Japanese Journal of Radiology

, Volume 36, Issue 4, pp 273–281 | Cite as

Global and Japanese regional variations in radiologist potential workload for computed tomography and magnetic resonance imaging examinations

  • Kanako K. Kumamaru
  • Akihiro Machitori
  • Ritsuko Koba
  • Shinpei Ijichi
  • Yasuo Nakajima
  • Shigeki Aoki
Original Article



To investigate the global variation in radiologist potential workload for CT and MRI examinations, and the regional variation in potential workload and extent of radiologists’ involvement in CT and MRI examinations in Japan.


“Radiologist potential workload” was defined as the annual number of CT plus MRI examinations divided by the total number of diagnostic radiologists. The extent of radiologists’ involvement was measured as the proportion of CT and MRI examinations to which “Added-fees for Radiological Managements on Imaging-studies (ARMIs)” were applied among eligible examinations. Maximum variation was computed as the ratio of the highest-to-lowest values among the countries or Japanese prefectures.


The radiologist potential workload in Japan was 2.78–4.17 times higher than those in other countries. A maximum prefecture-to-prefecture variation was 3.88. The average percentage of CT plus MRI examinations with ARMI applied was 43.3%, with a maximum prefecture-to-prefecture variation of 3.97. Prefectures with more radiologists tended to have a higher extent of radiologists’ involvement.


Japan had a far greater radiologist potential workload compared with other countries, with a large regional variation among prefectures. Prefectures with more radiologists tended to have a higher extent of radiologists’ involvement in CT and MRI examinations.


Computed tomography Magnetic resonance imaging Radiologist Workload 

Abbreviations and acronyms


Computed tomography


Magnetic resonance imaging


National database


Organisation for economic co-operation and development


Added-fee for Radiological Managements on Imaging-studies


Compliance with ethical standards

Conflict of interest

Ms. Koba and Mr. Ijichi are employees of GE healthcare, Japan. All data were entirely under the control of the corresponding author and the roles of Ms. Koba and Mr. Ijichi were the technical support for the analysis and drawing figures. The other authors have no conflict of interest.

Ethical approval

This study was exempt from Institutional Review Board approval at the institution where the analyses were performed, because only aggregated anonymous data were used.


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Copyright information

© Japan Radiological Society 2018
corrected publication March 2018

Authors and Affiliations

  • Kanako K. Kumamaru
    • 1
  • Akihiro Machitori
    • 2
  • Ritsuko Koba
    • 3
    • 4
  • Shinpei Ijichi
    • 4
  • Yasuo Nakajima
    • 3
  • Shigeki Aoki
    • 1
  1. 1.Department of Radiology, School of MedicineJuntendo UniversityTokyoJapan
  2. 2.Department of RadiologyNational Center for Global Health and Medicine, Kohnodai HospitalChibaJapan
  3. 3.Department of RadiologySt. Marianna University School of MedicineKawasakiJapan
  4. 4.GE Healthcare Japan CorporationTokyoJapan

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