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No technique can now be used without previously considering the safety of patients, staff and public and risk management. This is the case for brachytherapy. The various aspects of brachytherapy are discussed for both the patient and the staff. For all, the risks must be minimized while achieving a treatment of quality. It is therefore necessary to establish a list as comprehensive as possible regardless of the type of brachytherapy (low, high, pulsed dose-rate). Then, their importance must be assessed with the help of their criticality. Radiation protection of personnel and public must take into account the many existing regulation texts. Four axes have been defined for the risk management for patients: organization, preparation, planning and implementation of treatment. For each axis, a review of risks is presented, as well as administrative, technical and medical dispositions for staff and the public.

National audience; Purpose: At the request of the French nuclear safety authority (Autorité de Sûreté Nucléaire, ASN) a working party of multidisciplinary experts was initiated to elaborate a report regarding propositions for the clinical practice of stereotactic radiation therapy and the related medical physics. Material and methods: Several stereotactic radiation therapy experts were audited by the working party, especially neurosurgeons and neuroradiologists, as well as radiation oncologists, medical physicists and radiation technologists. An international survey was conducted looking at legal requirements and guidelines concerning stereotactic radiation therapy. A national survey was conducted in France among 29 departments performing stereotactic radiation therapy. The working party report was submitted for advice to the permanent group of medical experts of ASN. Results: Among the 13 countries who responded, very few have legal documents. Some of them are stating that stereotactic radiation therapy must be performed in a radiotherapy department and only by well-trained professionals. Guidelines describing the role of each participant have been published in the USA. In France, stereotactic radiation therapy is performed with dedicated machines or adapted linear accelerators. In 2009, within the 29 departments, 4247 patients were treated with stereotactic radiation therapy representing 4% of the patients treated with external beam radiation therapy. Intracranial lesions were: 3383 and extracranial: 864. The working party of multidisciplinary experts made 7 recommendations. The first one saying that stereotactic radiation therapy must be considered as a radiotherapy. The permanent group of medical experts is asking to modify the "décret du 19 mars 2007" regarding "radiosurgery" Conclusion: The medical benefit of stereotactic radiation therapy is well admitted and it is an increasingly used technique. This work through practical guidelines and legal propositions intends to promote a well-controlled development of this radiotherapy technique. © 2012.; Objectif de l’étude :À la demande de l’Autorité de sûreté nucléaire (ASN), un groupe de travail composé d’experts pluridisciplinaires a travaillé pour élaborer un rapport sur les conditions d’exercice de la radiothérapie stéréotaxique et de la radiophysique médicale associée.Matériel et méthodes : Le groupe de travail a auditionné plusieurs experts en radiothérapie stéréotaxique, notamment les neurochirurgiens et neuroradiologues, mais aussi les oncologues radiothérapeutes, les physiciens médicaux et les manipulateurs en radiothérapie. Le groupe de travail a réalisé une enquête internationale pour connaître les réglementations et recommandations existantes en matière de radiothérapie stéréotaxique. Un état des lieux de la pratique de radiothérapie stéréotaxique en France a été réalisé auprès de 29 centres pratiquant cette technique. Le rapport du groupe de travail a été soumis à l’avis du groupe d’experts médicaux de l’ASN.Résultats : Parmi les 13 pays interrogés, les textes réglementaires sont rares et mentionnent pour certains l’obligation de réaliser la radiothérapie stéréotaxique au sein d’un service de radiothérapie et de réserver sa pratique à des professionnels disposant d’une formation spécifique. Des recommandations ont été publiées aux États-Unis décrivant le rôle de chaque intervenant au cours de l’acte de radiothérapie stéréotaxique. En France, il existe des appareils dédiés à cette technique qui est aussi réalisée avec des accélérateurs classiques adaptés. En 2009, dans les 29 centres interrogés, 4247 patients ont bénéficié d’une radiothérapie stéréotaxique (soit environ 4 % des radiothérapies externes), dont 3383 pour des lésions intracrâniennes et 864 extracrâniennes. Dans son rapport, le groupe de travail a émis sept recommandations, dont notamment la nécessité de considérer tout acte de radiothérapie stéréotaxique comme un acte de radiothérapie. Le rapport du groupe d’experts médicaux de l’ASN recommande de modifier le décret du 19 mars 2007 concernant « la radiochirurgie ».Conclusion : La radiothérapie stéréotaxique, dont le service médical rendu est reconnu, verra sa pratique se développer dans les années prochaines. Ce travail à travers ses recommandations pratiques et ses propositions réglementaires, souhaite participer à une croissance maîtrisée de cette technique de radiothérapie.

