| Summary: | 碩士 === 國立陽明大學 === 生物醫學影像暨放射科學系 === 107 === Background
The canine nasal tumor cannot be completely removed by surgery because of its characteristic of nasal bone invasion in the early diagnosis. Even if the veterinarians perform surgery, there are still higher risks of complications. Surgery alone for the canine nasal tumors may not only reduce the quality of life but also cause the difficulty of care. In recent years, human medicine has been translated to veterinary medicine which can be enhanced in the clinical veterinary diagnosis and treatment, especially in radiation therapy of canine tumor. Radiation therapy can be used to treat tumors curatively or to palliate the symptoms of the disease. Therefore, this study aims to compare dosimetric differences of three types radiotherapy plans for canine nasal tumors based on stereotactic radiotherapy (SRT).
Materials and Methods
The nine dogs diagnosed of nasal tumor were enrolled. The prescription dose of planning target volume (PTV) was 3000 cGy in 3 fractions. Three different plans were simulated for each case: intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT) and VMAT with flattening filter free (VMAT-FFF) plans. The dose distributions for PTV, organs at risk (OARs) including eyeballs, lens, tongue, mandible, brain and region of interest (ROI) including salivary glands, hard palate, lacrimal glands and skin were compared. The monitor units (MUs) and treatment delivery time were also evaluated.
Results
In the conformity index (CI) of PTV, VMAT (1.194 ± 0.146) was significantly better than IMRT (1.320 ± 0.221) and VMAT-FFF (1.305 ± 0.203) (p < 0.05). In homogeneity index (HI) of PTV, IMRT (1.038 ± 0.011) was significantly better than VMAT (1.052 ± 0.015) and VMAT-FFF (1.038 ± 0.014) (p < 0.05). Maximal mandible dose was significantly lower in IMRT as compared to VMAT and VMAT-FFF. There were no significant differences in other OARs or ROI. The treatment time of VMAT-FFF was the fast.
Conclusion
The SRT for canine nasal tumors could be successfully translated from human medicine to veterinary medicine in IMRT, VMAT and VMAT-FFF. All three kinds of SRT treatment planning have good conformity and good homogeneity. However, more clinical trials are necessary to verify the side effects of normal tissues in the future.
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