High-dose-rate brachytherapy of rhabdomyosarcoma limited to the external auditory canal Journal Article

Authors: King, M. T.; Voros, L.; Cohen, G. N.; Lanning, R. M.; Ganly, I.; O'Suoji, C. C.; Wolden, S. L.
Article Title: High-dose-rate brachytherapy of rhabdomyosarcoma limited to the external auditory canal
Abstract: Purpose To report on the single-catheter high-dose-rate brachytherapy treatment of a 21-month-old girl child with an embryonal, botryoid-type, rhabdomyosarcoma limited to the external auditory canal (EAC). Methods and Materials A 2.4-mm diameter catheter was inserted into the right EAC and placed against the tympanic membrane. A computed tomography simulation scan was acquired. A brachytherapy treatment plan, in which 21 Gy in seven fractions was prescribed to a 1-mm depth along the distal 2 cm of the catheter, was generated. Treatments were delivered under anesthesia without complication. A dosimetric comparison between this plan and an intensity-modulated radiation therapy (IMRT) plan was then conducted. A clinical target volume (CTV), which encompassed a 1-mm margin along the distal 2 cm of the catheter, was delineated for both plans. Given positioning uncertainty under image guidance, a planning target volume (PTV = CTV + 3-mm margin) was defined for the IMRT plan. The IMRT plan was optimized for maximal CTV coverage but subsequently normalized to the same CTV volume receiving 100% of the prescription dose (V100) of the brachytherapy plan. Results The IMRT plan was normalized to the brachytherapy CTV V100 of 82.0%. The PTV V100 of this plan was 34.1%. The PTV exhibited dosimetric undercoverage within the middle ear and toward the external ear. Mean cochlea doses for the IMRT and brachytherapy plans were 26.7% and 10.5% of prescription, respectively. Conclusions For rhabdomyosarcomas limited to the EAC, a standard brachytherapy catheter can deliver a highly conformal radiation plan that can spare the nearby cochlea from excess radiation. © 2016 American Brachytherapy Society
Keywords: rhabdomyosarcoma; pediatrics; high-dose rate; external auditory canal
Journal Title: Brachytherapy
Volume: 16
Issue: 1
ISSN: 1538-4721
Publisher: Elsevier Science, Inc.  
Date Published: 2017-01-01
Start Page: 181
End Page: 185
Language: English
DOI: 10.1016/j.brachy.2016.07.003
PROVIDER: scopus
PMCID: PMC5253256
PUBMED: 27528589
Notes: Article -- Export Date: 2 February 2017 -- Source: Scopus
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MSK Authors
  1. Suzanne L Wolden
    438 Wolden
  2. Laszlo Voros
    16 Voros
  3. Gilad N Cohen
    139 Cohen
  4. Ian Ganly
    255 Ganly
  5. Ryan Michael Lanning
    13 Lanning
  6. Martin T King
    3 King