open access

Vol 25, No 3 (2020)
Reviews
Published online: 2020-05-01
Submitted: 2019-10-29
Get Citation

Plan evaluation indices: A journey of evolution

Ganeshkumar Patel, Abhijit Mandal, Sunil Choudhary, Ritusha Mishra, Ravindra Shende
DOI: 10.1016/j.rpor.2020.03.002
·
Rep Pract Oncol Radiother 2020;25(3):336-344.

open access

Vol 25, No 3 (2020)
Reviews
Published online: 2020-05-01
Submitted: 2019-10-29

Abstract

Aim

A systemic review and analysis of evolution journey of indices, such as conformity index (CI), homogeneity index (HI) and gradient index (GI), described in the literature.

Background

Modern radiotherapy techniques like VMAT, SRS and SBRT produce highly conformal plans and provide better critical structure and normal tissue sparing. These treatment techniques can generate a number of competitive plans for the same patients with different dose distributions. Therefore, indices like CI, HI and GI serve as complementary tools in addition to visual slice by slice isodose verification while plan evaluation. Reliability and accuracy of these indices have been tested in the past and found shortcomings and benefits when compared to one another.

Material and methods

Potentially relevant studies published after 1993 were identified through a pubmed and web of science search using words “conformity index”, “Homogeneity index”, “Gradient index”,” Stereotactic radiosurgery”,” stereotactic Body radiotherapy” “complexity metrics” and “plan evaluation index”. Combinations of words “plan evaluation index conformity index” were also searched as were bibliographies of downloaded papers.

Results and conclusions

Mathematical definitions of plan evaluation indices modified with time. CI definitions presented by various authors tested at their own and could not be generalized. Those mathematical definitions of CI which take into account OAR sparing grant more confidence in plan evaluation. Gradient index emerged as a significant plan evaluation index in addition to CI whereas homogeneity index losing its credibility. Biological index base plan evaluation is becoming popular and may replace or alter the role of dosimetrical indices.

Abstract

Aim

A systemic review and analysis of evolution journey of indices, such as conformity index (CI), homogeneity index (HI) and gradient index (GI), described in the literature.

Background

Modern radiotherapy techniques like VMAT, SRS and SBRT produce highly conformal plans and provide better critical structure and normal tissue sparing. These treatment techniques can generate a number of competitive plans for the same patients with different dose distributions. Therefore, indices like CI, HI and GI serve as complementary tools in addition to visual slice by slice isodose verification while plan evaluation. Reliability and accuracy of these indices have been tested in the past and found shortcomings and benefits when compared to one another.

Material and methods

Potentially relevant studies published after 1993 were identified through a pubmed and web of science search using words “conformity index”, “Homogeneity index”, “Gradient index”,” Stereotactic radiosurgery”,” stereotactic Body radiotherapy” “complexity metrics” and “plan evaluation index”. Combinations of words “plan evaluation index conformity index” were also searched as were bibliographies of downloaded papers.

Results and conclusions

Mathematical definitions of plan evaluation indices modified with time. CI definitions presented by various authors tested at their own and could not be generalized. Those mathematical definitions of CI which take into account OAR sparing grant more confidence in plan evaluation. Gradient index emerged as a significant plan evaluation index in addition to CI whereas homogeneity index losing its credibility. Biological index base plan evaluation is becoming popular and may replace or alter the role of dosimetrical indices.

Get Citation

Keywords

Conformity index; Homogeneity index; Gradient index; Complexity metric

About this article
Title

Plan evaluation indices: A journey of evolution

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 25, No 3 (2020)

Pages

336-344

Published online

2020-05-01

DOI

10.1016/j.rpor.2020.03.002

Bibliographic record

Rep Pract Oncol Radiother 2020;25(3):336-344.

Keywords

Conformity index
Homogeneity index
Gradient index
Complexity metric

Authors

Ganeshkumar Patel
Abhijit Mandal
Sunil Choudhary
Ritusha Mishra
Ravindra Shende

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