Hemibody and total body radiation
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This document discusses hemi-body and total body irradiation techniques. Total body irradiation (TBI) delivers a uniform whole body radiation dose and is used as a conditioning regimen before bone marrow transplantation. It was developed in the early 1900s and is now used to treat various cancers and blood disorders. TBI can be delivered using dedicated or modified conventional irradiators. Dosimetry and compensators are used to ensure uniform dose delivery. Adverse effects include nausea, vomiting, pneumonitis and cataracts. Hemi-body irradiation treats only the upper or lower half of the body and has fewer side effects than total body irradiation.
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Hemibody and total body radiation
- 1. HEMIBODY & TOTAL BODY IRRADIATION Dr. Dhiman Das 2nd year resident. Dept. of Radiotherapy Medical College & Hospital kolkata
- 2. Total Body Irradiation TBI is a special radiotherapy technique that delivers to a patients whole body a dose uniform to within +/- 10% of the prescribed dose. It is performed as conditioning regime
- 3. Journey started only a decade after discovery of X-ray by German biophysical engineer Friedrich J. Dessauer
- 4. In 1907, Alad叩r Elfer,a medical professor in Hungary, reported his experience using a TBI technique . Arthur C. Heublein, in collaboration with Gioacchino Failla, is credited with the development of the first TBI unit in North America, located at Memorial Hospital in New York City.
- 5. In 1959, a kidney was successfully transplanted between dizygotic twins after TBI at exposures of up to 450 R. In 1957, Nobel laureate E. Donnall Thomas first reported the use of bone marrow infusion in humans following whole body irradiation or chemotherapy, and less than 1 year later he published his experience in using TBI with exposures up to 600 R followed by bone marrow transplantation.
- 6. Diseases treated with TBI Malignant Leukaemia. Aplastic anaemia. Lymphoma. Multiple Myeloma. Non Malignant Autoimmune Diseases. Inborn errors of metabolism. Aplastic anaemia
- 7. Mode of Action 1. Cytotoxicity-Destroy the bone marrow & tumour cells of the recipient. 2. Immunosuppression-Immunosuppress the patient sufficiently.
- 8. auto-SCT cytotoxicity allo-SCT cytotoxicity immunosuppression
- 9. Types of allo-SCT Myeloablative a) immunosuppression b) To create space in bone marrow for donor cells. c) To provide further cytoreduction. Example- total dose of 12- 15Gy Nonmyeloablative Mainly a) & b) c) to a much lesser degree. Example- 2Gy single #
- 10. Types of TBI TOTAL DOSE NO. OF # 1.HIGH DOSE TBI 12Gy 1-6 2.LOW DOSE TBI 10-15cGy/# 10-15 3.TOTAL NODAL IRRADIATION 40Gy 20
- 11. TBI based regime vs Chemotherapy alone
- 12. To conclude.. TBI Pros. Access to sanctuary sites Controllable dose delivery. Cons. Interstitial pneumonitis. Catarct. Endocrine deficiency Chemotherapy. Pros. No special arrangements needed like TBI Cons. Hepatic VOD/SOS.(BuCy) Haemorrhagic cystitis.(BuCy) Seizures.(oral busalphan)
- 13. Mode of Delivery A. Dedicated irradiator. B. Modified conventional irradiator.
- 14. A. Dedicated Irradiators. 1. Treatment at extended SSD.
- 16. 2.Treatment at standard SSD after the Co饗collimator is removed.
- 17. B.Modified Conventional Irradiator. 1.Treatment with a translational beam
- 18. 2.Treatment with a sweeping beam.
- 20. Choice of Technique Depends on- Available equipment Photon beam energy Maximum possible field size Treatment distance Dose rate Patient dimension
- 21. Choice of Beam Energy
- 22. Choice of Portals 1. AP/PA. o Pros a) Better dose uniformity along the longitudinal body axis. b) Convenient for treating small children. o Cons-patient positioning (other than standing upright) may pose problem. Developed in Memorial Sloan Kattering hospital,New York. Shielding (Dusenbery & Gerbi)- Lung,kidney, Brain.
- 24. 2.Bilateral TBI Pros- More comfortable to the patient. Cons- Greater variation in body thickness along the path of the beam.
- 26. Patient positioning Semifetal position(khan et al.) Arms are positioned laterally to follow the body contour. Arms should shadow the lungs, not the Spinal Column. Pt set-up. SAD
- 27. Compensators are designed for H&N ,lungs,legs. Reference thickness for compensator is the lateral diameter of the body at the level
- 28. Compensator Design Challenges Large variation in body thickness. Lack of complete body immobilisation. Internal tissue heterogeneities.
- 29. Compensator Thickness along a ray line a) Tissue deficit, compared to the reference depth at the prescription point. b) Material(density). c) Distance from the point of compensation. d) Depth of the point of compensation. e) Field size. f) Beam energy.
- 30. Thickness Ratio() The required thickness of a tissue equivalent compensator that gives the same dose at the point of interest as would a bolus of thickness equal to the tissue deficit. For TBI an average value of 0.7 provides good approximation of all beam energies & compensation conditions.
- 31. Formulae to obtain compensator thickness 1. Tc=comp thickness TD=tissue deficit 痢c=density of comp 2. I/I魅=doses before & after comp added. T(A甦d甦) &T(A d)=TPR for ref body section & sectn to be compensated.
- 33. Dosimetry A.Directly By using a 0.6cm甬 Farmer- type ionisation chamber placed in a 40cm甬 water phantom. By placing TLD capsule/chips in strategic locations in body.(in-vivo dosimetry) B.Indirectly By using this formula.
- 34. Adverse effects In nonmyeloablative regimen Acute Nausea Vomiting Long term cataract
- 35. Adverse effects In myeloablative regimens Acute Nausea, Vomiting mucositis Diarrhoea Xerostomia Headache Fever HTN Reversible alopecia Parotiditis Long-term Lung-interstitial pneumonitis. Lens-cataract. Growth & gonadal & Endocrine effects. Liver-VOD & SOS Kidney. 2属 cancers.
- 36. HEMI BODY IRRADIATION INDICATIONS- To alleviate symptoms in metastatic diseases. Delaying progression of existing asymptomatic mets. Defers development of new mets.
- 37. Difference with TBI Different therapeutic goal. Smaller field size. Lesser side effects
- 38. Technique Bottom of L4 separates uper & lower half. A/P parallal opposed fields. Patients positioned with vertical beam allowing coverage of hemibody. Necessary shielding. Dose prescribed to mid-plane of the patient at the central axis of the beam.
- 39. Dose Upper HBI-6Gy Lower HBI-8Gy Rx for other half Wait for 6-8 weeks.
- 40. Side effects Nausea ,vomiting(M/C) Fatigue. Cough, breathlessness. Interstitial pneumonitis. Reversible alopecia Dry mouth, stomatitis. Parotid swelling.