Quantifying the effect of intrafraction motion during breast IMRT planning and dose delivery.

Respiratory motion during intensity modulated radiation therapy (IMRT) causes two types of problems. First, the clinical target volume (CTV) to planning target volume (PTV) margin needed to account for respiratory motion means that the lung and heart dose is higher than would occur in the absence of such motion. Second, because respiratory motion is not synchronized with multileaf collimator (MLC) motion, the delivered dose is not the same as the planned dose. The aims of this work were to evaluate these problems to determine (a) the effects of respiratory motion and setup error during breast IMRT treatment planning, (b) the effects of the interplay between respiratory motion and multileaf collimator (MLC) motion during breast IMRT delivery, and (c) the potential benefits of breast IMRT using breath-hold, respiratory gated, and 4D techniques. Seven early stage breast cancer patient data sets were planned for IMRT delivered with a dynamic MLC (DMLC). For each patient case, eight IMRT plans with varying respiratory motion magnitudes and setup errors (and hence CTV to PTV margins) were created. The effects of respiratory motion and setup error on the treatment plan were determined by comparing the eight dose distributions. For each fraction of these plans, the effect of the interplay between respiratory motion and MLC motion during IMRT delivery was simulated by superimposing the respiratory trace on the planned DMLC leaf motion, facilitating comparisons between the planned and expected dose distributions. When considering respiratory motion in the CTV-PTV expansion during breast IMRT planning, our results show that PTV dose heterogeneity increases with respiratory motion. Lung and heart doses also increase with respiratory motion. Due to the interplay between respiratory motion and MLC motion during IMRT delivery, the planned and expected dose distributions differ. This difference increases with respiratory motion. The expected dose varies from fraction to fraction. However, for the seven patients studied and respiratory trace used, for no breathing, shallow breathing, and normal breathing, there were no statistically significant differences between the planned and expected dose distributions. Thus, for breast IMRT, intrafraction motion degrades treatment plans predominantly by the necessary addition of a larger CTV to PTV margin than would be required in the absence of such motion. This motion can be limited by breath-hold, respiratory gated, or 4D techniques.

[1]  Daniel W. Miller,et al.  The Relative Biological Effectiveness of Attenuated Protons , 1993 .

[2]  Qiuwen Wu,et al.  Monte Carlo-based dosimetry of H&N patients treated with SIB-IMRT , 2003 .

[3]  H. Kubo,et al.  Respiration gated radiotherapy treatment: a technical study. , 1996, Physics in medicine and biology.

[4]  R. Mohan,et al.  Motion adaptive x-ray therapy: a feasibility study , 2001, Physics in medicine and biology.

[5]  R Mohan,et al.  Converting absorbed dose to medium to absorbed dose to water for Monte Carlo based photon beam dose calculations , 2000, Physics in medicine and biology.

[6]  E. Larsen,et al.  A method for incorporating organ motion due to breathing into 3D dose calculations. , 1999, Medical physics.

[7]  J. Siebers,et al.  TU‐FF‐A1‐01: An Investigation On the Impact of Incident Fluence Prediction On the Computed Doses , 2005 .

[8]  M. V. van Herk,et al.  Physical aspects of a real-time tumor-tracking system for gated radiotherapy. , 2000, International journal of radiation oncology, biology, physics.

[9]  R. Mohan,et al.  A four-dimensional controller for DMLC-based tumor tracking , 2004 .

[10]  D A Jaffray,et al.  The effects of intra-fraction organ motion on the delivery of dynamic intensity modulation. , 1998, Physics in medicine and biology.

[11]  H. Shirato,et al.  Four-dimensional treatment planning and fluoroscopic real-time tumor tracking radiotherapy for moving tumor. , 2000, International journal of radiation oncology, biology, physics.

[12]  R. Mohan,et al.  Reducing dose calculation time for accurate iterative IMRT planning. , 2002, Medical physics.

