Dosimetric comparison between proton and photon beams in the moving gap region in cranio-spinal irradiation (CSI)

Chee Wai Cheng, Indra J. Das, Shiv P. Srivastava, Li Zhao, Mark Wolanski, Joseph Simmons, Peter A S Johnstone, Jeffrey C. Buchsbaum

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Purpose. To investigate the moving gap region dosimetry in proton beam cranio-spinal irradiation (CSI) to provide optimal dose uniformity across the treatment volume. Material and methods. Proton beams of ranges 11.6 cm and 16 cm are used for the spine and the brain fields, respectively. Beam profiles for a 30 cm snout are first matched at the 50% level (hot match) on the computer. Feathering is simulated by shifting the dose profiles by a known distance two successive times to simulate a 2 × feathering scheme. The process is repeated for 2 mm and 4 mm gaps. Similar procedures are used to determine the dose profiles in the moving gap for a series of gap widths, 0-10 mm, and feathering step sizes, 4-10 mm, for a Varian iX 6MV beam. The proton and photon dose profiles in the moving gap region are compared. Results. The dose profiles in the moving gap exhibit valleys and peaks in both proton and photon beam CSI. The dose in the moving gap for protons is around 100% or higher for 0 mm gap, for both 5 and 10 mm feathering step sizes. When the field gap is comparable or larger than the penumbra, dose minima as low as 66% is obtained. The dosimetric characteristics for 6 MV photon beams can be made similar to those of the protons by appropriately combining gap width and feathering step size. Conclusion. The dose in the moving gap region is determined by the lateral penumbras, the width of the gap and the feathering step size. The dose decreases with increasing gap width or decreasing feathering step size. The dosimetric characteristics are similar for photon and proton beams. However, proton CSI has virtually no exit dose and is beneficial for pediatric patients, whereas with photon beams the whole lung and abdomen receive non-negligible exit dose.

Original languageEnglish
Pages (from-to)553-560
Number of pages8
JournalActa Oncologica
Volume52
Issue number3
DOIs
StatePublished - Apr 2013

Fingerprint

Photons
Protons
Abdomen
Spine
Pediatrics
Lung
Brain

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Hematology

Cite this

Cheng, C. W., Das, I. J., Srivastava, S. P., Zhao, L., Wolanski, M., Simmons, J., ... Buchsbaum, J. C. (2013). Dosimetric comparison between proton and photon beams in the moving gap region in cranio-spinal irradiation (CSI). Acta Oncologica, 52(3), 553-560. https://doi.org/10.3109/0284186X.2012.681065

Dosimetric comparison between proton and photon beams in the moving gap region in cranio-spinal irradiation (CSI). / Cheng, Chee Wai; Das, Indra J.; Srivastava, Shiv P.; Zhao, Li; Wolanski, Mark; Simmons, Joseph; Johnstone, Peter A S; Buchsbaum, Jeffrey C.

In: Acta Oncologica, Vol. 52, No. 3, 04.2013, p. 553-560.

Research output: Contribution to journalArticle

Cheng, CW, Das, IJ, Srivastava, SP, Zhao, L, Wolanski, M, Simmons, J, Johnstone, PAS & Buchsbaum, JC 2013, 'Dosimetric comparison between proton and photon beams in the moving gap region in cranio-spinal irradiation (CSI)', Acta Oncologica, vol. 52, no. 3, pp. 553-560. https://doi.org/10.3109/0284186X.2012.681065
Cheng, Chee Wai ; Das, Indra J. ; Srivastava, Shiv P. ; Zhao, Li ; Wolanski, Mark ; Simmons, Joseph ; Johnstone, Peter A S ; Buchsbaum, Jeffrey C. / Dosimetric comparison between proton and photon beams in the moving gap region in cranio-spinal irradiation (CSI). In: Acta Oncologica. 2013 ; Vol. 52, No. 3. pp. 553-560.
@article{d1e518769c034a9f866507f6fa7b6de3,
title = "Dosimetric comparison between proton and photon beams in the moving gap region in cranio-spinal irradiation (CSI)",
abstract = "Purpose. To investigate the moving gap region dosimetry in proton beam cranio-spinal irradiation (CSI) to provide optimal dose uniformity across the treatment volume. Material and methods. Proton beams of ranges 11.6 cm and 16 cm are used for the spine and the brain fields, respectively. Beam profiles for a 30 cm snout are first matched at the 50{\%} level (hot match) on the computer. Feathering is simulated by shifting the dose profiles by a known distance two successive times to simulate a 2 × feathering scheme. The process is repeated for 2 mm and 4 mm gaps. Similar procedures are used to determine the dose profiles in the moving gap for a series of gap widths, 0-10 mm, and feathering step sizes, 4-10 mm, for a Varian iX 6MV beam. The proton and photon dose profiles in the moving gap region are compared. Results. The dose profiles in the moving gap exhibit valleys and peaks in both proton and photon beam CSI. The dose in the moving gap for protons is around 100{\%} or higher for 0 mm gap, for both 5 and 10 mm feathering step sizes. When the field gap is comparable or larger than the penumbra, dose minima as low as 66{\%} is obtained. The dosimetric characteristics for 6 MV photon beams can be made similar to those of the protons by appropriately combining gap width and feathering step size. Conclusion. The dose in the moving gap region is determined by the lateral penumbras, the width of the gap and the feathering step size. The dose decreases with increasing gap width or decreasing feathering step size. The dosimetric characteristics are similar for photon and proton beams. However, proton CSI has virtually no exit dose and is beneficial for pediatric patients, whereas with photon beams the whole lung and abdomen receive non-negligible exit dose.",
author = "Cheng, {Chee Wai} and Das, {Indra J.} and Srivastava, {Shiv P.} and Li Zhao and Mark Wolanski and Joseph Simmons and Johnstone, {Peter A S} and Buchsbaum, {Jeffrey C.}",
year = "2013",
month = "4",
doi = "10.3109/0284186X.2012.681065",
language = "English",
volume = "52",
pages = "553--560",
journal = "Acta Oncologica",
issn = "0284-186X",
publisher = "Informa Healthcare",
number = "3",

