title: Skin-sparing helical tomotherapy vs 3D-conformal radiotherapy for adjuvant breast radiotherapy: in vivo skin dosimetry study.
abstract: OBJECTIVE
  We investigated whether treatment-planning system (TPS)-calculated dose accurately reflects skin dose received for patients receiving adjuvant breast radiotherapy (RT) with standard three-dimensional conformal RT (3D-CRT) or skin-sparing helical tomotherapy (HT).
  
  
  METHODS
  Fifty patients enrolled in a randomized controlled trial investigating acute skin toxicity from adjuvant breast RT with 3D-CRT compared to skin-sparing HT, where a 5-mm strip of ipsilateral breast skin was spared. Thermoluminescent dosimetry or optically stimulated luminescence measurements were made in multiple locations and were compared to TPS-calculated doses. Skin dosimetric parameters and acute skin toxicity were recorded in these patients.
  
  
  RESULTS
  With HT there was a significant correlation between calculated and measured dose in the medial and lateral ipsilateral breast (r = 0.67, P<.001; r = 0.44, P=.03, respectively) and the medial and central contralateral breast (r = 0.73, P<.001; r = 0.88, P<.001, respectively). With 3D-CRT there was a significant correlation in the medial and lateral ipsilateral breast (r = 0.45, P=.03; r = 0.68, P<.001, respectively); the medial and central contralateral breast (r = 0.62, P=.001; r = 0.86, P<.001, respectively); and the mid neck (r = 0.42, P=.04, respectively). On average, HT-calculated dose overestimated the measured dose by 14%; 3D-CRT underestimated the dose by 0.4%. There was a borderline association between highest measured skin dose and moist desquamation (P=.05). Skin-sparing HT had greater skin homogeneity (homogeneity index of 1.39 vs 1.65, respectively; P=.005) than 3D-CRT plans. HT plans had a lower skin(V50) (1.4% vs 5.9%, respectively; P=.001) but higher skin(V40) and skin(V30) (71.7% vs 64.0%, P=.02; and 99.0% vs 93.8%, P=.001, respectively) than 3D-CRT plans.
  
  
  CONCLUSIONS
  The 3D-CRT TPS more accurately reflected skin dose than the HT TPS, which tended to overestimate dose received by 14% in patients receiving adjuvant breast RT.
authors.affiliation: Division of Radiation Oncology, Cross Cancer Institute and University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Lisa
authors.initials: L
authors.lastname: Capelle
authors.forename: Heather
authors.initials: H
authors.lastname: Warkentin
authors.forename: Marc
authors.initials: M
authors.lastname: Mackenzie
authors.forename: Kurian
authors.initials: K
authors.lastname: Joseph
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Gabos
authors.forename: Nadeem
authors.initials: N
authors.lastname: Pervez
authors.forename: Keith
authors.initials: K
authors.lastname: Tankel
authors.forename: Susan
authors.initials: S
authors.lastname: Chafe
authors.forename: John
authors.initials: J
authors.lastname: Amanie
authors.forename: Sunita
authors.initials: S
authors.lastname: Ghosh
authors.forename: Matthew
authors.initials: M
authors.lastname: Parliament
authors.forename: Bassam
authors.initials: B
authors.lastname: Abdulkarim
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001940:Breast / Q000033:anatomy & histology / Q000528:radiation effects; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008163:Luminescent Measurements / Q000379:methods; D008875:Middle Aged; D009333:Neck / Q000528:radiation effects; D009929:Organ Size; D059351:Organ Sparing Treatments / Q000379:methods*; D011832:Radiation Injuries / Q000517:prevention & control*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D018714:Radiotherapy, Adjuvant; D020266:Radiotherapy, Conformal / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012867:Skin / Q000528:radiation effects*