[13]  N. Robert,et al.  Factors influencing cosmetic outcome and complication risk after conservative surgery and radiotherapy for early-stage breast carcinoma. , 1992, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[14]  P. Keall,et al.  Adaptive set-up correction (ASC) to account for set-up errors in prostate radiotherapy , 2004 .

[15]  J. Siebers,et al.  Shielding calculations for 230-MeV protons using the LAHET code system , 1996 .

[16]  H. Mostafavi,et al.  Breathing-synchronized radiotherapy program at the University of California Davis Cancer Center. , 2000, Medical physics.

[17]  R. J. Lee,et al.  Comparison of the homogeneity of breast dose distributions with and without the medial wedge. , 1998, Medical dosimetry : official journal of the American Association of Medical Dosimetrists.

[18]  P. Keall,et al.  TU‐FF‐A2‐05: The Dosimetric Stability of the Prostate and Critical Structures in the Presence of Internal Motion for An Adaptive Correction Strategy , 2005 .

[19]  B J Mijnheer,et al.  Accuracy in tangential breast treatment set-up: a portal imaging study. , 1991, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[20]  P. Keall,et al.  SU-FF-T-265: Comparison of Absorbed Dose-To-Medium and Absorbed-Dose-To-Water for (head and Neck and Prostate) IMRT Treatment Plans , 2005 .

[21]  P. Keall,et al.  The effect of random setup errors on prostate intensity modulated radiotherapy (IMRT) plans , 2004 .

[22]  J. Siebers,et al.  Modelling production of β1 + emitting isotopes by proton therapy beams using the Lahet code system , 1998 .

[23]  J. Siebers,et al.  Calorimetric determination of the absorbed dose-to-water beam quality correction factor kQ for high-energy photon beams. , 1995, Medical physics.

[24]  E. Yorke,et al.  Dosimetric advantage of using 6 MV over 15 MV photons in conformal therapy of lung cancer: Monte Carlo studies in patient geometries , 2002, Journal of applied clinical medical physics.

[25]  R Mohan,et al.  Monte Carlo dose calculations for dynamic IMRT treatments. , 2001, Physics in medicine and biology.

[26]  L. Cozzi,et al.  Critical appraisal of treatment techniques based on conventional photon beams, intensity modulated photon beams and proton beams for therapy of intact breast. , 2002, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[27]  C. J. Ritchie,et al.  Predictive respiratory gating: a new method to reduce motion artifacts on CT scans. , 1994, Radiology.

[28]  Lili Wang,et al.  Introduction of audio gating to further reduce organ motion in breathing synchronized radiotherapy. , 2002, Medical physics.

[29]  Jeffrey V Siebers,et al.  Effect of patient setup errors on simultaneously integrated boost head and neck IMRT treatment plans. , 2005, International journal of radiation oncology, biology, physics.

[30]  Ben J Mijnheer,et al.  Intensity modulated versus non-intensity modulated radiotherapy in the treatment of the left breast and upper internal mammary lymph node chain: a comparative planning study. , 2002, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[31]  Steve B. Jiang,et al.  Effects of intra-fraction motion on IMRT dose delivery: statistical analysis and simulation. , 2002, Physics in medicine and biology.

[32]  Linda Hong,et al.  A simplified intensity modulated radiation therapy technique for the breast. , 2002, Medical physics.

[33]  P. Keall,et al.  SU‐FF‐T‐269: Dosimetric Properties of Scattered Photon Subsources Within a Source Model for Different Initial Electron Energies , 2005 .

[34]  W A Beckham,et al.  Evaluation of the validity of a convolution method for incorporating tumour movement and set-up variations into the radiotherapy treatment planning system. , 2000, Physics in medicine and biology.

[35]  J. Siebers,et al.  Measurement of Neutron Dose Equivalent and Penetration in Concrete for 230 MeV Proton Bombardment of Al, Fe, and Pb Targets , 1992 .

