Biomedical subjects

G Boisserie

Publications and source records attributed to G Boisserie.

At least 19 recordsLinked to original sources

PubMed2005

[Contribution of registered and/or fused images to radiotherapy].

The quality of treatment that one can realize today in conformal radiotherapy, can be reached only if one has access to 3D imaging allowing a precise determination of the volume of the organs at risk and of the GTV. For this reason, one has access to anatomical imaging, CT or MRI, and functional and metabolic imaging, PET or SPECT imaging. CT gives the electronic density of the tissues, which is essential to ensure a very precise calculation of dose distribution. Its insufficiency in the visualization of the tumour and some anatomical structures makes necessary the registration of these images with MRI of which distortions are sufficiently weak to be usable in radiotherapy. The registration will be usable only if images of each modality are realised with the patient in treatment position, except for brain, where only CT, on which is based the registration, must be done in treatment position. The images registration is also called images fusion by some authors. Others consider fusion of images as a way to display registered images on a screen, specially for CT images and PET, and MRI and SPECT. Nevertheless, the fusion of images is a function offered by some softwares. It allows obtaining a single volume of voxels from those of the registered images (CT and MR images). This volume is not usable in radiotherapy because it keeps only partially the contributions of the CT scan images and the MRI. At least, if one wants to visualize the active parts of a tumour or to make the difference between fibrosis and tumour left or recurrence after radiotherapy or chemotherapy, it is necessary to use PET or SPECT. To define correctly the CTV using these images, one must realize the anatomical localization of the metabolic abnormalities, which they highlight with a registration based on CT or MRI. The difficulties to obtain the registration of these images led the manufacturer to propose mixed machines allowing realizing, at the same time, a CT imaging and a PET or a SPECT imaging with the patient in treatment position.

Humans↗

PubMed2005

[Chordomas of the base of the skull and upper cervical spine. 100 patients irradiated by a 3D conformal technique combining photon and proton beams].

OBJECTIVE: To define prognostic factors for local control and survival in 100 consecutive patients treated by fractionated photon and proton radiation for chordoma of the skull base and upper cervical spine. PATIENTS AND METHODS: Between December 1995 and August 2002, 100 patients (median age: 53 years, range: 8-85, M/F sex-ratio: 3/2), were treated by a combination of high-energy photons and protons. The proton component was delivered by the 201 MeV proton beam of the Centre de Protonthérapie d'Orsay (CPO). The median total dose delivered to the gross tumour volume was 67 Cobalt Gray Equivalent (CGE) (range: 60-71). A complete surgery, incomplete surgery or a biopsy was performed before the radiotherapy in 16, 75 and 9 cases, respectively. RESULTS: With a median follow-up of 31 months (range: 1-87), 25 tumours failed locally. The 2 and 4-year local control rates were 86.3% (+/-3.9%) and 53.8% (+/-7.5%), respectively. According to multivariate analysis, less than 95% of the tumour volume encompassed by the 95% isodose line (P=0.048; RR: 3.4 IC95% [1.01-11.8]) and a minimal dose less than 56 CGE (p=0.042; RR: 2.3 IC95% [1.03-5.2]) were independent prognostic factors of local control. Ten patients died. The 2 and 5-year overall survival rates were 94.3% (+/-2.5%) and 80.5% (+/-7.2%). According to multivariate analysis, a controlled tumour (P=0.005; RR: 21 IC95% [2.2-200]) was the lonely independent favourable prognostic factor for overall survival. CONCLUSION: In chordomas of the skull base and upper cervical spine treated by surgical resection followed by high-dose photon and proton irradiation, local control is mainly dependent on the quality of radiation, especially dose-uniformity within the gross tumour volume. Special attention must be paid to minimise underdosed areas due to the close proximity of critical structures and possibly escalate dose-constraints to tumour targets in future studies, in view of the low toxicity observed to date.

Adolescent↗

PubMed2004

[First-line radiosurgery of brain metastases. Interest and results of reduced dose].

