Authors: Daiki Senzaki ^∗, Takahiro Kato ^∗,1, Shinya Komori ^†, Yuki Tominaga^‡,§, Takaomi Harada ^∗, Hisashi Sato^∗

^∗ Department of Radiological Sciences, Graduate School of Health Sciences, Fukushima Medical University, Fukushima, Japan
^† Southern Tohoku BNCT Research Center, Department of Radiation Physics and Technology, Fukushima, Japan
^‡ Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
^§ Division of Health Science, Graduate School of Medicine, Medical Physics Laboratory, The University of Osaka, Osaka, Japan
^† Southern Tohoku BNCT Research Center, Department of Radiation Physics and Technology, Fukushima, Japan
^‡ Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
^§ Division of Health Science, Graduate School of Medicine, Medical Physics Laboratory, The University of Osaka, Osaka, Japan

Permanent alopecia following craniospinal irradiation (CSI) remains a clinically signi?cant quality-of-life concern for pediatric and adolescent and young adult (AYA) patients, particularly when combined with high-dose chemotherapy. This study aimed to evaluate scalp dose-sparing according to irradiation technique and photon beam energy in CSI, using anthropomorphic phantom models representative of pediatric and AYA patients. Anthropomorphic head phantoms simulating a 5-year-old pediatric patient and an adult AYA patient were used to generate CSI cranial ?eld plans. For each phantom, 3-dimensional conformal radiotherapy (3DCRT) and volumetric-modulated arc therapy (VMAT) plans were created using 5 ?attened photon beam energies (4, 6, 8, 10, and 15 MV). Scalp structures were delineated as a 5-mm subcutaneous layer and subdivided into top, left, right, and back regions. Dose evaluation focused on the equivalent dose in 2-Gy fractions to 50% of the scalp volume (EQD50%) and generalized equivalent uniform dose (gEUD), based on published threshold values predictive of permanent alopecia. Target coverage and organ-at-risk (OAR) doses were also compared. VMAT provided signi?cantly lower scalp doses than 3DCRT across all photon energies and scalp regions in both models. Notably, EQD50% in all regions fell below the clinically suggested 19.9 Gy threshold with VMAT, whereas 3DCRT failed to achieve this consistently. The most favorable balance between scalp-sparing and target coverage was observed with VMAT using 10 MV photons. gEUD values, although reduced with VMAT, generally remained above the reference threshold. Compared with 3DCRT, VMAT achieved substantially improved scalp-sparing in both pediatric and AYA CSI simulations, with 10 MV representing a potentially optimal photon energy. Further clinical validation, including consideration of noncoplanar strategies, is warranted to re?ne scalp-sparing CSI planning in pediatric settings.

As of January 1, 2022, ARRT requires CE Credits for Directed Journal Readings to be based on the word count for each article. So, the number of CE Credits for each DJR article will vary for ARRT. 

ARRT CQR Credit Distribution
Radiation Therapy 2022       
   Procedures    
   Prescription and Dose Calculation = 1.0
   Radiation Therapy 2017     
   Procedures    
   Prescription and Dose Calculation = 1.0