and the enhanced biologic and physical dose potential (carbon, neon) in a controlled trial against the best available megavoltage irradiation techniques.

Helium ion charged particle therapy for choroidal melanoma

Nine patients with choroidal melanomas were treated with helium ion charged particle irradiation. No patient demonstrated tumor enlargement, and most lesions followed for more than five months have demonstrated tumor shrinkage. The most effective method of choroidal melanoma management is unclear. Heavy charged particle irradiation may be more applicable and have less ocular morbidity associated with it in either radioactive plaques or photocoagulation.

Computerized tomography in the quantitative assessment of tumour response

While Computerized Tomographic (CT) scans have been a valuable asset to radiotherapy treatment planning, their role in the critical assessment of tumour response has been less well defined. Recent refinements in radiotherapy treatment techniques have intensified the need for non-invasive methods to evaluate the local control of inaccessible neoplasms. In this study, 20 cases in which both pre- and post-treatment CT scans were available up to 27 months post-therapy were reviewed. The majority of the patients had pancreatic carcinoma. In both pre- and post-therapy scans, the tumour volume was calculated from contours outlined on sequential CT slices. These interpretations were compared with surgical findings, clinical course and patient survival. The rate of the primary tumour regression had little bearing on the clinical outcome. However, there was CT scan evidence of initial local tumour stabilization or regression in > 80% of the cases. In addition, CT scan evidence of tumour progression was correlated with clinical progression in > 90% of the patients. This suggests that a growth delay analysis might be possible with the use of CT scans, at least for the evaluation of pancreatic carcinoma.

Radiotherapy with heavy charged particles at Lawrence Berkeley Laboratory

Since July 1975, 157 patients have been irradiated with heavy charged particles at the Lawrence Berkeley Laboratory in a Phase I-II clinical trial to study the usefulness of these particles in the irradiation of human cancers. The particles utilized have included helium, primarily of interest because of improved dose distributions with reduction of dose to adjacent normal tissues, and heavier particles such as carbon, neon and argon ions which have the additional potential of increased biologic effectiveness against the tumor, especially hypoxic tumor cells. Initial results with helium particles have been sufficiently good to warrant a Phase III randomized trial in carcinoma of the pancreas; in other tumor sites, and with other particles, Phase I -- Phase II studies are in progress. Although follow-up is short, control within the irradiated area in this heterogeneous group of patients appears at least as good as with current megavoltage irradiation and complications to date are acceptably low, warranting further studies with heavy charged particles.

5 alpha-Reductase activity in human placenta

The concentration of 5 alpha-pregnane-3,20-dione in peripheral blood of pregnant women is higher than that found in blood obtained from nonpregnant women throughout the luteal phase of the ovulatory cycle. The in vitro synthesis of 5 alpha-reduced pregnanes from [3H]progesterone by placental tissue was investigated using tissue minces and homogenates in the presence of added nicotinamide-adenine dinucleotide phosphate. The metabolites, [3H]5 alpha-pregnane-3,20-dione and [3H]3 beta-hydroxy-5 alpha-pregnan-20-one, were isolated and characterized employing a combination of chromatographic techniques, derivative formation, and crystallization with authentic [14C]5 alpha-pregnane-3,20-dione and [14C]3 beta-hydroxy-5 alpha-pregnan-20-one to constant 3H:14C ratios. In short-term incubations with placenta homogenates, the apparent pH optimum for the synthesis of 5 alpha-pregnane-3,20-dione was 8.8. There was no evidence for the formation of 5 beta-reduced pregnanes from [3H]progesterone by placental tissue. The in vitro metabolism of [3H]progesterone by minces of five term placentas, during 1 hour incubations at pH 7.4, was studied. The rate of formation of 5 alpha-pregnane-3,20-dione varied from 109 to 197 pmoles/gm placental tissue/hr.

