Using a systems-theoretic approach to analyze safety in radiation therapy-first steps and lessons learned

N. Silvis-Cividjian, W.F.A.R. Verbakel, Marjan Admiraal

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Radiation therapy is an important technique to treat cancer. Due to the high occupational risks involved, the process is subject to severe safety regulations and standards. However, these standards do not mandate the usage of a particular hazard analysis method. The de facto methods currently used are the reliability theory-based Fault Tree Analysis (FTA) and Healthcare Failure Mode and Effects Analysis (HFMEA). Systems Theoretic Process Analysis (STPA) is a new, essentially different hazard analysis method, based on systems theory. Although successfully applied in many industries, there are only a few reports on STPA implementation in radiation therapy. This paper contributes to filling this gap with a preliminary assessment of STPA applied to a mature Intensity Modulated Radiation Therapy (IMRT) process. The analysis was conducted by a team consisting of two experts in radiation therapy and one software systems engineer, with little domain knowledge. 142 potentially unsafe control actions were identified and compared with the results of an earlier HFMEA. The main lesson we have learned is that a graphical, system-wise modeling of the analyzed process, although challenging for beginners, is a powerful instrument to catch the same and even other, new hazards. A causal analysis of a subset of these newly found hazards has led to meaningful and valuable risk mitigation measures. These results suggest considering STPA as a viable option for safety analysis in radiation therapy. We expect that this top-down, well-structured way of analysis can especially be advantageous for safety assessment in early design phases, when an HFMEA is not possible yet, because most of system's implementation and behavior is still unknown.
Original languageEnglish
Pages (from-to)104519
JournalSafety Science
Volume122
Publication statusPublished - 2020

Fingerprint

Radiotherapy
Hazards
Safety
Failure modes
process analysis
systems analysis
Occupational risks
Reliability theory
Fault tree analysis
Systems Theory
System theory
Industry
Software
causal analysis
Engineers
system theory
engineer
cancer
Healthcare Failure Mode and Effect Analysis
Neoplasms

Cite this

@article{c0e55166d3f04b679a6e0dac5cb5a5af,
title = "Using a systems-theoretic approach to analyze safety in radiation therapy-first steps and lessons learned",
abstract = "Radiation therapy is an important technique to treat cancer. Due to the high occupational risks involved, the process is subject to severe safety regulations and standards. However, these standards do not mandate the usage of a particular hazard analysis method. The de facto methods currently used are the reliability theory-based Fault Tree Analysis (FTA) and Healthcare Failure Mode and Effects Analysis (HFMEA). Systems Theoretic Process Analysis (STPA) is a new, essentially different hazard analysis method, based on systems theory. Although successfully applied in many industries, there are only a few reports on STPA implementation in radiation therapy. This paper contributes to filling this gap with a preliminary assessment of STPA applied to a mature Intensity Modulated Radiation Therapy (IMRT) process. The analysis was conducted by a team consisting of two experts in radiation therapy and one software systems engineer, with little domain knowledge. 142 potentially unsafe control actions were identified and compared with the results of an earlier HFMEA. The main lesson we have learned is that a graphical, system-wise modeling of the analyzed process, although challenging for beginners, is a powerful instrument to catch the same and even other, new hazards. A causal analysis of a subset of these newly found hazards has led to meaningful and valuable risk mitigation measures. These results suggest considering STPA as a viable option for safety analysis in radiation therapy. We expect that this top-down, well-structured way of analysis can especially be advantageous for safety assessment in early design phases, when an HFMEA is not possible yet, because most of system's implementation and behavior is still unknown.",
author = "N. Silvis-Cividjian and W.F.A.R. Verbakel and Marjan Admiraal",
year = "2020",
language = "English",
volume = "122",
pages = "104519",
journal = "Safety Science",
issn = "0925-7535",
publisher = "Elsevier",

}

Using a systems-theoretic approach to analyze safety in radiation therapy-first steps and lessons learned. / Silvis-Cividjian, N.; Verbakel, W.F.A.R.; Admiraal, Marjan.

In: Safety Science, Vol. 122, 2020, p. 104519.

Research output: Contribution to JournalArticleAcademicpeer-review

TY - JOUR

T1 - Using a systems-theoretic approach to analyze safety in radiation therapy-first steps and lessons learned

AU - Silvis-Cividjian, N.

AU - Verbakel, W.F.A.R.

AU - Admiraal, Marjan

PY - 2020

Y1 - 2020

N2 - Radiation therapy is an important technique to treat cancer. Due to the high occupational risks involved, the process is subject to severe safety regulations and standards. However, these standards do not mandate the usage of a particular hazard analysis method. The de facto methods currently used are the reliability theory-based Fault Tree Analysis (FTA) and Healthcare Failure Mode and Effects Analysis (HFMEA). Systems Theoretic Process Analysis (STPA) is a new, essentially different hazard analysis method, based on systems theory. Although successfully applied in many industries, there are only a few reports on STPA implementation in radiation therapy. This paper contributes to filling this gap with a preliminary assessment of STPA applied to a mature Intensity Modulated Radiation Therapy (IMRT) process. The analysis was conducted by a team consisting of two experts in radiation therapy and one software systems engineer, with little domain knowledge. 142 potentially unsafe control actions were identified and compared with the results of an earlier HFMEA. The main lesson we have learned is that a graphical, system-wise modeling of the analyzed process, although challenging for beginners, is a powerful instrument to catch the same and even other, new hazards. A causal analysis of a subset of these newly found hazards has led to meaningful and valuable risk mitigation measures. These results suggest considering STPA as a viable option for safety analysis in radiation therapy. We expect that this top-down, well-structured way of analysis can especially be advantageous for safety assessment in early design phases, when an HFMEA is not possible yet, because most of system's implementation and behavior is still unknown.

AB - Radiation therapy is an important technique to treat cancer. Due to the high occupational risks involved, the process is subject to severe safety regulations and standards. However, these standards do not mandate the usage of a particular hazard analysis method. The de facto methods currently used are the reliability theory-based Fault Tree Analysis (FTA) and Healthcare Failure Mode and Effects Analysis (HFMEA). Systems Theoretic Process Analysis (STPA) is a new, essentially different hazard analysis method, based on systems theory. Although successfully applied in many industries, there are only a few reports on STPA implementation in radiation therapy. This paper contributes to filling this gap with a preliminary assessment of STPA applied to a mature Intensity Modulated Radiation Therapy (IMRT) process. The analysis was conducted by a team consisting of two experts in radiation therapy and one software systems engineer, with little domain knowledge. 142 potentially unsafe control actions were identified and compared with the results of an earlier HFMEA. The main lesson we have learned is that a graphical, system-wise modeling of the analyzed process, although challenging for beginners, is a powerful instrument to catch the same and even other, new hazards. A causal analysis of a subset of these newly found hazards has led to meaningful and valuable risk mitigation measures. These results suggest considering STPA as a viable option for safety analysis in radiation therapy. We expect that this top-down, well-structured way of analysis can especially be advantageous for safety assessment in early design phases, when an HFMEA is not possible yet, because most of system's implementation and behavior is still unknown.

M3 - Article

VL - 122

SP - 104519

JO - Safety Science

JF - Safety Science

SN - 0925-7535

ER -