At the request of the French nuclear safety authority (Autorité de Sûreté Nucléaire, ASN) a working party of multidisciplinary experts was initiated to elaborate a report regarding propositions for the clinical practice of stereotactic radiation therapy and the related medical physics.Several stereotactic radiation therapy experts were audited by the working party, especially neurosurgeons and neuroradiologists, as well as radiation oncologists, medical physicists and radiation technologists. An international survey was conducted looking at legal requirements and guidelines concerning stereotactic radiation therapy. A national survey was conducted in France among 29 departments performing stereotactic radiation therapy. The working party report was submitted for advice to the permanent group of medical experts of ASN.Among the 13 countries who responded, very few have legal documents. Some of them are stating that stereotactic radiation therapy must be performed in a radiotherapy department and only by well-trained professionals. Guidelines describing the role of each participant have been published in the USA. In France, stereotactic radiation therapy is performed with dedicated machines or adapted linear accelerators. In 2009, within the 29 departments, 4247 patients were treated with stereotactic radiation therapy representing 4% of the patients treated with external beam radiation therapy. Intracranial lesions were: 3383 and extracranial: 864. The working party of multidisciplinary experts made 7 recommendations. The first one saying that stereotactic radiation therapy must be considered as a radiotherapy. The permanent group of medical experts is asking to modify the "décret du 19 mars 2007" regarding "radiosurgery".The medical benefit of stereotactic radiation therapy is well admitted and it is an increasingly used technique. This work through practical guidelines and legal propositions intends to promote a well-controlled development of this radiotherapy technique.

To investigate if the regular use of kV-CBCT notably increases the dose delivered to tumor and surrounding healthy tissues.Images were obtained using a Varian equipment (OBI version 1.3, 645 to 650 projections in 370 degrees to acquire image), and patients were irradiated at source-tumor distance: 100cm. In vivo measurements were performed using radio-thermoluminescent dosimeters Harshaw-TLD700H (TLD) at skin (anterior-posterior and lateral axis crossing the rotation axis), with a fourth TLD group under the table thanks to a retrolaser. TLD's were calibrated at the kV-CBCT effective energy (64 keV), and the method validated using an anthropomorphic phantom, in which Gafchromic EBT films were also inserted.The phantom study showed that the dose distribution depends on the phantom position relative to the axis and that the doses measured at the phantom surface using TLD and films (good agreement) were maximum at the entrance of the anterior-posterior axis. Their arithmetic mean was equal, or a slightly greater than doses measured at mid-thickness of the phantom and at the level of the rectum (OAR). In vivo measurements performed on the five first patients (125 kV-CBCT) yield a mean skin dose per kV-CBCT varying from 5.8+/-0.1 to 7.3+/-0.2 cGy on the anterior-posterior axis. Lateral skin doses vary from 3.4+/-0.2 to 4.5+/-0.2 cGy.Doses delivered by repeated kV-CBCT are not negligible. They should be taken into account, but questions about the RBE to be applied to kilovoltage X-rays are raised.

The purpose of this study was to determine, when assuming the worst case scenario of bone contamination, the sterility assurance level in bone transplantation treated by irradiation and after donor screening.The virus: We employed the HIV-1, LAV-1 as our reference strain, which has always been cultured on normal human cells (and has therefore never been in contact with cell lines). To test viral virulence, we used a very sensitive cell line: MT2 cell line, a T lymphoblastoid cell line which is HTLV-I positive and is sensitive to HIV-1/LAV-1 infection. It was maintained in RPMI 1640 culture medium containing 10 per cent heat-inactivated fetal calf serum (Boehringer Mannheim), 2 mM L-glutamine (Boehringer Mannheim) and 1 per cent antibiotics (PSN 100 x, Gibco). Cell concentration was 100,000 cells per milliliter. Irradiation was performed using an accelerator delivering electrons of 6.2 MeV providing several tens of kilograys in a few seconds. The dose delivered was checked by placing alanine dosimeters at the site of the HIV aliquots. Alanine is a solid amino acid which, when irradiated, gives rise to free radicals; these were counted using electron paramagnetic resonance (relative standard deviation of less than 1 per cent).25 kilograys irradiation of 316,227 TCID50/ml at -80 degrees C led to a considerable titer reduction (3 logs) with 316 TCID50/ml remaining. According to the technique's sensitivity (100 TCID50/ml) and to the sensitivity with which the dose of irradiation can be measured (less than 1 per cent), the D10 value with "99 per cent confidence limits" was between 8.3 kilograys and 7.2 kilograys. Assuming the worst characteristics of irradiation, we have chosen 8.3 kilograys as the D10 value for -80 degrees C.Considering a mean level of contamination of 30 TCID50 per milliliter of plasma during the asympomatic phase of infection, the reduction of the transmission risk of HIV by a femoral head allograft was calculated in the best case to be only 5 per cent when performed at 25 kilograys. Irradiation cannot be considered as a process able to achieve sterility of the graft and has to be associated to an extensive screening. However irradiation associated with appropriate screening of donors decreases the risk of transmission of the disease under one out of one million in femoral allograft implantation.

