The overall goal of this procedure is to treat lung tumors with dynamic tracking during stereotactic ablative body radiation therapy. This is accomplished by first discussing treatment options with the patient, including dynamic tracking during delivery of therapeutic radiation to a lung tumor. Next, the lung tumor target is identified by tagging it with a permanent gold coated fiducial marker.
Then CT guided simulation, physician contouring and radiation dose planning are carried out. The final step is to build a respiratory correlation model and initiate dynamic tracking radiation treatment. Ultimately, dynamic tracking.
During stereotactic ablative body radiation therapy is used to treat moving lung tumors with therapeutic radiation dose and with minimal toxicity. The main advantage of this stereotactic body radiation technique over existing methods like conventional 3D radiation therapy, is that precise high dose radiation can be delivered with minimal radiation toxicity. This method can help answer key questions in the radiation oncology field, such as whether new generation radiation therapy machines can hit moving lung targets precisely Before beginning the procedure.
Describe the new lung SBRT treatment to the patient and discuss the treatment risks to perform a percutaneous CT guided or bronchoscopic placement of a single gold coated marker inserted into the tumor target center of mass. Ask a radiologist to perform a three to five millimeter thick contiguous axial tomographic imaging of the patient's chest. Determine a safe needle approach minimizing the amount of lung tissue traversed and avoiding bull eye and fissures.
Next, inject local subcutaneous anesthesia such as 1%lidocaine. Then introduce a 17 or 18 gauge coaxial needle to place a single short or single long marker. Alternatively, ask a pulmonologist to acquire a tomographic imaging of the chest for endo bronchial mapping.
Then wedge the bronchoscope into the suspected bronchial segment. Steer the bronchoscope sensor probe to the target lesion, and using the trans bronchial needle, deploy a fiducial marker. After performing a CT guided simulation four to seven days following marker placement, ask the patient to lay supine headfirst on the treatment machine.
Flat tabletop position the patient's arms over their head supported by upper arm and wrist holders, or a vacuum bag immobilizer, ensure that the thorax and abdomen are not immobilized. Optionally, use a two pin localized knee sponge for indexing. Place at least four infrared tracted body markers on the chest for localization and to demonstrate consistent vertical respiratory motion.
After conducting a non contrasted contiguous helical axial CT scan, according to the text protocol, have the patient lie in a head first scanning position and ask the physician to order 18 FFDG PET CT scans for enhanced capture of lung tumor motion. Then during quiet breathing, perform a contiguous helical CT scan from the orbital me adal line to the upper thighs contour, the primary lung gross target volume or volumes by hand drawing on four D CT data sets, preferably the exhale phase. Then contour nearby normal tissue structures by hand, drawing on four D CT data sets, preferably the exhale phase.
Click on the dynamic tracking button in the planning software to engage the gimbal pan and tilt tracking. Prescribe a radiation dose to the PTV as outlined in the text protocol to build a quiet breathing correlation model. After supine headfirst alignment, place four infrared body markers on the body in the same marked locations identified at CT simulation.
At the treatment console, verify positional accuracy of the body markers and patient alignment by infrared camera and screens. Acquire cross plane dual diagnostic KV x-rays or cone beam CT images to detect implanted markers for internal positional accuracy using computer software linked to the new SBRT platform workflow associate and correlate body marker motion as a surrogate for respiration and internal implanted marker motion to generate a lung tumor motion Correlation model derive a gimbal pan and tilt path for the accelerator to track tumor motion, visually assess the lung tumor motion correlation model prior to radiation delivery. Evaluate machine patient collisions due to gantry rotation, O-ring, pivot, and gimbal pan, and tilt actions prior to plan delivery as shown here.
SBRT on the new platform currently involves multiple static radiation beams converging on single or multiple closely associated clinical radiation targets. A representative good planning outcome delivers ablative radiation with 95%coverage of cancer, target volume, and cancer target dose conformity. This figure shows five coplanar and four non coplanar beams used to treat a single PTV representing squamous cell carcinoma.
In the right lung beam margins for the PTV were one millimeter radiation dose prescribed to the 95%isod dose line rendered 95%PTV coverage with a conformity index of 1.48. The prescription was 50 grays in five every other day. 10 gray fractions structures depicted here include the planning target volume, the internal target volume, spinal cord, and esophagus ISO dose lines are as indicated.
After watching this video, you should have a good understanding of how to deliver radiation therapy with dynamic tracking of lung tumors After its development. This stereotactic body radiation therapy technique paved the way for researchers in the field of radiation oncology to explore precise high dose radiation therapy that can be delivered safely to moving lung tumors.
