RPC Liver Phantom Highly Conformal Stereotactic Body Radiation Therapy

Transcription

1 RPC Liver Phantom Highly Conformal Stereotactic Body Radiation Therapy Guidelines for Planning and Irradiating the RPC Liver Phantom. Revised Dec 2005 Credentialing for this protocol requires four steps: (1) submission of the 3D QA Facility Questionnaire for Stereotactic Body Radiation Therapy with supporting documentation to the Image Guided Therapy Center (ITC, (2) a successful dry run test, (3) completion of the phantom treatment experiment and (4) submission of the treatment plan for the first patient treated at the site on this protocol prior to delivering any protocol treatment. The purpose of steps (2) and (3) is to confirm that the dose distribution planned by each institution can be delivered by that institution, and treatment plans can be correctly submitted to the ITC. The RTOG is requesting that each institution keep the phantom for no more than 1 week. During this one-week period, the institution will image, plan, and irradiate the phantom and return it to the Radiological Physics Center (RPC). Thank you for your cooperation with this constraint. This phantom has been designed and constructed by the RPC. The RPC phantom contains two imaging/ dosimetry inserts representing two targets within the liver. The inserts contain a centrally located GTV. There are three orthogonal sheets of radiochromic film passing through the center of the target and two TLD capsules within 0.5 cm of the center of the target. The phantom also contains normal structures: the stomach, a kidney and the spinal cord, each with TLD in the center. If you have any questions, please contact the appropriate person. RPC Paola Alvarez (713) palvarez@mdanderson.org RPC Andrea Molineu (713) amolineu@mdanderson.org RPC Geoff Ibbott (713) gibbott@mdanderson.org MD Anderson Mike Gillin (713) mgillin@mdanderson.org ITC Bill Straube (314) itc@castor.wustl.edu ITC Walter Bosch (314) bosch@radonc.wustl.edu DOSIMETRY INFORMATION TO BE SUBMITTED: The following information is to be submitted to the RPC (include in the phantom shipping box): Original hard-copy isodose distributions in the sagittal, axial and coronal planes through the center of each of the target volumes. Please ensure that each plane fills an entire page, there are greater than 10 isodose lines and that a scale is printed on the page. A completed RPC Liver Phantom Institution Information form. The following information is to be submitted to the ITC (see protocol for additional submissions): The digital treatment planning data in DICOM- RT or the RTOG Data Exchange format using either FTP, CD or tape (see the ITC web site for details). Please cc the RPC (rpc@mdanderson.org) when you inform the ITC of the electronic submission. This will allow us to keep better track of who has and has not submitted the benchmark electronically. Original hard copy isodose distributions in the sagittal, axial and coronal plane through the target center (identical to those sent to the RPC) A copy of the completed RPC Liver Phantom- Institution Information form that was sent to the RPC Send the hard copy data (isodoses and forms) to: Bill Straube, M.S. Image Guided Therapy Center Washington University 4511 Forest Park Ave, Suite 200 St Louis, MO

2 DOSE PRESCRIPTION: Only photon beams with nominal energies ranging from 6 to 25 MV are allowed. The prescribed dose to the phantom is 20 Gy to the isodose line circumscribing the PTV. It should be delivered in 5 fractions with the following constraints: PTV: CTV = GTV (Note that this differs from the protocol). PTV = GTV + (0.4 cm to 1.0 cm) depending on the immobilization device used and/or the individual patient breathing motion (see the protocol and ATC website at The tumors will be labeled GTV1and PTV1 for the first tumor and GTV2 and PTV2 for the second tumor. The most lateral tumor shall be labeled tumor 1and is in the insert labeled A. Prescribed dose of 20 Gy to the PTV. Minimum PTV dose of 18 Gy. No more than 0.5 cc may receive a dose less than 18Gy. Maximum dose of 24 Gy allowed within the PTV. Any hotspots greater than 22 Gy must be within the PTV. DVHs shall be calculated for the liver (liver minus the GTV), kidney, spinal cord, stomach and target lesions (CTV and PTV). Critical Normal Structures Constraints over the normal structures are specified in the following table Normal structure Spinal Cord Volume Any point Dose 17 Gy Kidney 10% 5 Gy Stomach 1 cc 18.5 Gy Normal liver 50% 12 Gy Normal liver 30% 13.5 Gy 2

