Automaticin vivoportal dosimetry of all treatments

Abstract

At our institution EPID (electronic portal imaging device) dosimetry is routinely applied to perform in vivo dose verification of all patient treatments with curative intent since January 2008. The major impediment of the method has been the amount of work required to produce and inspect the in vivo dosimetry reports (a time-consuming and labor-intensive process). In this paper we present an overview of the actions performed to implement an automated in vivo dosimetry solution clinically. We reimplemented the EPID dosimetry software and modified the acquisition software. Furthermore, we introduced new tools to periodically inspect the record-and-verify database and automatically run the EPID dosimetry software when needed. In 2012, 95% of our 3839 treatments scheduled for in vivo dosimetry were analyzed automatically (27,633 portal images of intensity-modulated radiotherapy (IMRT) fields, 5551 portal image data of VMAT arcs, and 2003 portal images of non-IMRT fields). The in vivo dosimetry verification results are available a few minutes after delivery and alerts are immediately raised when deviations outside tolerance levels are detected. After the clinical introduction of this automated solution, inspection of the detected deviations is the only remaining work. These newly developed tools are a major step forward towards full integration of in vivo EPID dosimetry in radiation oncology practice.

Initial clinical experience with Epid-based in-vivo dosimetry for VMAT treatments of head-and-neck tumors

“…The largest clinical experience so far is the one carried out at Netherland NKI-AVL center where almost all curative patients irradiated with intensity-modulated techniques are nowadays verified by means of EPID-based IVD in their first three treatment fractions. The findings of this experience have been recently published by Olaciregui-Ruiz et al [22]; using a new automated IVD solution, the authors reported on average 18% of verified plans outside at least one of their tolerance levels.…”

“…In addition, following the approach of Olaciregui-Ruiz et al [22], future investigations will be addressed on the feasibility of implementing an automated analysis able to automatically run the IVD procedure.…”

Classification of changes occurring in lung patient during radiotherapy using relative γ analysis and hidden Markov models

“…It can hardly be applied indiscriminately to large cohorts of patients. Selecting which patients would really benefit from plan adaptation is not an obvious task because it can be dependent on treatment technique, evaluation method, anatomical site and even the patient . For lung, treatment plans are often assessed through weekly or daily CBCT imaging.…”

“…While not the most accurate dose verification tools, in vivo portal dosimetry nevertheless finds numerous clinical applications . Three‐dimensional dose evaluation has been successfully implemented through dose prediction or back‐projection of the EPID signal . While extremely promising, these methods can be labor‐intensive to implement, commission, and use.…”

A dual two dimensional electronic portal imaging device transit dosimetry model based on an empirical quadratic formalism

“…10,11 An EPID transit dosimetry model using the convolution approach was also widely published by researchers at the Netherlands Cancer Institute (NKI-AVL) where the model is now in clinical use. [12][13][14][15][16][17][18] Instead of using the convolution approach, an empirical method is more practical for the majority of clinical centres with limited resources for computationally intensive simulations or mathematical modelling. 2D transit dosimetry using an empirical method was first described by Evans et al 19 and Symonds-Tayler et al 20 for an in-house imaging panel and later by Evans et al 21 for a commercial scanning liquid-filled ionization chamber (SLIC) EPID.…”