Evaluation of permanent alopecia in pediatric medulloblastoma patients treated with proton radiation.
BACKGROUND
To precisely calculate skin dose and thus to evaluate the relationship between the skin dose and permanent alopecia for pediatric medulloblastoma patients treated with proton beams.


METHODS
The dosimetry and alopecia outcomes of 12 children with medulloblastoma (ages 4-15 years) comprise the study cohort. Permanent alopecia was assessed and graded after completion of the entire therapy. Skin threshold doses of permanent alopecia were calculated based on the skin dose from the craniospinal irradiation (CSI) plan using the concept of generalized equivalent uniform dose (gEUD) and accounting for chemotherapy intensity. Monte Carlo simulations were employed to accurately assess uncertainties due to beam range prediction and secondary particles.


RESULTS
Increasing the dose of the CSI field or the dose given by the boost field to the posterior fossa increased total skin dose delivered in that region. It was found that permanent alopecia could be correlated with CSI dose with a threshold of about 21 Gy (relative biological effectiveness, RBE) with high dose chemotherapy and 30 Gy (RBE) with conventional chemotherapy.


CONCLUSIONS
Our results based on 12 patients provide a relationship between the skin dose and permanent alopecia for pediatric medulloblastoma patients treated with protons. The alopecia risk as assessed with gEUD could be predicted based on the treatment plan information.
Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA. chmin@yonsei.ac.kr.|Department of Radiation Convergence Engineering, Yonsei University, Wonju, Korea. chmin@yonsei.ac.kr.
Chul Hee
CH
Min
Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA. HPAGANETTI@mgh.harvard.edu.
Harald
H
Paganetti
Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA. winey.brian@mgh.harvard.edu.
Brian A
BA
Winey
Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA. jadams3@mgh.harvard.edu.
Judith
J
Adams
Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA. smacdonald@mgh.harvard.edu.
Shannon M
SM
MacDonald
Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA. ntarbell@mgh.harvard.edu.
Nancy J
NJ
Tarbell
Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA. TYOCK@mgh.harvard.edu.
Torunn I
TI
Yock
D000293:Adolescent; D000505:Alopecia / Q000209:etiology*; D002528:Cerebellar Neoplasms / Q000532:radiotherapy*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D061888:Craniospinal Irradiation / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008527:Medulloblastoma / Q000532:radiotherapy*; D009010:Monte Carlo Method; D011379:Prognosis; D061766:Proton Therapy / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D012062:Relative Biological Effectiveness