TITLE:
A Post-Mastectomy Radiation Therapy Dose Distribution Study
AUTHORS:
Xin Qian, Kalpana Vaidya, Lindsay Puckett, Ferney Diaz, Xiaoli Tang, Lucille Lee, Eric Klein
KEYWORDS:
Breast Radiotherapy, Post-Mastectomy, Chest-Wall Surface Dose, OSLD, NanoDot
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.6 No.4,
November
29,
2017
ABSTRACT: Purpose: For post-mastectomy radiation therapy, skin dose must be accurately
estimated to assess skin reactions, such as: erythema, desquamation, and necrosis. Even with
advanced algorithms, planning systems do not always provide accurate dosimetry for target volumes distal to skin. Methods
and Materials: In this study, a female anthropomorphic (ART) phantom and
the newest generation of optically
stimulated luminescence dosimeters (OSLD) (nanoDots, Landauer Inc.) were
deployed to measure chest wall dose distribution. Since actual dose to
patients’ lung and heart cannot be measured using in-vivo dosimetry, film was also used to verify the dose distribution to the left lung
and heart. The treatment planning was performed using tolerance limits of 95%
to 107% of prescription dose. The ART phantom was irradiated according to 3 three-dimensional
(3D) conformal radiotherapy plans for 200 cGy dose per fraction using 6 MV medial and lateral
tangential photon beams. The dose distribution provided by treatment planning was studied
using nanoDots and film. Results: Results show that the largest
surface dose difference between nanoDots measurement and prescribed dose for
medial and lateral tangential beams, are 3.8% and 9.8%, respectively. This
difference may be due to higher effective point of measurement and angular
dependence of the nanoDots. The maximum differences in measured dose compared with prescribed dose,
using film for heart and the left lung, were 6.2% and 7.5% respectively. Conclusions: Both nanoDots and film provided reasonable estimation of dose distribution in
post-mastectomy radiation therapy.