BACKGROUND: The minimal radiosurgical dose required to control cerebral metastases remains unknown. The aim of this study was to test whether a lower peripheral dose than usually delivered could effectively control these lesions or not. PATIENTS AND METHODS: One hundred and eighty patients presenting 356 lesions were give first-line radiosurgery between 1995 and 2001 in Pitié-Salpêtrière hospital using a 10 MV LINAC. Mean age was 59 years, sex-ratio was 1.65, mean KI was 70. The lung was the most frequent primary site (n=85), followed by melanoma (n=29), kidney (n=21), digestive tract (n=14), breast (n=11), and others (n=20). Seventy-six percent of the patients presented 1 or 2 lesions. Mean tumor Volume was 5.5 cm3. Mean peripheral dose was 14.8Gy, mean isocenter dose was 21.6Gy. RESULTS: Median survival was 7.6 months, local control rate was 90% at 6 months, 76% at 1 Year and 70% at 2 years. Median "neurological disease free" survival was 15 months. Multivariate analysis demonstrated the influence of two parameters on survival: number of lesions (p=0.001) and KI (p=0.04). The only parameter significantly correlated with disease-free survival was the number of isocenters (p=0.005). Morbidity (grade 2 RTOG) was 7.2% with no perimortality. CONCLUSIONS: Low peripheral doses delivered by radiosurgery may control brain metastases with the same efficacy and fewer side-effects as the doses usually reported in the literature.

Adult↗

PubMed2004

[Results of salvage stereotactic radiosurgery in 14 patients with grade III or IV gliomas].

AIMS: To determine local control and overall survival rates of 14 patients treated for a grade III or IV glioma relapsing in a previously irradiated area and re-irradiated by stereotactic radiosurgery. PATIENTS AND METHODS: From January 1997 to October 2001, 14 patients (median age 52 Years, age range 49-58 Years, Karnofski performance score 80 to 100) received radiosurgery for a relapse of grade III (3 patients) and or grade IV (10 patients) malignant gliomas. Before relapse, all patients had undergone surgery and had been given with a classical radiation protocol. Median maximum diameter and Volume of the tumors were 38.5mm (24-86mm) and 7cm3 (2-35cm3), respectively. RESULTS: Median maximal dose at the isocenter and median minimal dose at the periphery of the lesion were 21Gy (16-38Gy) and 13Gy (9-17Gy), respectively. Mean follow-up was 8.5 Months (1-29). Median overall survival was 11.6 Months; 6-Month, 1- and 2-Year overall survival rates were 85p.100, 36p.100 and 12p.100, respectively. At univariate analysis, only histological grade was a significant prognostic factor of overall survival (p=0.03). Median disease-free survival was 8.2 Months while 6-Month and 1-Year disease-free survival rates were 69p.100 and 14p.100, respectively. According to univariate analysis, histological grade (p=0.033) and minimal dose delivered at the margin of the target Volume (p=0.02) were prognostic factors for disease-free survival. Two patients developed a symptomatic radionecrosis. CONCLUSION: Radiosurgery of relapsed primitive high-grade brain tumors is efficient and overall survival rates were encouraging.

Brain Neoplasms↗

PubMed2003

[Automatization and robotics of the set-up and treatment of patients irradiated for brain and base ot the skull tumors].

Progresses of the three-dimensional imageries and of the software of planning systems makes that the radiotherapy of the tumours of brain and the base of skull is increasingly precise. The set-up of the patients and the positioning of the beams are key acts whose realization can become extremely tiresome if the requirement of precision increases. This precision very often rests still on the visual comparison of digital images. In the near future, the development of the automated systems controlled by robots should allow a noticeable improvement of the precision, safety and speed of the patient set-up.

Automation↗

PubMed2002

[Intracerebral radiotherapy under stereotaxic conditions].

Stereotactic radiosurgery is used for treating several brain diseases. Radiosurgery is a non-invasive alternative to surgery for brain metastases, and randomized trials are on going to assess the role of radiosurgery. Radiosurgery has been advocated for patients with small benign meningioma or with vestibular schwannoma, but there is no proof of efficacy and safety of radiosurgery in comparison with other treatments. Radiosurgery can obliterate 80-90% of small arteriovenous malformations, but no information exists on the survival of treated compared with untreated patients. The limited information available suggests that radiosurgery should be fully evaluated in well-designed prospective studies.

Brain Neoplasms↗

PubMed2002

[Comparison with dose-volume histograms of two conformal irradiation techniques used for the treatment of T2N0M0 nasopharyngeal cancer, one with association of photons and protons and another with photons alone].

