Dose calculation of dynamic trajectory radiotherapy using Monte Carlo

Purpose

Using volumetric modulated arc therapy (VMAT) delivery technique gantry position, multi-leaf collimator (MLC) as well as dose rate change dynamically during the application. However, additional components can be dynamically altered throughout the dose delivery such as the collimator or the couch. Thus, the degrees of freedom increase allowing almost arbitrary dynamic trajectories for the beam. While the dose delivery of such dynamic trajectories for linear accelerators is technically possible, there is currently no dose calculation and validation tool available. Thus, the aim of this work is to develop a dose calculation and verification tool for dynamic trajectories using Monte Carlo (MC) methods.

The pseudokidney sign in intussusception

Abdominal Radiology -     

Are Nephroenteric Fistulas Only a Surgical Trouble?

Nephroenteric fistulas can be secondary to different etiologies, the most common of which are pyelocolic fistulas. The absence of pathognomonic symptoms and the heterogeneity of presentation can sometimes result in a delay in diagnosis. We report on three cases: a pyelo-duodenal fistula secondary to kidney stones and subsequent pyonephrosis, a pyelocolic fistula due to inveterate ureteral stones with hydropyonephrosis, and a rare case of posttraumatic pyelocolic fistula. All patients were treated with radical nephrectomy and resection of the involved intestinal tract. Fistulas of the kidney with the gastrointestinal tract are complex not only for the surgical treatment, which is mandatory in the majority of cases, but also for clinical and instrumental diagnosis. Severe infection is a major concern due to the admixture of the enteric bacterial flora with the urinary tract. Nephroenteric fistulas require skilled surgical procedures, close control of the septic risk, management of patient''s overall medical condition, and balance between invasive and conservative approach.