Past, present and future of radiotherapy technique in different sites: Breast, Head and Neck, Brain and Craniospinal irradiation for medduloblastoma and PNET treatment.
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Past, present and future of radiotherapy technique in different sites: Breast, Head and Neck, Brain and Craniospinal irradiation for medduloblastoma and PNET treatment.
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Past, present and future of radiotherapy technique in different sites: Breast, Head and Neck, Brain and Craniospinal irradiation for medduloblastoma and PNET treatment.
- 1. Dr.Biplab Sarkar 1,2 Seniormedicalphysicist Past, present and future of radiotherapy technique in different sites: Breast, Head and Neck, Brain and Craniospinal irradiation for medduloblastoma and PNET treatment.
- 2. Advancement in radiotherapy ïRadiotherapy has advanced with delivery technique in the recent past ïThis attribute to Volumetric Modulated arc therapy. ïWhat is ARC therapy : A Brief History ï Although arc therapy can be traced back to the dawn of the 20th century (Johns et al 1953), arcs involving dynamic field shaping using a multileaf collimator were first described by Takahashi (1965). ï Johns H E,Whitmore G F,Watson T A and Umberg F H 1953 A system of dosimetry for rotation therapy with typical rotation distributions J. Can. Assoc. Radiol. 4 ï Takahashi S 1965 Conformation radiotherapy. Rotation techniques as applied to radiography and radiotherapy ofcancer Acta. Radiol. (Stockh) Suppl. 242 3DCRT- 1980 IMRT- 1996 VMAT- 2008
- 3. Dynamic Conformal ARC Takahashi (1965)âŠâŠâŠ.. ïTakahashi described a method of rotational therapy, which we now refer to as conformal arc therapy, where the beam aperture shaped by a multiple leaf collimator (MLC) dynamically varies to match the beamâs-eye-view (BEV) of the target. Theoretical development ïIn 1982, Brahme et al (1982) solved an integral equation for a hypothetical target wrapped around a critical structure to be treated with arc therapy.
- 4. Development of ARC therapy ïThese initial developments on arc therapy were accompanied and followed by the development and wide adoption of three-dimensional conformal radiation therapy (3DCRT) in the 1980s ïIn 1995 Yu C X devolved the technique of Intensity modulated arc therapy technique (IMAT) : Did not get popular as many arc is required to generate a SnS or DMLC like dose distribution. ïIn 2008 Otto K developed the Single arc technique Which reduces the delivery time Significantly: Widely accepted as Volumetric modulated arc therapy.
- 5. Commercial Use and Functionality ïVarian has adapted the Technique developed by Otto K and commercially termed it as Rapid ARC ïImmediately after commercial release of Rapid ARC Elekta lunches its Rotational ARC solution in the name of VMAT. Basic Job is same only technique is different : Similarly Basic function between IMRT and VMAT is same : Radiation delivery ; with difference in technique
- 6. Comparison : VMAT over IMRT or 3DCRT VMAT: very conformal distribution with very short time delivery IMRT : VMAT comparable dose distribution with very long delivery time 3DCRT: Less conformal dose distribution with shorter treatment delivery time : Disclaimer: Not MLC shaped Field talking about true 3DCRT : A head neck true 3DCRT contains not less than 30 fields
- 7. Head Neck: Step n Shoot IMRT , Dynamic IMRT, Single Arc and Double Arc VMAT Double ARC VMAT
- 8. Step and Shoot IMRT
- 10. DMLC IMRT Plan
- 11. Comparison : 2 ARC VMAT; 1 ARC VMAT, Dynamic IMRT, Step and shoot IMRT 7 Beam SnS: Delivery Time 17.5 Min 7 beam DMLC IMRT: Delivery Time 9 Min Single Arc VMAT: Delivery time 1.6 min Double Arc VMAT: Delivery time 3 min
- 13. Lt Chest Wall, Lt Breast, Right Chest Wall, Right Breast Left chest Wall : Organ at risk: Heart , Left Lung . Acceptable heart dose : As low as reasonably achievable (2 Gy). Few prospective studies have addressed potential synergistic effects of RT and cardiac toxic chemotherapy among breast cancer patients. Achievable tolerance 1.5 Gy mean dose
- 14. Left Chest Wall
- 15. DVH analysis : To accept or not to accept: If to accept what to accept Loss of Dose
- 16. Right chest wall
- 17. VMAT: Partial Arc Wedge 3DCRT Field in Field 3DCRT
- 18. Most Important : Contouring and beam arrangement ïContouring Right contouring in RED Wrong contouring in GREEN
- 19. Most Important factor is contouring: A wrong contouring will lead to a disasters beam arrangement: hence a more disasters dose distribution.
- 20. Good contouring and beam arrangement A good contouring require only limited gantry rotational ARC. Required gantry angle do not exceed 30 degree for largest breast to thinnest chest wall.
- 21. IF limited arc is used for on a wrong contouring
- 22. Now what : use a full arc: Excellent distribution
- 23. Comparison: partial arc on right contour, partial arc on wrong contour, full arc on wrong contour Partial ARC and Good Contouring Full ARC and wrong Contouring Partial ARC and wrong Contouring
- 24. DVH analysis:
- 25. Choice of beam angle Classical Wedge field half beam 3DCRT beam arrangement. VMAT beam Angle: Reciprocal projection at the Midline where 3DCRT beam intersect.
- 26. Trick of the trade: Flash margin (2 cm)
- 27. Brain stereotaxy : 3DCRT : Required lots of expertise and significant amount of time. 3dcrtVMAT
- 28. VMAT gives a better conformity better OAR sparing, Higher MU, Similar treatment time, and sharper dose fall off. More Important : Very less physics time.
- 29. Myth : VMAT will give more spillage/integral dose Dose fall off :1-11 3DCRT and 12-30 VMAT
- 30. A Small Study: Effect of MLC and FFF beam in Brain Stereotaxy Synergy : 1 cm MLC Axesse :4 mm MLC Apex :2.5 mm MLC Vasha HD :5 mm MLC Varian 120HD :2.5 mm MLC Agility FFF :5 mm MLC Agility Flat :5 mm MLC
- 32. Craniospinal Irradiation 45 OAR Three sets of beam @ three isocentre. Total Nine DRR. Planning -3 times Plan and DRR sending 3 times. (A sudden call from console â today we are starting set two beams and set 2 DRR is not available in R&V system, however patient is on couch) Associated Risk: Right beam delivered at right isocentre ? Right DRR matched with right set? Significant amount of potential human error is involved in delivery
- 33. VMAT based CSI
- 36. Comparison 3DCRT and VMAT
- 37. DVH analysis : 3DCRT and VMAT
- 38. DVH Analysis : 3DCRT Vs Junction free CSI
- 40. A small Study
- 41. Hero Super Hero
- 42. I cannot tell how the truth may be; I say the tale as it was said to me." â Walter Scott " Thank You!