Purpose- There is a relationship between the local control rate of the nasopharyngeal cancer and the total dose delivered within the tumoral volume. In contrast, the relation between the dose and the irradiated volume and the risk of complication is not clearly defined. That is why, in patients presenting with a locally advanced nasopharyngeal cancer, we compared the dose-volume distribution of irradiated tissues, obtained from two 3D conformal irradiation techniques. Patients and methods- Between January 2000 and June 2001, 5 patients, 3 males and 2 females, with a median age of 32 years and presenting with a T4N0M0 nasopharyngeal cancer received a chemoradiotherapy. Radiotherapy combined photons and protons beams and the platin-based chemotherapy was delivered in three intravenous injections at d1, 22, 43 of the irradiation. To calculate the dosimetry, a CT scan and a MRI were performed in all the patients. The gross tumor volume (GTV) was delineated from the imagery, three clinical tumor volumes were defined, the CTV1 was the GTV and the whole nasopharynx, the CTV2 was the CTV plus a 10 mm-margin and the CTV3 was the CTV2 and the nodes areas (cervical and subclavicular). Prophylactic dose within node areas was 44 Gy. Prescribed doses within CTV2 and GTV or CTV1 were 54 Gy/CGE (Cobalt Gy Equivalent, for an EBR = 1,1) and 70 Gy/CGE, respectively. Irradiation was delivered with fractions of 1.8 or 2.0 Gy/CGE, with 44 Gy or 54 Gy by photons and with 16 or 26 CGE by protons. According to dose-volume histograms obtained from the dosimetry planning by protons and photons and from the theoretical dosimetry by photons lonely, for the different volumes of interest, GTV, CTV2, and organs at risk (optic nerves, chiasm, internal ears, brainstem, temporal lobes), we compared the averages of the maximum, minimum and mean doses and the averages of the volumes of organs of interest encompassed by different isodoses.Results- Calculated averages of minimum, maximum and mean doses delivered within GTV were superior for the treatment with combined photons and protons than with photons alone. The average GTV encompassed by the 70 Gy/CGE isodose was larger by 65% with the association compared to photons alone. The conformation ratio (tissue volume encompassed by the 95% isodose/GTV encompassed by the 95% isodose) was 3.1 with the association compared to 5.7 with photons alone. For the CTV2, there were no differences in different criteria according to the both irradiation techniques. For the critical, radiosensitive organs, the comparison of the majority of the criteria was in favour of the association of protons and photons. Overall, 78% of the criteria were in favour of the association.Conclusion- For locally advanced nasopharyngeal cancer without clinical adenopathy, irradiation by photons and protons increases the tumor volume irradiated at the prescribed dose and decreases the volume or critical organs irradiated and the total dose delivered within them.

Adult↗

PubMed2002

[The influence of age on radiation-induced cognitive deficit:experimental studies on brain irradiation of 30 gy in 10 sessions and 12 hours in the Wistar rat at 1 1/2, 4 and 18 months age].

The objective of this study was to determine the influence of age on the learning and memory dysfunction induced by cranial radiation in the male Wistar rat. Ninety-six 45-day-old, 70 4-month-old, and 78 18-month-old male rats were divided in two equal groups: (i) irradiated and (ii) control. A course of whole-brain radiation therapy (30 Gy in 10 fractions over 12 days) was administered to the irradiated group, while the control group received sham irradiation. Sequential behavioral studies including one and two-way avoidance tests were undertaken before and after the 7 months following radiation. The results suggest that radiation induced progressive and irreversible memory dysfunction in elderly (18-month-old) rats, but this effect was partial or almost reversible in the 4-month-old and 45-day-old rats, respectively. In return, the learning dysfunction was age non-dependent despite the fact that is occurs more rapidly in the young (45 days, 4 months) rats.

Aging↗

PubMed2001

Combination of photon and proton radiation therapy for chordomas and chondrosarcomas of the skull base: the Centre de Protonthérapie D'Orsay experience.

