Direct Segment Aperture and Weight Optimization for Intensity-Modulated Radiotherapy of Prostate Cancer

Abstract

SOWAT is a powerful planning tool to increase the therapeutic ratio of IMRT for prostate cancer. It leaves the delivery time unchanged, so that treatments can still be delivered within a time slot of 8 min.

The Incidence of Inclusion of the Sigmoid Colon and Small Bowel in the Planning Target Volume in Radiotherapy for Prostate Cancer

“…Plan optimization was done using a biophysical objective function [7][8][9]33]. All patients were planned to a mean CTV dose of at least 76 Gy.…”

“…When dose escalation is performed with conventional irradiation techniques, a rise in genitourinary and gastrointestinal toxicity is observed [2]. Therefore, new radiotherapy techniques have been developed [3,7,8,22,24,25,36]. Both conformal and intensity-modulated radiotherapy (IMRT) increase the radiation dose to the prostate and seminal vesicles while reducing the volume of normal surrounding tissue irradiated at high doses.…”

Intensity-Modulated Radiation Therapy (IMRT) with Different Combinations of Treatment-Planning Systems and Linacs

“…With the introduction of intensity-modulated radiation therapy (IMRT) a better conformation of the dose to non-convex targets became available. Thus, it is possible to escalate the dose to the target while keeping the dose to the OARs within tolerable limits [2,5,8,10,11,14].…”

Inverse Planning – a Comparative Intersystem and Interpatient Constraint Study

“…It is generally accepted that the trialand-error process typical of conformal planning has shifted inverse planning (IP) to an iterative adjustment of prescription, weights and penalties to obtain the desired dose distribution. Various IP systems are now commercially available, applying quadratic dose-based objective functions, anatomy-based segmentation and segment weighting [8,14,19], or the dynamic penalized likelihood method [16].…”

“…It is generally accepted that the trialand-error process typical of conformal planning has shifted inverse planning (IP) to an iterative adjustment of prescription, weights and penalties to obtain the desired dose distribution. Various IP systems are now commercially available, applying quadratic dose-based objective functions, anatomy-based segmentation and segment weighting [8,14,19], or the dynamic penalized likelihood method [16].The determination of prescription parameters of an objective function is a key issue in IP. If a constraint set has been determined for an individual patient, it is not obvious to which extent it holds for an IMRT class solution and whether it is specific to a treatment-planning system (TPS).…”