Commissioning and verification of the collapsed cone convolution superposition algorithm for SBRT delivery using flattening filter-free beams

Ryan D. Foster, Michael P. Speiser, Timothy D. Solberg

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Linacs equipped with flattening filter-free (FFF) megavoltage photon beams are now commercially available. However, the commissioning of FFF beams poses challenges that are not shared with traditional flattened megavoltage X-ray beams. The planning system must model a beam that is peaked in the center and has an energy spectrum that is softer than the flattened beam. Removing the flattening filter also increases the maximum possible dose rates from 600 MU/min up to 2400 MU/min in some cases; this increase in dose rate affects the recombination correction factor, Pion, used during absolute dose calibration with ionization chambers. We present the first-reported experience of commissioning, verification, and clinical use of the collapsed cone convolution superposition (CCCS) dose calculation algorithm for commercially available flattening filter-free beams. Our commissioning data are compared to previously reported measurements and Monte Carlo studies of FFF beams. Commissioning was verified by making point-dose measurement of test plans, irradiating the RPC lung phantom, and performing patient-specific QA. The average point-dose difference between calculations and measurements of all test plans and all patient specific QA measurements is 0.80%, and the RPC phantom absolute dose differences for the two thermoluminescent dosimeters (TLDs) in the phantom planning target volume (PTV) were 1% and 2%, respectively. One hundred percent (100%) of points in the RPC phantom films passed the RPC gamma criteria of 5% and 5 mm. Our results show that the CCCS algorithm can accurately model FFF beams and calculate SBRT dose distributions using those beams.

Original languageEnglish (US)
Pages (from-to)39-49
Number of pages11
JournalJournal of Applied Clinical Medical Physics
Volume15
Issue number2
StatePublished - 2014

Fingerprint

flattening
Convolution
convolution integrals
Cones
delivery
cones
Mesons
filters
dosage
Photons
Genetic Recombination
Calibration
Dosimetry
X-Rays
Planning
Lung
Ionization chambers
Dosimeters
planning
X rays

Keywords

  • Beam modeling
  • commissioning
  • Convolution superposition
  • Flattening filter-free

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiation
  • Instrumentation

Cite this

Commissioning and verification of the collapsed cone convolution superposition algorithm for SBRT delivery using flattening filter-free beams. / Foster, Ryan D.; Speiser, Michael P.; Solberg, Timothy D.

In: Journal of Applied Clinical Medical Physics, Vol. 15, No. 2, 2014, p. 39-49.

Research output: Contribution to journalArticle

@article{2620e3c2e45f4a4b922b991a8da3c223,
title = "Commissioning and verification of the collapsed cone convolution superposition algorithm for SBRT delivery using flattening filter-free beams",
abstract = "Linacs equipped with flattening filter-free (FFF) megavoltage photon beams are now commercially available. However, the commissioning of FFF beams poses challenges that are not shared with traditional flattened megavoltage X-ray beams. The planning system must model a beam that is peaked in the center and has an energy spectrum that is softer than the flattened beam. Removing the flattening filter also increases the maximum possible dose rates from 600 MU/min up to 2400 MU/min in some cases; this increase in dose rate affects the recombination correction factor, Pion, used during absolute dose calibration with ionization chambers. We present the first-reported experience of commissioning, verification, and clinical use of the collapsed cone convolution superposition (CCCS) dose calculation algorithm for commercially available flattening filter-free beams. Our commissioning data are compared to previously reported measurements and Monte Carlo studies of FFF beams. Commissioning was verified by making point-dose measurement of test plans, irradiating the RPC lung phantom, and performing patient-specific QA. The average point-dose difference between calculations and measurements of all test plans and all patient specific QA measurements is 0.80{\%}, and the RPC phantom absolute dose differences for the two thermoluminescent dosimeters (TLDs) in the phantom planning target volume (PTV) were 1{\%} and 2{\%}, respectively. One hundred percent (100{\%}) of points in the RPC phantom films passed the RPC gamma criteria of 5{\%} and 5 mm. Our results show that the CCCS algorithm can accurately model FFF beams and calculate SBRT dose distributions using those beams.",
keywords = "Beam modeling, commissioning, Convolution superposition, Flattening filter-free",
author = "Foster, {Ryan D.} and Speiser, {Michael P.} and Solberg, {Timothy D.}",
year = "2014",
language = "English (US)",
volume = "15",
pages = "39--49",
journal = "Journal of Applied Clinical Medical Physics",
issn = "1526-9914",
publisher = "American Institute of Physics Publising LLC",
number = "2",

