Clinical tumor dimensions may be useful to prevent geographic miss in conventional radiotherapy of uterine cervix cancer-a magnetic resonance imaging-based study

A practical review of magnetic resonance imaging for the evaluation and management of cervical cancer

Cervical cancer is a leading cause of mortality in women worldwide. Staging and management of cervical cancer has for many years been based on clinical exam and basic imaging such as intravenous pyelogram and x-ray. Unfortunately, despite advances in radiotherapy and the inclusion of chemotherapy in the standard plan for locally advanced disease, local control has been unsatisfactory. This situation has changed only recently with the increasing implementation of magnetic resonance image (MRI)-guided brachytherapy. The purpose of this article is therefore to provide an overview of the benefits of MRI in the evaluation and management of cervical cancer for both external beam radiotherapy and brachytherapy and to provide a practical approach if access to MRI is limited.

Conventional four field radiotherapy versus computed tomography-based treatment planning in cancer cervix: A dosimetric study

Background:

With advancements in imaging, wide variations in pelvic anatomy have been observed, thus raising doubts about adequate target volume coverage by conventional external radiotherapy fields based on bony landmarks. The present study evaluates the need for integrating computed tomography (CT)-based planning in the treatment of carcinoma cervix.

Aims:

To estimate inadequacies in target volume coverage when using conventional planning based on bony landmarks.

Materials and Methods:

The study consisted of 50 patients. Target volume delineation was done on planning CT scans, according to the guidelines given in literature. The volume of target receiving 95% of prescribed dose (V95) was calculated after superimposing a conventional four field box on digitally reconstructed radiograph. The geographic miss with conventional four field box technique was compared with the CT-based target volume delineation.

Results:

In 48 out of 50 patients, the conventional four field box failed to encompass the target volume. The areas of miss were at the superior and lateral borders of the anterior-posterior fields, and the anterior border of the lateral fields. The median V95 for conventional fields marked with bony landmarks was only 89.4% as compared to 93% for target delineation based on CT contouring.

Conclusions:

Our study shows inadequate target volume coverage with conventional four field box technique. We recommend routine use of CT-based planning for treatment with radiotherapy in carcinoma cervix.

Ressonância magnética para avaliação dos limites dos campos clássicos de radioterapia em pacientes portadoras de neoplasia maligna de colo uterino

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%) pacientes e que houve perda geográfica em 37,3% 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.