Estimation of planning organ at risk volumes for ocular structures in dogs undergoing three‐dimensional image‐guided periocular radiotherapy with rigid bite block immobilization
Autor: | Carla Rohrer Bley, Friederike Wolf, Jürgen Besserer, Valeria Meier |
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Přispěvatelé: | University of Zurich, Meier, Valeria Sabina |
Jazyk: | angličtina |
Rok vydání: | 2021 |
Předmět: |
Organs at Risk
10253 Department of Small Animals 3400 General Veterinary medicine.medical_treatment canine 10192 Physics Institute sinonasal PRV Dogs Imaging Three-Dimensional Medicine Animals Original Investigation Retrospective Studies 630 Agriculture General Veterinary business.industry Radiotherapy Planning Computer-Assisted Radiation dose toxicity Organ Size Cone-Beam Computed Tomography eye Radiation therapy Organ at risk Random error 570 Life sciences biology Bite block business Nuclear medicine Radiotherapy Image-Guided |
Zdroj: | Veterinary Radiology & Ultrasound |
ISSN: | 1740-8261 1058-8183 |
Popis: | Planning organ at risk volume (PRV) estimates have been reported as methods for sparing organs at risk (OARs) during radiation therapy, especially for hypofractioned and/or dose‐escalated protocols. The objectives of this retrospective, analytical, observational study were to evaluate peri‐ocular OAR shifts and derive PRVs in a sample of dogs undergoing radiation therapy for periocular tumors. Inclusion criteria were as follows: dogs irradiated for periocular tumors, with 3D‐image‐guidance and at least four cone‐beam CTs (CBCTs) used for position verification, and positioning in a rigid bite block immobilization device. Peri‐ocular OARs were contoured on each CBCT and the systematic and random error of the shifts in relation to the planning CT position computed. The formula 1.3×Σ+0.5xσ was used to generate a PRV of each OAR in the dorsoventral, mediolateral, and craniocaudal axis. A total of 30 dogs were sampled, with 450 OARs contoured, and 2145 shifts assessed. The PRV expansion was qualitatively different for each organ (1‐4 mm for the dorsoventral and 1‐2 mm for the mediolateral and craniocaudal axes). Maximal PRV expansion was ≤4 mm and directional for the majority; most pronounced for corneas and retinas. Findings from the current study may help improve awareness of and minimization of radiation dose in peri‐ocular OARs for future canine patients. Because some OARs were difficult to visualize on CBCTs and/ or to delineate on the planning CT, authors recommend that PRV estimates be institution‐specific and applied with caution. |
Databáze: | OpenAIRE |
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