This investigation focused on the clinical implications of the use of the Collapsed Cone Convolution algorithm (CCC) in breast radiotherapy and investigated the dosimetric differences as respect to Pencil Beam Convolution algorithm (PBC).
Material and methods
15 breast treatment plans produced using the PBC algorithm were re-calculated using the CCC algorithm with the same MUs. In a second step, plans were re-optimized using CCC algorithm with modification of wedges and beam weightings to achieve optimal coverage (CCCr plans). For each patient, dosimetric comparison was performed using the standard tangential technique (SWT) and a forward-planned IMRT technique (f-IMRT).
The CCC algorithm showed significant increased dose inhomogeneity. Mean and minimum PTV doses decreased by 1.4% and 2.8% (both techniques). Mean V95% decreased to 83.7% and 90.3%, respectively for the SWT and f-IMRT. V95% was correlated to the ratio of PTV and lung volumes into the treatment field. The re-optimized CCCr plans achieved similar target coverage, but high-dose volume was significantly larger (V107%: 7.6% vs 2.3% (SWT), 7.1% vs 2.1% (f-IMRT). There was a significantly increase in the ipsilateral lung volume receiving low doses (V5 Gy: 31.3% vs 26.2% in SWT, 27.0% vs 23.0% in f-IMRT). MUs needed for PTV coverage in CCCr plans were higher by 3%.
The PBC algorithm overestimated PTV coverage in terms of all important dosimetric metrics. If previous clinical experience are based on the use of PBC model, especially needed is discussion between medical physicists and radiation oncologists to fully understand the dosimetric changes.
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- Tissue inhomogeneity corrections for megavoltage photon beams.(AAPM report no 85 Task Group 65 of the Radiation Therapy Committee of the American Association of Physicists in Medicine) Medical Physics Publishing, Madison, WI2004
- Boosting runtime-performance of photon pencil beam algorithms for radiotherapy treatment planning.Phys Med. 2012; 28: 273-280
- Limitations of a pencil beam approach to photon dose calculations in lung tissue.Phys Med Biol. 1995; 40: 1411-1420
- Experimental evaluation of interface doses in the presence of air cavities compared with treatment planning algorithms.Med Phys. 1999; 26: 350-355
- Dosimetric verification of a commercial collapsed cone algorithm in simulated clinical situations.Radiother Oncol. 2004; 73: 79-88
- The effect of different lung densities on the accuracy of various radiotherapy dose calculation methods: implications for tumor coverage.Radiother Oncol. 2009; 91: 405-414
- Comparison of dose calculation algorithms in phantoms with lung equivalent heterogeneities under conditions of lateral electronic disequilibrium.Med Phys. 2004; 31: 2899-2911
- The impact of photon dose calculation algorithms on expected dose distributions in lungs under different respiratory phases.Phys Med Biol. 2008; 53: 2375-2390
- Dosimetry of oblique tangential photon beams calculated by superposition/convolution algorithms: a Monte Carlo evaluation.J Appl Clin Med Phys. 2011; 12: 108-121
- Comparison of dose calculation algorithms for treatment planning in external photon beam therapy for clinical situations.Phys Med Biol. 2006; 51: 5785-5807
- Clinical implications of the implementation of advanced treatment planning algorithms for thoracic treatments.Radiother Oncol. 2008; 86: 48-54
- The implementation of an advanced treatment planning algorithm in the treatment of lung cancer with conventional radiotherapy.Clin Oncol. 2009; 21: 168-174
- Comparison of different breast planning techniques and algorithms for radiation therapy treatment.Phys Med. 2014; 30: 160-170
- Comparison of 3D conformal breast radiation treatment plans using the anisotropic analytical algorithm and pencil beam convolution algorithm.Radiother Oncol. 2012; 103: 172-177
- International commission on radiation units and measurements (ICRU) report 62. Prescribing, recording and reporting photon beam therapy (supplement to ICRU report 50). ICRU Publications, Bethesda (MD)1999
- Phase I-II studies on accelerated IMRT in breast carcinoma: technical comparison and acute toxicity in 332 patients.Radiother Oncol. 2009; 90: 86-92
- Simplified field-in-field technique for a large-scale implementation in breast radiation treatment.Med Dosw. 2012; 37: 131-137
- Forward planned intensity modulated radiotherapy (IMRT) for whole breast postoperative radiotherapy. Is it useful? When?.J Appl Clin Med Phys. 2011; 12: 213-219
- Generation of photon energy deposition kernels using the EGS Monte Carlo code.Phys Med Biol. 1988; 33: 1-20
- A pencil beam model for photon dose calculation.Med Phys. 1992; 19: 263-273
- Collapsed cone convolution of radiant energy for photon dose calculation in heterogeneous media.Med Phys. 1989; 16: 577-592
- ROC curves and evaluation of radiation-induced pulmonary toxicity in breast cancer.Int J Radiat Oncol Biol Phys. 2006; 64: 765-770
- Three-dimensional distribution of radiation within the breast: an intercomparison of departments participating in the START trial of breast radiotherapy fractionation.Int J Radiat Oncol Biol Phys. 2003; 55: 271-279
- Photon dose calculation of a three-dimensional treatment planning system compared to the Monte Carlo code BEAM.Med Phys. 2000; 27: 1579-1587
- Verification of the accuracy of 3D calculations of breast dose during tangential irradiation: measurements in a breast phantom.J Appl Clin Med Phys. 2001; 2: 149-156
- Influence of calculation model on dose distribution in stereotactic radiotherapy for pulmonary targets.Int J Radiat Oncol Biol Phys. 2005; 61: 239-249
- The effect of planning algorithms in esophageal radiotherapy in the context of the SCOPE 1 trial.Radiother Oncol. 2009; 93: 462-467
- Transition from a simple to a more advanced dose calculation algorithm for radiotherapy of non-small cell lung cancer (NSCLC): implications for clinical implementation in an individualized dose-escalation protocol.Radiother Oncol. 2008; 88: 326-334
- The clinical implications of the collapsed cone planning algorithm.Clin Oncol. 2004; 16: 148-154
- Dose calculation for external photon beams in radiotherapy.Phys Med Biol. 1999; 44: 99-155
Published online: February 03, 2014
Accepted: January 11, 2014
Received in revised form: January 9, 2014
Received: September 26, 2013
© 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Inc. All rights reserved.