Precise measurement of the pi+-->pi0 e+nu branching ratio.

Using a large acceptance calorimeter and a stopped pion beam we have made a precise measurement of the rare pi(+)-->pi(0)e(+)nu (pi(beta)) decay branching ratio. We have evaluated the branching ratio by normalizing the number of observed pi(beta) decays to the number of observed pi(+)-->e(+)nu (pi(e2)) decays. We find the value of Gamma(pi(+)-->pi(0)e(+)nu)/Gamma(total)=[1.036+/-0.004(stat)+/-0.004(syst)+/-0.003(pi(e2))]x10(-8), where the first uncertainty is statistical, the second systematic, and the third is the pi(e2) branching ratio uncertainty. Our result agrees well with the standard model prediction.

Proportional versus projected glucose tolerance values: a quality control program.

OBJECTIVE: The objective of this study was to improve the reproducibility of the oral glucose tolerance test (OGTT). DESIGN: Ten patients were used to demonstrate the difference between proportional and projected values in an OGTT. A procedure that plots data points at their actual time of collection, producing an accurate graph, that can predict a proportional glucose value at the intersection of the curve with the two-hour specified collection time, was developed. The efficacy of this procedure was demonstrated by clinical trials on a second group of ten patients. SETTING: Hospital outpatient clinic for the first group of ten patients since heparin lock was not required; Columbia Medical Center, Ormond Beach, FL for the second group since heparin lock was required. PATIENTS: All subjects in the first group were referred to the clinic by their family physician for an OGTT. Subjects in the second group were selected to meet the following criteria: no overt symptoms of diabetes, but with at least two high risk factors for Type 2 diabetes. INTERVENTION: A glucose load was given to each patient after a fasting sample blood sugar was analyzed. MAIN OUTCOME MEASURES: The recommended OGTT procedure for obtaining accurate predicted proportional two hour plasma glucose (2hPG) values requires a three hour OGTT with 1/2 hourly mid-test samples. A sample collection form was used to record all pertinent aspects of the test, time of first swallow, amount ingested in five minutes and the exact times of sample collections. A digital clock, located in the phlebotomist's view, was used to accurately establish all time intervals, including zero time. RESULTS: The study demonstrated that inspection of the OGTT curve and calculated values provide additional useful information. It also identified five impaired glucose tolerance (IGT) subjects, one gestational diabetes mellitus (GDM) patient, thirteen normal subjects, and one flat curve. CONCLUSIONS: Accurate time intervals are not necessary since 2hPG can be accurately expressed as a predicted proportional value if the true intervals are recorded and used to calculate the glucose level at the desired time interval(s).

A scintillation spectrometer for direct comparison of neutron energy spectra at high and low rates.

The energy spectrum of the HB11 beam at HFR, Petten, has previously been measured by proton and alpha recoil in hydrogen and helium gas proportional counters at power levels of a few kW. There is some doubt whether the spectrum remains the same at the much higher power of 45 MW required for therapeutic fluxes. In order to test this point, a scintillation detector has been developed at the Paul Scherrer Institute, Villingen, Switzerland. While the device is again based on the proton recoil reaction, a combination of mm-sized plastic scintillators and fast electronics will allow it to operate at both a few kW and 45 MW, permitting direct comparison of energy spectra at these very different power levels. Results of preliminary tests at LFR, Petten, are presented.

Dynamic pion irradiation of unresectable soft tissue sarcomas.

Since November 1981, when pion irradiation was introduced for deep seated tumors at the Swiss Institute for Nuclear Research (SIN, now Paul Scherrer Institute, PSI) a dynamic, 3-dimensional spot scan treatment technique has been in use. To exploit this technique a special optimization treatment planning system has been designed. Of a total of 331 patients treated with pions from November 1981-December 1987, 35 were irradiated for unresectable soft tissue sarcomas. In 32/35 patients, tumor sites were retroperitoneal, pelvic or in the groin or thigh. Twenty-nine tumors had a maximum diameter of greater than 10 cm, 18 tumors of greater than 15 cm; 30 tumors had grade 2/3 and 32 Stage III B/IV A/IV B. Eight of 35 patients received a low pion total dose, 7-27 Gy. Twenty-seven patients received a total dose of 30-36 Gy, fraction size 150-170 cGy (90%-isodose), 20 fractions, 4 times per week. Of these 27 patients, severe late reactions appeared in five: 2/8 patients with extremity/groin sarcomas (1/2 caused by biopsy) and 3/19 patients with retroperitoneal/pelvic sarcomas (one a skin reaction after Actinomycin-D, one a small bowel reaction after 36 Gy, a dose no longer used). Seven of 27 patients had metastases at the beginning of irradiation. Three of 27 were treated with excisional biopsy, 9 with incisional biopsy or partial resection and in 15 patients biopsies were performed for histology only. The median follow-up of these 27 patients was 17 months (5-66). There was no progression in eight extremity/groin tumors but in 4 of 19 retroperitoneal/pelvic tumors. Three of these were marginal progressions. The actuarial 5-year rate of local tumor control is 64%; the actuarial 5-year survival rate of patients without metastases at the beginning of treatment is 58%. Dynamic spot scan pion irradiation proves to be a successful treatment technique for unresectable sarcomas with a high rate of tumor control and a very low rate of severe late reactions.

The production by 72 MeV protons of keV neutrons for 10B neutron capture therapy.

Fast neutrons, produced in a spallation process by 72 MeV protons hitting heavy nuclei, can be moderated down to keV energies, suitable for 10B capture therapy. Measurements of neutron flux from copper and lead targets, after moderation by water and hydrocarbons, have been performed, together with measurements of the fast neutron and gamma-backgrounds. The comparisons with Monte Carlo calculations show good agreement. As neutron fluences up to 10(12) to 10(13)n/cm2 can be produced within a few hours in about 0.5 m target distance the technique seems to be suitable for clinical experiments.

The PIOTRON: initial performance, preparation and experience with pion therapy.

The PIOTRON is a large solid angle superconducting channel built for the use of negative pi-mesons in radiotherapy. The pions are produced by protons of 590 MeV striking a target of molybdenum or beryllium. The pions are divided into 60 channels and deflected twice to enter the treatment volume radially. The momentum and the momentum band for all 60 channels can be chosen and the beam spot of Bragg peak pions at the isocenter of the applicator is a few centimeters in each direction. Dynamic scanning can thus achieve 3-dimensionally shaped treatment volumes. Two different methods are available: the ring scan, using changes of pion range; and the spot scan, involving translation of the patient through the fixed beam spot. Dose distributions of individual and multiple beams were plotted in a cylindrical water phantom. Radiobiological experiments with mammalian cells in gel and with mouse feet were performed. A special beam geometry using a sector of 15 beams was selected for the first treatments of patients with metastatic skin nodules. Six patients were treated. Acute skin reactions were scored and compared with those from orthovoltage therapy with comparable beam geometry. The RBE for 10 fractions is between 1.4 and 1.5. The next step involved treatment of patients inside water-bolus rings in preparation for dynamic therapy. Patients were then treated with the spot scan dynamic mode in the water bolus. The initial responses and reactions are favorable and confirm the feasibility and accuracy of dynamic pion therapy.

Measurement of digoxin by radioimmunoassay.

A sensitive, specific and precise procedure for the measurement of digoxin by radioimmunoassay is presented. The method is rapid, convenient and highly reliable for this very important measurement. Studies designed to evaluate the validity and reproducibility of the assay are presented and discussed.