Intrafractional tracking accuracy in infrared marker-based hybrid dynamic tumour-tracking irradiation with a gimballed linac

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• 作者：Nobutaka Mukumoto^a ; Mitsuhiro Nakamura^a ; ^{m_nkmr@kuhp.kyoto-u.ac.jp" class="auth_mail} ; Masahiro Yamada^a ; Kunio Takahashi^b ; Hiroaki Tanabe^c ; Shinsuke Yano^d ; Yuki Miyabe^a ; Nami Ueki^a ; Shuji Kaneko^a ; Yukinori Matsuo^a ; Takashi Mizowaki^a ; Akira Sawada^a ; ^e ; Masaki Kokubo^c ; ^f ; Masahiro Hiraoka^a
• 关键词：Four-dimensional image-guided radiotherapy ; Dynamic tumour-tracking irradiation ; Respiratory motion ; Vero4DRT ; Intra-fractional tracking accuracy
• 刊名：Radiotherapy and Oncology
• 出版年：May 2014
• 年：2014
• 卷：111
• 期：2
• 页码：301-305
• 全文大小：731 K

文摘

To verify the intrafractional tracking accuracy in infrared (IR) marker-based hybrid dynamic tumour tracking irradiation (“IR Tracking”) with the Vero4DRT.

bsSec_2">Materials and methods

The gimballed X-ray head tracks a moving target by predicting its future position from displacements of IR markers in real-time. Ten lung cancer patients who underwent IR Tracking were enrolled. The 95th percentiles of intrafractional mechanical (b=MathURL&_method=retrieve&_eid=1-s2.0-S0167814014001340&_mathId=si1.gif&_user=111111111&_pii=S0167814014001340&_rdoc=1&_issn=01678140&md5=6ce5c7ecac7c2c96fcfc8eeb1419b735">), prediction (b=MathURL&_method=retrieve&_eid=1-s2.0-S0167814014001340&_mathId=si2.gif&_user=111111111&_pii=S0167814014001340&_rdoc=1&_issn=01678140&md5=d9c230ed5099140c54f63d5ab46cc65e">), and overall targeting errors (b=MathURL&_method=retrieve&_eid=1-s2.0-S0167814014001340&_mathId=si3.gif&_user=111111111&_pii=S0167814014001340&_rdoc=1&_issn=01678140&md5=94de0b899d45a441ead0739364bd2d60">) were calculated from orthogonal fluoroscopy images acquired during tracking irradiation and from the synchronously acquired log files.

bsSec_3">Results

Averaged intrafractional errors were (left–right, cranio-caudal [CC], anterior–posterior [AP]) = (0.1 mm, 0.4 mm, 0.1 mm) for b=MathURL&_method=retrieve&_eid=1-s2.0-S0167814014001340&_mathId=si4.gif&_user=111111111&_pii=S0167814014001340&_rdoc=1&_issn=01678140&md5=d024c8d71e7b1a9a8bc828ca2322a831">, (1.2 mm, 2.7 mm, 2.1 mm) for b=MathURL&_method=retrieve&_eid=1-s2.0-S0167814014001340&_mathId=si5.gif&_user=111111111&_pii=S0167814014001340&_rdoc=1&_issn=01678140&md5=565197b7e0f0b2473fee2cfbc2eac754">, and (1.3 mm, 2.4 mm, 1.4 mm) for i6" class="mathmlsrc">b=MathURL&_method=retrieve&_eid=1-s2.0-S0167814014001340&_mathId=si6.gif&_user=111111111&_pii=S0167814014001340&_rdoc=1&_issn=01678140&md5=269b49edec4873f4715c08abfb1d5079">i6.gif">. By correcting systematic prediction errors in the previous field, the b=MathURL&_method=retrieve&_eid=1-s2.0-S0167814014001340&_mathId=si7.gif&_user=111111111&_pii=S0167814014001340&_rdoc=1&_issn=01678140&md5=4c6898130f5c33aa30261ce26052e5bb"> was reduced significantly, by an average of 0.4 mm in the CC (p < 0.05) and by 0.3 mm in the AP (p < 0.01) directions.

bsSec_4">Conclusions

Prediction errors were the primary cause of overall targeting errors, whereas mechanical errors were negligible. Furthermore, improvement of the prediction accuracy could be achieved by correcting systematic prediction errors in the previous field.