Volume 22, Number 4, 2017

Utility of intraoral stents in external beam radiotherapy for head and neck cancer

Hiroshi Doi, Masao Tanooka, Toshihisa Ishida, Kuniyasu Moridera, Kenji Ichimiya, Kazuo Tarutani, Kazuhiro Kitajima, Masayuki Fujiwara, Hiromitsu Kishimoto, Norihiko Kamikonya

Summary:

Aim

This study aimed to assess the utility and stability of intraoral stent during intensity-modulated radiation therapy (IMRT).

Background

The benefits of intraoral stents in radiotherapy are unclear.

Materials and methods

We analyzed 386 setup errors in 12 patients who received IMRT for head and neck cancers without intraoral stents (intraoral stent [−]) and 183 setup errors in 6 patients who received IMRT with intraoral stents (intraoral stent [+]). All patients were matched according to the immobilization method (masks and boards). Setup errors were measured as the distance from the initial setup based on the marking on the skin and mask to the corrected position based on bone matching on cone beam computed tomography.

Results

The mean interfractional setup errors in the right–left, craniocaudal, anterior–posterior (AP), and three-dimensional (3D) directions were −0.33, 0.08, −0.25, and 2.75 mm in the intraoral stent (−) group and −0.37, 0.24, −0.63, and 2.42 mm in the intraoral stent (+) group, respectively (P = 0.50, 0.65, 0.01, and 0.02, respectively). The systematic errors for the same directions were 0.89, 1.46, 1.15, and 0.88 mm in the intraoral stent (−) group and 0.62, 1.69, 0.68, and 0.56 mm in the intraoral stents (+) group, respectively. The random errors were 1.43, 1.43, 1.44, and 1.22 mm in the intraoral stent (−) group and 1.06, 1.11, 1.05, and 0.92 mm in the intraoral stents (+) group, respectively.

Conclusion

Setup errors can be significantly reduced in the AP and 3D-directions by using intraoral stents.

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