Comparison of three CT scan methods used in precise radiotherapy of non-small cell lung cancer

Abstract

Objective To compare the difference of decreasing radiation-induce lung injure among CT scans including active breathing control (ABC), slow CT scan and general axial CT scan under free breathing (FB) in precise radiotherapy of peripheral non-small cell lung cancer (NSCLC). Methods Ten patients of peripheral NSCLC were included. For each patient, three CT scans were obtained: (1) the general axial CT scans under FB;(2) the fast spiral CT scans under ABC;(3) the slow CT scans under FB. Three treatment plans based on three CT scans were optimized. Gross tumor volume (GTV), clinical target volume (CTV) and planning target volume (PTV) along with V20 (lung volume accepted > 20 Gy/all lung volume ×100%) and Dmean (average dosage accepted irradiation of all lung)of three treatment plans were calculated and compared. Results The GTV and CTV of the slow CT plan seem in largest, and those of ABC plan in smallest, but no statistics signification among the three plans (F = 1.513, P = 0.238;F = 1.376, P = 0.270). However, The PIV of the FB plan was largest, and the difference of PTV between plans of ABC and FB, plans of slow CT scans and FB were statistics significant (F = 26. 148, P = 0.000). The differences of V20 and Dmean between plans of FBand ABC, plans of FB and slow CT scans were statistics significant yet (F = 7.623, P = 0.002;F = 18.217, P = 0.000). Conclusion Compared with FB conditions, ABC or the slow CT scan method in precise radiotherapy of peripheral NSCLC can decrease radiation volume and dose to normal tissues as well as the probability of decreasing radiation-induce lung injure. Key words: Lung neoplasms; Radiotherapy; Three-dimensional conformal; Respiratory movement