Measurements and calculations of the influence of thin inhomogeneities on charged particle beams

The predictions of an analytic technique for calculating fluence and dose distributions beneath thin inhomogeneities are presented for a number of structures, including a rectangular cavity or bar, a cylinder, a disk, and an angled or diffuse edge. Experiments with both electrons and protons for several geometries are presented and compared with predictions based on this technique. We offer some clinical guidelines for avoiding large perturbations due to scattering effects.

Initiation of human parturition. IX. Progesterone metabolism by placentas of early and late human gestation

In in vitro studies it was found that, in the presence of added NADPH, the human placenta metabolizes progesterone to 20alpha-hydroxy-4-pregnen-3-one at increasing rates as pregnancy advances. A fivefold increase in 20alpha-hydroxysteroid oxidoreductase activity is observed in term placentas compared with the enzymic activity of placentas of 12 to 20 weeks' gestation (368 +/- 53 pmoles/mg protein/hr vs 71 +/- 8 pmoles/mg protein/hr). The 5alpha-reductase and 3beta-hydroxysteroid oxidoreductase activities were similar in placentas obtained from early and late human pregnancies.

Initiation of human parturition. VI. Identification and quantification of progesterone metabolites produced by the components of human fetal membranes

The fetal membranes play a central role in the initiation of human parturition, a role that may be subserved in part by quantitative changes in progesterone metabolism. In order to identify and to quantify the metabolites of progesterone produced by the components of the human fetal membranes, amnion and chorion laeve tissues and homogenates were incubated with [3H]progesterone in the presence of added NADPH. The radioactive metabolites, 20alpha-hydroxy-4-pregnen-3-one, 5alpha-pregnane-3,20-dione and 3beta-hydroxy-5alpha-pregnan-20-one, were isolated and identified by derivative formation, a combination of chromatographic techniques, and by crystallization to constant specific activity after addition of authentic standards. A simplified technique of metabolite quantification was developed that involves one thin layer chromatographic procedure and liquid scintillation assay of radioactivity. The accuracy of this method was established by comparison with data obtained using classical techniques. This study demonstrates the presence of human fetal membranes 5alpha-reductase, 20alpha-hydroxysteroid oxidoreductase, and 3beta-hydroxy-steroid oxidoreductase, and a qualitative difference between amnion and chorion laeve.

Initiation of human parturition. VIII. Metabolism of progesterone by fetal membranes of early and late human gestation

A decreased rate of progesterone metabolism is detected in human fetal membranes several weeks preceding normal parturition at term. A 10- to 20-fold decrease in 20alpha-hydroxysteroid oxidoreductase activity and a 2- to 6-fold decrease in 5alpha-reductase activity are observed in human amnion and chorion laeve after 33 weeks' gestation.

High-resolution dosimetry with stimulated phosphorescence

Thermally stimulated radiophosphorescence has been studied as a means of high-resolution dosimetry. Small grains of CaSO4:Mn phosphor, embedded in a thin Teflon tape, constitute the dosimeter. The light emitted after irradiation is measured with a photomultiplier coupled to the eyepiece of a scanning microscope. With CaSO4:Mn, the phosphorescence at room temperature is sufficient for measurement after doses in excess of 3000 rads. The spatial resolution of the technique is about 0.2 mm. The method has been tested by measuring the dose distributions from a radium needle and a beta-emitting eye applicator.

Spectrofluorometric determination of the antibiotic lasalocid in blood

A spectrofluorometric assay was developed for the determination of the antibiotic lasalocid in dog blood, based on the intrinsic fluorescence of the compound in ethyl acetate. The assay can measure "total" levels of drug and any metabolites present. The specificity of the assay was verified by TLC separation of the dog blood extract, which indicated the presence of only intact drug. The overall recovery (+/- SD) of lasalocid was 62.0 +/- 3.6% in the concentration range of 1.0-10 mug of compound/ml of dog blood. The sensitivity of the assay is 0.5 mug/ml. The assay was applied to the determination of blood levels of lasalocid in the dog following the intravenous administration of a 5-mg/kg dose.