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Daily image guidance reduces inter‐fractional variation in patient position for intracranial radiation therapy. However, the ability to detect and correct positioning errors is limited below a certain level. Because of these limitations, the accuracy achieved with a positioning system prior to image guidance may affect the error remaining after image guidance (the residual setup error). The objective of this study was to compare the setup accuracy achieved before and after megavoltage (MV) and cone‐beam computed tomography (CBCT) guidance between two intracranial positioning systems. Equipment included a four degrees‐of‐freedom couch capable of 1 mm translational moves. Six dog cadavers were positioned 24 times as for clinical treatment in a head re‐positioner (HPS), and the coordinates of five fiducial markers were measured before and after image‐guided correction. The values obtained for the HPS were compared with those previously reported for the standard positioning system (SPS) used at this facility. The mean three‐dimensional distance vector (3DDV) was lower for the HPS than for the SPS when no image guidance was used (P =.019). The mean 3DDV after MV guidance was lower for the HPS than for the SPS (P =.027), but not different after CBCT guidance (P =.231). The 95th percentiles of the 3DDV after MV and CBCT guidance were 2.1 and 2.9 mm, respectively, for the HPS, and 2.8 and 3.6 mm for the SPS. The setup error after MV guidance was lower for the positioning system that achieved a more accurate patient position before image guidance. [ABSTRACT FROM AUTHOR]

Sources of residual setup error after image guidance include image localization accuracy, errors associated with image registration, and inability of some treatment couches to correct submillimeter translational errors and/or pitch and roll errors. The purpose of this experimental study was to measure setup error after image‐guided correction of the canine intracranial region, using a four degrees‐of‐freedom couch capable of 1 mm translational moves. Six cadaver dogs were positioned 45 times as for clinical treatment using a vacuum deformable body cushion, a customizable head cushion, a thermoplastic mask and an indexed maxillary plate with a dental mould. The location of five fiducial markers in the skull bones was compared between the reference position and after megavoltage (MV), kilovoltage (kV) and cone‐beam computed tomography (CBCT)‐guided correction using orthogonal kV images. The mean three‐dimensional distance vectors (3DDV) after MV, kV and CBCT‐guided correction were 1.7, 1.5 and 2.2 mm, respectively. All values were significantly different (P <.01). The 95th percentiles of the 3DDV after online MV, kV and CBCT‐guided correction were 2.8, 2.6 and 3.6 mm, respectively. Residual setup error in the clinical scenario examined was on the order of millimetres and should be considered when choosing PTV margins for image‐guided radiation therapy of the canine intracranial region. [ABSTRACT FROM AUTHOR]

OBJECTIVE To describe response rate, tumor progression, patient survival times, prognostic factors associated with tumor progression and patient survival times, and radiation toxicoses (acute and latent) in dogs treated with curative-intent stereotactic body radiation therapy (SBRT) for soft tissue sarcomas (STS). ANIMALS 35 client-owned dogs with STS treated with curative-intent SBRT between October 2011 and May 2017. PROCEDURES Medical records were reviewed to identify dogs that underwent SBRT. Dogs with oral tumors, hemangiosarcoma, or histiocytic sarcoma were excluded. Data collected included patient-, STS-, and SBRT-related information, including follow-up information pertaining to tumor progression and patient survival time for ≥ 6 months, unless tumor progression or patient death occurred sooner. RESULTS Objective measurements allowing for evaluation of tumor response were available for 28 dogs, of which 13 (46%) had either a partial (10/28 [36%]) or complete (3/28 [11%]) response. Twenty-four dogs died, and the medians for progression-free survival time, time to progression of disease, overall survival time, and disease-specific survival time were 521, 705, 713, and 1,149 days, respectively. Low histologic grade and extremity locations of STSs were positive prognostic factors for patient survival times. Acute adverse effects were limited to skin, and 1 dog underwent limb amputation because of a nonhealing wound. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that SBRT for STS was well tolerated in most dogs and provided local tumor control. Additional studies are needed to determine the best SBRT protocol for treatment of STSs in dogs. [ABSTRACT FROM AUTHOR]

OBJECTIVE To assess outcomes, factors associated with survival time, and radiation-induced toxicoses in dogs treated for nasal tumors with curative-intent stereotactic body radiation therapy (SBRT). DESIGN Retrospective case series. ANIMALS 28 client-owned dogs. PROCEDURES By use of a 6-MV linear accelerator, dogs were treated with SBRT (3 consecutive-day fractions of 9 or 10 Gy or once with I fraction of 20 Gy). Data regarding adverse effects, outcomes, and survival times were obtained from the medical records. RESULTS The median survival time to death due to any cause was 388 days. Of the 24 dogs known to be dead, 14 (58%) died or were euthanized because of local disease progression. A cute radiation-induced adverse effects developed in the skin (excluding alopecia) in 26% (6/23) of dogs and in the oral cavity in 30% (7/23) of dogs. Acute ocular adverse effects included discharge in 26% (6/23) of dogs and keratoconjunctivitis sicca in 4% (I/23) of dogs. Among the 22 dogs alive at > 6 months after SBRT, 4 (18%) developed a unilateral cataract; 4 (18%) developed other complications that may have been late-onset radiation toxicoses (excluding leukotrichia and skin hyperpigmentation). CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that dogs treated with SBRT had outcomes comparable to those reported for dogs with nasal carcinomas and sarcomas that undergo conventionally fractionated radiation therapy. Administration of SBRT was associated with a comparatively lower frequency of acute radiation-induced adverse effects. For SBRT and conventionally fractionated radiation therapy, the frequencies of serious late-onset adverse effects appear similar. [ABSTRACT FROM AUTHOR]

