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Appendix C

Learn about IGRT in prostate cancer treatment, anatomical considerations, machine parameters, matching techniques, and troubleshooting tips. This module assists in optimizing radiation therapy procedures for prostate cancer patients.

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Appendix C

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  1. Appendix C Prostate Module

  2. Disclaimer • This learning module was created as starting point for each cancer centre to implement as part of IGRT Education in their radiation department. • The material included may not be suitable in every clinical environment. • This module is designed to be adjusted to include your centre’s site specific policies and procedures. • This material was developed by members of the Radiation Therapy Community of Practice – IGRT Education Group.

  3. Introduction • IGRT is a method to use imaging in the treatment unit to improve the delivery of IMRT • Allows better targeting of the location of the tumor while avoiding nearby healthy tissue everyday immediately prior to radiation treatment

  4. Cross Sectional Anatomy • Prostate • Bladder • Rectum • Seminal Vesicles • External/Internal iliac lymph nodes • Pubic Symphysis/Pubic Bone • Sacrum • LT/RT Femur • Small Bowel

  5. Region of Interest • Prostate/Prostate Bed • Bladder • Rectum • Seminal Vesicles • External/Internal iliac lymph nodes • Cowper’s gland

  6. Machine Parameters - Varian MV matching • EPI KV/KV matching • Orthogonal images taken using KV imager CBCT matching • Full Scan vs Half Scan, using KV source & detector • Bowtie Filter

  7. Matching Considerations • Organ at Risk • Rectum, Bladder • Priorities (center/case-specific) • Bony match • Prostate-Rectum Interface • Fiducial markers

  8. Matching Considerations • Center-specific – usually patients are required to have Full Bladder and Empty Rectum to decrease potential side effects from radiation treatments

  9. MV Matching • It is center-specific where fiducial markers are used for patients who have prostate still in tact • MV imaging are usually used in this case if no other imaging modalities are available • Reference fields are generally given to match seeds for patients

  10. MV Matching • 2 phases are usually used for treatment • Phase 1 – large volume to cover nodes • boney anatomy usually matched & check position of seeds • Phase 2 – small volume focusing on the prostate • usually matched to seeds

  11. KV/KV Matching • Orthogonal fields are generated for image matching • Prostate/prostate bed usually matched based on boney anatomy • Pubic Symphysis/Pubic Bone • Sacrum • Pelvic Brim

  12. KV/KV Matching • Center-specific – KV may used as confirmation after CBCT completed in order to confirm larger shifts.

  13. CBCT Matching • CBCT allows therapists to precisely check the daily rectum and bladder status prior to radiation treatment • CBCT allows therapists to perform daily soft tissue match prior to radiation treatment • Case-specific – if Full Scan vs Half Scan to be used on patients

  14. Full Scan vs Half Scan • Full Scan – Full contour of the body generated • Half Scan/Spot Light – Cone down field generated, focusing on the prostate • Bowtie Filter used

  15. CBCT Matching • In cases where there is no prostate seeds to help localize the prostate. Using prostate-rectal interface to match is a good indication to ensure prostate is within CTV volume and rectum is outside of treatment volume

  16. CBCT Matching • In cases where the prostate clips are present after prostatectomy, prostate clips allow therapists to localize the surgical site and ensure precise treatment localization

  17. Trouble Shooting Common Issues when imaging prostate patients • Gas in the rectum • Stool in the rectum • Empty bladder

  18. Trouble ShootingGas in the rectum

  19. Trouble ShootingGas in the rectum • In cases where there is gas in the rectum, rectum size is usually bigger then the contour • Anterior wall of the rectum is being pushed anteriorly into the CTV region, and this might increase the dose delivered to normal rectal tissues. • In most cases, patients are asked to step off the treatment couch and try to pass some gas

  20. Trouble ShootingStool in the rectum • Stool in the rectum also increase the area of the rectal wall into the CTV region. In most cases, patients are ask to empty their rectum before proceed on with radiation treatment

  21. Trouble ShootingEmpty bladder

  22. Trouble ShootingEmpty Bladder • In most cancer centers, bladder protocol is being followed by patients before radiation simulation and treatment • Having full bladder for treatment reduce the chance of potential diarrhea and radiation-induced cystitis • If patients’ bladder is empty, therapists will suggest patient to fill up the bladder prior treatment and re-enforce the importance of having full bladder

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