An optimal treatment of head and neck carcinoma is to be targeted at obtaining a good local control of the disease. Intraoperative radiotherapy is one of the means of increasing the irradiation dose in the tumoral volume. It appears particularly suitable for initial treatment of locally advanced head and neck lesions and treatment of recurrence of non irradiated tumors.
Out of 332 epidermoid carcinomas of the base of the tongue treated in Centre Alexis Vautrin from 1978 to 1992, 136 received. a treatment with a curative intent. The median age was 58 years, the median follow-up was 57 months. We numbered 55 T1-T2 and 81 N0 or N1. From the therapeutic point of view, the patients were classified into three groups: in group 1 (45 cases), they were treated by external irradiation only (median dose: 71 Gy); in group 2 (72 cases), they were treated by external irradiation and brachytherapy (the mean dose delivered by external irradiation was 50 Gy, and by brachytherapy, the mean dose was 30 Gy with a mean dose rate of 55 cGy/h); in group 3 (19 cases), they were treated by a radiosurgical association, the surgical resection was always mutilating and completed by an external irradiation (55 Gy), 8 patients received an associated barrier brachytherapy. Thirty-nine patients presented a local failure, 50 a locoregional evolution. The rate of local control at 5 years was 19% for group 1, 39% for group 2 and 32% for group 3. The calculation of the equivalent biologic dose in group 1 allows to separate this population into two subgroups whose survival rates are significantly different (at 3 years: 26% and 6%, P = 0.02) and shows the influence of fractionation and treatment time. The actuarial survival at 3 years is 19% for group 1, 55% for group 2 and 45% for group 3, the survival without evolution is 33% for group 1, 66% for group 2 and 72% for group 3. For the whole series, we numbered 18 complications of grade equal or superior to 2 (healing in more than 3 months, or sequelae or death) out of which four bone complication and 14 tissular complications that occurred in a mean delay of 9 months. Because of technical modifications, there have been no grade complications for implantations performed from 1989. The prognosis remains poor for cancers of the base of the tongue. The rates of survival are still low when they are treated by external irradiation only. There seems to exist a slight advantage in favour of the radio-brachytherapy association compared to the radiosurgical association with a lower rate of sequelae and mutilations.
In Europe to date, 501 patients with salivary gland tumors have been treated with neutrons alone or with combined modalities. The most common histological types are adenoid cystic carcinomas, mucoepidermoid carcinomas and malignant mixed tumors. The results of conventional radiotherapy are suboptimal in inoperable or incompletely resected salivary gland tumors and in recurrent disease. The pooled data of some international series for low linear energy transfer radiation show a local control of 28%. Especially in advanced tumors neutron therapy can improve local control and should be the treatment of choice. The clinical data from different therapy centers in Europe show local control of 67% in gross disease.
En Europe, 501 malades porteurs de tumeurs des glandes salivaires ont été traités avec des neutrons seuls ou en combinaison. Les histologies les plus fréquentes sont les cylindromes, les cancers muco-épidermoïdes et les tumeurs mixtes malignes. Les résultats de la radiothérapie conventionnelle sont médiocres en cas de tumeurs inopérables, ou en résection incomplète et en cas de récidive locale. Les données internationales indiquent pour la radiothérapie conventionnelle un contrôle local de 28%. Pour les tumeurs évoluées, une radiothérapie avec des neutrons peut améliorer le contrôle local et doit être adoptée comme le traitement de référence. Les données cliniques des différents centres européens montrent pour ces patients un contrôle local de 67%.