An experimental study was performed to investigate the efficacy of irradiating HIV-contaminated allografts. Irradiation was achieved using an accelerator delivering 6.3 MeV electrons, and the viral strain was HIV-1/LAV-1. At an activity equivalent to 600.000 counts of reverse transcriptase activity per minute and per millilitre, irradiation permitted total inactivation of HIV. In the light of present data concerning plasma viremia in HIV-infected patients, this experiment suggested that irradiation minimizes as far as possible the risk of transmitting HIV infection through bone transplantation from a seronegative, contaminant donor. However, in view of the relative imprecision of viral sensitivity curves, irradiation does not authorize bone transplantation from a seropositive patient, even though the bone has been irradiated.

The diffusion function of 25 MV Roentgen rays in a tissue-equivalent material was determined experimentally as a function of the size of the beam and of the depth into the material. In order to characterize the beam, the attenuation of the beam in various materials was previously investigated. The results of the investigation demonstrate the important contribution of diffused radiation to the dose when using very high energy radiation.

The systematic dosimetric control after all endocurietherapy implantations considered to be in conformity with the Paris System is often made manually from tracings of the radioactive threads and a series of tables which gives the strength of the dose as a function of the distance from the thread. The authors describe a calculating programme, developed in a small Hewlett Packard calculator associated with a printing-out apparatus (without graph tracings), which can determine the strength of the base dose and the tracing of the isodoses in the central plane for all radioactive implantations belonging to the field of application of the Paris System. A schematic representation of the organization of the programme includes feeding of information in the form of Cartesian co-ordinates; the geometric determination of the points for calculating the base doses, the calculation of the strength of the base dose, the reference dose, and doses at particular points in the central plane, and finally, tracing the isodoses. Several examples are presented, after which the authors discuss the advantages as well as the limits of this method.

Electron beam irradiation of the entire skin surface was used to treat 25 patients with mycosis fungoides from 1977 to January 1988. A plexiglas screen was used to reduce the energy of the 8 MeV beam of a Sagittaire linear accelerator to 4 MeV. A total dose of 30 Gy was delivered in 12 fractions over days. This series includes 17 men and 8 women with a mean age of 44 years (range 13-78 years) and a mean follow-up of 34 months (range 6-92 months). The following-up staging system was used: stage A: superficial lesions covering less than 50 p. 100 of the body surface; stage B: superficial lesions covering more than 50 p. 100 of the body surface; stage C: tumors of the skin, lymph nodes and/or visceral organs, Sezary's syndrome. All stage A patients achieved complete remission. One developed recurrent disease in a very limited area 17 months after radiation therapy. No stage A patient died of mycosis fungoides. 6/9 stage B patients achieved complete remission; 4 of these developed recurrent disease localized to the skin 6 to 13 months after electron therapy. These recurrences were controlled by topical nitrogen mustard, puva therapy or localized irradiation. 1 patient showed no response and died of cutaneous mycosis fungoides. 5/10 stage C patients obtained complete remission but all relapsed within a mean period of 7 months. 4/5 of the patients not responding to electron therapy died of their disease and one is alive 16 months after completion of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

In order to treat patients with mycosis fungoides, the authors were led to breakdown the energy of a 7 MeV electron bundle emitted by a linear accelerator. With this aim, they sought to determine the nature, thickness and position of the decelerating which should be used to obtain adequate flow and energy of the electron bundle. They then explain the technique of total body irradiation of the patients, and in particular the way in which the functions of the bundle are effected. Finally, in order to diminish under-dosage in regions of the human body irradiated tangentially, they suggest the use of a perspex screen of variable thickness.

The aim of the work was the evaluation of the dose delivered to the axilla during endocurietherapy for carcinoma of the breast using Iridium 192. The position of the radioactive material with respect to the axillary zone differing with the patient seated or lying, the authors carried out an vivo dosimetric study using Lithium fluoride. They refer to the chief properties of Lithium fluoride which render it the dosimetric agent of choice for clinical work and give details of their experimental conditions, stressing the problems encountered in practice (response in relation to dose, mass of thermoluminescent powder to use, fading, regeneration etc.). They then describe the technique used for placing the thermoluminescent dosimeter in the axillary zone adjacent to the target volume irradiated. Results concerning 43 patients made possible the establishment of a significant correlation between the dose delivered to the axillary region and the site of implantation of the radioactive material in the breast, and show that, with identical tumour doses, this dose is little dependent upon the structure of the radioactive implant itself. They conclude that the dose delivered to the axillary region is of the order of 25% of the tumour dose if the radioactive implant is localised in the axillary tail, 10% if it is in the upper outer quadrant and negligeable if it is elsewhere.

