Validation of New Bite Block‐type Head‐immobilization Devices for Radiotherapy in Dogs

Abstract

An ideal head-immobilization method provides a high level of accuracy and reproducibility in the immobilization. Various head-immobilization methods for radiotherapy have been published and are excellent in terms of accuracy; however, these methods are complicated to use, and labor intensive. The present study describes two new bite block-type head-immobilization devices designed for higher stability and lower vertical variation. The device designed in our previous study (the bite block-type head-immobilization device; Device A) was modified by making a groove on the top the horizontal plate (Device B) for a stable ventral-dorsal position, or beneath the horizontal plate (Device C) for a stable dorsal-ventral position. The three devices were objectively compared with respect to setup time, and accuracy of the computed tomography scan images by two authors independently. Five male healthy beagles were used in this study. For each device, the setup time and the variation in the coordinates were measured five times for each dog. The mean setup times for Devices A, B, and C were 3.3, 1.5, and 2.4 min, respectively, showing the groove modifications were able to reduce the setup time (in device B, by at least 50%). Moreover, three-dimensional analysis of the computed tomography images revealed that the measurement variability of Device A (1.6 ± 1.0 mm) was significantly higher than that of Device C (0.7 ± 0.4 mm; P < 0.001). Collectively, our results show that use of a bite block-type head-immobilization device with a groove improves the setup time and head-immobilization accuracy.

Implementation of immobilization accessories for positioning of small animals for radiation therapy

“…The accessories shown in the present study all features disclosed by Lage et al (2012), and the similarity to other immobilizers accessories used in small animals in the literature (Kippenes et al, 2000;Green et al, 2003;Schwarz and Saunders, 2011;Maruo et al, 2013;Larue and Custis, 2014;Hansen et al, 2015).…”

“…These devices must have characteristics that contribute to the comfortable handling of the patient and allow the focusing of the radiation field restricted to the volume of treatment and do not interfere in the released radiation dose (Lage et al, 2012;Maruo et al, 2013).…”

“…For the immobilization of small animals during treatment, as well as sedation and anesthesia are used some accessories like immobilizers to those used in human radiotherapy such as frames or frames for head thermoplastic masks, bite blocks and moldable mattresses (Kippenes et al, 2000;Green et al, 2003;Schwarz and Saunders, 2011;Maruo et al, 2013;Larue and Custis, 2014;Hansen et al, 2015).…”

A retrospective analysis of radiation oncology related scientific articles in the journal Veterinary Radiology and Ultrasound: Trends over 40 years (1976‐2015)

“…In Category 3, no article was published during Period 1, and only one article was published during Period 2 . The number increased to four articles during Period 3, and to 10 articles during Period 4 . All of the 10 articles published during Period 4 involved immobilization of the head and neck.…”

A Novel Support Device for Head Immobilization During Radiation Therapy That Is Applicable to Both Cats and Dogs

“…To allow precise and reproducible positioning, preparation instruments are individualized for each animal. Many materials have been used to achieve appropriate positioning, including cushions and bite blocks . In 2013, we proposed two simple and innovative approaches to head immobilization.…”