[36]  J. Wong,et al.  The use of active breathing control (ABC) to reduce margin for breathing motion. , 1999, International journal of radiation oncology, biology, physics.

[37]  J. Yarnold,et al.  The influence of breast size on late radiation effects and association with radiotherapy dose inhomogeneity , 1995 .

[38]  J Hanson,et al.  Dosimetric evaluation of lung tumor immobilization using breath hold at deep inspiration. , 2001, International journal of radiation oncology, biology, physics.

[39]  J. Yarnold,et al.  The influence of breast size on late radiation effects and association with radiotherapy dose inhomogeneity. , 1994, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[40]  Gikas S. Mageras,et al.  Phase I dose escalation study using the deep inspiration breath hold technique to safely increase dose to 81 Gy in the treatment of inoperable non-small cell lung cancer , 2000 .

[41]  P. Keall,et al.  WE-C-J-6C-02: Investigation of Variables Affecting Residual Motion for Respiratory Gated Radiotherapy , 2005 .

[42]  P. Keall,et al.  Determination of maximum leaf velocity and acceleration of a dynamic multileaf collimator: implications for 4D radiotherapy. , 2005, Medical physics.

[43]  J. Siebers,et al.  SU-EE-A1-01: Comparison of Monte Carlo and Convolution/Superposition Calculation Methods: Quantification of the Dose Prediction Errors Arising From Tissue Heterogeneities , 2005 .

[44]  J Siebers,et al.  Validation of Monte Carlo generated phase-space descriptions of medical linear accelerators. , 1999, Medical physics.

[45]  K. Murata,et al.  Accurate contiguous sections without breath-holding on chest CT: value of respiratory gating and ultrafast CT. , 1994, AJR. American journal of roentgenology.

[46]  J. Siebers,et al.  Deduction of the air w value in a therapeutic proton beam. , 1995, Physics in medicine and biology.

[47]  H Shirato,et al.  Detection of lung tumor movement in real-time tumor-tracking radiotherapy. , 2001, International journal of radiation oncology, biology, physics.

[48]  R Mohan,et al.  Acceleration of dose calculations for intensity-modulated radiotherapy. , 2001, Medical physics.

[49]  R. Mohan,et al.  Monte Carlo computation of dosimetric amorphous silicon electronic portal images. , 2004, Medical physics.

[50]  J. Siebers,et al.  Investigation of the optimal backscatter for an aSi electronic portal imaging device , 2004, Physics in Medicine and Biology.

[51]  Paul J. Keall,et al.  Performance benchmarks of the MCV Monte Carlo system , 2000 .

[52]  R. Mohan,et al.  A Monte Carlo study of radiation transport through multileaf collimators. , 2001, Medical physics.

[53]  R. Mohan,et al.  Comparison of EGS4 and MCNP4b Monte Carlo codes for generation of photon phase space distributions for a Varian 2100C. , 1999, Physics in medicine and biology.

[54]  S Webb,et al.  The dosimetric consequences of inter-fractional patient movement on conventional and intensity-modulated breast radiotherapy treatments. , 2000, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[55]  R Mohan,et al.  Determining parameters for respiration-gated radiotherapy. , 2001, Medical physics.

[56]  Frank Verhaegen,et al.  International Workshop on Current Topics in Monte Carlo Treatment Planning , 2005 .

[57]  R Mohan,et al.  Algorithms and functionality of an intensity modulated radiotherapy optimization system. , 2000, Medical physics.

[58]  Lambert Zijp,et al.  Reduction of cardiac and lung complication probabilities after breast irradiation using conformal radiotherapy with or without intensity modulation. , 2002, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[59]  Martin J Murphy,et al.  Issues in respiratory motion compensation during external-beam radiotherapy. , 2002, International journal of radiation oncology, biology, physics.

[60]  Proton beam output measurement with an extrapolation chamber. , 1998, Medical dosimetry : official journal of the American Association of Medical Dosimetrists.

