Inverse planning for IMRT with nonuniform beam profiles using total-variation regularization (TVR)

• Published in: Medical physics (Lancaster) Vol. 38; no. 1; pp. 57 - 66
• Main Authors: Kim, Taeho, Zhu, Lei, Suh, Tae-Suk, Geneser, Sarah, Meng, Bowen, Xing, Lei
• Format: Journal Article
• Language: English
• Published: United States American Association of Physicists in Medicine 01.01.2011
• Subjects: 60 APPLIED LIFE SCIENCES; ALGORITHMS; BEAM PROFILES; biological organs; Cancer; compressed sensing; DOSE RATES; Dose‐volume analysis; DOSIMETRY; Dosimetry/exposure assessment; EFFICIENCY; flattening filter; HEAD; HEALTH HAZARDS; Humans; IMRT; Intensity modulated radiation therapy; inverse planning; Linear accelerators; lung; LUNGS; Male; Medical treatment planning; Multileaf collimators; NECK; NEOPLASMS; Neoplasms - radiotherapy; Numerical solutions; OPTIMIZATION; PLANNING; PROSTATE; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; RADIATION PROTECTION AND DOSIMETRY; radiation therapy; Radiation Therapy Physics; Radiation treatment; RADIOLOGY AND NUCLEAR MEDICINE; RADIOTHERAPY; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted - methods; Radiotherapy, Intensity-Modulated - methods; Therapeutic applications, including brachytherapy; total‐variation; VARIATIONS; inverse planning; compressed sensing; IMRT; total-variation; flattening filter
• ISSN: 0094-2405; 2473-4209; 1522-8541; 2473-4209; 0094-2405
• DOI: 10.1118/1.3521465

Purpose: Radiation therapy with high dose rate and flattening filter-free (FFF) beams has the potential advantage of greatly reduced treatment time and out-of-field dose. Current inverse planning algorithms are, however, not customized for beams with nonuniform incident profiles and the resultant IMRT plans are often inefficient in delivery. The authors propose a total-variation regularization (TVR)-based formalism by taking the inherent shapes of incident beam profiles into account. Methods: A novel TVR-based inverse planning formalism is established for IMRT with nonuniform beam profiles. The authors introduce a TVR term into the objective function, which encourages piecewise constant fluence in the nonuniform FFF fluence domain. The proposed algorithm is applied to lung and prostate and head and neck cases and its performance is evaluated by comparing the resulting plans to those obtained using a conventional beamlet-based optimization (BBO). Results: For the prostate case, the authors’ algorithm produces acceptable dose distributions with only 21 segments, while the conventional BBO requires 114 segments. For the lung case and the head and neck case, the proposed method generates similar coverage of target volume and sparing of the organs-at-risk as compared to BBO, but with a markedly reduced segment number. Conclusions: TVR-based optimization in nonflat beam domain provides an effective way to maximally leverage the technical capacity of radiation therapy with FFF fields. The technique can generate effective IMRT plans with improved dose delivery efficiency without significant deterioration of the dose distribution.