PURPOSE: Prospective analysis of local tumor control, survival, and treatment complications in 44 consecutive patients treated with fractionated photon and proton radiation for a chordoma or chondrosarcoma of the skull base. METHODS AND MATERIALS: Between December 1995 and December 1998, 45 patients with a median age of 55 years (14-85) were treated using a 201-MeV proton beam at the Centre de Protonthérapie d'Orsay, 34 for a chordoma and 11 for a chondrosarcoma. Irradiation combined high-energy photons and protons. Photons represented two-thirds of the total dose and protons one-third. The median total dose delivered within the gross tumor volume was 67 cobalt Gray equivalent (CGE) (range: 60-70). RESULTS: With a mean follow-up of 30.5 months (range: 2-56), the 3-year local control rates for chordomas and chondrosarcomas were 83.1% and 90%, respectively, and 3-year overall survival rates were 91% and 90%, respectively. Eight patients (18%) failed locally (7 within the clinical tumor volume and 1 unknown). Four patients died of tumor and 2 others of intercurrent disease. In univariate analysis, young age at time of radiotherapy influenced local control positively (p < 0.03), but not in multivariate analysis. Only 2 patients presented Grade 3 or 4 complications. CONCLUSION: In skull-base chordomas and chondrosarcomas, the combination of photons with a proton boost of one-third the total dose offers an excellent chance of cure at the price of an acceptable toxicity. These results should be confirmed with a longer follow-up.

Adolescent↗

PubMed2001

Radiosurgery for re-irradiation of brain metastasis: results in 54 patients.

PURPOSE: To evaluate in terms of probabilities of local-regional control and survival, as well as of treatment-related toxicity, results of radiosurgery for brain metastasis arising in previously irradiated territory. PATIENTS AND METHODS: Between January 1994 and March 2000, 54 consecutive patients presenting with 97 metastases relapsing after whole brain radiotherapy (WBRT) were treated with stereotactic radiotherapy. Median interval between the end of WBRT and radiosurgery was 9 months (range 2-70). Median age was 53 years (24-80), and median Karnofski performance status (KPS) 70 (60-100). Forty-seven patients had one radiosurgery, five had two and two had three. Median metastasis diameter and volume were 21 mm (6-59) and 1.2 cc (0.1-95.2), respectively. A Leksell stereotactic head frame (Leksell Model G, Elektra, Instrument, Tucker, GA) was applied under local anesthesia. Irradiation was delivered by a gantry mounted linear accelerator (linacs) (Saturne, General Electric). Median minimal dose delivered to the gross disease was 16.2 Gy (11.8-23), and median maximal dose 21.2 Gy (14- 42). RESULTS: Median follow-up was 9 months (1-57). Five metastases recurred. One- and 2-year metastasis local control rates were 91.3 and 84% and 1- and 2-year brain control rates were 65 and 57%, respectively. Six patients died of brain metastasis evolution, and three of leptomeningeal carcinomatosis. One- and 2-year overall survival rates were 31 and 28%, respectively. According to univariate analysis, KPS, RPA class, SIR score and interval between WBRT and radiosurgery were prognostic factors of overall survival and brain free-disease survival. According to multivariate analysis, RPA was an independent factor of overall survival and brain free-disease survival, and the interval between WBRT and radiosurgery longer than 14 months was associated with longer brain free-disease survival. Side effects were minimal, with only two cases of headaches and two of grade 2 alopecia. CONCLUSION: Salvage radiosurgery of metastasis recurring after whole brain irradiation is an effective and accurate treatment which could be proposed to patients with a KPS>70 and a primary tumour controlled or indolent. We recommend that a dose not exceeding 14 Gy should be delivered to an isodose representing 70% of the maximal dose since local control observed rate was similar to that previously published in literature with upper dose and side effects were minimal.

Adult↗

PubMed2001

[Gross tumor volume and clinical target volume in brachytherapy of malignant tumors].

Tumours treated with radioactive implants are in most cases small and accessible to clinical examination or endoscopy. Gross tumour volume is consequently mainly determined clinically or with endoscopy. Imaging may also be useful, with classical techniques, as mammography, or with CT-scan or MRI. Clinical target volume includes gross tumour volume and a 5-10 mm margin. Distribution of dose is estimated on the basis of images performed after implantation, classically with two orthogonal films of the implant. It can then be optimised. Dose-volume histogram of gross tumour volume and critical organs can be obtained with a CT-scan or a MRI of the implant, which may be difficult to perform because of implantation material and dummy sources.

Brachytherapy↗

PubMed2001

[Use of multimodality imagery in radiotherapy].

