Clinical application of Delta4 / 中华放射肿瘤学杂志

ABSTRACT

Objective To compare two verification tools for intensity modulated radiotherapy (IM-RT) and to investigate the feasibility of a new three dimensitional verification tool. Methods Five patients receiving IMRT were randomly chosen for the quality assurance plans with MapCHECK Model 1175 (SunNu-clear, Melbourne, FL,USA) and Delta4(ScandiDos, Sweden) by using Philips Pinnacle 8.0D treatment planning system. Dose verification was measured with the Varian Clinical 23EX LA. Results The overall average percentages of pass points in DD2% DTA2 mm, DD3% DTA3 mm and DD4% DTA4 mm were 84.7%, 97. 1% and 99.3% with MapCHECK Model 1175, 86.2%, 98.2% and 99.6% with Delta4 re-spectively. The differences were statisticically significant (t = 3.94, P = 0.003 ; t = 3.17, P = 0.011 ; t = 3.05 ,P =0.014,respectively). The gantry angle was changed to zero degree with MapCHECK, but not with Delta. The effects were embodied with Delta, such as the gravity on leaf position accuracy of MLC, the treat-ment table on dose distribution and the earth magnetism on dose system. Conclusion Delta4 is an ideal verification tool for intensity modulated radiotherapy.