Eclipse(TM) Treatment Planning System with Proton Convolution Superposition algorithm license only The Eclipse Treatment Planning System (Eclipse TPS) is used to plan radiotherapy treatments for patients with malignant or benign diseases. Eclipse TPS is used to plan external beam irradiation with photon, elec- tron and proton beams, as well as for internal irradiation (brachytherapy) treatments. In addition, the Eclipse Proton Eye algorithm is specifically indicated for planning proton treatm

There is an anomaly with the Eclipse(TM) Treatment Planning System [TPS] Proton Convolution Superposition [PCS] dose calculation algorithm. The PCS algo- rithm calculates the water equivalent range incorrectly for non-square 3D CT images (either different number of pixels in X and Y, or non-square pixels). Before the dose is calculated, Eclipse resamples the CT images to create a calculation image with a maximum resolution of 256 x 256. The PCS algorithm assumes uniform resolution in X and Y directions, or that X = Y for all images, and erroneously sets the Y = X for dose calcu- lation. For images that are not square, where either X<>Y, or the length of X does not equal the length of Y, the computed water equivalent range R is erroneous compared to the correct range R: 1) X=Y; R =R (R is correct); 2) X<Y: R <R (R is too small) and 3) X>Y R >R (R is too big).

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