The quality of treatment that one can realize today in conformal radiotherapy, can be reached only if one has access to 3D imaging allowing a precise determination of the volume of the organs at risk and of the GTV. For this reason, one has access to anatomical imaging, CT or MRI, and functional and metabolic imaging, PET or SPECT imaging. CT gives the electronic density of the tissues, which is essential to ensure a very precise calculation of dose distribution. Its insufficiency in the visualization of the tumor and some anatomical structures makes necessary the registration of these images with MRI of which distortions are sufficiently weak to be usable in radiotherapy. The registration will be usable only if images of each modality are realized with the patient in treatment position, except for brain, where only CT, on which is based the registration, must be done in treatment position. At least, if one wants to visualize the active parts of a tumor or to make the difference between fibrosis and tumor left or recurrence after radiotherapy or chemotherapy, it is necessary to use PET or SPECT. To define correctly the CTV using these images, one must realize the anatomical localization of the metabolic abnormalities, which they highlight with a registration based on CT or MRI. The difficulties to obtain the registration of these images led the manufacturer to propose mixed machines allowing to realize, at the same time, a CT imaging and a PET or a SPECT imaging with the patient in treatment position.

Diagnostic Imaging↗

PubMed1998

An experimental model of acute encephalopathy after total body irradiation in the rat: effect of liposome-entrapped Cu/Zn superoxide dismutase.

PURPOSE: To develop an experimental model of acute encephalopathy following total body irradiation in rats and to define the therapeutic effect of liposome-entrapped Cu/Zn superoxide dismutase. METHODS AND MATERIALS: A total of 120 4-month-old rats received 4.5 Gy total body irradiation (TBI) while 120 rats received sham irradiation. A behavioral study based on a conditioning test of negative reinforcement, the one-way avoidance test, was performed 5 hours before irradiation and repeated the following days. Subcutaneous treatment was started 1 hour after irradiation and repeated daily for 2 weeks. In both the irradiated and sham group, three subgroups were defined according to the treatment received: liposome-entrapped Cu/Zn superoxide dismutase (0.5 mg/kg), liposomes only, normal saline. RESULTS: This work comprised two consecutive studies. In study A (90 rats) the one-way avoidance test was administered daily from day 0 to day 4 with a recall session at day 14. In study B (validation phase in 150 rats) the behavioral test was performed only from day 0 to day 6. Before irradiation, all rats showed a similar behavioral response. Study A (6 groups of 15 rats): Following TBI, irradiated rats treated with liposomes only or saline demonstrated a significant delay in learning the one-way avoidance test in comparison with sham-irradiated rats (0.05 < p <0.001 depending upon the day of evaluation and the subgroup type). In contrast, irradiated rats treated with liposome-entrapped Cu/Zn superoxide dismutase did not differ from sham-irradiated rats. Study B (6 groups of 25 rats): The results were the same as those in study A, demonstrating a significant delay in the learning of the test in the liposome and saline-treated irradiated rats in comparison with sham-irradiated rats (0.02 < p < 0.001). The irradiated rats, treated with liposome-entrapped Cu/Zn superoxide dismutase did not differ from the sham-irradiated controls. CONCLUSION: This study indicates that a relatively low dose of total body irradiation induces a substantial acute learning dysfunction in the rat. This effect is prevented by the administration of liposome-entrapped Cu/Zn superoxide dismutase.

Animals↗

PubMed1998

[The alpha/beta connection].

Explore the source record for details and available documents.

Cell Survival↗

PubMed1997

Prevention of graft-versus-host disease in mice using a suicide gene expressed in T lymphocytes.

Alloreactive T cells present in a bone marrow transplant are responsible for graft-versus-host disease (GVHD), but their depletion is associated with impaired engraftment, immunosuppression, and loss of the graft-versus-leukemia effect. We developed a therapeutic strategy against GVHD based on the selective destruction of these alloreactive T cells, while preserving a competent T-cell pool of donor origin. We generated transgenic mice expressing in their T lymphocytes the Herpes simplex type 1 thymidine kinase (TK) suicide gene that allows the destruction of dividing T cells by a ganciclovir treatment. T cells expressing the TK transgene were used to generate GVHD in irradiated bone marrow grafted mice. We show that a short 7-day ganciclovir treatment, initiated at the time of bone marrow transplantation, efficiently prevented GVHD in mice receiving TK-expressing T cells. These mice were healthy and had a normal survival. They maintained a T-cell pool of donor origin that responded normally to in vitro stimulation with mitogens or third party alloantigens, but were tolerant to recipient alloantigens. Our experimental system provides the proof of concept for a therapeutic strategy of GVHD prevention using genetically engineered T cells.

