ABSTRACT
Thermoluminescent response of LiF:Mg,Cu,P+PTFE under clinical photon irradiation was obtained. Thermoluminescent dosimeters (TLDs) were irradiated for determining entrance surface dose (ESD) in a solid water phantom when using standard clinical adult treatment protocols. A Monte Carlo simulation of photon interaction with matter was performed and absorbed dose determined. ESD calculated by MCNPX code was greater than those determined by direct measurements in phantom. The results obtained open the possibility for using this material as a TLDs in medical accelerators.
Subject(s)
Models, Statistical , Monte Carlo Method , Thermoluminescent Dosimetry/instrumentation , Computer Simulation , Photons/therapeutic use , Protons , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
The aim of this study is to assess the efficiency of radiosurgery (RS) in the treatment of brain cavernomas. The series included intra-axial 17 lesions in 15 patients, 10 women and 5 men. Eleven were infratentorial lesions (brain stem and cerebellum) and 6 supratentorial (thalamus, hippocampus, brain cortex and paraventricular region). Fifteen lesions bled once or twice. Two lesions revealed by focal epilepsy displayed a rim of hemosiderin on MRI. RS was performed for all 17 lesions. The risk of morbidity was considered too high for surgery in 13 patients and 2 patients wished to be treated by RS. RS was delivered by a 6 MeV linear accelerator with a conic collimators device. Stereotactic localization and dosimetry were carried out with STP system 3.O (Fischer-Liebinger TM, Germany). Doses ranged between 16 and 23 Gy, the lower doses being delivered to brain stem lesions. All the lesions received a single fraction isocentric radiation. Lesion volumes ranged between 0.7 and 4.7 cm(3). Twelve lesions disappeared on MRI, the volume reduced (50-80%) in 3 lesions, and did not change in 2 lesions. Volume reduction was significant (P<0.01, P<0.001). In the follow up, 4 patients experienced bleeding, 1 of them died. Edema diagnosed in 2 patients at 3 and 13 months was treated by corticosteroids. The risk of hemorrhage without treatment in this group of patients was estimated about 34.45% a year. Hemorrhage incidence observed after RS was 7.17% (significant with P<0.01, P<0.001). At the end of follow up, 12 patients were symptom-free, 2 had sequels from bleeding, 1 patient died. Radiosurgery is an efficient treatment of cavernomas leading to a total disappearance of 70% of the lesions and significantly reducing the risk of new hemorrhages.
Subject(s)
Central Nervous System Neoplasms/surgery , Hemangioma, Cavernous, Central Nervous System/surgery , Radiosurgery , Adolescent , Adult , Brain Edema/etiology , Brain Stem Neoplasms/complications , Brain Stem Neoplasms/surgery , Central Nervous System Neoplasms/complications , Cerebellar Neoplasms/complications , Cerebellar Neoplasms/surgery , Cerebral Hemorrhage/etiology , Cerebral Hemorrhage/prevention & control , Epilepsies, Partial/etiology , Female , Hemangioma, Cavernous, Central Nervous System/complications , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Postoperative Complications/epidemiology , Radiosurgery/adverse effects , Supratentorial Neoplasms/complications , Supratentorial Neoplasms/surgeryABSTRACT
En el Servicio de Radioterapia de la Unidad de Oncología del Hospital General de México, entre agosto de 1993 a diciembre de 1995, se realizó una investigación sobre altas dosis de radiación con hipofraccionamiento administradas en pacientes con recurrencias locorregionales de melanoma maligno, previamente manejado por los servicios quirúrgicos de nuestra unidad. Un total de 28 lesiones en 22 pacientes con diagnóstico de melanoma maligno metastásico o recurrente fueron tratados con altas dosis de radiación por fracción. El seguimiento osciló entre nueve y 30 meses (promedio 11.2 meses). Fueron analizados dos esquemas de tratamiento: Esquema A: 40 Gy en ocho fracciones administradas en cuatro semanas y esquema B: 24 Gy en tres fracciones, una por semana. Se analizó la respuesta local a estas dosis y el control del dolor. Veintiún campos de tratamiento fueron tratados con el esquema A y siete con el esquema B. Se obtuvieron respuestas completas en siete campos de tratamiento, parciales (entre 50 y 90 por ciento) en 12 campos y menores de 50 por ciento o estatismo en nueve campos. Se obtuvo paliación total del dolor en 18 pacientes. Existe evidencia de progresión de la enfermedad en seis pacientes, a pulmón en cuatro casos y óseas en dos. Seis pacientes se encuentran con vida y sin actividad tumoral, ocho están vivos con actividad tumoral y los ocho restantes se perdieron con actividad tumoral. El análisis de estos datos muestra que el melanoma maligno es más radiosensible de lo que tradicionalmente se había señalado y puede tener un manejo en el papel de estas lesiones, ya sea en la paliación local, en la satelitosis y en el control del dolor
