A Comparison Between Electronic Portal Imaging Device and Cone Beam CT in Radiotherapy Verification of Nasopharyngeal Carcinoma

Optimization of the margin expanded from the clinical to the planned target volume during intensity-modulated radiotherapy for nasopharyngeal carcinoma

“…In the early IMRT used for NPC, the set-up errors were obtained from EPID. The CTV-PTV margin reported was 5 mm [ 12 , 13 ]. By the analysis of EPID images of 32 patients with NPC, the set-up errors were an X-axis error of 1.36(±1.02) mm, Y-axis error of 1.23(±1.05) mm, and a Z-axis error of 1.34 (±1.08)mm.…”

“…The results suggest that the 5 mm margin of CTV-PTV was relatively safe [ 20 ]. The emergence of CBCT with more accuracy has replaced EPID [ 13 ]. Based on CBCT, the mean and standard deviation of the three dimensional directions were ML 0.180(±0.119) cm, SI 0.136(±0.112) cm, and AP 0.107(±0.084) cm [ 7 ].…”

The risk of secondary cancer in nasopharyngeal carcinoma paediatric patients due to intensity modulated radiotherapy and mega‐voltage cone beam computed tomography

“…In IMRT, treatment accuracy is an important issue because with its steeper dose gradient, a small deviation of the treatment field can result in unnecessary irradiation of the OARs or under‐dosing the target . This problem can be solved using Image Guided Radiation Therapy (IGRT).…”

“…[2][3][4][5][6] In IMRT, treatment accuracy is an important issue because with its steeper dose gradient, a small deviation of the treatment field can result in unnecessary irradiation of the OARs or under-dosing the target. 7,8 This problem can be solved using Image Guided Radiation Therapy (IGRT). Using mega-voltage cone beam computed tomography (MV-CBCT), 3D images that are weekly obtained for head and neck patients not only provides verification of positioning 9 but also opens the possibility of adapting the treatment course for anatomical changes such as weight loss or tumour shrinkage.…”