{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2023,9,17]],"date-time":"2023-09-17T06:43:23Z","timestamp":1694933003603},"reference-count":19,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2015,3,19]],"date-time":"2015-03-19T00:00:00Z","timestamp":1426723200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/3.0\/"},{"start":{"date-parts":[[2015,9,1]],"date-time":"2015-09-01T00:00:00Z","timestamp":1441065600000},"content-version":"tdm","delay-in-days":166,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["aip.org"],"crossmark-restriction":true},"short-container-title":["Medical Physics"],"published-print":{"date-parts":[[2015,4]]},"abstract":"<jats:sec><jats:title>Purpose:<\/jats:title><jats:p>Fluence field modulated CT (FFMCT) and volume of interest (VOI) CT imaging applications require adjustment of the profile of the x\u2010ray fluence incident on a patient as a function of view angle. Since current FFMCT prototypes can theoretically take on an infinite number of configurations, measuring a calibration data set for all possible positions would not be feasible. The present work details a methodology for calculating an atlas of configurations that will span all likely body regions, patient sizes, patient positioning, and imaging modes. The hypothesis is that there exists a finite number of unique modulator configurations that effectively span the infinite number of possible fluence profiles with minimal loss in performance.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods:<\/jats:title><jats:p>CT images of a head, shoulder, thorax, abdominal, wrist, and leg anatomical slices were dilated and contracted to model small, medium, and large sized patients. Additionally, the images were positioned from iso\u2010center by three different amounts. The modulator configurations required to compensate for each image were computed assuming a FFMCT prototype, digital beam attenuator, (DBA), was set to equalize the detector exposure. Each atlas configuration should be different from the other atlas configurations. The degree of difference was quantified using the sum of the absolute differences in filter thickness between configurations. Using this metric, a set of unique wedge configurations for which no two configurations have a metric value smaller than some threshold can be constructed. Differences in the total number of incident photons between the unconstrained filters and the atlas were studied as a function of the number of atlas positions for each anatomical site and size\/off\u2010centering combination.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results:<\/jats:title><jats:p>By varying the threshold used in creating the atlas, it was found that roughly 322 atlas positions provided an incident number of photons within 20% of using 19\u2009440 unique filters (the number of atlas entries ranged from 7213 to 1). Additionally, for VOI applications implemented with a single VOI region, the number of required filter configurations was expressed in a simple closed form solution.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions:<\/jats:title><jats:p>The methodology proposed in this work will enable DBA\u2010FFMCT and DBA\u2010VOI imaging in the clinic without the need for patient specific air\u2010scans to be performed. In addition, the methodology proposed here is directly applicable to other modulator designs such as piecewise linear, TomoTherapy multi leaf collimators, 2D fluid arrays, and inverse geometry CT.<\/jats:p><\/jats:sec>","DOI":"10.1118\/1.4915123","type":"journal-article","created":{"date-parts":[[2015,3,20]],"date-time":"2015-03-20T14:09:23Z","timestamp":1426860563000},"page":"1779-1786","update-policy":"http:\/\/dx.doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":3,"title":["Creation of an atlas of filter positions for fluence field modulated CT"],"prefix":"10.1002","volume":"42","author":[{"given":"Timothy P.","family":"Szczykutowicz","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"James","family":"Hermus","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2015,3,19]]},"reference":[{"key":"e_1_2_6_2_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.4773879"},{"key":"e_1_2_6_3_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.4773880"},{"key":"e_1_2_6_4_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031\u20109155\/59\/5\/1305"},{"key":"e_1_2_6_5_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.4789630"},{"key":"e_1_2_6_6_1","doi-asserted-by":"publisher","DOI":"10.1117\/12.2008229"},{"key":"e_1_2_6_7_1","first-page":"101","volume-title":"International Conference on Image Formation in X\u2010ray Computed Tomography","author":"Bartolac S.","year":"2010"},{"key":"e_1_2_6_8_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.3574885"},{"key":"e_1_2_6_9_1","first-page":"119","volume-title":"International Conference on Image Formation in X\u2010ray Computed Tomography","author":"Bartolac S.","year":"2012"},{"key":"e_1_2_6_10_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.3427641"},{"key":"e_1_2_6_11_1","first-page":"3470","volume-title":"IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS\/MIC)","author":"Heuscher D.","year":"2011"},{"key":"e_1_2_6_12_1","first-page":"115","volume-title":"The Second International Conference on Image Formation in X\u2010Ray Computed Tomography","author":"Heuscher D.","year":"2012"},{"key":"e_1_2_6_13_1","article-title":"Ct volume\u2010of\u2010interest (voi) scanning: Determination of radiation reduction outside the voi","author":"Chen L.","year":"2011","journal-title":"RSNA SSK15\u201007"},{"key":"e_1_2_6_14_1","first-page":"279","volume-title":"The Third International Conference on Image Formation in X\u2010Ray Computed Tomography","author":"Oktay M.","year":"2014"},{"key":"e_1_2_6_15_1","article-title":"Fluence field modulated CT on a clinical TomoTherapy radiation therapy machine","author":"Szczykutowicz T.","journal-title":"Proc. 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