Funding sources: Companion Animal Health Fund, Western College of Veterinary Medicine.
IMPACT OF TISSUE INHOMOGENEITY ON DOSE DISTRIBUTION IN THE CANINE CARPAL AND TARSAL REGIONS FOR COBALT AND 6 MV PHOTONS
Article first published online: 21 APR 2009
© 2009 American College of Veterinary Radiology
Veterinary Radiology & Ultrasound
Volume 50, Issue 3, pages 319–322, May/June 2009
How to Cite
MAYER, M. N., YOSHIKAWA, H. and SIDHU, N. (2009), IMPACT OF TISSUE INHOMOGENEITY ON DOSE DISTRIBUTION IN THE CANINE CARPAL AND TARSAL REGIONS FOR COBALT AND 6 MV PHOTONS. Veterinary Radiology & Ultrasound, 50: 319–322. doi: 10.1111/j.1740-8261.2009.01543.x
Meeting: 2008 American College of Veterinary Radiology Annual Scientific Meeting.
- Issue published online: 21 APR 2009
- Article first published online: 21 APR 2009
- Received August 5, 2008; accepted for publication October 11, 2008.
- distal extremity;
- dose distribution;
- radiation therapy;
- tissue inhomogeneity
We quantified the effect of tissue inhomogeneity on dose distribution in a canine distal extremity resulting from treatment with cobalt photons and photons from a 6 MV accelerator. Monitor units for a typical distal extremity treatment were calculated by two methods, using equally weighted, parallel-opposed fields. The first method was a computed tomography (CT)-based, computerized treatment plan, calculated without inhomogeneity correction. The second method was a manual point dose calculation to the isocenter. A computerized planning system was then used to assess the dose distribution achieved by these two methods when tissue inhomogeneity was taken into account. For cobalt photons, the median percentage of the planning target volume (PTV) that received <95% of the prescribed dose was 4.5% for the CT-based treatment plan, and 26.2% for the manually calculated plan. For 6 MV photons, the median percentage of the PTV that received <95% of the prescribed dose was <1% for both planning methods. The PTV dose achieved without using inhomogeneity correction for cobalt photons results in potentially significant under dosing of portions of the PTV.