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Hypofraction radiotherapy of liver tumor using cone beam computed tomography guidance combined with active breath control by long breath-holding

  • Renming Zhong
    • ,
  • Jin Wang
    • ,
  • Xiaoqin Jiang
    • ,
  • Yinbo He
    • ,
  • Hong Zhang
    • ,
  • Nianyong Chen
    • ,
  • Sen Bai

      Affiliations

    • Corresponding Author InformationCorresponding authors. Address: Department of Radiation Oncology, West China Hospital/West China School of Medicine, Sichuan University, Chengdu 610041, Sichuan Province, PR China.
    • These authors equally contributed to this work.
    • ,
  • Feng Xu

      Affiliations

    • Corresponding Author InformationCorresponding authors. Address: Department of Radiation Oncology, West China Hospital/West China School of Medicine, Sichuan University, Chengdu 610041, Sichuan Province, PR China.
    • These authors equally contributed to this work.

Department of Radiation Oncology, Sichuan University, Chengdu, PR China

Received 14 March 2011; received in revised form 7 November 2011; accepted 22 November 2011. published online 20 January 2012.
Corrected Proof

Abstract 

Background and purpose

To evaluate the feasibility and validity of cone beam computed tomography (CBCT) and active breath control (ABC) by long breath-holding in hypofraction radiotherapy of liver tumor.

Methods and materials

Twenty-four patients received hypofraction radiotherapy of liver tumor with long breath-holding at end-inhale; four prescriptions were used: 6Gy×7 (n=8), 10Gy×4 (n=7), 5Gy×9 (n=6), 4Gy×10 (n=3). For each fraction, all patients received pre-correction CBCT scans with ABC, some patients received post-correction and post-treatment CBCT. The interfraction and intrafraction liver positioning errors on medial–lateral (ML), cranial–caudal (CC) and anterior–posterior (AP) directions were obtained. The theoretic margin from clinical target volume (CTV) to planning target volume (PTV) was calculated based on post-treatment error. The dosimetric parameters of PTV and normal tissue were compared between ABC and free breathing (FB).

Results

The interfraction error in liver positioning showed system errors (Σ) of 3.18mm (ML), 6.80mm (CC) and 3.05mm (AP); random error (σ) of 3.03mm (ML), 6.78mm (CC) and 3.62mm (AP). These errors were significantly reduced with CBCT guided online correction. The intrafraction systematic error was 0.72mm (ML), 2.21mm (CC), 1.49mm (AP), and random error was 2.30mm (ML), 3.58mm (CC), 2.49mm (AP). Dosimetric parameters such as PTV, the liver’s volume included by 23, 30Gy isodose curve (V23, V30), mean dose to normal liver (MDTNL) and mean dose to cord were significantly larger for FB (P<0.05).

Conclusion

Liver radiotherapy with long time breath-holding at end-inhale is an effective method to reduce liver motion, PTV and dose to normal tissue. Interfraction and intrafraction liver positioning errors were substantial. CBCT guided online correction of positioning error is recommended for liver radiotherapy with end-inhale ABC.

Keywords: Active breathing control (ABC), Cone beam CT (CBCT), Liver positioning error, Radiotherapy

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PII: S0167-8140(11)00705-5

doi:10.1016/j.radonc.2011.11.007

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