3 The phantom should be imaged, planned and irradiated as if it were an actual protocol patient, incorporating all of your customary quality assurance checks. IRRADIATING THE PHANTOM Material included in the 2 boxes: Liver Phantom Dosimetric/Imaging inserts Motor driver Motor to platform linkage 2D Reciprocating platform Rubber hose Three acrylic rods containing TLD Envelope with background film and TLD (hidden from view; please don t try to find it) Mailing label to return case at RPC s expense. Traditional RPC TLD block and irradiation table. (Please irradiate this at the time you irradiate the phantom.) Procedures: 1. Call the RPC ( ) with the date that you expect to irradiate the phantom. Ask for Nadia Hernandez or leave a message. Fill the phantom with water: 2. Thread the rubber hose into the filler hole placed on the base of the phantom Fill slowly with water (the rubber hose stretches over most faucets). You may need to jiggle the phantom to release air trapped inside the cavity Remove hose and replace acrylic screw. 3. Allow the phantom to sit with water in it for 20 min. to check for leaks. 4. Look in the insert spaces and check for water leakage. If you find any water call the RPC. If not, proceed to the next step. 5. Position both of the inserts (A and B). The end labeled bottom of insert should be inserted first in the space labeled with the corresponding letter. Align the 2 black arrows. Make sure that each insert is seated properly by making small rotations of the insert around its central axis. 6. Insert the acrylic rod labeled spinal cord rod in the hole labeled spinal cord. The hole and the rod are marked in blue. You will see a TLD capsule in the cavity closed with a screw. The end with the TLD should be inserted first. 7. Insert the acrylic rod labeled stomach rod in the hole labeled stomach. The hole and the rod are marked in green. You will see a TLD capsule in the cavity closed with a screw at the end of the rod and in a slot in the middle of the rod. The end with the TLD should be inserted first. 8. Insert the acrylic rod labeled kidney rod in the hole labeled kidney. The hole and the rod are marked in red. You will see a TLD capsule in the cavity closed with a screw. The end with the TLD should be inserted first. 9. Assemble the 2D reciprocating platform and motor drive system per the attached instructions. Do this on the CT couch so that the phantom and the platform can be imaged. 10. The motor driver for the platform will have been programmed to simulate the manner in which your institution instructs its patients to breathe during the 4D CT. 11. Position and CT the phantom as you would a patient including immobilization techniques. You may wish to scan with 1 mm slices, especially near the target, to better identify the TLD capsules. 12. Turn on the motor drive and acquire your CT images for treatment planning. 13. Segment the phantom images, contouring the skin, liver, stomach, kidney, spinal cord and PTV. Note that the CTV = GTV. PTV = GTV + (0.4 cm to 1.0 cm) depending on the immobilization device used and/or the individual patient breathing motion. Also contour all 8 TLD volumes. Please use the following names for these contours: PTV1_TLD_sup for the superior TLD in target A (lateral), PTV1_TLD_inf for the inferior TLD in target A, PTV2_TLD_sup for the superior TLD in target B (anterior), PTV2_TLD_inf for the inferior TLD in target B, Stomach_TLD for the TLD at the end of the stomach rod, Mid Stomach_TLD for the TLD in the middle of the stomach rod, Kidney_TLD for TLD in the kidney, Cord_TLD for the TLD in the spinal cord The dimensions of the TLD volume are approximately 10 mm long by 2 mm diameter The outside dimensions of the TLD capsules are 15 mm long by 4 mm diameter; the TLD axis is normal to the axial plane. (The capsules and the TLD should be visible on CT image) 14. Plan the treatment as specified in the DOSE PRESCRIPTION above. 15. Remove the inserts and look in the insert space and check for water leakage. If you find any water call the RPC. If not, follow the instructions in step 4 to position the inserts again and proceed to the next step. 16. Perform your customary QA of the plan prior to irradiating the phantom. 17. Irradiate the RPC TLD block according to the instructions provided to measure the reference machine output prior to irradiating the phantom. 3

4 18. Assemble the 2D reciprocating platform and motor drive system per the attached instructions. Do this on the treatment machine couch so that the phantom and the platform can be irradiated. 19. Position the phantom as you would a patient including immobilization techniques prior to delivering the radiation dose. 20. Turn on the motor drive. 21. Irradiate the phantom with the developed plan as you would a protocol patient including immobilization techniques. Try to avoid positioning the axial film at the abutment of adjacent MLC leaves or adjacent arcs. Abutting fields or leaves on the film may increase the uncertainty of the measurement. 22. Remove the insert and place it in the box. 23. Remove the acrylic cylinders from holes and place them in the box. 24. Please verify that there is no water in the insert space. If you find any water call the RPC. 25. Remove the screw on the base of the phantom and drain the water from the phantom. 26. Put the empty phantom in the box. 27. Make sure that the rubber hose is in the box. 28. Include the dosimetry data discussed above. Complete the attached forms. Be sure to include the scale used on the images coming from your TPS. 29. Return the complete package to the RPC. 4

5 RPC Liver Phantom Institution Information (Original to RPC, copy to ITC) Please call the RPC to let us know when you are going to irradiate the phantom. We will irradiate TLD standards to meet your schedule. Ask for Nadia Hernandez or leave a message. Phone number: (713) Institution: Address: Person performing irradiation: Person to receive report: Radiation Oncologist to receive report: Person to call in case of questions: Phone Number: Fax Number: address: Treatment Unit: Manufacturer: Model: In-house specification: Photon Beam: Nominal Energy: (MV) IR (TMR 20/TMR 10): %dd(10) x Collimation Used: MLC MIMIC Other: No. of leaves: Stereotactic System (if modification to linac): Manufacter: Model: Other: 5

6 Please enclose original copies of your treatment plans. Include the coronal, axial and sagittal planes through the target center. Include scaling factors for each plane. Treatment Planning System: Manufacturer: Model: Software: Version Number: Method to Account for Respiratory Induced Target Motion: Please describe your method: 6

7 Treatment of Phantom: Date of Irradiation: Dose specified is to: Muscle Water Indicate the dose delivered to the TLD as determined by your treatment planning computer TLD Mean Dose (Gy) Min. Dose (Gy) Max. Dose (Gy) PTV1_TLD_sup PTV1_TLD_inf PTV2_TLD_sup PTV2_TLD_inf STOMACH_TLD Mid-STOMACH_TLD KIDNEY_TLD CORD_TLD Results of the QA: Did you adjust the MU based on these results? If so, how much? Attach copies of the treatment plan including slices in the sagittal, axial and coronal film planes from both targets. Comments: For Office Use Only TLD Batch Film Batch Phantom ID # Code Date Sent Date Rec'd 7

8 This is a cross sectional view of the phantom. Liver Stomach B Right A Left GTV2 GTV1 Kidney Cord 8