}

TY - JOUR

T1 - Dosimetric comparison between proton and photon beams in the moving gap region in cranio-spinal irradiation (CSI)

AU - Cheng, Chee Wai

AU - Das, Indra J.

AU - Srivastava, Shiv P.

AU - Zhao, Li

AU - Wolanski, Mark

AU - Simmons, Joseph

AU - Johnstone, Peter A S

AU - Buchsbaum, Jeffrey C.

PY - 2013/4

Y1 - 2013/4

N2 - Purpose. To investigate the moving gap region dosimetry in proton beam cranio-spinal irradiation (CSI) to provide optimal dose uniformity across the treatment volume. Material and methods. Proton beams of ranges 11.6 cm and 16 cm are used for the spine and the brain fields, respectively. Beam profiles for a 30 cm snout are first matched at the 50% level (hot match) on the computer. Feathering is simulated by shifting the dose profiles by a known distance two successive times to simulate a 2 × feathering scheme. The process is repeated for 2 mm and 4 mm gaps. Similar procedures are used to determine the dose profiles in the moving gap for a series of gap widths, 0-10 mm, and feathering step sizes, 4-10 mm, for a Varian iX 6MV beam. The proton and photon dose profiles in the moving gap region are compared. Results. The dose profiles in the moving gap exhibit valleys and peaks in both proton and photon beam CSI. The dose in the moving gap for protons is around 100% or higher for 0 mm gap, for both 5 and 10 mm feathering step sizes. When the field gap is comparable or larger than the penumbra, dose minima as low as 66% is obtained. The dosimetric characteristics for 6 MV photon beams can be made similar to those of the protons by appropriately combining gap width and feathering step size. Conclusion. The dose in the moving gap region is determined by the lateral penumbras, the width of the gap and the feathering step size. The dose decreases with increasing gap width or decreasing feathering step size. The dosimetric characteristics are similar for photon and proton beams. However, proton CSI has virtually no exit dose and is beneficial for pediatric patients, whereas with photon beams the whole lung and abdomen receive non-negligible exit dose.

AB - Purpose. To investigate the moving gap region dosimetry in proton beam cranio-spinal irradiation (CSI) to provide optimal dose uniformity across the treatment volume. Material and methods. Proton beams of ranges 11.6 cm and 16 cm are used for the spine and the brain fields, respectively. Beam profiles for a 30 cm snout are first matched at the 50% level (hot match) on the computer. Feathering is simulated by shifting the dose profiles by a known distance two successive times to simulate a 2 × feathering scheme. The process is repeated for 2 mm and 4 mm gaps. Similar procedures are used to determine the dose profiles in the moving gap for a series of gap widths, 0-10 mm, and feathering step sizes, 4-10 mm, for a Varian iX 6MV beam. The proton and photon dose profiles in the moving gap region are compared. Results. The dose profiles in the moving gap exhibit valleys and peaks in both proton and photon beam CSI. The dose in the moving gap for protons is around 100% or higher for 0 mm gap, for both 5 and 10 mm feathering step sizes. When the field gap is comparable or larger than the penumbra, dose minima as low as 66% is obtained. The dosimetric characteristics for 6 MV photon beams can be made similar to those of the protons by appropriately combining gap width and feathering step size. Conclusion. The dose in the moving gap region is determined by the lateral penumbras, the width of the gap and the feathering step size. The dose decreases with increasing gap width or decreasing feathering step size. The dosimetric characteristics are similar for photon and proton beams. However, proton CSI has virtually no exit dose and is beneficial for pediatric patients, whereas with photon beams the whole lung and abdomen receive non-negligible exit dose.

UR - http://www.scopus.com/inward/record.url?scp=84875132096&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84875132096&partnerID=8YFLogxK

U2 - 10.3109/0284186X.2012.681065

DO - 10.3109/0284186X.2012.681065

M3 - Article

C2 - 22554342

AN - SCOPUS:84875132096

VL - 52

SP - 553

EP - 560

JO - Acta Oncologica

JF - Acta Oncologica

SN - 0284-186X

IS - 3

ER -