Radiat Oncol J.  2019 Mar;37(1):22-29. 10.3857/roj.2019.00059.

Whole brain radiotherapy using four-field box technique with tilting baseplate for parotid gland sparing

Affiliations
  • 1Department of Radiation Oncology, Yeungnam University College of Medicine, Daegu, Korea. yjw1160@ynu.ac.kr

Abstract

PURPOSE
The aim of this study is to evaluate the efficacy and feasibility of four-field box whole brain radiotherapy (FB-WBRT) with tilting baseplate by comparing bilateral WBRT (B-WBRT).
METHODS
AND MATERIALS: Between March 2016 and September 2018, 20 patients with brain metastases underwent WBRT using the four-field box technique. WBRT is performed with a dose of 30 Gy in 10 fractions daily. Two computed tomography simulations per person were performed. One was in the traditional supine position for B-WBRT and the other by applying the tilting acrylic supine baseplate to elevate the head by 40° for FB-WBRT. The B-WBRT used the field-in-field technique, which is the most commonly used method in our institution. The FB-WBRT comprised anterior, posterior, and bilateral beams. A wedge was applied in anterior and posterior fields to compensate for skull convexity.
RESULTS
The average of Dmean of both parotid glands was 10.2 Gy (range, 3.8 to 17.8 Gy) in B-WBRT and 5.4 Gy (range, 2.0 to 11.7 Gy) in FB-WBRT (p < 0.05). Compared to B-WBRT, FB-WBRT reduced the mean dose of the right and left parotid glands from 10.1 Gy to 4.9 Gy and from 10.4 Gy to 5.8 Gy, respectively (p < 0.05). Further, V₅, V₁₀, V₁₅, V₂₀ for the parotid gland decreased significantly in FB-WBRT (p < 0.05). The Dmax and Dmean of lens decreased according to the dose-volume histogram.
CONCLUSION
Compared to B-WBRT, FB-WBRT with a tilting baseplate is a simple and effective method that takes feature of noncoplanar beam to protect the parotid gland.

Keyword

Whole brain radiotherapy; Four-field box technique; Brain metastases; Parotid gland sparing

MeSH Terms

Brain*
Head
Humans
Methods
Neoplasm Metastasis
Parotid Gland*
Radiotherapy*
Skull
Supine Position
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