[en] Improving the efficiency of radiotherapy is a constant concern in oncology. Use of charged particle in radiotherapy represents indispensable progress in localization of the dose delivered to tumour masses, allowing reduction of dose received by adjacent healthy tissues. Protons improve the physical selectivity of spatial dose distribution. The first tumours that have been treated in the two french centres of protontherapy (Antoine-Lacassagne-Nice and Orsay) are choroid melanoma of the eye. The author presents a protontherapy centre and describes the treatment of an ocular melanoma

[en] Published in summary form only

[en] Improving the efficiency of radiotherapy is a constant concern in oncology: more than half of the patients who contract cancer receive radiotherapy at some stage. Use of charged particles in radiotherapy represents indisputable progress in localization of the dose delivered to tumour masses, thereby allowing reduction of dose received by adjacent healthy tissues. Protons improve the physical selectivity of the irradiation, i.e. the dose distribution. High-LET (Linear Energy Transfer) radiations produce different biological effects, decreasing the differences in radiosensitivity, and allowing radiation therapy to control radioresistant tumours. Fast neutrons represent the most known of these high-LET particles, but they suffer of a relatively poor physical selectivity. The two approaches (physical selectivity and biological advantages) are joined in by light ions (Carbon, Oxygen, Neon). Highly selective high-LET radiation therapy can be performed for radioresistant tumours without damage to healthy tissues. Preliminary results obtained in Berkeley (USA) demonstrate an improved local control of unresectable, slowly growing tumours, confirming what could be extrapolated from proton and neutrontherapy. Furthermore, radioactive light ion beams can be used to verify the accuracy of treatment planning by checking the range of the particle with a PET camera, and in the future for the treatment itself. In the framework of its programme Europe against Cancer, the Commission of the European Communities participates in the funding of the EULIMA (European Light Ion Medical Accelerator) project feasibility study, aiming to design an hospital-based light ion therapy facility in Europe

[en] The use of heavy charged particles in radiotherapy potentially represents an advance towards better local tumour control and a decrease in morbidity related to radiation injury of healthy tissues surrounding the target volume. This assertion only holds, however, if treatment planning systems give a real representation of the three-dimensional dose distribution, including physical and biological aspects, especially for heavier ions. The influence of linear energy transfer on the biological effects, its variations related to depth, particle, target tissue, position in the Bragg peak, etc. make the possible models for treatment planning extremely complex. A brief review of the problems to be addressed and some solutions is presented from the radiation oncologist's point of view. (orig.)

[en] In Nice biomedical cyclotron, proton beams of 65 MeV of energy are used since June 1991 to treat ocular tumours (mainly uveal melanomas): up today 550 patients have been treated. Another application of the facility is tumour treatment by using fast neutron beams. The neutron beams are produced by bombarding beryllium targets with 60 MeV protons. The treatment unit consist of a vertical beam completed with a multileaf collimator. The maximum aperture of the collimator at the treatment distance, 20 cm from the end of collimator, is 23x24.5 cm². The depth dose characteristics are similar to those ones of a 8 MeV Linac. For 10x10 cm² field the maximum dose is at 2 cm and the 50% isodose at 17 cm. The penumbra (80% - 20%) at 5 cm depth for this field is about 8 mm. Neutrons interact with biological targets giving rise to charge particle secondary spectra of protons, deuterons, alfa particles and light ions. Since neutron energy spectrum changes with depth, charge particle energy spectra is expected to change as well as their LET spectra. On the other words, the quality of the neutron beam is expected to change with the depth. Dosimetric measurements performed with ionisation chambers are not able to measure the variation of radiation quality. Microdosimetry is a well known scientific tool able to describe the radiation quality and to measure its variation. We have performed microdosimetric measurements in the Nice fast neutron beam at different depths with a spherical tissue-equivalent proportional counter which simulates 2 μm of thickness. Experimental data will be compared with the dose depth curve and with radiobiological experiment data. Results and comparisons will be discussed

[en] Neutron capture irradiation aims to selectively destroy the tumoral cells with nuclear reactions produced inside themselves. Therefore, ¹⁰B is selectively carried into tumours, being linked to a molecular vehicle. The tissues are then irradiated with thermal neutrons, and the boron neutron capture leads to the formation of α and ⁷Li particles which produce high levels of radiolytic damage along their range of 10μm. Boron neutron capture therapy (BNCT) uses a thermal/epithermal neutron beam for irradiation, while boron neutron capture potentiation uses the addition of the captures in a fast neutron irradiation. A first trial, conducted in 1951 to 1961 in the USA to test BNCT on patients suffering of glioblastoma, was a failure, essentially because ¹⁰B was located in the cerebral capillaries rather than in the tumoral cells. Today, with great improvement in the boronated compounds which show an uptake preferentially inside the cells; the quality of neutron beams; and the knowledge of the microdosimetry of the technique, this technique may be clinically used to increase the local control of radioresistant tumours, like the high grade gliomas, cutaneous or uveal melanoma, and perhaps soft tissue sarcomas. (authors). 145 refs., 3 figs., 1 tab

[en] The present status of protontherapy in 'extended' European Community is: six machines presently running at low to medium energy, three for medical purpose only, three for part-time medical applications. Three of these machines could be used for higher energy applications. Proposals for the construction of new facilities and their organization are presented, covering the evaluation of cost problems. (R.P.)

[en] In spite of the progress made in radiotherapy in regard to dose distribution, proton-therapy is certainly of advantage in the high-precision treatment of tumours located near normal and essential structures. But the high cost of accelerators slows the development of proton-therapy. Efforts should therefore be directed at the building of more compact accelerators, making use in particular of new technologies centered on superconductivity. With regard to manpower, the technicians needed to maintain a cyclotron are few in number when compared with the personnel needed for the treatment -which is similar in proton-therapy and in radiotherapy. (author). 7 figs., 2 tabs

[en] Short communication

[en] The in vivo colony method used to generate survival curves following exposure to ionizing irradiation allows to score large clones, representing surviving cells, and small colonies, representing late reproductive death. By subtraction, early-dying cells can be estimated. In the three human tumour cell lines examined, we have observed that early cell death is a major mode of action of irradiation. The contribution of early cell death to total mortality increases as the dose increases. Moreover, repair due to dose-splitting and delayed plating in densely-inhibited cells is not observed in early-dying cells. (authors)