ABSTRACT
Between July 1984 and May 1990, 25 children (median age 9 years) classified as low risk medulloblastoma were treated post-operatively with low dose craniospinal irradiation (25 Gy) followed by a boost to the posterior fossa (total dose 55 Gy), with or without chemotherapy. Simulator and portal films were reviewed for all patients. Doses delivered at the mid cerebral and spinal axis, anterior vertebral body, field junctions and posterior fossa were recalculated and correlated with outcome. Three children were excluded because of inadequate data leaving 22 cases for study. The 5-year actuarial survival is 55%. Nine recurrences and one second tumour (astrocytoma) were observed. Sites of recurrence were either in the posterior fossa (5), in the brain (3), in the spinal axis (1), or combined (2). The dose delivered was within +/- 5% of that prescribed to the brain in 21/22 cases, and to the posterior fossa and the anterior surface of the vertebral body in 17/22 cases. The only patient who received less than 95% of the prescribed dose to the brain (23 Gy) failed in the subfrontal area and olfactory plate. One of the five patients who received less than 95% of the prescribed dose to the posterior fossa (50.3 Gy) failed at the primary site. None of the five patients who received less than 95% of the dose to the spinal axis failed. Quality control of radiation treatment showed that failures could not be correlated with incorrect technique.
Subject(s)
Cerebellar Neoplasms/radiotherapy , Medulloblastoma/radiotherapy , Radiotherapy Dosage , Adolescent , Cerebellar Neoplasms/mortality , Child , Child, Preschool , Female , Humans , Male , Medulloblastoma/mortality , Neoplasm Recurrence, Local , Quality Control , Risk Factors , Survival RateABSTRACT
The purpose of this document is to provide radiologists with a simple, but realistic means of determining the individual dose delivered to a patient during a radiological examination both in the region under investigation and at any other particularly sensitive organs. Fourteen types of examinations were considered corresponding to those most frequently carried out in France. The choice of examinations and methods of taking the films approaches as closely as possible, the average situations, and the frequency of different techniques is influenced by the results of a national study of radiodiagnostic examinations carried out in France in 1982. In the first section, the influence on the radiation dose of varying different physical parameters and techniques is analysed, with an aim of defining the limits of validity of the presented dosimetric values and the possible adaptation of these values to any individual situation, which is slightly different from these considered in this study. The second section describes the model used for determining the absorbed dose presented in the tables, concerning each type of examination, as well as bibliographic references referring to methods and results of determining the dose. The suggested calculation model may be used as a base for dose estimation for other types of examination.
Subject(s)
Radiation Dosage , Radiography , Abdomen/radiation effects , Head/radiation effects , Humans , Hysterosalpingography , Mammography , Pelvis/radiation effects , Radiography, Thoracic , Spine/radiation effects , Tomography, X-Ray Computed , UrographyABSTRACT
Radiotherapy still represents with surgery the cornerstone in the management of pediatric brain tumors. Techniques of irradiation have benefited greatly from modern imaging, CT scan and MRI for tumor-volume delineation, as well as megavoltage equipment, mainly linear accelerators delivering both high-energy X-Rays and electrons, widely used in cranial-spinal irradiations. Furthermore, new modalities of doses and volumes have been tested in various tumors (medulloblastomas, germ cell tumors...), in studies frequently combining chemotherapy with conventional therapies. Nevertheless, local control remains a major concern in tumors such as brain stem and high grade supratentorial gliomas. Concerning iatrogenic neurological sequelae, particularly harmful in children, limited data suggest an improvement in recent years. This improvement is partly due to the reduced prophylactic doses for the treatment of medulloblastomas, but further long-term observations are necessary. For these reasons, multiple technical innovations have been investigated. Some of them concern irradiation selectivity: stereotactic pencil beams, interstitial brachytherapy, heavy charged particles, 3-dimensional treatment planning. Others aim to increase the irradiation "efficacy": multifractionation, high LET particles, radiation-sensitizers.
Subject(s)
Brain Neoplasms/radiotherapy , Radiotherapy/methods , Brain Neoplasms/pathology , Child , Humans , Radiotherapy DosageABSTRACT
Twenty-five cases of presumed radiation-induced brachial plexopathy were identified out of a population treated at the Institut Gustave-Roussy, in 3 different ways, during the period 1967-1980. The incidence of this complication is given for each group, and the radiation dosage and natural history is described, with results of neurolysis when it was possible. The absence of successful treatment methods makes prevention of this complication crucial. The use of fraction sizes no greater than 2.5 Gy, and the avoidance of radiation treatment to the completely dissected axilla, are advocated.
Subject(s)
Brachial Plexus , Neuritis/etiology , Radiotherapy/adverse effects , Cancer Care Facilities , Female , France , Humans , Mastectomy , Neuritis/epidemiology , Postoperative Care , Preoperative Care , Radiotherapy Dosage , Retrospective StudiesABSTRACT
The dose considered necessary to adequately treat Hodgkin's disease lesions is 4,000 rads in four weeks. The different possibilities of fractioning this dose may have a direct effect upon late tolerance to this type of irradiation. On the one hand, the authors determined the single equivalent doses for each type of fractioning according to ELLIS, COHEN and J. DUTREIX, and secondly calculated the number of sessions necessary in order to come as close as possible to the dose equivalent to 5 times 200 rads. For example, it emerges that 15 sessions of 250 rads, i.e. 3,750 rads, and 10 sessions of 330 rads, i.e. 3300 rads are equivalent to 20 times 200 rads, i.e. 4,000 rads in 26 days for healthy tissue. The authors finally established for each reference system a graph making it possible to determine according to the type of fractioning and for a spread of 26 days the total dose necessary to obtain the same effects as 4,000 rads delivered in 20 sessions of 200 rads.
