Summary and recommendations of a National Cancer Institute workshop on issues limiting the clinical use of Monte Carlo dose calculation algorithms for megavoltage external beam radiation therapy

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135029/1/mp6990.pd

A dose‐gradient analysis tool for IMRT QA

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135372/1/acm20062.pd

Lexicographic ordering: intuitive multicriteria optimization for IMRT

Optimization problems in IMRT inverse planning are inherently multicriterial since they involve multiple planning goals for targets and their neighbouring critical tissue structures. Clinical decisions are generally required, based on tradeoffs among these goals. Since the tradeoffs cannot be quantitatively determined prior to optimization, the decision-making process is usually indirect and iterative, requiring many repetitive optimizations. This situation becomes even more challenging for cases with a large number of planning goals. To address this challenge, a multicriteria optimization strategy called lexicographic ordering (LO) has been implemented and evaluated for IMRT planning. The LO approach is a hierarchical method in which the planning goals are categorized into different priority levels and a sequence of sub-optimization problems is solved in order of priority. This prioritization concept is demonstrated using two clinical cases (a simple prostate case and a relatively complex head and neck case). In addition, a unique feature of LO in a decision support role is discussed. We demonstrate that a comprehensive list of planning goals (e.g., ∼23 for the head and neck case) can be optimized using only a few priority levels. Tradeoffs between different levels have been successfully prohibited using the LO method, making the large size problem representations simpler and more manageable. Optimization time needed for each level was practical, ranging from ∼26 s to ∼217 s. Using prioritization, the LO approach mimics the mental process often used by physicians as they make decisions handling the various conflicting planning goals. This method produces encouraging results for difficult IMRT planning cases in a highly intuitive manner.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58100/2/pmb7_7_006.pd

Dosimetric comparison of extended dose range film with ionization measurements in water and lung equivalent heterogeneous media exposed to megavoltage photons

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135483/1/acm20025.pd

Characteristics of scattered electron beams shaped with a multileaf collimator

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134775/1/mp8046.pd

Calibration and quality assurance for rounded leaf‐end MLC systems

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134970/1/mp3517.pd

Enhanced spectral discrimination through the exploitation of interface effects in photon dose data

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134954/1/mp7731.pd

The Antarctic Ozone Hole: An Update

The stratospheric ozone hole, an annual occurrence during austral spring, is caused by heterogeneous conversion of hydrogen chloride and chlorine nitrate to chlorine radicals. These reactions take place of polar stratospheric cloud particles in the cold, isolate Antarctic winter vortex. The chlorine radicals participate in chemical reactions that rapidly deplete ozone when sunlight returns at the end of polar night. International agreements eliminated production of the culprit anthropogenic chlorofluorocarbons in the late 1990s, but due to their long stratospheric lifetime (50-100 years), the ozone hole will continue its annual appearance for years to come

An Active Matrix Flat Panel Dosimeter (AMFPD) for inâ phantom dosimetric measurements

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135086/1/mp5012.pd