Determining the difference between measured and calculated dose to canine oral mucosa during stereotactic radiation therapy using Gafchromic™ film

2011 2011

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Abstract (summary)

Among the therapeutic approaches available to manage canine nasal tumors, radiation therapy is considered the standard of care for achieving improved quality of life and overall survival time for these patients. Long-term local tumor control remains the goal for many radiation therapy protocols applied to patients with canine nasal tumors. Stereotactic radiation therapy (SRT), utilized by Colorado State University Animal Cancer Center (CSU-ACC), delivers maximum dose to the tumor volume, while preferentially sparing the surrounding normal structures. When treating dogs with nasal SRT, there is uncertainty with regard to the actual dose delivered to the oral mucosa due to the anatomical proximity of the tumor and the inherent error of most algorithms in calculating doses at air-tissue interfaces. A canine head phantom, dogs with spontaneously-occurring tumors, and the Gafchromic EBT film analysis system were utilized to measure radiation dose. Further comparison between measured film dose and dose calculated by the Varian Eclipse inverse planning algorithm was conducted. The results from this study demonstrate the high variability of the Analytical Anisotropic Algorithm (AAA) in calculating doses for this particular geometry. The high degree of variability results in uncertainty with regard to the prediction of delivered dose. The differences between measured and calculated doses in both the phantom (mean difference of 104 cGy per fraction, p-value of <0.0001) and the dogs (mean difference of 74 cGy per fraction, p-value of 4.2 x 10-5), suggest that the AAA underestimates the dose delivered to oral mucosa of dogs treated with SRT to manage their nasal tumors. Based upon a dose prescription of 10 Gy tumor dose per fraction in this population of dogs, an oral mucosa dose range of 3.5-6.5 Gy per fraction was measured in 88% of the cases, this range might be considered by clinicians in an effort to estimate the dose delivered to the oral mucosa while treating canine nasal tumors with SRT.

Indexing (details)

0992: Oncology
Identifier / keyword
Health and environmental sciences; Canine nasal tumors; Dosimetry; Gafchromic films; Varian eclipse inverse planning
Determining the difference between measured and calculated dose to canine oral mucosa during stereotactic radiation therapy using Gafchromic™ film
Mazyad, Ward
Number of pages
Publication year
Degree date
School code
MAI 50/03M, Masters Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
LaRue, Susan
Committee member
Custis, James T.; Harmon, Joseph F.; Kavanagh, Brian D.; Lunn, Katharine F.
Colorado State University
Environmental & Radiological Health Sciences
University location
United States -- Colorado
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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