(Sunday, 7/14/2019)
Room: ePoster Forums
Purpose: To determine a clinical decision tool for optimal delivery of liver particle radiotherapy.
Methods: Spherical gross tumor volumes (GTVs) with diameters of 2 cm to 10 cm were contoured at the dome, caudal, center, left and right lobes of the liver for a typical liver cancer patient. Planning target volumes were generated by expanding the GTVs uniformly by 5 mm. Intensity modulated proton and carbon-ion plans were made using a prescription dose of 66 Gy(RBE) in 10 fractions. The criteria for a clinical acceptable plan were: the absolute volume of normal liver (liver minus GTV) receiving dose less than 15 Gy(RBE) was less than 600 cc; 95% of the prescription dose covered at least 99% of the GTV; the maximum doses of the GI organs and spinal cord was less than 30 Gy(RBE); and the mean dose of the right kidney was less than 10 Gy(RBE).
Results: All carbon-ion plans met the criteria. Proton plans in which the target sizes were 10 cm at dome and center did not meet all of the criteria (see figure 1). The integral doses and the normal liver mean dose from carbon-ion plans were 70 ± 20% and 68 ± 15% of the doses from proton plans respectively.
Conclusion: For tumor sizes less than 8 cm, proton and carbon-ion can be used to treat the patients at any positions. For tumor size larger than 10 cm, however, carbon-ion had better target dose coverage and liver sparing. Reproducibility of the results using more patients is still needed.
Keywords
Not Applicable / None Entered.
Taxonomy
TH- External Beam- Particle therapy: Carbon ion therapy - experimental dosimetry
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