Faculty Collaboration Database

Respiratory organ motion and dosimetric impact on breast and nodal irradiation. Int J Radiat Oncol Biol Phys 2010 Oct 01;78(2):609-17

Date

05/18/2010

Pubmed ID

20472366

DOI

10.1016/j.ijrobp.2009.11.053

Scopus ID

2-s2.0-79151472430 (requires institutional sign-in at Scopus site)   40 Citations

Abstract

PURPOSE: To examine the respiratory motion for target and normal structures during whole breast and nodal irradiation and the resulting dosimetric impact.

METHODS AND MATERIALS: Four-dimensional CT data sets of 18 patients with early-stage breast cancer were analyzed retrospectively. A three-dimensional conformal dosimetric plan designed to irradiate the breast was generated on the basis of CT images at 20% respiratory phase (reference phase). The reference plans were copied to other respiratory phases at 0% (end of inspiration) and 50% (end of expiration) to simulate the effects of breathing motion on whole breast irradiation. Dose-volume histograms, equivalent uniform dose, and normal tissue complication probability were evaluated and compared.

RESULTS: Organ motion of up to 8.8mm was observed during free breathing. A large lung centroid movement was typically associated with a large shift of other organs. The variation of planning target volume coverage during a free breathing cycle is generally within 1%-5% (17 of 18 patients) compared with the reference plan. However, up to 28% of V(45) variation for the internal mammary nodes was observed. Interphase mean dose variations of 2.2%, 1.2%, and 1.4% were observed for planning target volume, ipsilateral lung, and heart, respectively. Dose variations for the axillary nodes and brachial plexus were minimal.

CONCLUSIONS: The doses delivered to the target and normal structures are different from the planned dose based on the reference phase. During normal breathing, the dosimetric impact of respiratory motion is clinically insignificant with the exception of internal mammary nodes. However, noticeable degradation in dosimetric plan quality may be expected for the patients with large respiratory motion.

Author List

Qi XS, White J, Rabinovitch R, Merrell K, Sood A, Bauer A, Wilson JF, Miften M, Li XA

MESH terms used to index this publication - Major topics in bold

Adult
Aged
Breast
Breast Neoplasms
Female
Four-Dimensional Computed Tomography
Heart
Humans
Lung
Lymphatic Irradiation
Mastectomy, Segmental
Middle Aged
Movement
Organ Size
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted
Radiotherapy, Conformal
Respiration
Retrospective Studies
Statistics, Nonparametric
Tumor Burden