ABSTRACT
BACKGROUND: Although conventional four‑ field radiotherapy based on bony landmarks has been traditionally used, areas of geographical miss due to individual variation in pelvic anatomy have been identified with advanced imaging techniques. AIMS: The primary aim of this study is to evaluate the geographical miss in patientswhen using the conventional four‑field planningplanning and to find out the impact of 3‑D conformal CT based in patients with locally advanced carcinoma cervix. MATERIALS AND METHODS: In 50 patients, target volume delineation was done on planning computed tomography (CT) scans, according to guidelines by Taylor et al. Patients were treated with modified four field plan, except for the superior, where field border was kept at L4‑L5 interspace A dosimetric comparison was done between the conventional four‑field based on bony landmarks and the target volume delineated on computed tomography. The disease free survival, pelvic and para aortic nodal free survival, distant failures free survival were calculated using Kaplan Meir Product Limit Method. RESULTS: Patients were followed‑up for a median period of 11 months. The median V95 for conventional and modified extended four field plans were 89.4% and 91.3% respectively. Patients with V95 for modified extended pelvic fields less than 91.3% had a trend toward inferior disease free survival (mean DFS 9.8 vs. 13.9 months) though the difference was not statistically significant log rank test. CONCLUSIONS: Our preliminary data shows trend toward lower DFS in patients with inadequate target volume coverage. We recommend routine use of CT based planning for four field technique.
ABSTRACT
OBJETIVO: Avaliar os limites de campo padronizados para radioterapia de neoplasia maligna de colo uterino com o uso de ressonância magnética e verificar a importância deste exame na redução de possíveis erros de planejamento com técnica convencional. MATERIAIS E MÉTODOS: Foram analisados, retrospectivamente, exames de ressonância magnética do planejamento de 51 pacientes tratadas devido a neoplasia de colo uterino. Os parâmetros estudados foram limites anterior e posterior no corte sagital. RESULTADOS: Observou-se, no corte sagital das ressonâncias magnéticas, que o limite de campo anterior apresentou-se inadequado em 20 (39,2 por cento) pacientes e que houve perda geográfica em 37,3 por cento dos casos no limite posterior. A inadequação de ambos os limites de campo não se relacionou com parâmetros clínicos como idade das pacientes, estadiamento, tipo e grau histológico. CONCLUSÃO: A avaliação dos limites de campo padronizados pela literatura com o uso de ressonância magnética mostrou altos índices de inadequação dos limites do campo lateral, assim como a importância do uso deste exame no planejamento radioterápico de pacientes portadoras de câncer de colo uterino com a finalidade de reduzir a perda geográfica no volume alvo de tratamento.
OBJECTIVE: To evaluate, by means of magnetic resonance imaging, the standardized field borders in radiotherapy for malignant neoplasm of uterine cervix, and to determine the role of this method in the reduction of possible planning errors related to the conventional technique. MATERIALS AND METHODS: Magnetic resonance imaging studies for planning of treatment of 51 patients with uterine cervix cancer were retrospectively analyzed. The parameters assessed were the anterior and posterior field borders on sagittal section. RESULTS: The anterior field border was inappropriate in 20 (39.2 percent) patients and geographic miss was observed in 37.3 percent of cases in the posterior border. The inappropriateness of both field borders did not correlate with clinical parameters such as patients' age, tumor staging, histological type and degree. CONCLUSION: The evaluation of standardized field borders with the use of magnetic resonance imaging has demonstrated high indices of inappropriateness of the lateral field borders, as well as the relevant role of magnetic resonance imaging in the radiotherapy planning for patients with uterine cervix cancer with a view to reduce the occurrence of geographic miss of the target volume.