JRSBRT 4.1, p. 75-76

Intrafractional positioning accuracy during stereotactic brain radiotherapy with a modified thermoplastic mask system, on-board cone-beam CT, and a six-degrees-of-freedom couch
Naohisa Mizukami and Kiyoshi Yoda

A recent article reported that a mouthpiece-assisted mask system could result in an intrafractional positioning accuracy with a standard deviation of 0.6 mm, where a mouthpiece, Precise Bite (CIVCO, Iowa, USA) was used for each patient [1].

In this letter, a more practical mask system without employing a mouthpiece is proposed by modifying a commercial thermoplastic mask, Type-S IMRT Reinforced Style 20 Mask (CIVCO, Iowa, USA) with a thickness of 3.5 mm, in such a way that a portion of the thermoplastic shell is pushed into a patient's mouth by 2 cm using a ruler so that the patient can byte it with lips and teeth.