An on-line replanning scheme for interfractional variationsa).

Ability of online adaptive replanning is desirable to correct for interfraction anatomic changes. A full-scope replanning/reoptimization with the current planning techniques takes too long to be practical. A novel online replanning strategy to correct for interfraction anatomic changes in real time is presented. The scheme consists of three steps: (1) rapidly delineating targets and organs at risk on the computed tomography of the day by modifying original planning contours using robust tools in a semiautomatic manner, (2) online segment aperture morphing (SAM) (adjusting beam/segment apertures) by applying the spatial relationship between the planning target contour and the apertures to the new target contour, and (3) performing segment weight optimization (SWO) for the new apertures if necessary. The entire scheme was tested for direct-aperture-based IMRT on representative prostate and abdomen cases. Dose volume histograms obtained with the online scheme are practically equivalent to those obtained with full-scope reoptimization. For the days of small to moderate organ deformations, only the SAM is necessary, while for the large deformation days, both SAM and SWO are required to adequately account for the deformation. Both the SAM and SWO programs can be completed within 1 min, and the overall process can be completed within 10 min. The proposed SAM-SWO scheme is practically comparable to full-scope reoptimization, but is fast enough to be implemented for on-line adaptive replanning, enabling dose-guided RT.

[1]  Raj Shekhar,et al.  Direct aperture deformation: an interfraction image guidance strategy. , 2006, Medical physics.

[2]  R. Cormack,et al.  Automatic online adaptive radiation therapy techniques for targets with significant shape change: a feasibility study , 2006, Physics in medicine and biology.

[3]  Qiuwen Wu,et al.  Geometric and dosimetric evaluations of an online image-guidance strategy for 3D-CRT of prostate cancer. , 2006, International journal of radiation oncology, biology, physics.

[4]  V. Khoo,et al.  X-ray volumetric imaging in image-guided radiotherapy: the new standard in on-treatment imaging. , 2006, International journal of radiation oncology, biology, physics.

[5]  C. Yu,et al.  An examination of the number of required apertures for step-and-shoot IMRT , 2005, Physics in medicine and biology.

[6]  Geoffrey D. Hugo,et al.  Evaluation of 4D Image-Guided Planning and Treatment Techniques for Lung Cancer: Potential of Daily Online Correction , 2005 .

[7]  Fang-Fang Yin,et al.  A technique for on-board CT reconstruction using both kilovoltage and megavoltage beam projections for 3D treatment verification. , 2005, Medical physics.

[8]  Jake Van Dyk,et al.  Image-guided adaptive radiation therapy (IGART): Radiobiological and dose escalation considerations for localized carcinoma of the prostate. , 2005, Medical physics.

[9]  D. Yan,et al.  Computed tomography guided management of interfractional patient variation. , 2005, Seminars in radiation oncology.

[10]  M. Oldham,et al.  Cone-beam-CT guided radiation therapy: technical implementation. , 2005, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[11]  Mark Oldham,et al.  Cone-beam-CT guided radiation therapy: A model for on-line application. , 2005, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[12]  Robert Jeraj,et al.  A novel method to correct for pitch and yaw patient setup errors in helical tomotherapy. , 2005, Medical physics.

[13]  He Wang,et al.  An automatic CT-guided adaptive radiation therapy technique by online modification of multileaf collimator leaf positions for prostate cancer. , 2005, International journal of radiation oncology, biology, physics.

[14]  Benedick A Fraass,et al.  Improving IMRT delivery efficiency using intensity limits during inverse planning. , 2005, Medical physics.

[15]  S Webb,et al.  The effect on IMRT conformality of elastic tissue movement and a practical suggestion for movement compensation via the modified dynamic multileaf collimator (dMLC) technique , 2005, Physics in medicine and biology.

[16]  He Wang,et al.  Use of deformed intensity distributions for on-line modification of image-guided IMRT to account for interfractional anatomic changes. , 2005, International journal of radiation oncology, biology, physics.

[17]  John Wong,et al.  Assessment of residual error for online cone-beam CT-guided treatment of prostate cancer patients. , 2004, International journal of radiation oncology, biology, physics.

[18]  Margrit Betke,et al.  The correlation between internal and external markers for abdominal tumors: implications for respiratory gating. , 2003, International journal of radiation oncology, biology, physics.

[19]  Marcel van Herk,et al.  Quantification of shape variation of prostate and seminal vesicles during external beam radiotherapy. , 2005, International journal of radiation oncology, biology, physics.

[20]  David Jaffray,et al.  Online image-guided intensity-modulated radiotherapy for prostate cancer: How much improvement can we expect? A theoretical assessment of clinical benefits and potential dose escalation by improving precision and accuracy of radiation delivery. , 2004, International journal of radiation oncology, biology, physics.

[21]  H. Rehbinder,et al.  Adaptive radiation therapy for compensation of errors in patient setup and treatment delivery. , 2004, Medical physics.

[22]  Stanley J. Rosenthal,et al.  Moving targets: detection and tracking of internal organ motion for treatment planning and patient set-up. , 2004, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[23]  Wolfgang A Tomé,et al.  The impact of daily shifts on prostate IMRT dose distributions. , 2004, Medical physics.

[24]  Fang-Fang Yin,et al.  Image-Guided Radiosurgery of Head and Neck Cancers , 2004, Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery.

[25]  Weiguo Lu,et al.  Fast treatment plan modification with an over-relaxed Cimmino algorithm. , 2004, Medical physics.

[26]  Martin J Murphy,et al.  Tracking moving organs in real time. , 2004, Seminars in radiation oncology.

[27]  Cedric X. Yu,et al.  Supine vs. prone setup for prostate radiotherapy: a prospectively randomized study to assess dosimetric variability , 2003 .

[28]  F Nüsslin,et al.  Adapting inverse planning to patient and organ geometrical variation: algorithm and implementation. , 2003, Medical physics.

[29]  Radhe Mohan,et al.  Evaluation of mechanical precision and alignment uncertainties for an integrated CT/LINAC system. , 2003, Medical physics.

[30]  R. Jeraj,et al.  Re-optimization in adaptive radiotherapy. , 2002, Physics in medicine and biology.

[31]  J. Wong,et al.  Flat-panel cone-beam computed tomography for image-guided radiation therapy. , 2002, International journal of radiation oncology, biology, physics.

[32]  D M Shepard,et al.  Direct aperture optimization: a turnkey solution for step-and-shoot IMRT. , 2002, Medical physics.

[33]  D Yan,et al.  An off-line strategy for constructing a patient-specific planning target volume in adaptive treatment process for prostate cancer. , 2000, International journal of radiation oncology, biology, physics.

[34]  J C Chu,et al.  Applications of simulator computed tomography number for photon dose calculations during radiotherapy treatment planning. , 2000, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[35]  T. Mackie,et al.  Delivery Modification as an Alternative to Patient Repositioning in Tomotherapy , 2000 .

[36]  Daniel Rueckert,et al.  Nonrigid registration using free-form deformations: application to breast MR images , 1999, IEEE Transactions on Medical Imaging.

[37]  Jean-Philippe Thirion,et al.  Non-rigid matching using demons , 1996, Proceedings CVPR IEEE Computer Society Conference on Computer Vision and Pattern Recognition.

[38]  K Lam,et al.  Measurement of prostate movement over the course of routine radiotherapy using implanted markers. , 1995, International journal of radiation oncology, biology, physics.

[39]  K. Schittkowski NLPQL: A fortran subroutine solving constrained nonlinear programming problems , 1986 .

[40]  Shih-Ping Han A globally convergent method for nonlinear programming , 1975 .