Dosimetric impact of daily setup variations during treatment of canine nasal tumors using intensity-modulated radiation therapy

Michael A. Deveau, Alonso N. GutiÉrrez, Thomas R. MacKie, Wolfgang A. Tome, Lisa J. Forrest

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Intensity-modulated radiation therapy (IMRT) can be employed to yield precise dose distributions that tightly conform to targets and reduce high doses to normal structures by generating steep dose gradients. Because of these sharp gradients, daily setup variations may have an adverse effect on clinical outcome such that an adjacent normal structure may be overdosed and/or the target may be underdosed. This study provides a detailed analysis of the impact of daily setup variations on optimized IMRT canine nasal tumor treatment plans when variations are not accounted for due to the lack of image guidance. Setup histories of ten patients with nasal tumors previously treated using helical tomotherapy were replanned retrospectively to study the impact of daily setup variations on IMRT dose distributions. Daily setup shifts were applied to IMRT plans on a fraction-by-fraction basis. Using mattress immobilization and laser alignment, mean setup error magnitude in any single dimension was at least 2.5 mm (0-10.0 mm). With inclusions of all three translational coordinates, mean composite offset vector was 5.9±3.3 mm. Due to variations, a loss of equivalent uniform dose for target volumes of up to 5.6% was noted which corresponded to a potential loss in tumor control probability of 39.5%. Overdosing of eyes and brain was noted by increases in mean normalized total dose and highest normalized dose given to 2% of the volume. Findings suggest that successful implementation of canine nasal IMRT requires daily image guidance to ensure accurate delivery of precise IMRT distributions when non-rigid immobilization techniques are utilized. Unrecognized geographical misses may result in tumor recurrence and/or radiation toxicities to the eyes and brain.

Original languageEnglish (US)
Pages (from-to)90-96
Number of pages7
JournalVeterinary Radiology and Ultrasound
Volume51
Issue number1
DOIs
StatePublished - Jan 2010
Externally publishedYes

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radiotherapy
Nose
Canidae
Radiotherapy
neoplasms
dogs
dosage
Neoplasms
Immobilization
Therapeutics
eyes
Intensity-Modulated Radiotherapy
brain
Brain
Lasers
lasers
Radiation
Recurrence
adverse effects
toxicity

Keywords

  • Canine nasal tumors
  • Intensity-modulated radiation therapy
  • Setup variations
  • Tomotherapy

ASJC Scopus subject areas

  • veterinary(all)

Cite this

Dosimetric impact of daily setup variations during treatment of canine nasal tumors using intensity-modulated radiation therapy. / Deveau, Michael A.; GutiÉrrez, Alonso N.; MacKie, Thomas R.; Tome, Wolfgang A.; Forrest, Lisa J.

In: Veterinary Radiology and Ultrasound, Vol. 51, No. 1, 01.2010, p. 90-96.

Research output: Contribution to journalArticle

Deveau, Michael A. ; GutiÉrrez, Alonso N. ; MacKie, Thomas R. ; Tome, Wolfgang A. ; Forrest, Lisa J. / Dosimetric impact of daily setup variations during treatment of canine nasal tumors using intensity-modulated radiation therapy. In: Veterinary Radiology and Ultrasound. 2010 ; Vol. 51, No. 1. pp. 90-96.
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