Oops, you're using an old version of your browser so some of the features on this page may not be displaying properly.

MINIMAL Requirements: Google Chrome 24+Mozilla Firefox 20+Internet Explorer 11Opera 15–18Apple Safari 7SeaMonkey 2.15-2.23

Poster lunch

1939 - Evaluation of Tissue Computed Tomography Number Changes and Dosimetric Shifts after Conventionally Fractionated Irradiation in Patients Undergoing Breast Conserving Surgery (79P)


18 Nov 2017


Poster lunch


Staging Procedures (not Imaging);  Surgical Oncology;  Radiation Oncology;  Breast Cancer


Dong Soo Lee


Annals of Oncology (2017) 28 (suppl_10): x16-x24. 10.1093/annonc/mdx655


D.S. Lee1, Y.K. Lee1, J.S. Kim2, J. Lee1, Y.S. Kim2

Author affiliations

  • 1 Department Of Radiation Oncology, College of Medicine, The Catholic University of Korea, 113 - Seoul/KR
  • 2 Department Of General Surgery, College of Medicine, The Catholic University of Korea, 113 - Seoul/KR


Abstract 1939


The aim of this study was to assess tissue computed tomography (CT) number changes and corresponding dosimetric shifts in repeatedly performed simulation CT (re-sim CT) scans after conventionally fractionated irradiation in breast cancer patients.


A total of 28 breast cancer patients who underwent breast conserving surgery were enrolled in this study. All patients had received 50.4 Gy of conventionally fractionated irradiation and underwent re-sim CT scans for tumor bed boost. For evaluation of dosimetric shifts between initial and re-sim CT scans, electron boost plans in the same field size, same monitor unit with source-to-skin distance (SSD) 100cm were conducted. Dosimetric parameters (D105%, D103%, D100%, D98%, D95%, D90%: Dx% indicates volumes which receive X% of prescribed doses) between initial and re-sim CT scans were compared. The CT number data (CTmean, CTmax, CTmin) of original and irradiated CT (re-sim CT) scans from each representative structure (lung, rib bone, soft tissue, muscle, etc) were examined and recruited.


CT numbers showed highly variable changes. Soft tissue CTmean and muscle CTmax/CTmin showed statistically and significantly increased values in re-sim CT compared with original CT scans. Rib bone CTmean/CTmin showed statistically and significantly decreased values in re-sim CT compared with original CT scans. Other CT number values showed no statistically significant changes. Among dosimetric parameters, only D105% (p = 0.015, mean 3.07cc versus 1.63cc) and D103% (p = 0.017, mean 13.8cc versus 11.9cc) showed statistically increased values in re-sim CT compared with original CT scans.


CT number changes after conventionally fractionated irradiation were different according to the tissue component. For electron boost plans, implementation of re-sim CT might be considered because significant dosimetric factor changes were observed especially in the high dose areas (hot spots; D105% andD103%).

Clinical trial identification

Legal entity responsible for the study

CMC IRB Ethics Committee




All authors have declared no conflicts of interest.

This site uses cookies. Some of these cookies are essential, while others help us improve your experience by providing insights into how the site is being used.

For more detailed information on the cookies we use, please check our Privacy Policy.

Customise settings
  • Necessary cookies enable core functionality. The website cannot function properly without these cookies, and you can only disable them by changing your browser preferences.