Treatment planning for metals using an extended CT number scale

John P. Mullins, Michael P. Grams, Michael G. Herman, Debra H Brinkmann, John A. Antolak

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Metal implants which saturate the CT number scale may require dosimetrist and physicist involvement to manually contour and assign an appropriate value to the metal for accurate dose calculation. This study investigated dose calculation based directly on extended CT scale images for different metals and geometries. The aim was to evaluate extended CT accuracy as a suitable alternative to standard CT methods in the presence of high-Z materials and artifacts, despite the reduced HU resolution of extended CT. Gafchromic film measurements were made for comparison to calculated doses. The method of direct dose calculation on extended CT scale was compared to our institution's standard method of manually contouring and assigning metal values on saturated CT images for each of the metal samples. Clinical patient plans with metal implants were investigated and DVHs were compared between standard CT and extended CT dose calculations. Dose calculations showed agreement within 2% between the two methods of metal characterization and the film measurement in the case of the strongest metal attenuator, cobalt-chromium. In the clinical treatment plans, the greatest dose discrepancy between the two methods was 1.2%. This study suggests that direct dose calculation on an extended scale CT image in the presence of metal implants can produce accurate clinically viable treatment plans, thereby improving efficiency of clinical workflow and eliminating a potential source of human error by manual CT number assignment.

Original languageEnglish (US)
Pages (from-to)179-188
Number of pages10
JournalJournal of Applied Clinical Medical Physics
Volume17
Issue number6
DOIs
StatePublished - 2016

Fingerprint

planning
Metals
Planning
dosage
metals
Therapeutics
Cobalt
Chromium
attenuators
Workflow
Artifacts
Geometry
artifacts
chromium
Research Design
cobalt
Metal implants
geometry

Keywords

  • Extended CT scale
  • Metal implant dosimetry

ASJC Scopus subject areas

  • Radiation
  • Instrumentation
  • Radiology Nuclear Medicine and imaging

Cite this

Treatment planning for metals using an extended CT number scale. / Mullins, John P.; Grams, Michael P.; Herman, Michael G.; Brinkmann, Debra H; Antolak, John A.

In: Journal of Applied Clinical Medical Physics, Vol. 17, No. 6, 2016, p. 179-188.

Research output: Contribution to journalArticle

Mullins, John P. ; Grams, Michael P. ; Herman, Michael G. ; Brinkmann, Debra H ; Antolak, John A. / Treatment planning for metals using an extended CT number scale. In: Journal of Applied Clinical Medical Physics. 2016 ; Vol. 17, No. 6. pp. 179-188.
@article{ed0f2ed2ae644c03b84762670d986ef5,
title = "Treatment planning for metals using an extended CT number scale",
abstract = "Metal implants which saturate the CT number scale may require dosimetrist and physicist involvement to manually contour and assign an appropriate value to the metal for accurate dose calculation. This study investigated dose calculation based directly on extended CT scale images for different metals and geometries. The aim was to evaluate extended CT accuracy as a suitable alternative to standard CT methods in the presence of high-Z materials and artifacts, despite the reduced HU resolution of extended CT. Gafchromic film measurements were made for comparison to calculated doses. The method of direct dose calculation on extended CT scale was compared to our institution's standard method of manually contouring and assigning metal values on saturated CT images for each of the metal samples. Clinical patient plans with metal implants were investigated and DVHs were compared between standard CT and extended CT dose calculations. Dose calculations showed agreement within 2{\%} between the two methods of metal characterization and the film measurement in the case of the strongest metal attenuator, cobalt-chromium. In the clinical treatment plans, the greatest dose discrepancy between the two methods was 1.2{\%}. This study suggests that direct dose calculation on an extended scale CT image in the presence of metal implants can produce accurate clinically viable treatment plans, thereby improving efficiency of clinical workflow and eliminating a potential source of human error by manual CT number assignment.",
keywords = "Extended CT scale, Metal implant dosimetry",
author = "Mullins, {John P.} and Grams, {Michael P.} and Herman, {Michael G.} and Brinkmann, {Debra H} and Antolak, {John A.}",
year = "2016",
doi = "10.1120/jacmp.v17i6.6153",
language = "English (US)",
volume = "17",
pages = "179--188",
journal = "Journal of Applied Clinical Medical Physics",
issn = "1526-9914",
publisher = "American Institute of Physics Publising LLC",
number = "6",

}

TY - JOUR

T1 - Treatment planning for metals using an extended CT number scale

AU - Mullins, John P.

AU - Grams, Michael P.

AU - Herman, Michael G.

AU - Brinkmann, Debra H

AU - Antolak, John A.

PY - 2016

Y1 - 2016

N2 - Metal implants which saturate the CT number scale may require dosimetrist and physicist involvement to manually contour and assign an appropriate value to the metal for accurate dose calculation. This study investigated dose calculation based directly on extended CT scale images for different metals and geometries. The aim was to evaluate extended CT accuracy as a suitable alternative to standard CT methods in the presence of high-Z materials and artifacts, despite the reduced HU resolution of extended CT. Gafchromic film measurements were made for comparison to calculated doses. The method of direct dose calculation on extended CT scale was compared to our institution's standard method of manually contouring and assigning metal values on saturated CT images for each of the metal samples. Clinical patient plans with metal implants were investigated and DVHs were compared between standard CT and extended CT dose calculations. Dose calculations showed agreement within 2% between the two methods of metal characterization and the film measurement in the case of the strongest metal attenuator, cobalt-chromium. In the clinical treatment plans, the greatest dose discrepancy between the two methods was 1.2%. This study suggests that direct dose calculation on an extended scale CT image in the presence of metal implants can produce accurate clinically viable treatment plans, thereby improving efficiency of clinical workflow and eliminating a potential source of human error by manual CT number assignment.

AB - Metal implants which saturate the CT number scale may require dosimetrist and physicist involvement to manually contour and assign an appropriate value to the metal for accurate dose calculation. This study investigated dose calculation based directly on extended CT scale images for different metals and geometries. The aim was to evaluate extended CT accuracy as a suitable alternative to standard CT methods in the presence of high-Z materials and artifacts, despite the reduced HU resolution of extended CT. Gafchromic film measurements were made for comparison to calculated doses. The method of direct dose calculation on extended CT scale was compared to our institution's standard method of manually contouring and assigning metal values on saturated CT images for each of the metal samples. Clinical patient plans with metal implants were investigated and DVHs were compared between standard CT and extended CT dose calculations. Dose calculations showed agreement within 2% between the two methods of metal characterization and the film measurement in the case of the strongest metal attenuator, cobalt-chromium. In the clinical treatment plans, the greatest dose discrepancy between the two methods was 1.2%. This study suggests that direct dose calculation on an extended scale CT image in the presence of metal implants can produce accurate clinically viable treatment plans, thereby improving efficiency of clinical workflow and eliminating a potential source of human error by manual CT number assignment.

KW - Extended CT scale

KW - Metal implant dosimetry

UR - http://www.scopus.com/inward/record.url?scp=84997216923&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84997216923&partnerID=8YFLogxK

U2 - 10.1120/jacmp.v17i6.6153

DO - 10.1120/jacmp.v17i6.6153

M3 - Article

C2 - 27929492

AN - SCOPUS:84997216923

VL - 17

SP - 179

EP - 188

JO - Journal of Applied Clinical Medical Physics

JF - Journal of Applied Clinical Medical Physics

SN - 1526-9914

IS - 6

ER -