Image-guided IMRT for localized prostate cancer with daily repositioning: inferring the difference between planned dose and delivered dose distribution.

INTRODUCTION To investigate the dosimetric impact of daily on-line repositioning during a full course of IMRT for prostate cancer. MATERIALS AND METHODS Twenty patients were treated with image-guided IMRT. Each pre-treatment plan (Plan A) was compared with a post-treatment plan sum (Plan B) based on couch shifts measured. The delivered dose to the prostate without a daily repositioning was inferred by considering each daily couch shift during the whole course of image-guided IMRT (i.e., plan B). Dose metrics were compared for prostate CTV (P-CTV) and PTV (P-PTV) and for organs at risk. Ten patients were treated with a 5 mm margin and 10 patients with a 10 mm margin. RESULTS For plan A vs. plan B: the average D95, D98, D50, D mean and EUD were: 76.4 Gy vs. 73.9 Gy (p = 0.0007), 75.4 Gy vs. 72.3 Gy (p = 0.001), 78.9 Gy vs. 78.4 Gy (p = 0.014), 78.7 Gy vs. 77.8 Gy (p = 0.003) and 78.1 Gy vs. 75.9 Gy (p = 0.002), respectively for P-CTV, and 73.2 Gy vs. 69.3 Gy (p = 0.0006), 70.7 Gy vs. 66.0 Gy (p = 0.0008), 78.3 Gy vs. 77.5 Gy (p = 0.001), 77.8 Gy vs. 76.4 Gy (p = 0.0002) and 74.4 Gy vs. 69.2 Gy (p = 0.003), respectively for P-PTV. Margin comparison showed no differences in dose metrics between the two plans except for D98 of the rectum in plan B which was significantly higher with a 10 mm margin. CONCLUSIONS The absence of daily image-guided IMRT resulted in a significantly less uniform and less homogeneous dose distribution to the prostate. A reduction in PTV margin showed neither a lower target coverage nor a better spare of OAR with and without daily image-guided IMRT.

[1]  I. Barillot,et al.  Clinical assessment of the use of the Sonarray system for daily prostate localization. , 2006, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[2]  R. Mohan,et al.  Optimization of intensity-modulated radiotherapy plans based on the equivalent uniform dose. , 2002, International journal of radiation oncology, biology, physics.

[3]  A. Niemierko.  Reporting and analyzing dose distributions: a concept of equivalent uniform dose. , 1997, Medical physics.

[4]  J. Fowler,et al.  On cold spots in tumor subvolumes. , 2002, Medical physics.

[5]  K. Griffith,et al.  Dose escalation for localized prostate cancer: substantial benefit observed with 3D conformal therapy. , 2001, International journal of radiation oncology, biology, physics.

[6]  Frank Van den Heuvel,et al.  Independent verification of ultrasound based image-guided radiation treatment, using electronic portal imaging and implanted gold markers. , 2003, Medical physics.

[7]  Franck Bonnetain,et al.  Clinical impact of margin reduction on late toxicity and short-term biochemical control for patients treated with daily on-line image guided IMRT for prostate cancer. , 2012, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[8]  Eric Strom,et al.  Ultrasound-based localization. , 2005, Seminars in radiation oncology.

[9]  Sanford L Meeks,et al.  Commissioning and quality assurance of an optically guided three-dimensional ultrasound target localization system for radiotherapy. , 2002, Medical physics.

[10]  George Starkschall,et al.  Late rectal toxicity: dose-volume effects of conformal radiotherapy for prostate cancer. , 2002, International journal of radiation oncology, biology, physics.

[11]  J. Bosset,et al.  Equivalent uniform dose concept evaluated by theoretical dose volume histograms for thoracic irradiation. , 2007, Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics.

[12]  M Zarza-Moreno,et al.  The use of non-standard CT conversion ramps for Monte Carlo verification of 6 MV prostate IMRT plans. , 2013, Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics.

[13]  J. Malicki,et al.  Dosimetric consequences of prostate-based couch shifts on the precision of dose delivery during simultaneous IMRT irradiation of the prostate, seminal vesicles and pelvic lymph nodes. , 2014, Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics.

[14]  Joos V Lebesque,et al.  Dose-response in radiotherapy for localized prostate cancer: results of the Dutch multicenter randomized phase III trial comparing 68 Gy of radiotherapy with 78 Gy. , 2006, Journal of clinical oncology : official journal of the American Society of Clinical Oncology.

[15]  Randomized trial comparing two fractionation schedules for patients with localized prostate cancer. , 2005 .

[16]  Y Kim,et al.  On the impact of functional imaging accuracy on selective boosting IMRT. , 2009, Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics.

[17]  George Starkschall,et al.  Prostate cancer radiation dose response: results of the M. D. Anderson phase III randomized trial. , 2002, International journal of radiation oncology, biology, physics.

[18]  M van Herk,et al.  Quantification of organ motion during conformal radiotherapy of the prostate by three dimensional image registration. , 1995, International journal of radiation oncology, biology, physics.

[19]  M. Parmar,et al.  Escalated-dose versus standard-dose conformal radiotherapy in prostate cancer: first results from the MRC RT01 randomised controlled trial. , 2007, The Lancet. Oncology.

[20]  P. Karaiskos,et al.  Anatomy- vs. fluence-based planning for prostate cancer treatments using VMAT. , 2014, Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics.

[21]  Radhe Mohan,et al.  Dose sculpting with generalized equivalent uniform dose. , 2005, Medical physics.

[22]  G S Bauman,et al.  Dosimetric impact of image-guided 3D conformal radiation therapy of prostate cancer , 2005, Physics in medicine and biology.

[23]  P. Xia,et al.  Relationship of imaging frequency and planning margin to account for intrafraction prostate motion: analysis based on real-time monitoring data. , 2013, International journal of radiation oncology, biology, physics.

[24]  J. Kurhanewicz,et al.  Management of prostate cancer patients with lymph node involvement: a rapidly evolving paradigm. , 2012, Cancer treatment reviews.

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

[26]  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.

[27]  Daniel W. Miller,et al.  Comparison of conventional-dose vs high-dose conformal radiation therapy in clinically localized adenocarcinoma of the prostate: a randomized controlled trial. , 2005, JAMA.

[28]  T Falco,et al.  Ultrasound imaging for external-beam prostate treatment setup and dosimetric verification. , 2002, Medical dosimetry : official journal of the American Association of Medical Dosimetrists.

[29]  David A Jaffray,et al.  Online ultrasound image guidance for radiotherapy of prostate cancer: impact of image acquisition on prostate displacement. , 2004, International journal of radiation oncology, biology, physics.

[30]  Jean-François Aubry,et al.  Measurements of intrafraction motion and interfraction and intrafraction rotation of prostate by three-dimensional analysis of daily portal imaging with radiopaque markers. , 2004, International journal of radiation oncology, biology, physics.