Oncotarget

Research Papers:

Compared planning dosimetry of TOMO, VMAT and IMRT in rectal cancer with different simulated positions

Jang-Chun Lin, Jo-Ting Tsai, Li-Jhen Chen, Ming-Hsien Li and Wei-Hsiu Liu _

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Oncotarget. 2017; 8:42020-42029. https://doi.org/10.18632/oncotarget.14923

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Abstract

Jang-Chun Lin1,2,3,4, Jo-Ting Tsai1,2, Li-Jhen Chen1, Ming-Hsien Li1 and Wei-Hsiu Liu5,6

1Department of Radiation Oncology, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan, ROC

2Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, ROC

3Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, ROC

4Department of Radiation Oncology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC

5Department of Neurological Surgery, Tri-Service General Hospital and National Defense Medical Center, Taipei, Taiwan, ROC

6Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC

Correspondence to:

Wei-Hsiu Liu, email: liubear0812bear@yahoo.com.tw

Keywords: rectal cancer (RC), helical tomotherapy (TOMO), volumetric modulated arc therapy (VMAT), intensity modulated radiotherapy (IMRT), radiation dosimetry

Received: October 21, 2016     Accepted: December 27, 2016     Published: January 31, 2017

ABSTRACT

Objectives: To compare treatment plans for helical tomotherapy (TOMO), volumetric modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) for locally advanced rectal cancer (LARC).

Materials and Methods: This retrospective study from December 2010 to June 2013 included 20 patients with LARC who received neoadjuvant concurrent chemoradiotherapy (CCRT) with radiation doses of greater than 50.4 Gy. Dosimetric quality was evaluated based on doses to organs at risk (OARs), including small bowel, urinary bladder and bilateral femoral head, over the same coverage of the clinical target volume (CTV).

Results: In supine comparison of IMRT with VMAT, VMAT treatment plan had a lower hot spot dose (p=0.0154) and better conformity index (CI, p=0.0036) and homogeneity index (HI, p=0.0246). Lower bladder V34.98 (p=0.0008), V40 (p=0.0058), mean dose (p<0.0001), femoral head mean dose (p=0.0089), V30 (p<0.0001), V40 (p=0.0013) and better CI (p<0.0001) and HI (p=0.0001) were observed for TOMO compared with IMRT. Patients with LARC receiving TOMO planning had lower bladder V34.98 (p=0.0021), V40 (p=0.0055), mean dose (p=0.0039), femoral head mean dose (p=0.0060), V30 (p<0.0001), and V40 (p=0.0044) and better CI (p=0.0157) and HI (p=0.0292) than VMAT. Comparing prone and supine position image planning, there were no significant differences, including in OARs in the three planning systems, except for lower bladder V34.98 (p=0.0403) in the supine position using TOMO.

Conclusions: Using modern radiation techniques, neither prone nor supine positions provide better values for OARs. TOMO was superior to IMRT and VMAT in sparing OARs and planning quality parameters.


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