Verification and correction of geometrical uncertainties in conformal radiotherapy

Abstract

Geometrical errors are presented as deviation between intended geometry of radiotherapy plan and real geometry of radiotherapy treatment. Total geometrical error is build up of smaller errors, which can be generally classified as set-up, organ motion, organ delineation, and technical condition related errors. The clear distinction must be made between systematic and random component of these errors and its amount should be encountered in treatment planning process. Errors’ measuring for specific patient group with electronic portal imaging device and proper correction strategy enables to predict, minimize, and keep under control the amount for most of geometrical errors; it also improves the preciseness of treatment and consequent results. Nature and characteristics of most frequent geometrical errors are discussed and clinically applicable methods for their proper managing are described in this paper

Assessment of Set-Up Error in Three-Dimensional Conformal Radiotherapy (3-Dcrt) During the Treatment of Patients With Prostate or Bladder Cancers in Ayadi El-Mostakbal Hospital (Alexandria, Egypt)

“…If this were to be applied to all prostate and bladder patients, the daily workload would increase by one hour and 40 min. However, this practice will still be helpful compared to reducing normal tissue dose, especially in the rectum [11].…”

“…The set-up errors in the radiation therapy treatment can negatively affect the accuracy of the treatment. Therefore, it is essential to add a safety margin around the tumor to assure that the radiation dose will cover the whole tumor size [11] .…”

Determination of an optimal treatment margin for intracranial tumours treated with radiotherapy at Groote Schuur Hospital

“…When determining the CTV-PTV margin, it is therefore recommended to use institution-specific data on setup error. 14,15,16…”