A Program is in place to ensure that the radiation is being delivered safely and accurately and that all the computers and machines are in proper working order and calibrated accurately
1. Quality Assurance at Wellspring The program is in place to ensure that patients are treated properly and that the radiation treatments are being delivered safely and accurately
2. Recent articles in the news have raised questions and concerns about the accuracy and safety of radiation treatments . The process of monitoring and verifying both safety and accuracy is included in the quality assurance (QA) program.
3. Radiation therapy is one of the safest, most effective ways to treat cancer. There were an estimated 35.4 million radiotherapy treatments on Varian and Tomotherapy machines last year. Errors do occur, but they are extremely rare, with less than 0.0001 percent of treatments involving an incident that puts a patient at risk of harm .
4. QA Starts with the staff or medical team that is taking care of the patient
11. Simulation At the time of simulation the patient is placed in a reproducible position, often with immobilization . For patients with cancer in the head or neck area a face mask ( auqaplast ) is usually made to hold the head still and allow the targeting markings to be painted on the mask. For other areas of the body a vaclock bag will mold around the body to ensure that the patient is in the same position every day. Skin marks or tattoo's are used to match the laser mounted in the room and on the machine
12. CT scan, MRI or PET is obtained at this time CT images are then imported into the treatment planning computer
13. In the simulation process the CT and PET scan images are used to create a computer reconstruction of the patient and cancer
14. PET and CT Scan used to create radiation target PET Scan , showing cancer in right tongue Computer generated reconstruction, the target area is in red
15. Using the computer generated images the physician can carefully target the cancer and avoid normal structures
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18. Hitting the right spot Once the patient is laying on the radiation table, images can be taken to verify that the beam is targeting the correct site (called portal imaging) or on the Tomotherapy machine a true CT scan is obtained daily prior to treatment
19. Hitting the right spot…the same machine that produces the radiation can take a picture at the same time and the image (portal image) is compared with the computer generated target image (DRR) DRR – computer generated image The portal image showing the actual area treated that day
20. CT Scan prior to radiation Tomo image after only 19 treatments cancer cancer With image guided therapy (Tomotherapy) a CT scan is obtained prior to every treatment to check the accuracy of the targeting and determine if the tumor is shrinking or changing position
21. Importance of daily CT targeting on Tomotherapy and adjusting the treatment daily Very little bowel gas on initial study and the dose (red) targets the prostate gland closely large bowel gas on later treatment day and the dose (red) will cover half the rectum if an adjustment is not made
22. If no adjustment was made Actual treatment on Tomotherapy prior to treating the patient, the radiation beam (in red) was shifted upward and no longer hits the rectum
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24. Using the proper dose of radiation “ It may be a bit over-exposed”
25. Radiation History Radiation has been used to treat patients since the late 1890’s and there is extensive information available about the proper and safe dose
26. Information about the safe and effective doses of radiation Tables about the safe and recommended doses of radiation can be found on our web site, and the NCCN now publishes online, very detailed information about recommended doses of radiation
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28. Am I getting the right dose? After the patient has been simulated and computer plans generated by the staff and reviewed by the physicist, the physician enters the dose into the electronic chart and locks this in with a password , this prevents the machine or the staff from exceeding this dose .
29. How do I know if the machine has been calibrated correctly and am actually receiving the dose called for by the computer plans or the physicians prescription ?
30. Calibrating and verifying that the machines and computers are working properly - 5 steps 1. Every day prior to treating patients, the linear accelerator and TomoTherapy machines are tested with a device (the QA beam checker) that verifies that the output of the machine is correct in shape, energy level and dose
31. Calibrating and verifying that the machines and computers are working properly - 5 steps 2. The machines also undergo monthly and annual evaluation and calibration by the medical physicist to verify they are exactly calibrated
32. Calibrating and verifying that the machines and computers are working properly - 5 steps 3. On a regular basis a device (TLD) is radiated to a fixed dose and then mailed to an outside expert center (MD Anderson) to independently verify that the dose output is accurate, as well as a body ‘phantom’ is used to verify the proper dose distribution
33. Calibrating and verifying that the machines and computers are working properly - 5 steps 4. Other radiation measurement devices are placed on the patient (mosfet and electronic dosimeters) to independently verify that the patients is receiving the dose predicted by the computer plan
34. Calibrating and verifying that the machines and computers are working properly - 5 steps 5. Prior to treating the patient with any complex plan (e.g. IMRT or Tomotherapy) a measurement device (called a phantom) is treated with the patient’s dose plan to verify that the computer calculations and the shaping devices (MLC) are working properly