}

TY - JOUR

T1 - Commissioning and verification of the collapsed cone convolution superposition algorithm for SBRT delivery using flattening filter-free beams

AU - Foster, Ryan D.

AU - Speiser, Michael P.

AU - Solberg, Timothy D.

PY - 2014

Y1 - 2014

N2 - Linacs equipped with flattening filter-free (FFF) megavoltage photon beams are now commercially available. However, the commissioning of FFF beams poses challenges that are not shared with traditional flattened megavoltage X-ray beams. The planning system must model a beam that is peaked in the center and has an energy spectrum that is softer than the flattened beam. Removing the flattening filter also increases the maximum possible dose rates from 600 MU/min up to 2400 MU/min in some cases; this increase in dose rate affects the recombination correction factor, Pion, used during absolute dose calibration with ionization chambers. We present the first-reported experience of commissioning, verification, and clinical use of the collapsed cone convolution superposition (CCCS) dose calculation algorithm for commercially available flattening filter-free beams. Our commissioning data are compared to previously reported measurements and Monte Carlo studies of FFF beams. Commissioning was verified by making point-dose measurement of test plans, irradiating the RPC lung phantom, and performing patient-specific QA. The average point-dose difference between calculations and measurements of all test plans and all patient specific QA measurements is 0.80%, and the RPC phantom absolute dose differences for the two thermoluminescent dosimeters (TLDs) in the phantom planning target volume (PTV) were 1% and 2%, respectively. One hundred percent (100%) of points in the RPC phantom films passed the RPC gamma criteria of 5% and 5 mm. Our results show that the CCCS algorithm can accurately model FFF beams and calculate SBRT dose distributions using those beams.

AB - Linacs equipped with flattening filter-free (FFF) megavoltage photon beams are now commercially available. However, the commissioning of FFF beams poses challenges that are not shared with traditional flattened megavoltage X-ray beams. The planning system must model a beam that is peaked in the center and has an energy spectrum that is softer than the flattened beam. Removing the flattening filter also increases the maximum possible dose rates from 600 MU/min up to 2400 MU/min in some cases; this increase in dose rate affects the recombination correction factor, Pion, used during absolute dose calibration with ionization chambers. We present the first-reported experience of commissioning, verification, and clinical use of the collapsed cone convolution superposition (CCCS) dose calculation algorithm for commercially available flattening filter-free beams. Our commissioning data are compared to previously reported measurements and Monte Carlo studies of FFF beams. Commissioning was verified by making point-dose measurement of test plans, irradiating the RPC lung phantom, and performing patient-specific QA. The average point-dose difference between calculations and measurements of all test plans and all patient specific QA measurements is 0.80%, and the RPC phantom absolute dose differences for the two thermoluminescent dosimeters (TLDs) in the phantom planning target volume (PTV) were 1% and 2%, respectively. One hundred percent (100%) of points in the RPC phantom films passed the RPC gamma criteria of 5% and 5 mm. Our results show that the CCCS algorithm can accurately model FFF beams and calculate SBRT dose distributions using those beams.

KW - Beam modeling

KW - commissioning

KW - Convolution superposition

KW - Flattening filter-free

UR - http://www.scopus.com/inward/record.url?scp=84896373251&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84896373251&partnerID=8YFLogxK

M3 - Article

VL - 15

SP - 39

EP - 49

JO - Journal of Applied Clinical Medical Physics

JF - Journal of Applied Clinical Medical Physics

SN - 1526-9914

IS - 2

ER -