Room: ePoster Forums
Purpose: to investigate the volume of liver spared in the high dose region with voluntary Deep Inspiration Breath Hold (vDIBH) during right breast 3D conformal radiation therapy.
Methods: five patients receiving 50.4 Gy in 28 fractions 3DCRT to the right breast /right chest wall. Simulations were performed with free breathing FB and vDIBH technique. Two of patientsâ€™ breathing signals were monitored and tracked using calypso system, while three patientsâ€™ breathing signals were monitored and tracked using respiratory motion management system RPM. Contours of targets and organs at risks were delineated on both FB and vDIBH simulation CTs. 3D tangential field-in-field treatment plans using Varian Eclipse 13.7 treatment planning system were generated on both FB-CT and vDIBH-CT achieving comparable and acceptable target coverage (D95% covering 100% of the CTV contoured by the clinicians). Mean dose, Max dose, V40, V30, and V20 of the liver were obtained from Dose Volume Histograms for each patientsâ€™ FB-plan and vDIBH-plan.
Results: The mean dose to the liver was reduced by 64.5% on average for all 5 patients, and 25.6% on average for max dose. V40, V30, and V20 were reduced by 55.7%, 75.3%, and 75% on average respectively for all 5 patients.
Conclusion: Partial liver volumes falling into the high dose region was inevitable in pursuance of achieving adequate target coverage in FB-plans, while liver avoidance was significant in vDIBH-plans for the same target coverage. The mean doses to the liver in FB- plans were less than the dosimetric toxicity parameter (30Gy) associated with the risk of Radiation Induced Liver Disease (RILD), nevertheless FB-plans were sub-optimal considering the good prognosis of the patients and the feasibility of optimal plans with vDIBH. In addition, sparing liver tissues becomes a necessity to reduce RILD probability in the case of preexisting liver dysfunction comorbid with RT breast cancer.
Radiation Therapy, Treatment Techniques, Breast
TH- External beam- photons: Motion management (intrafraction)