Interphysician variability in defining the planning target volume in the irradiation of prostate and seminal vesicles

Radiother Oncol. 1998 Jun;47(3):293-6. doi: 10.1016/s0167-8140(98)00028-0.

Abstract

With the improvements in treatment accuracy the risk exists of over-reliance on the capability of the physician to estimate the extent of the tumour. We assessed the variability between six radiotherapists in defining the planning target volume (PTV) on CT slices for three prostate tumour cases. Percentage differences between measured volumes and mean values calculated for each case ranged from -53.64 to +60.48% (SD 36.00%). There is a considerable variation in delineating the PTV, both in the cranio-caudal direction and in the in-slice extension of the areas drawn on each slice (standard deviations ranged from 0.35 to 2.64 cm2). We also checked the uncertainty in the shape and position of the contours on each CT image. The analysis was performed on three slices of one test case. As we expected, the uncertainty seems largest for seminal vesicle slices and smallest for prostatic apex slices. These results endorse the need for uncertainty analysis of all departmental processes in order to define a detailed protocol and consequently to minimize the interphysician differences in PTV delineations.

Publication types

  • Comparative Study

MeSH terms

  • Analysis of Variance
  • Humans
  • Male
  • Observer Variation
  • Physicians
  • Practice Patterns, Physicians'
  • Prostate / diagnostic imaging*
  • Prostate / radiation effects
  • Prostatic Neoplasms / diagnostic imaging
  • Prostatic Neoplasms / radiotherapy*
  • Radiation Dosage
  • Radiotherapy Planning, Computer-Assisted*
  • Reproducibility of Results
  • Seminal Vesicles / diagnostic imaging*
  • Seminal Vesicles / radiation effects
  • Tomography, X-Ray Computed
  • Urethra / diagnostic imaging
  • Urography