OBJECTIVE To describe animal owners’ experiences with palliative radiation therapy (PRT) of pets and identify factors influencing satisfaction with their pets’ treatment. DESIGN Retrospective, cross-sectional study. SAMPLE 118 owners of dogs, cats, or rabbits. PROCEDURES Medical records were searched to identify animals that underwent PRT between 2004 and 2013. Signalment, tumor-related data, and outcome information were recorded. Owners completed an electronic survey assessing satisfaction with treatment (ie, satisfaction with the decision for their pet to undergo PRT and indication that they would choose PRT for their pet again), expectations regarding PRT, and perceptions of their pets’ quality of life (QOL) and signs of discomfort from acute adverse radiation effects. Additional data regarding practical aspects of treatment, pet death, communications with veterinarians, and owner demographics were collected. Variables were tested for association with measures of owner satisfaction. RESULTS 92 of 116 (79%) owners were satisfied with the decision to have their pets undergo PRT. Most (92/118 [78%]) owners reported their pet’s QOL improved after PRT; these owners were significantly more likely to be satisfied than those who did not report improved QOL. Owners who perceived their pets had discomfort from adverse radiation effects (38/116 [33%]) were significantly less likely to be satisfied than owners who did not report this observation. Measures of satisfaction were not associated with patient survival time. Twenty-one of 118 (18%) owners indicated they expected PRT would cure their pet’s tumor. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that short life expectancy should not deter recommendation of PRT for pets. Protocols that minimize risk of acute adverse effects may be advantageous. Veterinarians should attempt to ensure that owners understand the goals of PRT. [ABSTRACT FROM AUTHOR]

Objective--To measure respiratory motion of the thoracic wall region in dogs using a real-time motion tracking system and compare the amount of respiratory motion between dogs positioned with and without a vacuum-formable cushion. Animals--8 healthy adult mixed-breed dogs (median weight, 23 kg). Procedures--Dogs were anesthetized and positioned in sternal and dorsal recumbency with and without a vacuum-formable cushion. Three-dimensional movement of anatomic landmarks was measured with a real-time motion capture system that tracked the locations of infrared light-emitting diodes attached externally to the dorsal or ventral and lateral aspects of the thoracic wall. Results--Dogs positioned in sternal recumbency had significantly less cranial-to-caudal and left-to-right respiratory motion at the lateral aspect of the thoracic wall, compared with dogs positioned in dorsal recumbency, whether or not a cushion was used. For dogs treated in sternal recumbency, use of a cushion significantly increased the peak displacement vector (overall movement in 3-D space) for 3 of 4 marker locations on the dorsal thoracic wall. As respiratory rate increased, respiratory motion at the lateral and ventral aspects of the thoracic wall decreased when data for all dogs in dorsal recumbency were evaluated together. Conclusions and Clinical Relevance--Associations between respiratory rate and respiratory motion suggested that the use of rapid, shallow ventilation may be beneficial for dogs undergoing highly conformal radiation treatment. These results provide a basis for further research on respiratory motion in anesthetized dogs. [ABSTRACT FROM AUTHOR]

Objective—To assess the perioperative and postoperative complications associated with use of vascular access ports (VAPs) in the jugular and lateral saphenous veins of dogs requiring frequent anesthetic episodes for radiation therapy. Design—Cohort study. Animals—40 dogs referred to a veterinary teaching hospital. Procedures—VAPs were used in 23 dogs, and intravenous catheters inserted in a peripheral vein were used in 17 dogs. The frequency of perioperative and postoperative complications associated with VAP use and the frequency of infection associated with intravenous catheter use were recorded. Results of bacterial culture of VAP tips and amount of time required for VAP placement and removal and for anesthetic induction were also recorded. Results—VAP-associated perioperative complications included malposition of the catheter tip in 4 of 23 (174%) dogs. The VAP-associated postoperative complications included seroma formation in 7 (30.4%) dogs, breakage of port-anchoring sutures in 3 (13.0%) dogs, suspected fatal catheter-related septicemia in 1 14.3%) dog, and temporary partial withdrawal occlusion in 18 of 255 (71%) anesthetic episodes. Conclusions and Clinical Relevance—Placement of VAPs provided ready access in dogs receiving radiation therapy. Most complications were minor and self-limiting; however, a low risk of serious complications existed. Use of fluoroscopy to assess position of the catheter tip is recommended to decrease the risk of malposition. Immediate removal of a VAP is recommended when clinical signs of infection develop. Removal of a VAP at the completion of radiation therapy should be performed unless the benefit of continued vascular access outweighs the risks. [ABSTRACT FROM AUTHOR]

Focuses on the opening of the Magnetic Resonance Imaging and Radiation Therapy Centre of Western College of Veterinary Medicine at the University of Saskatchewan. Features of the magnetic resonance imaging (MRI); Discussion on the application of MRI for the examination of brain, spinal cord and adjacent structures; Details of its acquisition of a radiation therapy unit that provides another option for treatment and control of many types of neoplasia.