Quantitative analysis of intra-fractional variation in CT-based image guided brachytherapy for cervical cancer patients.
Phys Med
; 73: 164-172, 2020 May.
Article
em En
| MEDLINE
| ID: mdl-32361574
ABSTRACT
We quantified intra-fractional dose variation and organ movement during CT-based 3D-image guided brachytherapy (3D-IGBT) in cervical cancer patients. Fifteen patients who underwent CT-based 3D-IGBT were studied. For all patients, pre-delivery CT for treatment planning after applicator insertion and post-delivery CT after dose delivery without changing the applicator position were acquired. Pre- and post-delivery CT were rigidly fused by matching the inserted applicator and planned dose on pre-delivery CT (pre-delivery dose) was mapped on post-delivery CT (post-delivery dose). D2, D1, and D0.1 cm3 of the rectum and bladder were compared between pre- and post-delivery doses with contours on each CT image. Organ movement and deformation was evaluated using deformation vector fields calculated by deformable image registration between pre- and post-delivery CT. We also evaluated dose variation and DVF between with and without a catheter to control filling. Differences in all DVH parameters were <±3% in physical dose and ± 5% in EQD2. However, a > 15% dose difference was found in 13.8% of the fractions in rectum D2 cm3 and in 11.1% of those in bladder D2 cm3. The mean value of DVF for bladder was larger than that of rectum, especially for the superior-inferior (S-I) direction. Insertion catheters in bladder reduced mean dose and DVF variation compared with that of without catheters. In fraction groups with large dose increasing, DVF in the S-I direction was significantly larger than that of other fraction groups. Our results indicated that preparation is needed to reduce changes in the S-I direction affect dose variation.
Palavras-chave
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Braquiterapia
/
Tomografia Computadorizada por Raios X
/
Neoplasias do Colo do Útero
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Fracionamento da Dose de Radiação
/
Radioterapia Guiada por Imagem
Tipo de estudo:
Etiology_studies
Limite:
Female
/
Humans
Idioma:
En
Revista:
Phys Med
Assunto da revista:
BIOFISICA
/
BIOLOGIA
/
MEDICINA
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Japão