In fast neutron therapy, the relative biological effectiveness (RBE) of a given beam varies to a large extent with the neutron energy spectrum. This spectrum depends primariiy on the energy of the incident particles and on the nuclear reaction used for neutron production. However, it also depends on other factors which are specific to the local facility, eg, target, collimation System, etc. Therefore direct radiobiological intercomparisons are justified. The present paper reports the results of an intercomparison performed at seven neutrontherapy centres: Orléans, France (p(34)+Be), Riyadh, Saudi Arabia (p(26)+Be), Ghent, Belgium (d(14.5)+Be), Faure, South Africa (p(66)+Be), Detroit, USA (d(48)+Be), Nice, France (p(65)+Be) and Louvain-la-Neuve, Belgium (p(65)+Be). The selected radiobiological system was intestinal crypt regeneration in mice after single fraction irradiation. The observed RBE values (ref cobalt-60 γ-rays) were 1.79 ± 0.10, 1.84 ± 0.07, 2.24 ± 0.11, 1.55 ± 0.04, 1.51 ± 0.03, 1.50 ± 0.04 and 1.52 ± 0.04, respectively. When machine availability permitted, additional factors were studied: two vs one fraction (Ghent, Louvain-la-Neuve), dose rate (Detroit), influence of depth in phantom (Faure, Detroit, Nice, Louvain-la-Neuve). In addition, at Orleans and Ghent, RBEs were also determined for LD50 at 6 days after selective abdominal irradiation and were found to be equal to the RBEs for crypt regeneration. The radiobiological intercomparisons were always combined with direct dosimetrie intercomparisons and, when possible in some centres, with microdosimetric investigations.
En neutronthérapie, l’efficacité biologique relative (EBR) d’un faisceau donné varie dans une large mesure avec le spectre d’énergie. Le spectre dépend principalement de l’énergie de la particule incidente et de la réaction nucléaire utilisée pour produire les neutrons. Il dépend également d’autres facteurs spécifiques de chaque installation (par exemple, composition de la cible et système de collimation), ce qui justifie les intercomparaisons radiobiologiques. Le présent article donne les résultats d’une intercomparaison réalisée auprès de sept centres de neutronthérapie : Orléans, France (p(34)+Be); Riyadh, Arabie Saoudite (p(26)+Be); Gand, Belgique (d(14.5)+Be); Faure, Afrique-du-Sud (p(66)+Be); Detroit, États-Unis (d(48)+Be); Nice, France (p(65)+Be) et Louvain-la-Neuve, Belgique (p(65)+Be). Le système biologique utilisé a été la regeneration des cryptes intestinales chez la souris après irradiation en une seule fraction. L’EBR des faisceaux (Réf rayons gamma du cobalt-60) ont été respectivement trouvée égale à 1,79 ± 0,10, 1,84 ± 0,07, 2,24 ± 0,11, 1,55 ± 0,04, 1,51 ± 0,03, 1,50 ± 0,0
The development of clinical neutron facilities in the 1980s, capable of delivering high energy neutrons spurred full scale phase III testing of neutron beam radiotherapy in a number of tumors including salivary gland, head and neck, prostate, and non small-cell lung cancer. The Radiation Therapy Oncology Group (RTOG) and the Médical Research Council (MRC) jointly sponsored a randomized trial for the treatment of advanced stage salivary gland tumors comparing neutron to conventional photon and/or electron radiotherapy. Although no improvement in survival was seen, the study demonstrated a striking and statistically significant difference in the local-regional control of unresectable salivary gland tumors (56 vs 17%), favoring neutron beam irradiation. Subsequent clinical trials of neutron beam irradiation were initiated by the Neutron Therapy Collaborative Working Group (NTCWG) sponsored by the National Cancer Institute (NCI). A phase III trial comparing neutron to photon radiotherapy for inopérable régional non-small cell lung cancer showed no overall improvement in survival. However, a statistically significant improvement in survival was observed in the subset of patients with squamous cell histology. The NTCWG trial comparing fast-neutron therapy versus conventional photon irradiation in the treatment of advanced squamous cell carcinomas of the head and neck showed a statistically significant improvement in initial complete response (70 vs 52%) favoring neutrons. However, subsequent failures erased any difference in ultimate local-regional control rates and survival curves were essentially the same in both arms. The randomized study of the NTCWG for locally advanced prostate cancer demonstrated a significant decrease in local-regional failure (11 vs 32%) at 5 years, favoring the neutron arm. Furthermore, biochemical measures of disease control also favored the neutron arm with prostate spécifie antigen (PSA) levels elevated in 17% of the neutron-treated patients compared to 45% of the photon-treated patients at 5 years. At the 5-year analysis, no significant difference in survival was observed between the two arms; however, longer follow-up is necessary to assess the ultimate impact of improved local-regional control on survival. An analysis of complications in this series revealed the importance of beam shaping and treatment planning capabilities in maintaining long-term sequelae following neutron irradiation at an acceptably low level.
