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Monte Carlo simulation of tilted contact plaque brachytherapy placement for juxtapapillary retinoblastoma.
Nakamura, Satoshi; Murakami, Naoya; Suzuki, Shigenobu; Ito, Kimiteru; Takemori, Mihiro; Nakayama, Hiroki; Kaga, Keita; Chiba, Takahito; Iijima, Kotaro; Takahashi, Kana; Goka, Tomonori; Itami, Jun; Okamoto, Hiroyuki; Igaki, Hiroshi.
Afiliação
  • Nakamura S; Department of Medical Physics, National Cancer Center Hospital, Tokyo, Japan.
  • Murakami N; Devision of Research and Development for Boron Neutron Capture Therapy, National Cancer Center Exploratory Oncology Research & Clinical Trial Center, Tokyo, Japan.
  • Suzuki S; Department of Radiation Oncology, National Cancer Center Hospital, Tsukiji 5-1-1, Chuo-ku, Tokyo, 104-0045, Japan. namuraka@ncc.go.jp.
  • Ito K; Department of Ophthalmic Oncology, National Cancer Center Hospital, Tokyo, Japan.
  • Takemori M; Department of Diagnostic Radiology, National Cancer Center Hospital, Tokyo, Japan.
  • Nakayama H; Department of Medical Physics, National Cancer Center Hospital, Tokyo, Japan.
  • Kaga K; Department of Radiological Science, Graduate School of Human Health Sciences, Higashi-ogu 7-2-10, Arakawa-ku, Tokyo, 116-8551, Japan.
  • Chiba T; Department of Medical Physics, National Cancer Center Hospital, Tokyo, Japan.
  • Iijima K; Department of Radiological Science, Graduate School of Human Health Sciences, Higashi-ogu 7-2-10, Arakawa-ku, Tokyo, 116-8551, Japan.
  • Takahashi K; Department of Medical Physics, National Cancer Center Hospital, Tokyo, Japan.
  • Goka T; Department of Radiological Technology, National Cancer Center Hospital, Tokyo, Japan.
  • Itami J; Department of Medical Physics, National Cancer Center Hospital, Tokyo, Japan.
  • Okamoto H; Department of Radiological Science, Graduate School of Human Health Sciences, Higashi-ogu 7-2-10, Arakawa-ku, Tokyo, 116-8551, Japan.
  • Igaki H; Department of Medical Physics, National Cancer Center Hospital, Tokyo, Japan.
Radiat Oncol ; 17(1): 16, 2022 Jan 24.
Article em En | MEDLINE | ID: mdl-35073956
ABSTRACT

BACKGROUND:

The 106-Ruthenium contact plaque applicator is utilized for the treatment of intraocular tumor within a thickness of less than 6 mm. If anything obstructs the placement of the plaque applicator, the treatment is generally difficult because the applicator has to be temporarily located just on the opposite side of the retinal tumor. Furthermore, the plaque applicator edge of approximately 1 mm does not contain 106Ru, estimating the delivered radiation dose for eccentric tumor is challenging because the lateral dose profile is inadequately provided by the manufacture's certification. This study aims to simulate tumor coverage of the tilted applicator placement for treating an infant with juxtapapillary retinoblastoma and to achieve the effective treatment. CASE PRESENTATION We present an infant with retinoblastoma whose tumor involved macular and was invading just temporal side of the optic disc. Additionally, posterior staphyloma was induced by a series of previous treatments, making it more difficult to treat the standard plaque placement. Thus, the applicator type of CCA was intentionally tilted to the eyeball and the distance between the posterior edge of the applicator and the eyeball had to be then equal to or more than 2 mm based on the dose distribution of the applicator calculated using Monte Carlo simulation to minimize damage to surrounding tissues while covering the tumor. It was then comparable to the certification and previous reports. Based on the acquired dose distribution, the optimal placement of the applicator was derived from varying the distance between the applicator's edge and the eyeball, and the distance was then determined to be 2 mm. In this case, the minimum dose rate in the tumor was 25.5 mGy/min, and the time required to deliver the prescribed dose was 26.2 h. Therefore, the tilted 106Ru plaque applicator placement could deliver the required dose for the treatment. The physical examination revealed no active tumor as a result of the treatment.

CONCLUSIONS:

Optimizing the placement of the 106Ru plaque applicator, it was possible to guarantee that the prescribed dose will be delivered to the tumor even if the standard placement is not possible for the juxtapapillary tumor.
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Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Retinoblastoma / Braquiterapia / Método de Monte Carlo / Neoplasias da Retina Tipo de estudo: Health_economic_evaluation Limite: Child, preschool / Humans / Male Idioma: En Revista: Radiat Oncol Assunto da revista: NEOPLASIAS / RADIOTERAPIA Ano de publicação: 2022 Tipo de documento: Article País de afiliação: Japão

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Retinoblastoma / Braquiterapia / Método de Monte Carlo / Neoplasias da Retina Tipo de estudo: Health_economic_evaluation Limite: Child, preschool / Humans / Male Idioma: En Revista: Radiat Oncol Assunto da revista: NEOPLASIAS / RADIOTERAPIA Ano de publicação: 2022 Tipo de documento: Article País de afiliação: Japão