title: Postlumpectomy focal brachytherapy for simultaneous treatment of surgical cavity and draining lymph nodes.
abstract: 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.
authors.affiliation: Department of Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Hrycushko
authors.forename: Shihong
authors.initials: S
authors.lastname: Li
authors.forename: Chengyu
authors.initials: C
authors.lastname: Shi
authors.forename: Beth
authors.initials: B
authors.lastname: Goins
authors.forename: Yaxi
authors.initials: Y
authors.lastname: Liu
authors.forename: William T
authors.initials: WT
authors.lastname: Phillips
authors.forename: Pamela M
authors.initials: PM
authors.lastname: Otto
authors.forename: Ande
authors.initials: A
authors.lastname: Bao
mesh_terms: 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*
chemical_list: D008081:Liposomes; D011868:Radioisotopes; D012211:Rhenium