The authors recall the functional principles of thermoluminescent dosimeters: heating, apparatus for measuring the emitted light, circulation of nitrogen, reference source. They take this opportunity to stress the essential role played by the circulation of nitrogen over the dosimeters which equilibrates the temperature of the photo multiplier, reduces the emission of unwanted light, prevents the combustion of dust or other possible impurities and finally improves the reproductibility of the measurements even for high dosod for finding the optimum working conditions for the heating apparatus of the planchette in the most simple T.L.D. readers and in those where the heating apparatus of the planchette has a pre-heating phase. They then study the dosimetric properties of lithium borate incorporated in thin teflon discs (type DLB. 0.13 and 0.4). This shows itself to be very interesting for certain uses because it is a solid dosimeter which does not require annealing between two measurements. The reproductibility of the measurements obtained with this material, the stability of its response relative to the delay between radiation and reading (fading), its response relative to the absorbed dose plus the nature and the energy of the rays, are presented with the usual reservations made for this type of dosimetry. The authors conclude by citing a few applications where they have been able to achieve a satisfactory result with the aid of lithium borate.

Between 1961 and 1975, 300 women with cancer of the breast (T1:72; T2:167; T3:61) were treated conservatively with radiotherapy alone (T3) or with partial or predominant radiotherapy combined with tumorectomy without axillary dissection (T1 or T2). The results, normalized at 10 years, confirmed that the survival rate (crude or NED) was exactly the same as with other conservative treatments or mutilating surgical treatments. Relapses were few (8%) in T1 cases and acceptable in T2 and T3 cases (13% and 18% respectively); in almost every patient they were amenable to surgery, with good local postoperative course. The prevalence of metastases was directly proportional to the size of the tumour; it was neither more nor less frequent than after radical surgery. Complications were rare and not very severe. Cosmetic results were either excellent (T1) or satisfactory (T2, T3). Finally, the proportions of breasts preserved at 10 years among patients alive and NED was very high, ranging from 96% (T1) to 91% (T2) and 87% (T3). These good results were associated with the possibility of high dosage additional endocurietherapy of the tumoral area with iridium 192, particularly in extensive forms where tumorectomy was cosmetically precluded. Since 1975, we have been using the conservative treatment in closer association with non mutilating surgery.

The Paris System is a previsional dosimetric system which facilitates the work of curietherapists working with iridium 192 wires. Introduced about twelve years ago for radio-active implantations in one linear plane, this system has now become more generalized for implantations in two or more linear planes. After a brief review of the principles on which the Paris System is based, and introducing the new definitions arising from its development, the authors present the results of a systematic computerized study. The results obtained were used to establish, among others, the simple relationships between the geometric implantation data (disposition, length, number, separation... of the radioactive lines) and the dimensions of the volume treated, for the coplanar patterns and those called "in squares"

The difference of potential of supply of ionisation chambers is often inadequate to collect all the ions formed under the effects of a pulsed ray. The authors thus decided to determine the effectiveness of the collection of ions in one of the types of cylindrical ionisation chambers used most commonly at present in calibrating teleradiotherapy beams : Nuclear Enterprises chambers type 2505/3 A and 3 B. They determined essentially the value of effectiveness of the collection of ions using lithium borate, a thermoluminescent dosimeter the response of which is independent of dose up to very high flow rates. In the case of a pulsed ray emitted at constant frequency, it is easy to evaluate the dose delivered by impulsion and then compare the values obtained experimentally with those calculated using theoretical formulae such as Boag's formula. By contrast, in the case of an accelerator equipped with an electromagnetic sweep system of the beam in order to ensure a homogeneous dose of electrons, instantaneous flow doses (dose/impulsion) are difficult to evaluate by virtue of the sweep and variables from one type of energy to another. The authors thus sought an empirical method making it possible to evaluate the effectiveness of the collection of ions, knowing the energy of the incident electron beam and the dose flow indicated by the ionisation chamber receiving its usual supply tension. The results of this study as a whole show not only that it is essential to take into account the recombination of ions when ionisation chambers are used to calibrate the irradiation beams of new accelerators for medical use, but also that the effectiveness of the collection of ions is dependent upon the electronic equipment associated with the chamber.

An essential success factor for tympanoplasties is effective aeration of middle ear, lack of tubular permeability being a factor for failure. The anti-inflammatory effect of curietherapy with Iridium 192 introduced into the tube during middle ear surgery was studied in 38 patients. Tubular dysfunction was evaluated by clinical and manometric examinations. During operation, a sealed plastic tube 1.6 mm in diameter was introduced into the Eustachian tube, an Iridium wire inserted on the following day, and a dose of 1.5 and 3 Gy applied to two groups respectively. Tubular function was assessed as normal or almost normal in 61% of cases. Results were compared with a group of 30 patients not receiving curietherapy.