Entropy as a quality descriptor for the dose distribution - theory and practice for the patient target volume
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The most common and established way to evaluate the quality of a radiotherapy plan is to use the dose-volume histogram (DVH). The evaluation of the DVH, however, is a subjective procedure. This may not be crucial as long as the two plans are significantly different. In the case of several plans obtained with different planning or optimisation strategies the differences are often subtle and therefore a more objective comparison method is desirable. A commonly used approach is based on evaluation of the conformity index, however we show how it can fail for plans of similar quality.Therefore we propose a new method based on the similarity of DVH to statistical distributions, which can be characterised uniquely by their entropy. The concept is defined separately for target volumes, where it is derived from the Fermi-like distribution, and for organs at risk, where the traditional approach is also considered in its derivation. The artificial illustratory and clinical examples show the properties of the entropy as the quality descriptor and compare it to the conformity index. The examples are focused to the patient target volumes, where the advantage of the concept is more evident.
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- Viggars D A, et al. The objective evaluation of alternative treatment plans III: The quantitative analysis of dose volume histograms. Int J Rad Oncol Biol Phys. 1992; 23: 419-427.[Crossref]
- Goitein M, Niemierko A. Intensity modulated therapy and inhomogeneous dose to the tumour: a note of caution. Int J Rad Oncol Biol Phys. 1996; 36: 519-522.[Crossref]
- Ragazzi G, Cattaneo GM, Fiorino C et al. Use of dose-volume histograms and biophysical models to compare 2D and 3D irradiation techniques for non-small cell lung cancer. Brit J Radiology. 1999; 72: 279-288.
- Niemierko A, Goitein M. Dose-volume distributions: a new approach to dose-volume histograms in three-dimensional treatment planning. Med Phys. 1994; 21(1): 3-11.[PubMed]
- Paddick I. A simple scoring ratio to index the conformity of radiosurgical treatment plans. J Neurosurg. 2000; 93(S3): 219-222.[PubMed]
- Knoos T, Kristensen I, Nilsson P. Volumetric and dosimetric evaluation of radiation treatment plans: Radiation conformity index. Int J Rad Oncol Biol Phys. 1998; 42: 1169-1176.[Crossref]
- ICRU Prescribing, Recording and Reporing Photon Beam Therapy (Supplement to ICRU Report 50). ICRU Report 62, International Commission on Radiation Units and Measurements. 1999.
- van't Riet A, Mak A, Moerland M, Elders L, van der Zee W. A conformation number to quatify the degree of conformality in brachytherapy and external beam irradiation: Application to the prostate. Int J Rad Oncol Biol Phys. 1997; 37: 731-736.
- Drzymala RE. Dose-volume histograms. Int J Rad Oncol Biol Phys. 1991; 21: 71-78.[Crossref]
- Lu Y, Spelbring DR, Chen G. Functional dose-volume histograms for functionally heterogeneous normal organs. Phys Med Biol. 1997; 42: 345-356.[Crossref][PubMed]
- Jani AB, Hand CM, Pelizzari CA, Roeske JC, Krauz L, Vijayakumar S. Biological-effective versus conventional dose volume histograms correlated with late genitourinary and gastrointestinal toxicity after external beam radiotherapy for prostate cancer: a matched pair analysis. BMC Cancer. 2003 May 13; 3: 16.[Crossref]
- Alber M, Nusslin F. Tools for the analysis of dose optimisation: I. Effect-volume histogram. Phys Med Biol. 2002; 47: 2451-2458.[Crossref]
- Fu W, Wang LH, Zhou ZM, Dai JR, Hu YM, Zhao LJ. Comparison of conformal and intensity-modulated techniques for simultaneous integrated boost radiotherapy of upper esophageal carcinoma. World J Gastroenterol. 2004; 10: 1098-1102.[PubMed]
- Gibbons JP. Technical note: The effect of the 4-mm collimator output factor on gamma knife dose distributions. J Applied Clinical Medical Physics. 2003; 4: 386-389.[Crossref]
- Webb S, Nahum AE. A model for calculating tumour control probability in radiotherapy including the effect of inhomogeneous dose distribution and clonoginic cell density. Phys Med Biol. 1993; 38: 653-666.[Crossref][PubMed]
- Wu X, Zhu Y. A maximum-entropy method for the planning of conformal radiotherapy. Med Phys. 2001; 28 (11): 2241-2246.[PubMed][Crossref]
- ICRU Prescribing, Recording and Reporing Photon Beam Therapy. ICRU Report 50, International Commission on Radiation Units and Measurements. 1993.
- Rickhey M, Moravek Z, Bogner L. Inverse treatment planning and integration of segmentation procedures. Z Med Phys. 2008; 18(3): 163-169.[PubMed][WoS][Crossref]
- Bogner L, Hartmann M, et al. Application of an inverse kernel concept to Monte Carlo based IMRT. Med Phys. 2006;33: 4749-4757.[PubMed][Crossref]
- Fippel M Fast Monte Carlo dose calculation for photon beams based on the VMC electron algorithm. Med Phys. 1999;26: 1466-1475.[Crossref][PubMed]
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