TBI is the radiotherapy technique to irradiate whole body before doing stem cell transplant. The main purpose of doing TBIB is to condition the immune system of body so that there will be maximum chance of transplant acceptance.

1. Total body irradiation
Planning Meet 22nd November 2018
Dr. Subhash Thakur

2. • Mr X, 12 years old male
• Diagnosed with CML, Post induction phase, being planned for Stem
Cell transplant
• Refd to RT department for TBI

3. TotaL Body irradiation
• TBI is a radiotherapy technique to provide uniform dose of radiation
to the entire body
• Can sterilize areas like CNS and Testes where traditional
chemotherapy is ineffective

4. The purpose of TBI is:
• To Eliminate Residual Cancer Cells
• To Provide Space For Stem Cell Engraftment Through Bone Marrow
Depletion And
• To Prevent Rejection Of Donor Stem Cells Through
Immunosuppression

5. RT Planning
• Planning CT
• Contouring OARs : Brain, Lungs, Liver, Bowel, Kidneys, testes
• Planning : intensity modulated TBI (IM-TBI)/VMAT-TBI.
• Radiation Delivery

6. Planning CT
• Immobilisation device, Vaclok and orfit cast and foot rest
• Positioning of patient : supine arms straight arms by side no gap,
fingers on thigh, closely approximates each other
• Fiducials : head abdomen and lower limb, marking done on body as
well as vaclok
• Length is more, so needs to be taken in 2 parts
• Head first and then foot first

7. Immobilisation device : Vacloc, foot rest and
orfit cast

8. Planning CT
• Head First Foot First

9. Ct images Acquired : Whole Body
Upper body + Lower Body

10. CT UPPER Body and LOWER Body Images
Fused

11. TBI Planning : intensity modulated TBI (IM-
TBI)/VMAT-TBI.
• PTV = Whole body = PTV head + ptv thorax + PTV abdomen + PTV
pelvis + PTV thigh + PTV foot and toe

12. PTV Thigh & Foot and toe : 3DCRT : open
fields : AP-PA fields

13. PTV 3 Gy, PTV 6 Gy and PTV 9 Gy

15. PTV Pelvis

16. PTV Abdomen : VMAT

17. PTV Thorax : Fixed Field IMRT

18. PTV head : VMAT

19. Plan Sum

20. Whole Body covered by 95% isodose curve
Hotspot

21. Doses to OAR
Organs D mean
B/L lungs 12.3 Gy
B/L kidneys 12.3 Gy
Brain 11 Gy
Liver 12.6 Gy

22. Other methods of TBI
• Bilateral TBI
• Anteroposterior TBI
• Translational TBI

23. Bilateral TBI

25. AP/PA TOTAL BODY IRRADIATION :-
The patient is irradiated antero posteriorly by
parallel-opposed fields while positioned in a
standing upright position at the TBI distance.
In this technique the modifications made to it to
accommodate shielding of specific organs such as
lungs, kidneys, and brain etc.

26. 5) Treatment with Translational Beam :-Treatment
with a sweeping beam {patient stationary & beam
moving}

27. 6) Treatment with translational couch technique :-
{patient moving & beam stationary}

28. History
• IN 1959 ; Sahler developed a dual
source cobalt irradiator technique
Lutz et al have described a unique
dual source large field and TBI
facility using ceiling and floor
mounted parallel opposed 4 MeV
linear accelerators .
Each machine can travel vertically
and the source-to-source distances
can be varied from 240 cm to 410
cm. The field size is variable with a
maximum of 75 cm x 210cm.

29. • Thank you