Geometric uncertainty of 2D projection imaging in monitoring 3D tumor motion.

The purpose of this study was to investigate the accuracy of two-dimensional (2D) projection imaging methods in three-dimensional (3D) tumor motion monitoring. Many commercial linear accelerator types have projection imaging capabilities, and tumor motion monitoring is useful for motion inclusive, respiratory gated or tumor tracking strategies. Since 2D projection imaging is limited in its ability to resolve the motion along the imaging beam axis, there is unresolved motion when monitoring 3D tumor motion. From the 3D tumor motion data of 160 treatment fractions for 46 thoracic and abdominal cancer patients, the unresolved motion due to the geometric limitation of 2D projection imaging was calculated as displacement in the imaging beam axis for different beam angles and time intervals. The geometric uncertainty to monitor 3D motion caused by the unresolved motion of 2D imaging was quantified using the root-mean-square (rms) metric. Geometric uncertainty showed interfractional and intrafractional variation. Patient-to-patient variation was much more significant than variation for different time intervals. For the patient cohort studied, as the time intervals increase, the rms, minimum and maximum values of the rms uncertainty show decreasing tendencies for the lung patients but increasing for the liver and retroperitoneal patients, which could be attributed to patient relaxation. Geometric uncertainty was smaller for coplanar treatments than non-coplanar treatments, as superior-inferior (SI) tumor motion, the predominant motion from patient respiration, could be always resolved for coplanar treatments. Overall rms of the rms uncertainty was 0.13 cm for all treatment fractions and 0.18 cm for the treatment fractions whose average breathing peak-trough ranges were more than 0.5 cm. The geometric uncertainty for 2D imaging varies depending on the tumor site, tumor motion range, time interval and beam angle as well as between patients, between fractions and within a fraction.

[1]  Y Suh,et al.  Aperture maneuver with compelled breath (AMC) for moving tumors: a feasibility study with a moving phantom. , 2004, Medical physics.

[2]  Paul Keall,et al.  Real-time DMLC IMRT delivery for mobile and deforming targets. , 2005, Medical physics.

[3]  Eric C Ford,et al.  Measurement of lung tumor motion using respiration-correlated CT. , 2004, International journal of radiation oncology, biology, physics.

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

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

[6]  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.

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

[8]  S Webb,et al.  Limitations of a simple technique for movement compensation via movement-modified fluence profiles , 2005, Physics in medicine and biology.

[9]  Steve B Jiang,et al.  A technique for respiratory-gated radiotherapy treatment verification with an EPID in cine mode , 2005 .

[10]  J. Ciezki,et al.  Fluoroscopic study of tumor motion due to breathing: facilitating precise radiation therapy for lung cancer patients. , 2001, Medical physics.

[11]  J. Pouliot,et al.  Evaluation of ultrasound-based prostate localization for image-guided radiotherapy. , 2003, International journal of radiation oncology, biology, physics.

[12]  Gregory C Sharp,et al.  Integrated radiotherapy imaging system (IRIS): design considerations of tumour tracking with linac gantry-mounted diagnostic x-ray systems with flat-panel detectors , 2004, Physics in medicine and biology.

[13]  Steve B. Jiang,et al.  Technical aspects of image-guided respiration-gated radiation therapy. , 2006, Medical dosimetry : official journal of the American Association of Medical Dosimetrists.

[14]  Lech Papiez,et al.  DMLC leaf-pair optimal control for mobile, deforming target. , 2005, Medical physics.

[15]  Achim Schweikard,et al.  Respiration tracking in radiosurgery. , 2004, Medical physics.

[16]  Weiguo Lu,et al.  Real-time respiration monitoring using the radiotherapy treatment beam and four-dimensional computed tomography (4DCT)—a conceptual study , 2006, Physics in medicine and biology.

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

[18]  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.

[19]  Masahiro Hiraoka,et al.  Development of a four-dimensional image-guided radiotherapy system with a gimbaled X-ray head. , 2006, International journal of radiation oncology, biology, physics.

[20]  2207 Lung tumor motion with respiration does not correlate with location, pulmonary function, or chest wall motion , 1999 .

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

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

[23]  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.

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

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

[26]  Nzhde Agazaryan,et al.  The effects of tumor motion on planning and delivery of respiratory-gated IMRT. , 2003, Medical physics.

[27]  G Starkschall,et al.  Respiratory-driven lung tumor motion is independent of tumor size, tumor location, and pulmonary function. , 2001, International journal of radiation oncology, biology, physics.

[28]  J C Stroom,et al.  Inclusion of geometrical uncertainties in radiotherapy treatment planning by means of coverage probability. , 1999, International journal of radiation oncology, biology, physics.

[29]  M. V. van Herk,et al.  Precise and real-time measurement of 3D tumor motion in lung due to breathing and heartbeat, measured during radiotherapy. , 2002, International journal of radiation oncology, biology, physics.

[30]  Jerry T. Wong,et al.  Real-time tumor tracking using implanted positron emission markers: concept and simulation study. , 2006, Medical physics.

[31]  Uwe Oelfke,et al.  Online correction for respiratory motion: evaluation of two different imaging geometries , 2005, Physics in medicine and biology.

[32]  J O Deasy,et al.  Tomotherapy: a new concept for the delivery of dynamic conformal radiotherapy. , 1993, Medical physics.

[33]  M. Herk.  Errors and margins in radiotherapy. , 2004 .

[34]  Y Suh,et al.  A feasibility study on the prediction of tumour location in the lung from skin motion. , 2004, The British journal of radiology.

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

[36]  P. Giraud,et al.  [Respiration-gated radiotherapy: current techniques and potential benefits]. , 2003, Cancer radiotherapie : journal de la Societe francaise de radiotherapie oncologique.

[37]  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.

[38]  S. Nill,et al.  Linac-integrated kV-cone beam CT: technical features and first applications. , 2006, Medical dosimetry : official journal of the American Association of Medical Dosimetrists.

[39]  D L McShan,et al.  Automated determination of patient setup errors in radiation therapy using spherical radio-opaque markers. , 1993, Medical physics.

[40]  M van Herk,et al.  Automatic three-dimensional inspection of patient setup in radiation therapy using portal images, simulator images, and computed tomography data. , 1996, Medical physics.

[41]  Hilke Vorwerk,et al.  Interfractional and intrafractional accuracy during radiotherapy of gynecologic carcinomas: a comprehensive evaluation using the ExacTrac system. , 2003, International journal of radiation oncology, biology, physics.

[42]  S. Webb.  Motion effects in (intensity modulated) radiation therapy: a review , 2006, Physics in medicine and biology.

[43]  Steve B. Jiang,et al.  Synchronized moving aperture radiation therapy (SMART): improvement of breathing pattern reproducibility using respiratory coaching , 2006, Physics in medicine and biology.

[44]  Patrick A Kupelian,et al.  Evaluation of an infrared camera and X-ray system using implanted fiducials in patients with lung tumors for gated radiation therapy. , 2006, International journal of radiation oncology, biology, physics.

[45]  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.

[46]  Clifton D Fuller,et al.  Comparison of ultrasound and implanted seed marker prostate localization methods: Implications for image-guided radiotherapy. , 2006, International journal of radiation oncology, biology, physics.

[47]  P J Keall,et al.  Investigation of patient, tumour and treatment variables affecting residual motion for respiratory-gated radiotherapy , 2006, Physics in medicine and biology.