Timothy W. Holmes

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Tomotherapy, literally "slice therapy," is a proposal for the delivery of radiation therapy with intensity-modulated strips of radiation. The proposed method employs a linear accelerator, or another radiation-emitting device, which would be mounted on a ring gantry like a CT scanner. The patient would move through the bore of the gantry simultaneously with(More)
PURPOSE Intensity-modulated arc therapy (IMAT) is a method for delivering intensity-modulated radiation therapy (IMRT) using rotational beams. During delivery, the field shape, formed by a multileaf collimator (MLC), changes constantly. The objectives of this study were to (1) clinically implement the IMAT technique, and (2) evaluate the dosimetry in(More)
A commercial three-dimensional (3D) inverse treatment planning system, Corvus (Nomos Corporation, Sewickley, PA), was recently made available. This paper reports our preliminary results and experience with commissioning this system for clinical implementation. This system uses a simulated annealing inverse planning algorithm to calculate intensity-modulated(More)
PURPOSE Intensity-modulated arc therapy (IMAT) is an arc-based approach to intensity-modulated radiotherapy (IMRT) that can be delivered on a conventional linear accelerator using a conventional multileaf collimator. In a previous work, we demonstrated that our arc-sequencing algorithm can produce highly conformal IMAT plans. Through plan comparisons, we(More)
The availability of computerized radiation therapy treatment planning systems that utilize computed tomography (CT) scan data requires testing additional to that routinely needed for non-CT systems. These additional items include dimensioning verification, establishing CT number-to-tissue property conversions, verifying the accuracy of heterogeneity(More)
We recently implemented intensity-modulated arc therapy (IMAT) at our institution. In this study, we evaluate the dosimetric merits of the application of this technique to the treatment of prostate cancer. Each IMAT treatment plan incorporated bilateral overlapping arcs. The dose from each beam segment was computed using the three-dimensional dose model of(More)
The highly integrated adaptive radiation therapy (HI-ART II) helical tomotherapy unit is a new radiotherapy machine designed to achieve highly precise and accurate treatments at all body sites. The precision and accuracy of the HI-ART II is similar to that provided by stereotactic radiosurgery systems, hence the historical distinction between external beam(More)
The EGS4 Monte Carlo radiation transport code was used to systematically study the dose perturbation near planar and cylindrical air cavities in a water medium irradiated by megavoltage x-ray beams. The variables of the problem included x-ray energy, cavity shape and dimension, and depth of the cavity in water. The Monte Carlo code was initially validated(More)
PURPOSE An inverse treatment planning algorithm for tomotherapy is described. METHODS AND MATERIALS The algorithm iteratively computes a set of nonnegative beam intensity profiles that minimizes the least-square residual dose defined in the target and selected normal tissue regions of interest. At each iteration the residual dose distribution is(More)