Electronic Brachytherapy
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Electronic brachytherapy (EBX) is a treatment method utilizing miniaturized high dose rate x-ray sources to deliver targeted radiation directly to cancerous sites while minimizing exposure to healthy tissue. EBX offers advantages such as the absence of radioactive isotopes, lower shielding requirements, and the ability for medical personnel to remain in the room during treatment. With similar dose distributions to low and high dose rates, EBX has the potential to replace traditional radionuclide-based brachytherapy in the future.
Electronic Brachytherapy
- 1. ELECTRONIC BRACHYTHERAPY BASIL PAUL SUNNY Chief Radiation Therapist All India Instituite of Medical Sciences, Jodhpur, India
- 2. BRACHYTHERAPY Brachytherapy is a method of treatment in which sealed radioactive sources are used to deliver radiation at short distance. The prefix “Brachy" , derived from the Greek word, Literally means "short“.
- 3. SYNONYMS OF BRACHYTHERAPY Brachytherapy has also been called as Curietherapy Endocurietherapy Plesiotherapy
- 4. ADVANTAGES OF BRACHYTHERAPY High radiation dose can be delivered locally to the tumour. Rapid fall off dose in the surrounding normal tissue. Less integral dose.
- 5. LIMITATIONS OF BRACHYTHERAPY Accessibility of tumour volume and its size. If lesion is too big, too many radioactive foci are required. High risk of exposure during preparation and application of sources. Source reconstruction and dosimetry are laborious.
- 6. SOURCES FOR BRACHYTHERAPY Cs-137 Ir-192 Co-60 I-125 Pd-103 Ra-226 (discontinued)
- 7. FORMS OF BRACHYTHERAPY Pellets Seeds Miniature cylinders, tubes and wires
- 8. Treatment time Temporary Permanent TYPES OF BRACHYTHERAPY Dose Rate LDR MDR HDR PDR Application Surface mould Intracavitary Intraluminal Interstitial
- 9. ELECTRONIC BRACHYTHERAPY It is a type of radiotherapy that utilizes a miniaturized high dose rate (HDR) X-ray source to apply radiation directly to the cancerous site. The goal is to direct the radiation dose to the size and shape of the cancerous area, sparing healthy tissue and organs.
- 10. HISTORY Electronic brachytherapy (eBx) applies interstitial irradiation without radionuclides A miniature x-ray tube is commonly employed eBx conceived in the 1980s by Alan Sliski of PhotoElectron Corp. in collaboration with MIT
- 11. HISTORY Dosimetric properties and source characteristics first published in 1993 (Biggs et al., Gall et al., Smith et al.) in Medical Physics ~ 10 other companies pursued eBx since then
- 12. RATIONALE
- 13. VENDOR EXAMPLES Advanced X-ray Technologies Inc. Birmingham,US Carl Zeiss Ltd. Germany Xoft Inc. Fremont ,US
- 14. ADVANCED X-RAY TECHNOLOGIES Use of primary and secondary targets 90 kv x rays from primary target are directed down to impinge secondary target Variety of primary and secondary target materials Best penetration with W:Nd combo
- 15. ELECTRONIC BRACHYTHERAPY Courtesy : Gutmen et al , Phys Med Biol
- 18. Carl Zeiss Ltd.
- 19. Xoft Inc.
- 20. ADVANTAGES OF AXXENT eBx The Axxent eBx System does not utilize a radioactive isotope, or require a high dose rate (HDR) isotope afterloader, and thus does not require the heavily- shielded treatment rooms. The Axxent System has similar dose rates to HDR, however, the dose fall-off rate is lower, so the patient receives less dose to critical organs and healthy tissue."
- 21. COMPONENTS OF AXXENT eBx Controller Applicator X-ray source
- 22. CONTROLLER The controller is a mobile platform that is responsible for the overall operation of the device
- 23. CONTROLLER
- 24. X-RAY SOURCE The miniature x-ray source comprises low energy x-ray tube integrated into a flexible multilumen catheter that allows cooling fluid to circulate over the tube X-rays of 50 kV maximum energy are produced at the tip of the catheter, which otherwise closely resembles current remote afterloading units. Requires a high voltage connector
- 26. X-RAY SOURCE Assembly diameter = 5.4 mm Tube diameter = 2.25 mm Nominal dose rate =0.6 Gy/min at 3.0 cm in water
- 27. APPLICATORS Balloon applicator Vaginal cylinders Cones for skin or internal organ surfaces
- 28. APPLICATORS
- 29. BALLOON APPLICATOR Sterile, disposable, single use device that functions as a guide for the x-ray source. An integral drain is built into the balloon applicator for serom drainage, which can be evacuated using a syringe. Balloons are mostly used in breast irradiation
- 30. Accelerated Partial Breast Irradiation (APBI), system
- 31. USB Port Data transfer to the unit is done via USB drive Process includes • Download data to initiate treatment • store delivered data that will be printed
- 32. WORKFLOW Pretreatment imaging of the patient Creation of treatment plan Pretreatment QA of patient source Verify patient identity Load patient dwell time(s) into controller Calibration of source (correct for temperature & pressure) Verify proper dwell time adjustment
- 33. WORK FLOW Align controller and connect to the patient Place flexible shielding(to the benefit of the patient) Place rolling shield(to the benefit of operator) Begin treatment
- 34. SHIELDING Dose falls rapidly with distance Lead shield reduces exposure rate by 100-1000X Lead Apron reduces exposure rate by 1100X
- 35. FLEXISHIELD Is a flexible silicone and tungsten sheet Placed over the patient for all treatment applicators It reduces the ambient exposure rate in the treatment room It increases the skin dose by ~ 8% but this drops rapidly to less than 1% in 1 mm skin depth
- 36. SOURCE CALIBRATION Uses software for calibration Scan the source barcode and attach the source Place the source in well chamber Record the temperature and pressure System will calculate a calibration ratio
- 37. ADVANTAGES OF eBx delivery of therapeutic dose directly to the cancerous site; no radioisotope regulatory handling and safety issues; lower shielding requirements;
- 38. ADVANTAGES OF eBx medical personnel may remain in the room because of the unique characteristics of the system; less radiation delivered to surrounding healthy organs and tissue and the unique design allows for multiple applications.
- 40. SUMMARY eBx sources can have similar dose distribution to LDR and similar dose rates to HDR. eBx can have many attractive features like: ON-OFF, adjustable output , variable energy and independence from a radioactive material license. With further development, eBx can potentially replace radionuclide based brachytherapy, like LA replaced Co-60 in 1900s.
- 41. REFERENCES Brachytherapy with an Axxent : The Electronic Approach Brachytherapy with an Axxent :-ANITA CORRAO, MS, CMD, DABR,ASSISTANT CLINICAL PHYSICIST Electronic Brachytherapy Sources-Thomas W. Rusch National Medical Policy 503
- 42. THANK YOU