Respiratory Motion Management
Techniques for Chest and Abdominal
Radiation Therapy
Leia Szwedo
In partial fulfillment of RT 412
University of Wisconsin – La Crosse,
Radiation Therapy Program
Background
• Issue1:
▫ Respiratory motion caused by patient breathing
during radiation therapy treatment can cause
displacement of the tumor location.
 12 to 16 respiratory cycles every minute
 SI direction: three to 12 millimeters
 Anterior-posterior and lateral directions: five mm
▫ Causes difficulty localizing tumor
 Overdosing normal tissue, under dosing tumor
Background cont.
• Solution:
▫ Respiratory motion management
 Techniques:
 Immobilization of the diaphragm
 Breathing control
 Real-time tracking
▫ Consensus shows that in comparison to free breathing
radiation treatments, all motion management
techniques are beneficial in treating moving tumors.2-4
 minimal statistical differences in motion management
between the techniques.2-4
Immobilization of the Diaphragm
• Utilizes devices to compress the abdomen
• Limit the air intake of the patient
▫ Thereby reducing the amount the diaphragm can
move and the tumor motion associated with it2
• More precise tumor localization1
• Smaller margins achievable1
Immobilization of the Diaphragm
• Examples:
▫ BodyFix2





Dual-vacuum system
Mold
Plastic sheet
Hose
Compression Pillow
▫ Abdominal Compression Plate5
 Stereotactic body frame
 Pressure plate
 Screw
Immobilization of the Diaphragm
• Advantages2:
▫
▫
▫
▫
▫
Simplicity
Minimal technological devices
Easy use
Reduce respiratory motion
Reusable
• Disadvantages2:
▫ Increased setup time
▫ Slight discomfort to some patients
▫ Difficult for patients who experience claustrophobia.2
Breathing Control
• Voluntary or machine-regulated breath holds.1
• Causes a cession of breathing during the
duration that the beam is on.1
• Commonly used when treating breast, lung, and
esophageal cancer.1,3,4
• Techniques:
▫ Deep-inspiration breath-holds (DIBH)
▫ Active breathing control (ABC)
Breathing Control
• Deep-inspiration breath-holds (DIBH)1,3,6
▫ Breathing instructions given
 “Take a deep breath in, and hold it.”
▫ Beam is turned on during breath hold
▫ Patient instructed to breath when beam is turned off
• Advantages:1,3,6
▫
▫
▫
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No additional equipments
Cost effective
Reduces tumor motion
Decrease in cardiac treated volumes (V20 from 26.5 to 22.8 percent) and
esophageal treated volumes (V50 from 25.5 to 22.6 percent).9
▫ Increased doses and smaller tumor margins are possible
• Disadvantages:1,3,6
▫ Difficult to determine the breath hold reproducibility
▫ Unrealistic for many elderly or frail patients, or those with pulmonary
disease
Breathing Control
• Active breathing control (ABC)
▫ Mouthpiece placed in the patient’s mouth
 Hooked up the ABC.7,8
▫ Continuously monitors lung volume
▫ When the lung volume is at the ideal level, usually 70 to 80 percent of maximum
inspiration, the valve on the mouthpiece is closed off
 Prevents the patient from inhaling or exhaling.6-8
 Ensures breath hold reproduciblity.6-8
▫ The radiation beam is turned on, and once the radiation is finished being
delivered, the valve is reopened, allowing the patient to resume breathing.6-8
• Advantages:
▫ Guarantees reproducible breath holds3,6,8
▫ Reduces tumor motion and cardiac and esophageal treated volumes9
• Disadvantages:
▫ More invasive6,8
▫ Patient needs to hold their breath for a minimum of 15 seconds6,8
▫ May require verbal training by the therapist6
Real-Time Tracking
• Real time tumor localizations
▫ Techniques to track tumor position5:
 External respiratory surrogates
 Implanted radio-opaque fiducial markers
 Surface imaging
• Once the tumor is accurately located, the
radiation beam will turn on and begin treating5
• Examples:
▫ Real-time Position Management (RPM) System,
AlignRT, and CyberKnife
Real-Time Tracking
• Real-Time Position Management System
▫ Utilizes an external respiratory surrogate5
 A plastic box with infrared reflective markers
 Placed on top of the patient’s abdominal surface
▫ Infrared cameras detect the reflective markers5,10
▫ During treatment, the tumor is tracked5
 When the respiratory location matches the location
predetermined, the beam will turn on.
 When out of the assigned location, the beam turns
off
Real Time Tracking
• AlignRT11
▫ Surface imaging
▫ Uses two infrared cameras to triangulate the location of the
patient and derive depth information
▫ In order to precisely locate the patient position, an optical pattern
is projected onto the patient to identify the corresponding points
▫ An algorithm is computed to use the points to create a surface
image of the patient.11
▫ From the surface image, the therapists can then make shifts to
align the image to the original planning image.
▫ Throughout the entire treatment, AlignRT tracts the motion, and
only allows the continuation of treatment when the tumor
location is within the assigned tolerance location.
Real-Time Tracking
• CyberKnife5
▫ Machine moves along with the tumor.
