Comparison of organ-at-risk sparing and plan robustness for spot-scanning proton therapy and volumetric modulated arc photon therapy in head-and-neck cancer.

PURPOSE Proton radiotherapy for head-and-neck cancer (HNC) aims to improve organ-at-risk (OAR) sparing over photon radiotherapy. However, it may be less robust for setup and range uncertainties. The authors investigated OAR sparing and plan robustness for spot-scanning proton planning techniques and compared these with volumetric modulated arc therapy (VMAT) photon plans. METHODS Ten HNC patients were replanned using two arc VMAT (RapidArc) and spot-scanning proton techniques. OARs to be spared included the contra- and ipsilateral parotid and submandibular glands and individual swallowing muscles. Proton plans were made using Multifield Optimization (MFO, using three, five, and seven fields) and Single-field Optimization (SFO, using three fields). OAR sparing was evaluated using mean dose to composite salivary glands (CompSal) and composite swallowing muscles (CompSwal). Plan robustness was determined for setup and range uncertainties (±3 mm for setup, ±3% HU) evaluating V95% and V107% for clinical target volumes. RESULTS Averaged over all patients CompSal/CompSwal mean doses were lower for the three-field MFO plans (14.6/16.4 Gy) compared to the three-field SFO plans (20.0/23.7 Gy) and VMAT plans (23.0/25.3 Gy). Using more than three fields resulted in differences in OAR sparing of less than 1.5 Gy between plans. SFO plans were significantly more robust than MFO plans. VMAT plans were the most robust. CONCLUSIONS MFO plans had improved OAR sparing but were less robust than SFO and VMAT plans, while SFO plans were more robust than MFO plans but resulted in less OAR sparing. Robustness of the MFO plans did not increase with more fields.

[1]  V Grégoire,et al.  Comparison of setup accuracy of three different thermoplastic masks for the treatment of brain and head and neck tumors. , 2001, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[2]  Daniel W. Miller,et al.  Ion stopping powers and CT numbers. , 2010, Medical dosimetry : official journal of the American Association of Medical Dosimetrists.

[3]  A. Lomax,et al.  Is it necessary to plan with safety margins for actively scanned proton therapy? , 2011, Physics in medicine and biology.

[4]  F. Feng,et al.  Clinical Investigation : Head and Neck Cancer Reducing Xerostomia After Chemo-IMRT for Head-and-Neck Cancer : Beyond Sparing the Parotid Glands , 2012 .

[5]  Max Dahele,et al.  Toward optimal organ at risk sparing in complex volumetric modulated arc therapy: an exponential trade-off with target volume dose homogeneity. , 2014, Medical physics.

[6]  Johannes A Langendijk,et al.  Selection of patients for radiotherapy with protons aiming at reduction of side effects: the model-based approach. , 2013, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[7]  Sairos Safai,et al.  Comparison between the lateral penumbra of a collimated double-scattered beam and uncollimated scanning beam in proton radiotherapy , 2008, Physics in medicine and biology.

[8]  Anders Forsgren,et al.  Minimax optimization for handling range and setup uncertainties in proton therapy. , 2011, Medical physics.

[9]  Johannes A Langendijk,et al.  Using a reduced spot size for intensity-modulated proton therapy potentially improves salivary gland-sparing in oropharyngeal cancer. , 2012, International journal of radiation oncology, biology, physics.

[10]  E Pedroni,et al.  Experimental characterization and physical modelling of the dose distribution of scanned proton pencil beams , 2005, Physics in medicine and biology.

[11]  U Oelfke,et al.  Worst case optimization: a method to account for uncertainties in the optimization of intensity modulated proton therapy , 2008, Physics in medicine and biology.

[12]  B. Slotman,et al.  Increasing the number of arcs improves head and neck volumetric modulated arc therapy plans , 2015, Acta oncologica.

[13]  Alessandra Bolsi,et al.  Treatment planning and verification of proton therapy using spot scanning: initial experiences. , 2004, Medical physics.

[14]  Radhe Mohan,et al.  Robust optimization of intensity modulated proton therapy. , 2012, Medical physics.

[15]  A. Lomax,et al.  Intensity modulated proton therapy and its sensitivity to treatment uncertainties 1: the potential effects of calculational uncertainties , 2008, Physics in medicine and biology.

[16]  Wei Liu,et al.  Preliminary evaluation of multifield and single-field optimization for the treatment planning of spot-scanning proton therapy of head and neck cancer. , 2013, Medical physics.

