Four-dimensional stereotactic radiotherapy for early stage non-small cell lung cancer: a comparative planning study.
In this study we sought to assess the potential of the respiratory tumor tracking system of the CyberKnife to administer 3 fractions of 15 Gy in the treatment of early stage non-small cell lung cancer (NSCLC). The CyberKnife plans were compared to those developed for 3-D conformal radiotherapy (3-D CRT) administering 20 fractions of 3 Gy based on a slow CT. Ten patients with stage I NSCLC, who were previously treated with 3-D CRT, were re-planned with the CyberKnife treatment planning system. In the 3-D CRT plan, the planning target volume (PTV) included the gross tumor volume (GTV)(slow) and a 15-mm margin, whereas in the CyberKnife plan the margin was 8 mm. The physical doses from both treatment plans were converted to normalized total doses (NTD) using the linear quadratic model with an alpha/beta(tumor) of 10 Gy and alpha/beta(organs at risk (OAR)) of 3 Gy. The average minimal and mean doses administered to the PTV with the CyberKnife and 3-D CRT were 93 and 115.8 Gy and 61 and 66 Gy, respectively (p<0.0001). The mean V(20) of the CyberKnife and 3-D CRT plans were 8.2% and 6.8%, respectively (p=0.124). Both plans complied with the OAR constraints. In conclusion, 4-dimensional stereotactic radiotherapy can increase the minimal and mean biological dose with 51% and 75%, in comparison with 3-D CRT without significantly increasing the V(20), respectively.
Prevost
J-B
JB
Department of Radiation-Oncology, Erasmus MC-Daniel den Hoed Cancer Center, Rotterdam, The Netherlands.
Voet
P
P
Hoogeman
M
M
Praag
J
J
Levendag
P
P
Nuyttens
J J
JJ
D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000532:radiotherapy / Q000601:surgery*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal