Purpose End‐to‐end testing with quality assurance (QA) phantoms for deformable dose accumulation and real‐time image‐guided radiotherapy (IGRT) has recently been recommended by American Association of Physicists in Medicine (AAPM) Task Groups 132 and 76. The goal of this work was to develop a deformable abdominal phantom containing a deformable three‐dimensional dosimeter that could provide robust testing of these systems. Methods The deformable abdominal phantom was fabricated from polyvinyl chloride plastisol and phantom motion was simulated with a programmable motion stage and plunger. A deformable normoxic polyacrylamide gel (nPAG) dosimeter was incorporated into the phantom apparatus to represent a liver tumor. Dosimeter data were acquired using magnetic resonance imaging (MRI). Static measurements were compared to planned dose distributions. Static and dynamic deformations were used to simulate inter‐ and intrafractional motion in the phantom and measurements were compared to baseline measurements. Results The statically irradiated dosimeters matched the planned dose distribution with an average γ pass rates of 97.0 ± 0.5% and 97.5 ± 0.2% for 3%/5 mm and 5%/5 mm criteria, respectively. Static deformations caused measured dose distribution shifts toward the phantom plunger. During the dynamic deformation experiment, the dosimeter that utilized beam gating showed an improvement in the γ pass rate compared to the dosimeter that did not. Conclusions A deformable abdominal phantom apparatus which incorporates a deformable nPAG dosimeter was developed to test real‐time IGRT systems and deformable dose accumulation algorithms. This apparatus was used to benchmark simple static irradiations in which it was found that measurements match well to the planned distributions. Deformable dose accumulation could be tested by directly measuring the shifts and blurring of the target dose due to interfractional organ deformation and motion. Dosimetric improvements were achieved from the motion management during intrafractional motion.
OBJECTIVE To determine what perceived factors prevent small animal general practitioners from discussing pet nutrition with clients during healthy and sick pet appointments. SAMPLE 403 veterinarians in small animal general practice. PROCEDURES An online survey was used to gather veterinarians’ opinions on perceived barriers, knowledge levels, and confidence regarding pet nutrition discussions. RESULTS Reported barriers to discussing nutrition during healthy pet appointments included client resistance to changing brand (149/359), time constraints (146/359), misinformation online (138/359), and difficulty keeping up with products (132/359). Reported barriers to discussing nutrition during sick pet appointments included client cost concerns (101/349), pet not accepting new food (99/349), and time constraints (83/349). Veterinarians reported discussing nutrition less during healthy pet appointments, compared to sick pet appointments, and were significantly less confident with their knowledge regarding nontherapeutic food, compared to therapeutic food. Veterinarians also reported that they perceived conversations about therapeutic foods to be more positive than conversations about nontherapeutic foods, and veterinarians with more years in practice more commonly reported that there was nothing that would dissuade them from discussing nutrition. Veterinarians who reported barriers to discussing nutrition described a need for resources and reliable information for health-care teams and clients. CLINICAL RELEVANCE Results demonstrated a substantial gap between veterinarians’ assertion that nutrition conversations are indicated and the frequency with which they discuss nutrition during appointments. Veterinarians reported that they felt their nutrition conversations were frequently positive; therefore, it is important to overcome barriers to engage with clients about pet nutrition.
PURPOSE:The purpose of this work was to evaluate differences in air-kerma rate of the older, S7500 water-cooled Xoft Axxent source and newer, S7600 Galden-cooled source. METHODS AND MATERIALS:The Attix Free Air Chamber (FAC) at the UWMRRC was used to measure the air-kerma rate at 50 cm for six S7600 Xoft Axxent sources. The average measured air-kerma of the S7600 sources was compared with the measured average air-kerma rate from five S7500 sources. The air-kerma rates of the S7500 sources were measured in a Standard Imaging HDR 1000 + well chamber. The FAC measurements were used to determine a well chamber calibration coefficient for the S7600 source. The S7500 calibration coefficients were incorrectly applied to the S7600 sources to indicate the magnitude of error that can occur if the incorrect calibration coefficient is used. RESULTS: A 10.3% difference was observed between the average air-kerma rates of the two sources although a 17% difference was observed between their calibration coefficients. The application of the S7500 calibration coefficient to the S7600 sources resulted in measured air-kerma rates that were 20% greater than the true value. CONCLUSIONS: This work indicates the need for a new air-kerma rate standard for the S7600 sources, and the results presented in this work are indicative of values that would be obtained at National Institute of Standards and Technology.
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