Dose-volume effects in the rat cervical spinal cord after proton irradiation

HP Bijl*, P van Luijk, RP Coppes, JM Schippers, AWT Konings, AJ van der Kogel

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

79 Citations (Scopus)

Abstract

Purpose: To estimate dose-volume effects in the rat cervical spinal cord with protons.

Methods and Materials: Wistar rats were irradiated on the cervical spinal cord with a single fraction of unmodulated protons (150-190 MeV) using the shoot through method, which employs the plateau of the depth-dose profile rather than the Bragg peak. Four different lengths of the spinal cord (2, 4, 8, and 20 mm) were irradiated with variable doses. The endpoint for estimating dose-volume effects was paralysis of fore or hind limbs.

Results: The results obtained with a high-precision proton beam showed a marginal increase of ED(50) when decreasing the irradiated cord length from 20 mm (ED(50) = 20.4 Gy) to 8 mm (ED(50) = 24.9 Gy), but a steep increase in ED(50) when further decreasing the length to 4 mm (ED(50) = 53.7 Gy) and 2 mm (ED(50) = 87.8 Gy). These results generally confirm data obtained previously in a limited series with 4-6-MV photons, and for the first time it was possible to construct complete dose-response curves down to lengths of 2 mm. At higher ED(50) values and shorter lengths irradiated, the latent period to paralysis decreased from 125 to 60 days.

Conclusions: Irradiation of variable lengths of rat cervical spinal cord with protons showed steeply increasing ED(50) values for lengths of less than 8 mm. These results suggest the presence of a critical migration distance of 2-3 mm for cells involved in regeneration processes. (C) 2002 Elsevier Science Inc.

Original languageEnglish
Pages (from-to)205-211
Number of pages7
JournalInternational Journal of Radiation Oncology Biology Physics
Volume52
Issue number1
Publication statusPublished - 1-Jan-2002

Keywords

  • spinal cord
  • dose-volume effect
  • protons
  • white matter necrosis
  • latent period
  • CENTRAL-NERVOUS-SYSTEM
  • RADIATION RESPONSE
  • FIELD SIZE
  • X-RAYS
  • BEAMS
  • MYELOPATHY
  • TOLERANCE
  • PATHOLOGY
  • DOSIMETRY
  • LATENCY

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