RESUMO
PURPOSE: To develop and validate adaptive dose-constraint templates in intensity-modulated radiotherapy (IMRT) planning for advanced T-stage nasopharyngeal carcinoma (NPC). METHOD AND MATERIALS: Dose-volume histograms of clinically approved plans for 20 patients with advanced T-stage NPC were analyzed, and the pattern of distribution in relation to the degree of overlap between targets and organs at risk (OARs) was explored. An adaptive dose constraint template (ADCT) was developed based on the degree of overlap. Another set of 10 patients with advanced T-stage NPC was selected for validation. Results of the manual arm optimization protocol and the ADCT optimization protocol were compared with respect to dose optimization time, conformity indices, multiple-dose end points, tumor control probability, and normal tissue complication probability. RESULTS: For the ADCT protocol, average time required to achieve an acceptable plan was 9 minutes, with one optimization compared with 94 minutes with more than two optimizations of the manual arm protocol. Target coverage was similar between the manual arm and ADCT plans. A more desirable dose distribution in the region of overlap between planning target volume and OARs was achieved in the ADCT plan. Dose end points of OARs were similar between the manual arm and ADCT plans. CONCLUSIONS: With the developed ADCT, IMRT treatment planning becomes more efficient and less dependent on the planner's experience on dose optimization. The developed ADCT is applicable to a wide range of advanced T-stage NPC treatment and has the potential to be applied in a broader context to IMRT planning for other cancer sites.
Assuntos
Neoplasias Nasofaríngeas/radioterapia , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Tronco Encefálico/efeitos da radiação , Humanos , Neoplasias Nasofaríngeas/diagnóstico por imagem , Neoplasias Nasofaríngeas/patologia , Estadiamento de Neoplasias , Quiasma Óptico/efeitos da radiação , Nervo Óptico/efeitos da radiação , Lesões por Radiação/prevenção & controle , Radiografia , Planejamento da Radioterapia Assistida por Computador/métodos , Planejamento da Radioterapia Assistida por Computador/normas , Radioterapia de Intensidade Modulada/normas , Medula Espinal/efeitos da radiação , Fatores de Tempo , Carga TumoralRESUMO
We wish to report a rare case of clear-cell meningioma in the lumbosacral region in a 34-year-old male patient who presented to us with lower back pain and leg pain. The management of the patient will be reported and histological appearance discussed. This rare tumour in a difficult anatomical position presents a challenge that requires management in a multidisciplinary fashion.
