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Purpose

This study aimed to investigate 3 planning target volume (PTV) margin expansions and determine the most appropriate volume to be used in bladder preservation therapy when using daily cone beam computed tomography (CBCT). We aimed to establish whether a smaller PTV expansion is feasible without risking geographical miss.

Methods and materials

The study included patients with bladder cancer who were treated with a hypofractionated course of radiation therapy delivered with intensity modulated radiation therapy. The clinical target volume (CTV) was the whole empty bladder, and the PTV consisted of a 1.5-cm margin around the bladder (PTV1.5 cm). Patients underwent daily CBCT imaging before treatment to assess the bladder volume and ensure accurate positioning. We investigated 2 additional smaller PTV margin expansions to determine the most appropriate volume to be used with CBCT as a daily image guided radiation therapy modality. These margins were created retrospectively on every CBCT. The first additional volume was a uniform PTV margin of the surrounding 1 cm (PTV1 cm). When considering that the majority of the internal bladder movement was due to the variation in filling that occurs in the superior and anterior directions, a second volume of an anisotropic PTV margin with a 1.5-cm superior/anterior and 1 cm in other directions (PTV1/1.5 cm) was created. We recorded the frequency and measured the volume of bladder falling out of each PTV based on the daily CBCT.

Results

For the purpose of this study, we considered an arbitrary 5 cm3 of CTV falling out of the designated PTV as a clinically significant volumetric miss. The frequency of such a miss when applying the uniform PTV1 cm was 1%. However, when applying the uniform PTV1.5 cm and anisotropic PTV1/1.5 cm margins, the frequency was 0.5% and 0.5%, respectively.

Conclusions

The anisotropic PTV expansion of 1.5 cm superiorly and anteriorly and 1 cm in all other directions around the bladder (CTV) provides a safe PTV approach when daily CBCT imaging is used to localize an empty bladder.  相似文献   
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Journal of Digital Imaging - Vertebral Compression Fracture (VCF) occurs when the vertebral body partially collapses under the action of compressive forces. Non-traumatic VCFs can be secondary to...  相似文献   
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IntroductionPeople with Down syndrome (DS) have high respiratory morbidity, evaluating their respiratory health with standardized, objective tests is desirable. Thus, the objective of this study was to evaluate the technical quality of Pulmonary Function Tests (PFTs) to determine which ones are most suitable for this population.MethodsParticipants included children, teenagers and adults with DS, 5 years of age or older (n = 302). The technical quality of the impulse oscillometry system (IOS), forced spirometry, lung-diffusing capacity for carbon monoxide (DLCO), and 6-min walk test (6MWT) were analyzed by age group. Capnography and pulse oximetry were included in the study. Technical quality was determined on the basis of current international PFTs standards.ResultsFifty-one percent of participants were males. A total of 184 participants (71%) who completed the IOS fulfilled the quality criteria, while 210 (70%) completed the 6MWT. Performance on forced spirometry and DLCO was poor. All pulse oximetries and 96% percent heart rates obtained had good quality, but exhaled carbon dioxide (PetCO2) and respiratory rate (RR) showed deficient repeatability.ConclusionsIOS appears to be the most reliable instrument for evaluating lung mechanics in individuals with DS.  相似文献   
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The in vitro activities of povidone iodine, potassium peroxymonosulfate, and dimethyldidecylammonium chloride were investigated against 379 nosocomial isolates of Staphylococcus aureus and Pseudomonas aeruginosa responsible for surgical wound infections in patients operated on between July 1995 and June 2001. Overall, the isolates were inhibited by the antiseptics at concentrations below those used routinely. In spite of increasing resistance to the various antibiotics used to treat surgical wound infections, no significant variation in the susceptibility to antiseptics was demonstrated during this 6-year study. Electronic Publication  相似文献   
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