(Sunday, 7/12/2020) [Eastern Time (GMT-4)]
Room: AAPM ePoster Library
Purpose: Scleroderma is an autoimmune disease with considerable morbidity and mortality. Recently, Total Body Irradiation (TBI) conditioning as part of an autologous hematopoietic stem-cell transplantation has become standard of care per the outcome of the randomized phase II study The Scleroderma: Cyclophosphamide (CY) or Transplantation (SCOT) Trial. TBI for scleroderma involves coordination between multiple departments and individuals making it a challenging technique in terms of physics as well as practical aspects. These challenges have impeded its widespread implementation. Our purpose is to present our institution’s experience to assist other centers in starting up their own TBI for scleroderma programs.
Methods: Our TBI team consisted of a multi-department team including therapists, physicists, nurses, and physicians who developed comprehensive procedures for the entire workflow including commissioning/QA, scheduling, consultation, simulation, planning, and delivery. With our experience on the SCOT trial and our recent experience since TBI conditioning became standard of care, our team was able to address and overcome challenges that affected our workflow. TBI for Scleroderma is delivered using large parallel opposed AP/PA fields. 800 cGy in 4 fractions is prescribed BID to a point mid-plane at umbilicus level. Lung and kidneys are limited to 200 cGy in 4 fractions. Patient-specific partial-transmission cerrobend blocks for lung and kidneys are generated from CT (head-first-supine), MV (standing), and US (prone and sitting) imaging. A pre-treatment dry-run is performed to verify block positons via CR imaging. First fraction entrance and exit in-vivo dosimetry using OSLDs are performed for prescription point, lung, and kidneys and evaluated for a tolerance criteria of ±10%.
Results: Fourteen patients from 8/2018 to 12/2019 were treated since TBI for scleroderma became standard of care.
Conclusion: With TBI conditioning pre-transplantation becoming the new standard of care for scleroderma, careful implementation of not just physics but also practical aspects can achieve satisfactory dosimetry.
Keywords
Taxonomy
TH- External Beam- Photons: General (most aspects)
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