Jean Noel Foulquier

Radiosurgery With or Without A 2-mm Margin for 93 Single Brain Metastases

PURPOSE Retrospective comparison of Linac radiosurgery (RS) in 93 single brain metastases with or without a 2-mm margin. PATIENTS AND METHODS A total of 153 patients had Linac RS (between April 1992 and June 2004), with 139 patients (90.8%) evaluable in June 2005. Sixty-one patients (44%) had extracranial lesions and 65 patients had neurologic symptoms (47%). RS alone: 105 patients (66%); RS +whole brain radiotherapy: 34 patients (24%). Single metastasis: 93/139 patients; classic RS: 42/93 patients; 2-mm margin: 51/93 patients; 30 multiple lesions patients were excluded. TREATMENT 15 Mv X-ray Linac, circular minibeams, 8-30 mm, four to six noncoplanar coronal arcs. Isodose was 60-80%; doses were 10-20 Gy. FOLLOW-UP 12 months-13 years; median, 14 months. RESULTS Local control (LC) was not improved in 51 margin patients vs. 42 classic RS patients: 1 year: 69.1% and 72.4%. Two-year LC rate: 64% and 54.7%, respectively. Survival: median classic RS: 11.3 months; margin RS, 19 months (p = 0.34) and 1 year, 41.6% and 60.2%, respectively. Margin RS patients had a significantly higher rate of severe parenchymal complications: 19.6% vs. 7.1% (p = 0.02); surgery was necessary in 4 of 51 cases vs. 1 of 42 classic RS cases. CONCLUSION No increase of 1- and 2-year LC rate in margin RS or survival and median survival: 11.3 vs. 19 months (NS) 2-mm margin associated with more severe parenchymal complications (p = 0.02). This procedure is therefore not recommended. Late CT images and 1-mm margin as recommended by pathologists, use of three-dimensional magnetic resonance imaging and fuzzy method to calculate volumes may yield better results. Stereotactic hypofractionation requires further studies.

Aspects physiques et méthodologiques de l’imagerie multimodalités et principes de planification dosimétrique pour la radiothérapie conformationnelle tridimensionnelle

Resume Les evolutions recentes des techniques d’imagerie, du calcul de dose, des accelerateurs lineaires et l’imagerie portale permettent d’ameliorer la qualite de la planification d’une radiotherapie conformationnelle tridimensionnelle. Grâce aux protocoles de communication DICOM (digital imaging and communication in medicine), les sequences d’images tridimensionnelles obtenues par differentes modalites sont exploitees par des logiciels de fusion performants pour une meilleure definition des volumes–cibles et des organes a risque. Le passage du volume–cible clinique anatomoclinique (CTV) vers le volume–cible previsionnel (PTV) se fait a l’aide de techniques probabilistes evoluees. L’evaluation du traitement est fondee sur les histogrammes dose-volume dont la precision et la pertinence clinique sont renforcees par l’amelioration des donnees d’imagerie et des methodes de calcul de la distribution de dose. L’introduction de la planification inverse en radiotherapie permet l’obtention de distributions de dose optimisees a l’aide des faisceaux d’intensite modulee. Cependant, la mise en œuvre de ces irradiations exige des protocoles de controle de qualite nouveaux et rigoureux.

A modified 60C teletherapy unit for total body irradiation

PURPOSE A modified teletherapy unit to achieve total body irradiation with a vertical beam in a conventional treatment room. METHODS AND MATERIALS A standard 60C teletherapy unit has been modified to achieve total body irradiation with a vertical beam in a conventional treatment room. Patients are treated in prone and supine positions. Removal of the adjustable collimator assembly of this standard machine provides a circular field of 196 cm in diameter at 167 cm from the source. Second, the machine has been elevated by about 50 cm on a metallic base to enlarge irradiation field to obtain 248 cm in diameter at 210 cm from the source, and to encompass tall patients under better conditions. A special lead conical beam flattening filter, 10-mm thick at the center, was designed to compensate the spatial inhomogeneity of the beam. An instantaneous dose rate of 6.10(-2) Gy/min is attained at the L4 level (midplane) in an average 20-cm thick patient with a source activity of 5099 RHM (air kerma rate of 44.8 Gy.h-1.m2). Between February 2, 1984 and December 27, 1990, 244 total body irradiations were performed either by single dose (n = 69, 10 Gy were given to midplane at L4 level in about 6 to 8 h, 8 Gy to the lungs), or by fractionated dose (n = 175, 12 Gy were given in 6 fractions over 3 consecutive days to midplane at L4 level, 9 Gy to the lungs). RESULTS The dose distribution is similar than the ones obtained by a linear accelerator with patients lying on their sides. CONCLUSION Patients were treated in a comfortable and highly reproductible position. Organ shielding was easily achievable. This could be a less expensive and reasonable alternative to linear accelerator.

Évolution de la radiothérapie externe et intégration à l’hôpital Tenon (AP-HP) des innovations technologiques récentes dans la pratique de la radiothérapie externe des carcinomes bronchiques non à petites cellules

Resume Les modalites d’administration de la radiotherapie externe des cancers broncho-pulmonaires non a petites cellules ont fait l’objet de nombreux progres technologiques au cours de ces dernieres annees. La radiotherapie conformationnelle tridimensionnelle, avec ou sans modulation d’intensite des faisceaux d’irradiation, synchronisee aux mouvements respiratoires du patient et guidee par l’imagerie 3D embarquee, peut etre consideree comme la troisieme revolution en radiotherapie, apres le fractionnement de la dose et le developpement des appareils de traitement de haute energie. Nous decrivons cette evolution technologique et son integration dans le service d’Oncologie-Radiotherapie de l’Hopital Tenon (AP-HP).