title: Dosimetric analysis of the alopecia preventing effect of hippocampus sparing whole brain radiation therapy.
abstract: BACKGROUND
  Whole brain radiation therapy (WBRT) is widely used for the treatment of brain metastases. Cognitive decline and alopecia are recognized adverse effects of WBRT. Recently hippocampus sparing whole brain radiation therapy (HS-WBRT) has been shown to reduce the incidence of memory loss. In this study, we found that multi-field intensity modulated radiation therapy (IMRT), with strict constraints to the brain parenchyma and to the hippocampus, reduces follicular scalp dose and prevents alopecia.
  
  
  METHODS
  Suitable patients befitting the inclusion criteria of the RTOG 0933 trial received Hippocampus sparing whole brain radiation. On follow up, they were noticed to have full scalp hair preservation. 5 mm thickness of follicle bearing scalp in the radiation field was outlined in the planning CT scans. Conventional opposed lateral WBRT radiation fields were applied to these patient-specific image sets and planned with the same nominal dose of 30 Gy in 10 fractions. The mean and maximum dose to follicle bearing skin and Dose Volume Histogram (DVH) data were analyzed for conventional and HS-WBRT. Paired t-test was used to compare the means.
  
  
  RESULTS
  All six patients had fully preserved scalp hair and remained clinically cognitively intact 1-3 months after HS-WBRT. Compared to conventional WBRT, in addition to the intended sparing of the Hippocampus, HS-WBRT delivered significantly lower mean dose (22.42 cGy vs. 16.33 cGy, p < 0.0001), V24 (9 cc vs. 44 cc, p < 0.0000) and V30 (9 cc vs. 0.096 cc, p = 0.0106) to follicle hair bearing scalp and prevented alopecia. There were no recurrences in the Hippocampus area.
  
  
  CONCLUSIONS
  HS-WBRT, with an 11-field set up as described, while attempting to conserve hippocampus radiation and maintain radiation dose to brain inadvertently spares follicle-bearing scalp and prevents alopecia.
authors.affiliation: Department of Radiation Oncology, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, MA, 02215, USA. amahadev@bidmc.harvard.edu.
authors.forename: Anand
authors.initials: A
authors.lastname: Mahadevan
authors.affiliation: Department of Radiation Oncology, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, MA, 02215, USA. csampson@bidmc.harvard.edu.
authors.forename: Carrie
authors.initials: C
authors.lastname: Sampson
authors.affiliation: Department of Radiation Oncology, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, MA, 02215, USA. slarosa@bidmc.harvard.edu.
authors.forename: Salvatore
authors.initials: S
authors.lastname: LaRosa
authors.affiliation: Department of Radiation Oncology, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, MA, 02215, USA. sfloyd1@bidmc.harvard.edu.
authors.forename: Scott R
authors.initials: SR
authors.lastname: Floyd
authors.affiliation: Department of Neuro-Oncology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA. ewong@bidmc.harvard.edu.
authors.forename: Eric T
authors.initials: ET
authors.lastname: Wong
authors.affiliation: Department of Neuro-Oncology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA. euhlmann@bidmc.harvard.edu.
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Uhlmann
authors.affiliation: Department of Neuro-Oncology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA. ssengup1@bidmc.harvard.edu.
authors.forename: Soma
authors.initials: S
authors.lastname: Sengupta
authors.affiliation: Department of Neurosurgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA. ekasper@bidmc.harvard.edu.
authors.forename: Ekkehard M
authors.initials: EM
authors.lastname: Kasper
mesh_terms: D000505:Alopecia / Q000517:prevention & control*; D001932:Brain Neoplasms / Q000532:radiotherapy* / Q000556:secondary; D016371:Cranial Irradiation / Q000009:adverse effects / Q000379:methods*; D006624:Hippocampus / Q000528:radiation effects*; D006801:Humans; D011832:Radiation Injuries / Q000517:prevention & control*; D011874:Radiometry; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated; D012189:Retrospective Studies; D012535:Scalp / Q000528:radiation effects