Conformal rotation therapy with central axis beam block is a feasible alternative to intensity-modulated radiotherapy for chordomas of the cervical spine.

AIMS: Paraspinal tumours, such as chordoma, represent a treatment challenge for oncologists, requiring high dose to the target volume without exceeding the tolerance dose of the spinal cord. Intensity-modulated radiotherapy (IMRT) is helpful in achieving sharp dose gradients and conformation of dose to the target volume. We present a simpler technique--conformal rotation therapy with a central axis beam block (CRT + BB), which can provide similar dose distributions. MATERIALS AND METHODS: A patient with a cervical chordoma developed postoperative recurrence and was treated with high-dose palliative radiotherapy. Treatment was delivered using CRT + BB, with three fixed beams and three coplanar arcs. A dose of 62 Gy in 31 fractions was delivered to the 100% isodose, giving a maximum spinal cord dose of 49.6 Gy. The patient relapsed 2 years later, and was re-treated using the same technique to a dose of 57 Gy in 30 fractions. Estimates of spinal cord repair rates in primates were used to determine the tolerance dose of the spinal cord for re-treatment. The patient remained well for a further 25 months before developing local recurrence, which was treated with palliative chemotherapy. RESULTS: Re-treatment plans using CRT + BB and IMRT were compared. Dose-volume histograms show equivalence of dose to the spinal cord, although the IMRT plan delivered a slightly higher dose to tumour and lower dose to surrounding soft tissues. CONCLUSION: Treatment using CRT + BB requires careful planning and discussion with neurosurgeons before surgery. The normal curvature of the cervical spine must be eliminated if possible, and the patient must be immobilised with the neck horizontal. If these geometric constraints can be satisfied, then CRT + BB can be used as a safe and effective alternative treatment to IMRT for tumours at this site.

Analysis of boron-10 in soft tissue by dynamic secondary ion mass spectrometry.

We report here a preliminary study in which dynamic secondary ion mass spectrometry (SIMS) has provided images of boron-10 (10B) in biological tissue as used in research into boron neutron capture therapy. Cultured tumour cells incubated in media containing known concentrations of a 10B-containing compound, p-boronophenylalanine (BPA), and intracranial tumour tissue from animals previously injected with BPA were analysed by an in-house constructed SIMS. Investigations were conducted in positive secondary ion detection mode using a 25-keV, 5-nA gallium primary ion source. For calibration purposes, tissue standards were also analysed and their boron-to-carbon signal ratios correlated to bulk boron concentrations measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Ion maps of 10B, 12C, 23Na and 39K showing gross tissue and cell features were acquired. SIMS and ICP-AES standard measurements were in good agreement. Tissue regions with high or low 10B concentrations were identified along with 10B hotspots in normal brain areas. Cultured cells revealed the intracellular localization of 10B. SIMS is capable of producing images showing the distribution of 10B at p.p.m. levels in cells and in normal and tumour-bearing brain tissue.

The measurement of thermal neutron flux depression for determining the concentration of boron in blood.

Boron neutron capture therapy (BNCT) is a form of targeted radiotherapy that relies on the uptake of the capture element boron by the volume to be treated. The treatment procedure requires the measurement of boron in the patient's blood. The investigation of a simple and inexpensive method for determining the concentration of the capture element 10B in blood is described here. This method, neutron flux depression measurement, involves the determination of the flux depression of thermal neutrons as they pass through a boron-containing sample. It is shown via Monte Carlo calculations and experimental verification that, for a maximum count rate of 1 x 10(4) counts/s measured by the detector, a 10 ppm 10B sample of volume 20 ml can be measured with a statistical precision of 10% in 32 +/- 2 min. For a source activity of less than 1.11 x 10(11) Bq and a maximum count rate of less than 1 x 10(4) counts/s, a 10 ppm 10B sample of volume 20 ml can be measured with a statistical precision of 10% in 58 +/- 3 min. It has also been shown that this technique can be applied to the measurement of the concentration of any element with a high thermal neutron cross section such as 157Gd.

The morality of homosexuality.

Homosexuality has been considered a form of mental illness, morally wrong and socially deviant. The purpose of this paper is to present both sides of the homosexuality issue from a religious standpoint: opponents of homosexuality versus supporters of homosexuality. It is proposed that how one interprets the morality of homosexuality will depend upon one's level of moral development according to Kohlberg's theory. Ten churches in the Raleigh area of North Carolina completed a questionnaire designed to ascertain the church's position on the issue of homosexuality. Specifically, questions were asked to ascertain the church's level of moral development.