▫ Implements a lightweight 6MV linear accelerator
fixed on a robotic arm.5
▫ A real-time motion system tracks the motion of
the tumor, and the robotic arm moves in
synchrony to match the movement.5
▫ Moves in six degrees of freedom to compensate for
the true tumor motion.5
▫ However, the beam output, energy and size are
limited.5
Real-Time Tracking
• Advantages:
▫
▫
▫
▫
▫
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Accurate tracking of the tumor.5
Intrafractional movement regulation.1,5
Non-invasive and excludes rigid frames.5
Eliminates patient discomfort
Requires no active patient participation.5
Patient receives no additional radiation dose.5
 Infrared laser use
• Disadvantages
▫ Significantly increased treatment times5
▫ Tumor motion must be assumed to match the surface
motion, unless the system uses internal markers.5
Clinical Implications
• Study A2 (Han et al) :
▫ Compared:
 Free Breathing, BodyFix, Abdominal Compression Plate
▫ Looked at:
 Tumor motion and patient comfort
▫ Results:
 Tumor motion:
 FB = 6.1mm
 ACP = 4.7mm
 BodyFix = 5.3mm
 Patient comfort:
 63% of patients preferred ACP
Clinical Implications
• Study B 3 (STIC 2003 project):
▫ Compared:
 Free Breathing, Active Breathing Control, Deep-Inspiration Breath-Hold,
RPM
▫ Looked at:
 Target volumes, toxicities, survival, and local recurrence
▫ Results
 Gating Vs Free Breathing
 Target volumes:
▫ FB= 360  232 ml
▫ Gating=282  176 ml
 Acute toxicities:
▫ no notable difference except for pulmonary (48% FB vs. 36% gating)
 Late Toxicities:
▫ FB=9%
▫ Gating =6%
 Gating Techniques
 Survival: no difference
 Local recurrence:
▫ RPM: 13%
▫ DIBH= 36.7%
▫ ABC= 43.3%
Clinical Implications
• Study C 4 (Massachusetts General Hospital and Harvard Medical School):
▫ Compared:
 Deep-Inspiration Breath-Hold and AlignRT
▫ Looked at:
 Reproducibility
▫ Results:
 22% of breath holds were out of 5mm tolerance
 Combined DIBH and AlignRT produce greatest
reproducibility for breath holds.
Conclusion
• Respiratory motion management is beneficial in
the reduction of intrafractional motion
• Allows for a decrease in treatment volumes,
resulting in a reduction of normal tissue
toxicities while giving higher doses to the lesion
• Still recommended to use interfractional
imaging
References
1. Gilin MT. Special procedures. In: Washinton CM, Leaver D, eds. Principles and Practice of Radiation Therapy. 3rd ed. St. Louis, MO: Mosby-Elsevier;
2010: 321-322.
2. Han K, Cheung P, Basran PS. A comparison of two immobilization systems for stereotactic body radiation therapy of lung tumors. Radiotherapy &
Oncology. 2010;95(1): 103-108. 10.1016/j.radonc.2010.01.025.
3. Giraud P, Morvan E, Claude L, et al. Respiratory gating techniques for optimization of lung cancer radiotherapy. Journal of Thoracic Oncology.
2011;6(12):2058-2068. doi: 10.1097/JTO.0b013e3182307ec2.
4. Gierga DP, Turcotte JC, Sharp GC, et al. A voluntary breath-hold treatment technique for the left breast with unfavorable cardiac anatomy using
surface imaging. Internation Journal of Radiation Oncology Biology Physics. 2012;84(5): 663-668. doi: 10.1016/j.ijrobp.2012.07.2379.
5. Giraud P, Houle A. Respiratory gating for radiotherapy: Main technical aspects and clinical benefits. IRSN Pulmonary. 2013(2013).
doi:10.1155/2013/519602.
6. Wong J. Methods to manage respiratory motion in radiation treatment. American Association of Physicists in Medicine Wed site.
http://www.aapm.org/meetings/03SS/Presentations/Wong.pdf. Accessed January 14, 2014.
7. Saving the heart of breast cancer patients. Mercy Hospital Web site. http://www.mercy.net/newsroom/2013-03-20/savings-the-heart-of-breastcancer-patients. March 20, 2013. Accessed January 25, 2014.
8. Brock J, McNair HA, Panaskis N, et al. The use of the Active Breathing Coordinator throughout radical non-small-cell lung cancer (NSCLC)
radiotherapy. International Journal of Radiation Oncology, Biology, Physics. 2011;81(2): 369-375. doi: 10.1016/j.ijrobp.2010.05.038.
9. Sager O, Beyzadeoglu M, Dincoglan F, et al. Evaluation of active breathing conrol-moderate deep inspiration breath-hold in definite non-small cell
lung cancer radiotherapy. Neoplasma. 2012;59(3). doi: 10.4149/neo_2012_043.
10. Real-time position management system respiration synchronized imaging and treatment. Varian Web site.
http://varian.com/us/oncology/radiation_oncology/clinic/rpm_respiratory_gating.html. Accessed January 21, 2014.
11. 3D surface reconstruction. VisionRT Web site. http://www.visionrt.com/page-161.html. 2010. Accessed January 14, 2014.