Postlumpectomy focal brachytherapy for simultaneous treatment of surgical cavity and draining lymph nodes.
OBJECTIVE
The primary objective was to investigate a novel focal brachytherapy technique using lipid nanoparticle (liposome)-carried β-emitting radionuclides (rhenium-186 [(186)Re]/rhenium-188 [(188)Re]) to simultaneously treat the postlumpectomy surgical cavity and draining lymph nodes.


METHODS
Cumulative activity distributions in the lumpectomy cavity and lymph nodes were extrapolated from small animal imaging and human lymphoscintigraphy data. Absorbed dose calculations were performed for lumpectomy cavities with spherical and ellipsoidal shapes and lymph nodes within human subjects by use of the dose point kernel convolution method.


RESULTS
Dose calculations showed that therapeutic dose levels within the lumpectomy cavity wall can cover 2- and 5-mm depths for (186)Re and (188)Re liposomes, respectively. The absorbed doses at 1 cm sharply decreased to only 1.3% to 3.7% of the doses at 2 mm for (186)Re liposomes and 5 mm for (188)Re liposomes. Concurrently, the draining sentinel lymph nodes would receive a high focal therapeutic absorbed dose, whereas the average dose to 1 cm of surrounding tissue received less than 1% of that within the nodes.


CONCLUSIONS
Focal brachytherapy by use of (186)Re/(188)Re liposomes was theoretically shown to be capable of simultaneously treating the lumpectomy cavity wall and draining sentinel lymph nodes with high absorbed doses while significantly lowering dose to surrounding healthy tissue. In turn, this allows for dose escalation to regions of higher probability of containing residual tumor cells after lumpectomy while reducing normal tissue complications.
Hrycushko
Brian A
BA
Department of Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA.
Li
Shihong
S
Shi
Chengyu
C
Goins
Beth
B
Liu
Yaxi
Y
Phillips
William T
WT
Otto
Pamela M
PM
Bao
Ande
A
D000818:Animals; D001365:Axilla; D001918:Brachytherapy / Q000379:methods*; D001943:Breast Neoplasms / Q000532:radiotherapy*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008081:Liposomes; D008198:Lymph Nodes / Q000528:radiation effects; D015182:Lymphatic Irradiation / Q000379:methods*; D015412:Mastectomy, Segmental; D053758:Nanoparticles; D018365:Neoplasm, Residual; D011868:Radioisotopes / Q000008:administration & dosage*; D011879:Radiotherapy Dosage; D012211:Rhenium / Q000008:administration & dosage*
D008081:Liposomes; D011868:Radioisotopes; D012211:Rhenium