Spiral CT acquires its images with a moving table during many different phases of the breathing cycle
The resulting image is a blurred snapshot of the structure and may contain motion artifacts
CT table stationary
Info for complete cycle
Divided into phases
Table moves to next position
Information is gathered for each phase and combined to construct an image that represents the location of the anatomy at that precise moment.
Exhalation = Beam on
Anatomy is relatively stationary
More phases included
More efficient treatment
Treatment Planning Beam Off Beam On Beam On
Cancer Treatment with Respiratory Gating
Irregular Respiration System automatically shuts down until normal breathing pattern is reestablished. Beam On Beam On Beam Off Normal Respiration Normal Respiration Beam Off Inspiration Expiration Inspiration Expiration Expiration Beam On Irregular Respiration
Tumors subject to respiratory motion:
Inflates lung- minimizing amount in field
Separates breast from heart
Whole abdomen for ovarian cancer
Consistent and periodic respirations
Inadequate lung function prohibits
Tumor movement must correlate with breathing movement
More accurate prediction of target location
Sufficient overall tumor movement
Yet within 5mm displacement during “Beam On” time to increase treatment efficiency.
Require invasive surgical procedures submitting patient to infection:
Intraoperative radiation therapy
Uncomfortable breath holds that many cannot withstand due to decreased pulmonary function:
Deep inspiration breath hold (DIBH)
Active breathing control (ABC)
Continuous Monitoring Required!!
Waveform pattern to match the actual breathing pattern
Beam on time to correlate with the appropriate phase of the cycle
The beam is actually turning on and off at the right times
Brandner, E., Heron, D. E., Wu, A., Huq, M. S., Yue, N. J.,Chen, H. C., (2006). Localizing Moving Targets and organs using motion-managed CTs. Medical Dosimetry , 31(2), 134-140.
Bucsko, J. K., (2004, November). Managing Respiratory Motion. Radiology Today , 5(23), 33. Retrieved February 27, 2008, from http://www.radiologytoday.net/archive/rt_110804p33.shtml
Butler, L.E., Forster, K. M., Stevens, C. W., Bloch, C., Liu, H. H., Tucker, S. L., (2004). Dosimetric benefits of respiratory gating: a preminary study. Journal of Applied Clinical Medical Physics , 5 (1), 16-24.
Carlson, A. H., (2007, October). Breathing New Life into Respiratory Gating. Medical Imaging , 42. Retrieved February 27, 2008, from http://www.medicalimagingmag.com/issues/articles/2007-10_04.asp
Garsa, A.A., Andrade, R. S., Heron, D.E., Beriwal, S., Kim, H., Brandner, E., (2007). Four-dimensional computed tomography-based respiratory-gated whole abdominal intensity-modulated radiation therapy for ovarian cancer: a feasible study. International Journal of Gynecological Cancer , 17, 55-60.
Huntzinger, C., (n.d.). The Revolution in Radiation Therapy. In Looking Forward- The Future is in Motion. Varian Medical systems. Retrieved February 27, 2008, from varian.mediaroom.com/file.php/mr_varian/spinsite_docfiles/147/VRM395+IMRT+White+Paper+Final+Jan+2005.pdf -
Jiang, S. B., (2006). Technical aspects of image guided respiration-gated radiation therapy. Medical Dosimetry , 31(2), 141-151.
Keall, P., Vedam, S., George, R., Bartee, C., Siebers, J., Lerma, F., (2006). The clinical implementation of respiratory-gated intensity-modulated radiotherapy. Medical Dosimetry , 31(2), 152-162.
Kornmehl, C., (2005). Every Move You Make. Image, 18(10). Retrieved February 25, 2008, from http://www.rt-image.com/030705FO
Korreman, S., Mostafavi, H., Le, QT., Boyer, A., (2006). Comparison of respiratory surrogates for gated lung radiotherapy without internal fiducials. Acta Onclolgica , 45, 935-942.
Rosenzweig, KE., Yorke, E., Amols, H., Mageras, GS., Giraud, P., Katz, MS., (2005). Tumor Motion Control in the Treatment of Non Small Cell Lung Cancer. Cancer Investigation , 23, 129-133.
Saw CB, Brandner E, Selvaraj R, Chen H, Saiful Huq M, Heron DE, (2007). A review on the clinical implementation of respiratory-gated radiation therapy, Biomedical Imaging and Intervention Journal 3(1):e40. Retrieved February 25, 2008, from http://www.biij.org/2007/1/e40/>
Underberg, R., van Sornsen de Koste, JR., Lagerwaard, FJ, Vincent, A., Slotman, BJ., Senan, S., (2006). A dosimetric analysis of respiration-gated radiotherapy in patients with stage II lung cancer. Radiation Oncology . 1:8, Retrieved February 27, 2008, from http://www.ro-journal.com/content/pdf/1748-717X-1-8.pdf.