ESTRO 2023 - Abstract Book

S1026

Digital Posters

ESTRO 2023

Conclusion In our series, MSKCC nomogram does not reach statistical significance. Regarding other potential predictive risk factors of LR, non-expression of estrogen receptors was significantly associated with an increased risk of LR. The LR rate was 9.6%, in accordance with the published series.

PO-1282 In-field axial cardiac contact distance-a measure of adequate breath-hold in breast cancer radiation

Y. Sreenija 1 , A. Abdul Nizar 1 , A. Sasidharan 1 , S. Kalavagunta 1 , D. Dutta 1

1 Amrita Institute of Medical Sciences, Radiation Oncology, Kochi, India

Purpose or Objective Objective of this study was to assess whether the cardiac contact distance (CCD) parameters in the axial view of breath hold simulation scan – axial CCD (CCDax) and in-field axial CCD (CCDtf) correlates with mean heart dose, and its use as a measure to check the adequacy of breath-hold taken by the patient of left sided breast cancer. Materials and Methods In the current retrospective observational study, radiotherapy plans of twenty patients with left-sided breast cancer treated with ABC-controlled breath-hold were reviewed. The field-in-field bitangential technique was used in all treatment plans. Fields were placed using standard anatomical landmarks. The prescription dose for the whole breast radiotherapy was 40Gy in 15 fractions. CCDax was measured as the shortest linear distance from the points of contact of the cardiac silhouette with the chest wall, at the level of the dome of the right diaphragm, in the axial plane of the CT scan. The part of CCDax within the tangential field ie, the infield CCDax was documented as CCDtf [Figure 1]. The extent of shielding of the heart status was documented as: no shielding of the heart volume within the tangential field, partial shielding (33% of heart within the tangential field), almost shielding (66%), or fully shielded (100%). Pearson correlation coefficient was used for statistical analysis.

Results Median MHD was 1.5 Gy (IQR = 0.9Gy to 1.9Gy). The median inspiratory volume threshold was 1.1 litres (Range: 1 to 1.3 litres), and the median duration of breath-hold was 22 seconds (Range: 20 to 24 seconds). Pearson correlation coefficient