Search Courses

DJR 45-2B: Correlation of Hot Spot to Breast Separation in Patients Treated with Post-Lumpectomy Tangent 3D-CRT Using Field-in-Field Technique

Course Details

MDCB Credits: 2.50

ARRT Credits: 2.50

Available Until: 6/30/2021

Non-Member Price: $87.50

Member Price: $50.00

Member PLUS Price: $50.00

Add to My Courses

Once you have exceeded your annual free credit allowance you will be prompted to pay a per-credit fee.

Courses purchased using your credit allowance are non-refundable and need to be completed before their expiration date

View your annual credit allowance here.

Nancy R. Gustafson, D.V.M., M.S., C.M.D., D.A.C.V.R., Teri Burrier, M.S., C.M.D., R.T.(R)(T), Brittany Butler, M.S., C.M.D., R.T.(R)(CT), Ashley Hunzeker, M.S., C.M.D., Nishele Lenards, Ph.D., C.M.D., R.T.(R)(T), F.A.A.M.D., Lee Culp, M.S., C.M.D., R.T.(T)
Department of Health Professions, University of Wisconsin –La Crosse, La Crosse, Wisconsin, USA

Radiotherapy to an intact breast was previously determined to have a positive correlation between breast separation measurement and hot spot dose. As breast separation measurement increased, hot spot dose increased. The purpose of this retrospective study was to determine if this correlation persisted despite current techniques including field-in-field (FiF) blocking and mixed photon energies. Radiation treatment plans on unilateral intact breasts from 90 female, early-stage breast cancer patients treated with lumpectomy were analyzed. Plans were created using 3-dimensional conformal radiation therapy (3D-CRT) nondivergent opposing tangent beams, FiF technique, and 6 MV with or without higher energy photons. Data collected included breast separation measurement, hot spot point dose and location, number of beams, photon energy, clinical target volume (CTV) coverage and breast volume coverage. Correlations between breast separation measurement and each of these values were determined. The positive correlation between breast separation measurement and hot spot dose persisted despite incorporating FiF and mixed photon energies. Correlations were also found between breast separation and the number of beams as well as breast separation and photon energy. Larger breast separations tended to be treated with additional beams of higher photon energy. There were no correlations found between breast separation and CTV or breast volume coverage. The data in this study suggested the medical dosimetrist should expect hot spots above prescription dose of 106%, 107%, and 108% for small, medium and large breast separation sizes respectively. Additionally, adding a high energy photon bean may be indicated with medium and large breast separations.