[61]  J. Siebers,et al.  A prototype beam delivery system for the proton medical accelerator at Loma Linda. , 1991, Medical physics.

[62]  R. Mohan,et al.  On the use of EPID-based implanted marker tracking for 4D radiotherapy. , 2004, Medical physics.

[63]  R Mohan,et al.  Monte Carlo as a four-dimensional radiotherapy treatment-planning tool to account for respiratory motion. , 2004, Physics in medicine and biology.

[64]  B. Murray,et al.  Held-breath self-gating technique for radiotherapy of non-small-cell lung cancer: a feasibility study. , 2001, International journal of radiation oncology, biology, physics.

[65]  R. Mohan,et al.  Dynamic-MLC Modeling for Monte Carlo dose calculations , 2000 .

[66]  R. Mohan,et al.  Radiotherapy dose calculations in the presence of hip prostheses. , 2003, Medical dosimetry : official journal of the American Association of Medical Dosimetrists.

[67]  Jeffrey V. Siebers,et al.  TH‐B‐T‐6E‐01: Monte Carlo Applications in Conformal, IMRT and 4D Clinical Treatment Planning: Pitfalls and Triumphs , 2005 .

[68]  S. Webb,et al.  A simulation of the effects of set-up error and changes in breast volume on conventional and intensity-modulated treatments in breast radiotherapy. , 2001, Physics in medicine and biology.

[69]  P. Keall,et al.  Monte Carlo-based treatment planning for a spoiler system with experimental validation using plane-parallel ionization chambers , 2004, Physics in medicine and biology.

[70]  G J Kutcher,et al.  Deep inspiration breath-hold technique for lung tumors: the potential value of target immobilization and reduced lung density in dose escalation. , 1999, International journal of radiation oncology, biology, physics.

[71]  R Mohan,et al.  A method for determining multileaf collimator transmission and scatter for dynamic intensity modulated radiotherapy. , 2000, Medical physics.

[72]  J T Booth,et al.  Modelling the dosimetric consequences of organ motion at CT imaging on radiotherapy treatment planning. , 2001, Physics in medicine and biology.

[73]  Radhe Mohan,et al.  Incorporating multi-leaf collimator leaf sequencing into iterative IMRT optimization. , 2002, Medical physics.

[74]  C C Ling,et al.  The deep inspiration breath-hold technique in the treatment of inoperable non-small-cell lung cancer. , 2000, International journal of radiation oncology, biology, physics.

[75]  J M Balter,et al.  Quantization of setup uncertainties in 3-D dose calculations. , 1999, Medical physics.

[76]  R. Jeraj,et al.  The effect of dose calculation accuracy on inverse treatment planning. , 2002, Physics in medicine and biology.

[77]  J. Siebers,et al.  A beam intensity monitor for the Loma Linda cancer therapy proton accelerator. , 1991, Medical physics.

[78]  K. Langen,et al.  Organ motion and its management. , 2001, International journal of radiation oncology, biology, physics.

[79]  G J Kutcher,et al.  Intensity-modulated tangential beam irradiation of the intact breast. , 1999, International journal of radiation oncology, biology, physics.

[80]  R. Mohan,et al.  The effect of dose calculation uncertainty on the evaluation of radiotherapy plans. , 2000, Medical physics.

[81]  Robert C. Frazier,et al.  Intensity modulation to improve dose uniformity with tangential breast radiotherapy: initial clinical experience. , 2000, International journal of radiation oncology, biology, physics.

[82]  C. Ramsey,et al.  Clinical efficacy of respiratory gated conformal radiation therapy. , 1999, Medical dosimetry : official journal of the American Association of Medical Dosimetrists.

[83]  M Moyers,et al.  Application of solid state detectors for dosimetry of therapeutic proton beams. , 1995, Medical physics.

[84]  P. Keall,et al.  Monte Carlo source model for photon beam radiotherapy: photon source characteristics. , 2004, Medical physics.