Animals↗

PubMed1997

[Radiotherapy-induced cognitive dysfunction in 4-months-old male Wistar rats]].

PURPOSE: Behavioral dysfunction of memory process arising 4 months after whole brain irradiation (30 Gy/10 fractions/12 days) has been demonstrated in 16-27 month old rats, as compared with non irradiated rats. This study was therefore aimed at delivering the same irradiation in young rats and comparing results with those previously obtained in old rats. MATERIAL AND METHODS: Thirty-three 4-month old rats were included into the study. Eighteen received whole brain irradiation (30 Gy/10 fractions/12 days), and 18 were given sham irradiation. Sequential behavior studies were done before irradiation and during the 7 months following irradiation. RESULTS: Significant decrease in memory function was observed in irradiated rats 1 month (p < 0.001), 3 months (p < 0.013), and 6 months (p = 0.007) post-irradiation. This was accompanied by learning deficit 1 month (p = 0.01), 4.5 months (p = 0.03), and 7 months (p = 0.009) post-irradiation. CONCLUSION: Response to radiation therapy observed in young rats differed from that observed in old rats. Young rats showed earlier decrease in memory function than old rats, but this deficit was followed by partial recovery. Learning deficits also arised earlier in young rats than in old rats. In two cases this deficit was permanent.

Age Factors↗

PubMed1996

[Radiotherapy of brain tumors].

When radiotherapy is employed for central nervous system tumours, several clinical considerations relating to the special normal tissue environment in which they are located deserve recognition. First of all the radiosensitivity of normal brain is nearly equivalent to that of the majority of the primary tumours requiring irradiation. Secondly destroyed normal neural tissue never regenates, but partial recovery is possible following limited injury. Thirdly definition of the target volume is determined mostly by indirect means from a synthesis of neuroradiological findings (C.T. scans, M.R.I.). Finally the rigidity of the intact cranium confers greater clinical significance on mass effects including postradiotherapeutic edema. Most brain tumours respond to external irradiation which may be applied either postoperatively or definitively, e.g. gliomas, lymphomas, medulloblastomas, and metastases. New stereotactic techniques, including radiosurgery, interstitial brachytherapy, and proton beam radiotherapy allow the delivery of larger dose in a limited volume.

Adult↗

PubMed1996

[Iridium 192 brachytherapy of supra-tentorial high grade glioma recurring in irradiated areas: technique and preliminary results of the Pitié-Salpêtrière hospital group].

UNLABELLED: Our aim was to analyse feasibility and preliminary results obtained with iridium 192 re-irradiation of recurrent high grade gliomas. MATERIAL AND METHODS: a technique for implanting rigid plastic tubes afterloaded with iridium 192 wires was developed that utilised a stereotactic Leksell frame. Nineteen glioblastomas and one anaplastic glioma (12 males and 8 females: age: 20-69 years, median: 50) were implanted between January 1993 and December 1994. Previous treatments included surgery (18/20). 55-60 Gy external beam radiotherapy (20/20), and chemotherapy (16/20); interval between initial treatment and retreatment with iridium 192 was 6 to 39 months (median: 10). Maximum diameter of the tumour at the moment of implantation was 2.1-10.1 cm (median: 6.4 cm) and tumour volume 2.122 cm3 (median: 22 cm3). All tumours were supra-tentorial (right hemisphere: 9; left hemisphere: 11). Karnofsky index was 60-100 (median: 80). Implantation was carried out under local anaesthesia; tumour contours were visualised using either a CT-scan (16/20) or a MRI (4/20). Dosimetry was carried out using two orthogonal films and CT-scan images. Total dose on the reference isodose was 40-60 Gy (60 Gy: 9; 50 Gy: 7; 40 Gy: 4); dose-rate was 0.24-0.73 Gy/h (median: 0.38). RESULTS: probability of overall survival is 90% at 6 months, 55% at one year, and 26% at two years. Median survival is 56 weeks. Eleven patients died from local failure, and three from leptomeningeal metastasis. Six patients are alive, 15-30 months after the implantation. Two were reoperated for brain necrosis. Three patients showed evidence of bacterial meningitis, and three others of skin necrosis. CONCLUSION: according to this preliminary analysis, results obtained after reirradiation of high grade gliomas with iridium 192 are encouraging. More patients and longer follow-up are needed to draw definitive conclusions.

Adult↗