Background: Pancreatic abscess is one of the serious complications of acute pancreatitis. Traditionally, pancreatic abscess has been treated by operative drainage. Based on experience with endoscopic ...transpapillary drainage of pseudocysts, a similar technique was used in patients with pancreatic abscess.
Method: Patients were evaluated by endoscopic retrograde cholangiopancreatography. In those with pancreatic abscess communicating with the main pancreatic duct, pancreatic sphincterotomy, saline irrigation of the abscess cavity, and catheter dilation followed by 10F pancreatic stent placement were done. Instillation of gentamicin and nasopancreatic catheter drainage were used in difficult cases.
Results: Of 22 patients with pancreatic abscess, 11 underwent endoscopic transpapillary drainage with technical success in 10 patients (90%); 8 patients (74%) had resolution of pancreatic abscess, clinically and radiographically. Intracavitary instillation of gentamicin and nasopancreatic catheter drainage were used in 2 patients. Two patients in whom endoscopic transpapillary drainage failed underwent operative drainage with a favorable outcome, and the one patient in whom endoscopic treatment was technically unsuccessful underwent successful percutaneous drainage. One patient had mild pancreatitis.
Conclusion: Endoscopic transpapillary drainage is an effective nonoperative therapy for selected cases of pancreatic abscess and is associated with minimal morbidity and no mortality. (Gastrointest Endosc 2000;51:391-5.)
Purpose:
Flattening filter free (FFF) beams produce higher dose rates. Combined with compensator IMRT techniques, the dose delivery for each beam can be much shorter compared to the flattened beam ...MLC-based or compensator-based IMRT. This ‘snap shot’ IMRT delivery is beneficial to patients for tumor motion management. Due to softer energy, surface doses in FFF beam treatment are usually higher than those from flattened beams. Because of less scattering due to no flattening filter, peripheral doses are usually lower in FFF beam treatment. However, in compensator-based IMRT using FFF beams, the compensator is in the beam pathway. Does it introduce beam hardening effects and scattering such that the surface dose is lower and peripheral dose is higher compared to FFF beam MLC-based IMRT?
Methods:
This study applied Monte Carlo techniques to investigate the surface and peripheral doses in compensator-based IMRT using FFF beams and compared it to the MLC-based IMRT using FFF beams and flattened beams. Besides various thicknesses of copper slabs to simulate various thicknesses of compensators, a simple cone-shaped compensator was simulated to mimic a clinical application. The dose distribution in water phantom by the cone-shaped compensator was then simulated by multiple MLC defined FFF and flattened beams with various openings. After normalized to Dmax, the surface and peripheral dose was compared between the FFF beam compensator-based IMRT and FFF/flattened beam MLC-based IMRT.
Results:
The surface dose at the central 0.5mm depth was close between the compensator and 6FFF MLC dose distributions, and about 8% (of Dmax) higher than the flattened 6MV MLC dose. At 8cm off axis at dmax, the peripheral dose between the 6FFF and flattened 6MV MLC demonstrated similar doses, while the compensator dose was about 1% higher.
Conclusion:
Compensator does not reduce the surface doses but slightly increases the peripheral doses due to scatter inside compensator.
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