tomo qa
DESCRIPTION
Tomotherapy Physics Quality Assurance proceduresTRANSCRIPT
Wellspring Cancer Center
Physics Quality Assurance
Tomotherapy
TomoTherapy Hi-Art System
Photo of Tomotherapy Unit with covers removed
TomoTherapy Technical ProcessFrom Prescription to Treatment
• CT imaging scan• Treatment planning
– Contour target volumes (PTV) and organs at risk (OAR)
– Specify constraints on PTVs and OARs
– Inverse planning on computer which determines beam shape and intensity modulation every 7 degrees of rotation
– Reviewed and revised (if necessary) by physician
– Final approval by physician
• Delivery quality assurance (DQA) by medical physicist– Verifies that absolute dose delivered agrees with treatment plan
– Verifies that isodose distribution in a plane agrees with treatment plan
TomoTherapy Physics Quality Assurance
To verify the entire process of planning and performing treatments, two phantoms were obtained from the Radiological Physics Center at MD Anderson in Houston, TX
Pelvic / Prostate Phantom
Head & Neck Phantom
Prostate Treatment QAInstructions for irradiation of RPC pelvic/prostate phantom
Cross section view of Pelvic/prostate phantom
Dose instructions for pelvic/prostate phantom
Tomotherapy Quality Assurance• Daily Checks (performed by Radiation
Therapist, checked by Physicist)• Delivery Quality Assurance (DQA) on each
patient plan (Physicist)• Monthly Checks (Physicist)• Annual Calibration (Physicist)• Preventative Maintenance and Inspection
(PMI), Weekly Checks (Factory Service Engineer)
This device is used each day to check the calibration, energy, and beam profile. If any of these parameters fall outside of limits
set by the physicist, the reason must be determined and corrected before patient treatments can be performed.
Standard Imaging BeamChecker Plus
This photo shows the BeamChecker Plus in position for measurement of the radiation beam.
It is also used to verify the accuracy of the lasers used for patient positioning
Results of Daily QA Measurements on Tomotherapy using
Standard Imaging Beam Checker Plus
This equipment is used on a monthly basis to check the calibration and verify the energy of the
radiation beam.
This equipment is one method used to check the accuracy of each patient treatment plan