Keywords:
Breast, Radioprotection / Radiation dose, Dosimetry, Physics, Radiation therapy / Oncology
Authors:
T. Berris1, M. Mazonakis2, J. Stratakis2, A. Tzedakis1, A. Fasoulaki1, J. Damilakis2; 1Heraklion/GR, 2Iraklion/GR
DOI:
10.1594/ecr2011/C-0122
Results
Verification of the simulated beam's dosimetric properties
The calculations performed for the verification of the beam's dosimetric properties agreed very well with the measured data on a water phantom.
Figure 1 shows PDD calculations for a 20 x 20 cm2 field superimposed to measurement data for the same field size.
Doses were normalized to d10.
Local differences did not exceed 2%.
Figure 2 demonstrates the comparison between the measured and the calculated lateral dose profile for the 20 x 20 cm2 field at d10.
Local differences were less than 2% in the plateau region of the profile.
Breast cancer radiotherapy simulation
As expected the primary irradiated left breast received nearly the prescribed dose of 50.4 Gy. The dose to the contra-lateral breast was found to be equal to 1.4% of the prescribed dose for both field sizes.
The radiation dose to critical structures from irradiation with the small and large field sizes is presented in figures 3 and 4,
respectively.
For the small field dimensions of 10 x 16 cm2,
the doses to organs partially included in the therapeutic field (red bone marrow,
skin,
lung,
bone surface) ranged between 148.6 and 1935.7 mGy.
Organs outside the collimated field received lower doses of 18.2-333.3 mGy.
The field size was found to influence organ doses.
An average increase of 19.6% was observed when the therapeutic field area was increased by 25%.