Dosimetric consequences of tumor mobility in radiotherapy of stage I non-small cell lung cancer--an analysis of data generated using 'slow' CT scans.
Radiother Oncol
; 61(1): 93-9, 2001 Oct.
Article
em En
| MEDLINE
| ID: mdl-11578735
ABSTRACT
BACKGROUND:
The target coverage for radiotherapy of early-stage lung cancer was evaluated using two different CT techniques. MATERIALS ANDMETHODS:
A conventional planning CT scan and two limited scans of the tumor region were performed in seven patients with peripheral tumors. Three 'slow' scans (slice thickness 4mm, index 3mm, revolution time 4s/slice) were then performed, followed by three-dimensional image registration. Planning target volumes (PTV) were generated using these GTV-PTV margins (a) 1cm (PTV1.0); (b) 1.5 cm (PTV1.5); and (c) 0.9, 1.0, and 0.9 cm ('PTV(clinical)') when set-up errors are avoided.RESULTS:
PTVs derived from three 'slow' scans missed 1.9% of the volume derived from three planning scans for an immobile tumor and 9.3% in the case of a mobile tumor. For an immobile tumor, PTV1.5 achieved comparable coverage to that achieved using PTVclinical, which was generated from three 'slow' scans and a planning scan. For a mobile tumor, PTV(1.5) covered only 89% of the volume captured by PTVclinical. PTV1.0 resulted in inadequate target coverage in all the patients. Reductions in potential lung toxicity (V20) were achievable in six patients despite the larger GTVclinical when treatment set-up errors were minimized.CONCLUSIONS:
PTVs derived using 'slow' CT scans consistently produce superior target coverage than that using conventional scans. This may account for the poor local control observed in stage I lung cancer.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Radiometria
/
Planejamento da Radioterapia Assistida por Computador
/
Carcinoma Pulmonar de Células não Pequenas
/
Neoplasias Pulmonares
Tipo de estudo:
Diagnostic_studies
/
Evaluation_studies
Limite:
Humans
Idioma:
En
Revista:
Radiother Oncol
Ano de publicação:
2001
Tipo de documento:
Article
País de afiliação:
Holanda