La construction, dans les années 1980, d‘installations cliniques de neutronthérapie, capables de fournir des faisceaux de neutrons de haute énergie, a permis d‘entreprendre sur une grande échelle des essais de phase III pour un certain nombre de localisations comme les tumeurs des glandes salivaires, de la sphère ORL, de la prostate et les cancers bronchiques autres que ceux à petites cellules. Le Radiation Therapy Oncology Group (RTOG) des États-Unis et le Médical Research Council (MR
Proton therapy began at the ‘Centre de Protonthérapie d’Orsay’ (CPO) in September 1991. Our treatment protocol and the preliminary results have been presented on the first 146 irradiated patients with one-year minimal follow-up. The subsequent developments have also been mentioned.
Au centre de protonthérapie d’Orsay (CPO), les traitements ont débuté en septembre 1991. Nous présentons notre protocole et les résultats tout à fait préliminaires concernant les 146 premiers cas de mélanomes de la choroïde irradiés ayant un recul minimum de 1 an.
The importance of water calorimetry in clinieal proton beam dosimetry has increased for various reasons: there has been an increasing interest in proton therapy from the radiotherapy world; existing dosimetry protocols for clinical proton beams recommend calorimetry as the primary dosimetry method (ie, AAPM and ECHED); water has recently become the reference material for dose specification. For the water calorimetric dose evaluation, the water calorimeter developed in Ghent was used. Ionometry was performed following the ECHED protocol. The study resulted in a calorimetric to ionometric dose ratio of 0.974 ± 0.009. The discrepancy should in our opinion be attributed to the (W/e)p,air value of 35.2 J/C implemented in the protocol, possibly next to ion chamber dependent effects for which indications are found in the ionometry measurements.
Le nombre de centres de protonthérapie a considérablement augmenté dans le monde et les résultats cliniques sont prometteurs. Plusieurs protocoles dosimétriques existant (par exemple AAPM et ECHED) recommandent le calorimètre comme dosimètre de référence. De plus, il est couramment recommandé de prendre l’eau comme milieu de référence pour la spécification de la dose. Ceci explique l’intérêt porté au calorimètre à eau pour la dosimetrie clinique en protonthérapie. Les doses ont été mesurées, dans un faisceau de protons, d’une part au moyen du calorimètre à eau mis au point à l’Université de Gand et d’autre part au moyen d’une chambre d’ionisation selon le protocole de l’ECHED. Le rapport des doses mesurées par calorimetrie et ionométrie est de 0,974 ± 0,009. Cette discordance pourrait être liée au choix de la valeur 35,2 J/C admise pour la grandeur (W/e)p air prévue dans le protocole. Elle pourrait également provenir de facteurs liés au type de chambre d’ionisation.
A series of 133 patients, 35 years or less in age (mean: 31.8) presenting with a carcinoma of the cervix and treated at Salah Azaiz Institute from 1969 to 1989 was analysed and compared to a control group of patients older than 35 years (mean: 54). Neither clinical nor epidemiological particularities were found in the younger patients group, except an early sexual life and a high proportion of early stage tumours (33% versus 15.9% in the older women group). Overall survival of the younger women was dramatically worse than that of the older women: 40% and 50% at 5 years, 20% and 40% at 10 years, and 14% and 30% at 15 years, respectively. This difference is statistically significant in stage I-II patients. Young age, non-sterilization of the tumour after brachytherapy, and anemia, are associated with a poor prognosis.
Contention shells are frequently used in radiotherapy. They allow improvements in the reproducibility of treatments and take part in quality assurance. The aim of our survey is to establish how centers use contention masks. Ninety-five percent of the centers questioned use contention masks. The fixation device is in most cases made of Plexiglas. The masks are always made of thermoplastics materials with low modeling temperature. They are made just before simulation or scanner by a radiographer. The surface dose problem can be overcome by two different techniques. One consists in the stretching of the material to reduce the density. The other consists of cutting out the mask where the irradiation fields are projected. Whatever the technique, there is a loss of rigidity of the mask, which means the immobilization is not so effective. Despite drawbacks, contention masks have an important role in the quality insurance in radiotherapy.
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