[85]  J. Siebers,et al.  Verification of the optimal backscatter for an aSi electronic portal imaging device , 2004, Physics in medicine and biology.

[86]  Radhe Mohan,et al.  Image reconstruction and the effect on dose calculation for hip prostheses. , 2003, Medical dosimetry : official journal of the American Association of Medical Dosimetrists.

[87]  S Minohara,et al.  Respiratory gated irradiation system for heavy-ion radiotherapy. , 2000, International journal of radiation oncology, biology, physics.

[88]  J. Siebers,et al.  Relative biological effectiveness and microdosimetry of a mixed energy field of protons up to 200 MeV. , 1994, Advances in space research : the official journal of the Committee on Space Research.

[89]  Paul J. Keall,et al.  Deformed CT reconstruction from limited projection data , 2005 .

[90]  I El Naqa,et al.  A comparison of Monte Carlo dose calculation denoising techniques , 2005, Physics in medicine and biology.

[91]  R. Mohan,et al.  A method for photon beam Monte Carlo multileaf collimator particle transport. , 2002, Physics in medicine and biology.

[92]  Alvaro A. Martinez M. D. Facr,et al.  Active breathing control (ABC) for Hodgkin's disease: Reduction in normal tissue irradiation with deep inspiration and implications for treatment , 1998 .

[93]  R. Mohan,et al.  The impact of electron transport on the accuracy of computed dose. , 2000, Medical physics.

[94]  R. Mohan,et al.  Determining the incident electron fluence for Monte Carlo-based photon treatment planning using a standard measured data set. , 2003, Medical physics.

[95]  J. Siebers,et al.  kQ factors for ionization chamber dosimetry in clinical proton beams. , 1996, Medical physics.

[96]  J. Leong,et al.  Implementation of random positioning error in computerised radiation treatment planning systems as a result of fractionation. , 1987, Physics in medicine and biology.

[97]  T Kozuka,et al.  Lung cancer: intermittent irradiation synchronized with respiratory motion--results of a pilot study. , 1998, Radiology.

[98]  K. Ohara,et al.  Irradiation synchronized with respiration gate. , 1989, International journal of radiation oncology, biology, physics.

[99]  Radhe Mohan,et al.  Four-dimensional radiotherapy planning for DMLC-based respiratory motion tracking. , 2005, Medical physics.

[100]  J. Siebers,et al.  SU‐FF‐J‐63: Improved Dose Accuracy for On‐Line Adaptive Radiation Therapy Using Deformable Dose Registration , 2005 .

[101]  R. K. Münch,et al.  A novel tracking technique for the continuous precise measurement of tumour positions in conformal radiotherapy. , 2000, Physics in medicine and biology.

[102]  R Mohan,et al.  The impact of fluctuations in intensity patterns on the number of monitor units and the quality and accuracy of intensity modulated radiotherapy. , 2000, Medical physics.

[103]  J. Adler,et al.  Robotic Motion Compensation for Respiratory Movement during Radiosurgery , 2000, Computer aided surgery : official journal of the International Society for Computer Aided Surgery.

[104]  P Pemler,et al.  Influence of respiration-induced organ motion on dose distributions in treatments using enhanced dynamic wedges. , 2001, Medical physics.

[105]  P J Keall,et al.  A method to predict the effect of organ motion and set-up variations on treatment plans. , 1999, Australasian physical & engineering sciences in medicine.

[106]  P J Keall,et al.  A fluence-convolution method to calculate radiation therapy dose distributions that incorporate random set-up error. , 2002, Physics in medicine and biology.

[107]  Michael K Fix,et al.  Photon-beam subsource sensitivity to the initial electron-beam parameters. , 2005, Medical physics.

[108]  J. Siebers,et al.  Shielding measurements for 230-MeV protons , 1993 .

[109]  J. Siebers,et al.  Proton dosimetry intercomparison. , 1996, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.