A Novel 2D Probability Density Function Integrating the Rectal Motion and Wall Thickness in Prostate IMRT.

Background And Purpose: This study investigated the variations of rectal motion and wall thickness in prostate intensity-modulated radiotherapy using a novel 2D probability density function. To evaluate the impact of the position, thickness, and deformation of the rectum on the dose distribution in prostate intensity-modulated radiotherapy plans, probability density functions (pdf) of the deformation of rectal cross-section (D), rectal dose distribution (R), and changes in rectal wall thickness (T) were used in the planning optimization.

Materials And Methods: The problem of approximating the product of a number of Gaussian mixture distributions arises in the number of parameters describing the specific mean value, standard deviation, and weight in every Gaussian.

Leakage-Penumbra effect in intensity modulated radiation therapy step-and-shoot dose delivery.

Aim: To study the leakage-penumbra (LP) effect with a proposed correction method for the step-and-shoot intensity modulated radiation therapy (IMRT).

Methods: Leakage-penumbra dose profiles from 10 randomly selected prostate IMRT plans were studied. The IMRT plans were delivered by a Varian 21 EX linear accelerator equipped with a 120-leaf multileaf collimator (MLC).

Surgical treatment of benign diseases of the gastroesophageal junction in clinic of endoscopic surgery at MMA during the period 2005-2012: pathophysiology, surgical techniques and trends of their use.

Unlabelled: Treatment of the diseases of the gastroesophageal junction is one of the serious problems faced by gastroenteorologist and surgeons. In contrast to the proton pump inhibitors (PPI) surgery achieves a long symptoms free period. Laparoscopic surgery has its advantages as an alternative to conventional surgery.

Laparoscopic vs open resection for rectal carcinoma--a prospective analysis.

Unlabelled: In the recent years, laparoscopic surgery has established itself worldwide as a method of treatment for colorectal cancer. Several prospective randomized trials comparing laparoscopic with open resection of the colon, showing the advantages of laparoscopic surgery in terms of a shorter hospital stay, faster recovery of intestinal transit and physical activity in equivalent survival and recurrence rate. However, in many of the studies the data on laparoscopic resection for rectal cancer are scarce and it is still controversial.

Poster - Thur Eve - 22: Bone heterogeneity in kV x-ray radiotherapy.

This study evaluated the dosimetric impact of bone heterogeneity on the surface dose and dose prescription, when dose is assumed to be prescribed on a homogeneous medium in kV x-ray radiotherapy. A heterogeneous phantom containing a thin water layer (thickness = 1-5 mm) over a bone (thickness =1 cm) was used to mimic treatment sites of forehead, knee and chest wall. The phantom was irradiated by a 220 kVp photon beam with field size of 5 cm diameter.