[17]  S. Senan,et al.  RapidArc planning and delivery in patients with locally advanced head-and-neck cancer undergoing chemoradiotherapy. , 2011, International journal of radiation oncology, biology, physics.

[18]  Martin Stuschke,et al.  Multi-scenario based robust intensity-modulated proton therapy (IMPT) plans can account for set-up errors more effectively in terms of normal tissue sparing than planning target volume (PTV) based intensity-modulated photon plans in the head and neck region , 2013, Radiation oncology.

[19]  Arjen van der Schaaf,et al.  The potential of intensity-modulated proton radiotherapy to reduce swallowing dysfunction in the treatment of head and neck cancer: A planning comparative study , 2013, Acta oncologica.

[20]  D. Rietveld,et al.  Sparing the contralateral submandibular gland without compromising PTV coverage by using volumetric modulated arc therapy , 2011, Radiation oncology.

[21]  Prakash Chinnaiyan,et al.  The impact of daily setup variations on head-and-neck intensity-modulated radiation therapy. , 2005, International journal of radiation oncology, biology, physics.

[22]  Thomas Bortfeld,et al.  Reducing the sensitivity of IMPT treatment plans to setup errors and range uncertainties via probabilistic treatment planning. , 2008, Medical physics.

[23]  R. Mohan,et al.  Adjustment of the lateral and longitudinal size of scanned proton beam spots using a pre-absorber to optimize penumbrae and delivery efficiency , 2010, Physics in medicine and biology.

[24]  Johannes A Langendijk,et al.  Predictive modelling for swallowing dysfunction after primary (chemo)radiation: results of a prospective observational study. , 2012, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[25]  Uwe Schneider,et al.  Intensity modulated photon and proton therapy for the treatment of head and neck tumors. , 2006, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[26]  Hanne M Kooy,et al.  Dose uncertainties in IMPT for oropharyngeal cancer in the presence of anatomical, range, and setup errors. , 2013, International journal of radiation oncology, biology, physics.

[27]  Steven J Frank,et al.  PTV-based IMPT optimization incorporating planning risk volumes vs robust optimization. , 2013, Medical physics.

[28]  Steven J Frank,et al.  Spot-scanning beam proton therapy vs intensity-modulated radiation therapy for ipsilateral head and neck malignancies: a treatment planning comparison. , 2013, Medical dosimetry : official journal of the American Association of Medical Dosimetrists.

[29]  Holly Ning,et al.  Comparison of intensity-modulated radiotherapy, adaptive radiotherapy, proton radiotherapy, and adaptive proton radiotherapy for treatment of locally advanced head and neck cancer. , 2011, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[30]  Joseph O Deasy,et al.  Radiotherapy dose-volume effects on salivary gland function. , 2010, International journal of radiation oncology, biology, physics.

[31]  Suresh Senan,et al.  Volumetric intensity-modulated arc therapy vs. conventional IMRT in head-and-neck cancer: a comparative planning and dosimetric study. , 2009, International journal of radiation oncology, biology, physics.

[32]  Johannes A Langendijk,et al.  Potential benefits of scanned intensity-modulated proton therapy versus advanced photon therapy with regard to sparing of the salivary glands in oropharyngeal cancer. , 2011, International journal of radiation oncology, biology, physics.

[33]  A J Lomax,et al.  Intensity modulated proton therapy and its sensitivity to treatment uncertainties 2: the potential effects of inter-fraction and inter-field motions , 2008, Physics in medicine and biology.

[34]  R. Steenbakkers,et al.  Swallowing-sparing intensity-modulated radiotherapy for head and neck cancer patients: treatment planning optimization and clinical introduction. , 2013, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[35]  U Oelfke,et al.  Simulation and visualization of dose uncertainties due to interfractional organ motion. , 2006, Physics in medicine and biology.

[36]  Albin Fredriksson,et al.  A characterization of robust radiation therapy treatment planning methods-from expected value to worst case optimization. , 2012, Medical physics.

[37]  Lei Dong,et al.  A beam-specific planning target volume (PTV) design for proton therapy to account for setup and range uncertainties. , 2012, International journal of radiation oncology, biology, physics.

[38]  Radhe Mohan,et al.  Effectiveness of robust optimization in intensity-modulated proton therapy planning for head and neck cancers. , 2013, Medical physics.

[39]  A J Lomax,et al.  Treatment planning optimisation in proton therapy. , 2013, The British journal of radiology.