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  • On the sensitivity of IMRT dose optimization to the mathematical form of a biologcal imaging-based prescription function
    Bowen, S. ...
    Voxel-based prescriptions of deliberately non-uniform dose distributions basedon molecular imaging, so-called dose painting or theragnostic radiation therapy, require specification of a ... transformation that maps the image data intensities to prescribed doses. However, the functional form of this transformation is currently unknown. An investigation into the sensitivity of optimized dose distributions resulting from several possible prescription functions was conducted. Transformations between the radiotracer activity concentrations from Cu-ATSM PET images, as a surrogate of tumour hypoxia, and dose prescriptions were implemented to yield weighted distributions of prescribed dose boosts in high uptake regions. Dose escalation was constrainedto reflect clinically realistic whole tumour doses and constant normal tissue doses. Optimized heterogeneous dose distributions were found by minimizing a voxel-by-voxel quadratic objective function in which all tumour voxels were given equal weight. Prescriptions based on a polynomial mapping function were found to be least constraining on their optimized plans, while prescriptions based on a sigmoid mapping function were the most demanding to deliver. A prescription formalism that fixed integral dose was less sensitive to errors in the choice of the mapping function than one that boosted integraldose. Integral doses to normal tissue and critical structures were insensitive to the shape of the prescription function. Planned target dose conformity improved with smaller beamlet dimensions until the inherent spatialresolution of the functional image was matched. Clinical implementationof dose painting depends on advances in absolute quantification of functional images and improvements in delivery techniques over smaller spatial scales.
    Source: Physics in Medicine & Biology. - ISSN 0031-9155 (No. 6, Vol. 54, 2009, str. 1483-1501)
    Type of material - article, component part
    Publish date - 2009
    Language - english
    COBISS.SI-ID - 22936103

source: Physics in Medicine & Biology. - ISSN 0031-9155 (No. 6, Vol. 54, 2009, str. 1483-1501)
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