Correlation between dosimetric effect and intrafraction motion during prostate treatments delivered with helical tomotherapy

The dosimetric impact of intrafraction prostate motion was investigated for helical tomotherapy treatments. Measured motion tracks were used to calculate the dosimetric impact on delivered target dose distributions. A dynamic dose calculation engine was developed to facilitate this evaluation. It was found that the D95% (minimum dose to 95% of the volume) changes in the prostate were well correlated with D95% changes in the PTV. This means that the dosimetric impact of intrafraction motion is not restricted to the periphery of the target. The amount of motion was not well correlated with the dosimetric impact (measured in target D95% changes) of motion. The relationship between motion and its dosimetric impact is complex and depends on the timing and direction of the movement. These findings have implications for motion management techniques. It appears that the use of target margins is not an effective strategy to protect the prostate from the effects of observed intrafraction motion. The complex relationship between motion and its dosimetric effect renders simple threshold-based intervention schemes inefficient. Monitoring of actual prostate motion would allow the documentation of the dosimetric impact and implementation of corrective action if needed. However, when motion management techniques are evaluated, it should be kept in mind that the dosimetric impact of observed prostate motion is small for the majority of fractions.

[1]  Patrick A Kupelian,et al.  Influence of intrafraction motion on margins for prostate radiotherapy. , 2006, International journal of radiation oncology, biology, physics.

[2]  Jatinder R. Palta,et al.  Intensity-Modulated Radiation Therapy: The State of the Art , 2003 .

[3]  M. V. van Herk,et al.  Prostate gland motion assessed with cine-magnetic resonance imaging (cine-MRI). , 2005, International journal of radiation oncology, biology, physics.

[4]  Benjamin Movsas,et al.  Measurement of intrafractional prostate motion using magnetic resonance imaging. , 2002, International journal of radiation oncology, biology, physics.

[5]  Steve Webb,et al.  Intensity-Modulated Radiation Therapy , 1996, International journal of radiation oncology, biology, physics.

[6]  J M Balter,et al.  A comparison of ventilatory prostate movement in four treatment positions. , 2000, International journal of radiation oncology, biology, physics.

[7]  Ke Sheng,et al.  A motion phantom study on helical tomotherapy: the dosimetric impacts of delivery technique and motion , 2006, Physics in medicine and biology.

[8]  J Szanto,et al.  Respiratory-induced prostate motion: quantification and characterization. , 2000, International journal of radiation oncology, biology, physics.

[9]  Patrick A Kupelian,et al.  Initial experience with megavoltage (MV) CT guidance for daily prostate alignments. , 2005, International journal of radiation oncology, biology, physics.

[10]  John Wong,et al.  Accuracy of a wireless localization system for radiotherapy. , 2005, International journal of radiation oncology, biology, physics.

[11]  Weiguo Lu,et al.  Dosimetric effect of prostate motion during helical tomotherapy. , 2009, International journal of radiation oncology, biology, physics.

[12]  Jan J W Lagendijk,et al.  Measurements and clinical consequences of prostate motion during a radiotherapy fraction. , 2002, International journal of radiation oncology, biology, physics.

[13]  H Shirato,et al.  Use of an implanted marker and real-time tracking of the marker for the positioning of prostate and bladder cancers. , 2000, International journal of radiation oncology, biology, physics.

[14]  Robert Jeraj,et al.  Confirmation, refinement, and extension of a study in intrafraction motion interplay with sliding jaw motion. , 2005, Medical physics.

[15]  Henry M Kuerer,et al.  Locoregional treatment outcomes for inoperable anthracycline-resistant breast cancer. , 2002, International journal of radiation oncology, biology, physics.

[16]  John T. Wei,et al.  Target localization and real-time tracking using the Calypso 4D localization system in patients with localized prostate cancer. , 2006, International journal of radiation oncology, biology, physics.

[17]  R. Jeraj,et al.  Confirmation, refinement, and extension of a study in intrafraction motion interplay with sliding jaw motion. , 2005, Medical physics.

[18]  Indrin J Chetty,et al.  Synchronized dynamic dose reconstruction. , 2006, Medical physics.

[19]  Lei Dong,et al.  Intrafraction prostate motion during IMRT for prostate cancer. , 2001, International journal of radiation oncology, biology, physics.

[20]  Steven R. Moeckly,et al.  Respiratory motion effects on whole breast helical tomotherapy. , 2008, Medical physics.

[21]  T. Rosewall,et al.  Comparison of localization performance with implanted fiducial markers and cone-beam computed tomography for on-line image-guided radiotherapy of the prostate. , 2007, International journal of radiation oncology, biology, physics.

[22]  J O Deasy,et al.  An investigation of tomotherapy beam delivery. , 1997, Medical physics.

[23]  Timothy Solberg,et al.  Multi-institutional clinical experience with the Calypso System in localization and continuous, real-time monitoring of the prostate gland during external radiotherapy. , 2007, International journal of radiation oncology, biology, physics.

[24]  D P Dearnaley,et al.  Evaluating the effect of rectal distension and rectal movement on prostate gland position using cine MRI. , 1999, International journal of radiation oncology, biology, physics.

[25]  T E Schultheiss,et al.  A comparison of daily CT localization to a daily ultrasound-based system in prostate cancer. , 1999, International journal of radiation oncology, biology, physics.

[26]  James M. Balter,et al.  Ventilatory movement of the prostate during radiotherapy , 2000 .

[27]  Shinichi Shimizu,et al.  Three-dimensional intrafractional movement of prostate measured during real-time tumor-tracking radiotherapy in supine and prone treatment positions. , 2002, International journal of radiation oncology, biology, physics.

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

[29]  P. Maddock Intensity modulated radiation therapy. , 2006, Medicine and health, Rhode Island.

[30]  Patrick A Kupelian,et al.  Observations on real-time prostate gland motion using electromagnetic tracking. , 2008, International journal of radiation oncology, biology, physics.

[31]  J Pouliot,et al.  Electronic portal imaging device detection of radioopaque markers for the evaluation of prostate position during megavoltage irradiation: a clinical study. , 1997, International journal of radiation oncology, biology, physics.

[32]  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.

[33]  James M. Balter,et al.  The Influence of Intrafraction Movement on Margins for Prostate Radiotherapy , 2005 .