The 62 MeV proton beam for the treatment of ocular melanoma at Clatterbridge.

A second treatment room and beam line has been constructed at the Cyclotron Unit at Clatterbridge for the purpose of using 62 MeV protons for the treatment of ocular melanoma. A uniform beam is produced by a double foil scattering system. The initial Bragg peak is spread across the target volume by the use of beam modulators. These are rotating four-vaned stepped absorbers made from Perspex. Two beam lines can be configured with different positions of modulators and range limiters. The first has a maximum penetration of 31.9 +/- 0.2 mm in water and the second a penetration of 31.2 +/- 0.2 mm. The second configuration has the advantage of less variation in beam penumbra, with a typical value of 1.7 +/- 0.1 mm for the 90% to 10% decrement lines. The patients are treated with individually shaped collimators. Beam output varies by less than 2% over the range of collimator areas used. The resulting whole-body dose equivalent to patient has also been assessed. In the first three years of operation over 250 patients have been treated.

High energy neutron treatment for pelvic cancers: study stopped because of increased mortality.

OBJECTIVE: To compare high energy fast neutron treatment with conventional megavoltage x ray treatment in the management of locally advanced pelvic carcinomas (of the cervix, bladder, prostate, and rectum). DESIGN: Randomised study from February 1986; randomisation to neutron treatment or photon treatment was unstratified and in the ratio of 3 to 1 until January 1988, when randomisation was in the ratio 1 to 1 and stratified by site of tumour. SETTING: Mersey regional radiotherapy centre at Clatterbridge Hospital, Wirral. PATIENTS: 151 patients with locally advanced, non-metastatic pelvic cancer (27 cervical, 69 of the bladder, seven prostatic, and 48 of the rectum). INTERVENTION: Randomisation to neutron treatment was stopped in February 1990. MAIN OUTCOME MEASURES: Patient survival and causes of death in relation to the development of metastatic disease and treatment related morbidity. RESULTS: In the first phase of the trial 42 patients were randomised to neutron treatment and 14 to photon treatment, and in the second phase 48 to neutron treatment and 47 to photon treatment. The relative risk of mortality for photons compared with neutrons was 0.66 (95% confidence interval 0.40 to 1.10) after adjustment for site of tumour and other important prognostic factors. Short term and long term complications were similar in both groups. CONCLUSIONS: The trial was stopped because of the increased mortality in patients with cancer of the cervix, bladder, or rectum treated with neutrons.