Tomo Qa

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