Image-guided IMRT for localized prostate cancer with daily repositioning: inferring the difference between planned dose and delivered dose distribution.
Phys Med
; 30(6): 669-75, 2014 Sep.
Article
em En
| MEDLINE
| ID: mdl-24792687
ABSTRACT
INTRODUCTION:
To investigate the dosimetric impact of daily on-line repositioning during a full course of IMRT for prostate cancer. MATERIALS ANDMETHODS:
Twenty patients were treated with image-guided IMRT. Each pre-treatment plan (Plan A) was compared with a post-treatment plan sum (Plan B) based on couch shifts measured. The delivered dose to the prostate without a daily repositioning was inferred by considering each daily couch shift during the whole course of image-guided IMRT (i.e., plan B). Dose metrics were compared for prostate CTV (P-CTV) and PTV (P-PTV) and for organs at risk. Ten patients were treated with a 5 mm margin and 10 patients with a 10 mm margin.RESULTS:
For plan A vs. plan B the average D95, D98, D50, D mean and EUD were 76.4 Gy vs. 73.9 Gy (p = 0.0007), 75.4 Gy vs. 72.3 Gy (p = 0.001), 78.9 Gy vs. 78.4 Gy (p = 0.014), 78.7 Gy vs. 77.8 Gy (p = 0.003) and 78.1 Gy vs. 75.9 Gy (p = 0.002), respectively for P-CTV, and 73.2 Gy vs. 69.3 Gy (p = 0.0006), 70.7 Gy vs. 66.0 Gy (p = 0.0008), 78.3 Gy vs. 77.5 Gy (p = 0.001), 77.8 Gy vs. 76.4 Gy (p = 0.0002) and 74.4 Gy vs. 69.2 Gy (p = 0.003), respectively for P-PTV. Margin comparison showed no differences in dose metrics between the two plans except for D98 of the rectum in plan B which was significantly higher with a 10 mm margin.CONCLUSIONS:
The absence of daily image-guided IMRT resulted in a significantly less uniform and less homogeneous dose distribution to the prostate. A reduction in PTV margin showed neither a lower target coverage nor a better spare of OAR with and without daily image-guided IMRT.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Contexto em Saúde:
1_ASSA2030
Base de dados:
MEDLINE
Assunto principal:
Neoplasias da Próstata
/
Doses de Radiação
/
Planejamento da Radioterapia Assistida por Computador
/
Radioterapia de Intensidade Modulada
/
Posicionamento do Paciente
/
Radioterapia Guiada por Imagem
Tipo de estudo:
Etiology_studies
Limite:
Humans
/
Male
Idioma:
En
Revista:
Phys Med
Ano de publicação:
2014
Tipo de documento:
Article