Radiation Therapy Technologists (RTT) Section

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Ongoing: Delineation project

EORTC trials

The EORTC runs numerous multicentre trials, most of them involving radiotherapy. Target areas for radiotherapy are delineated on CT scans with or without the help of other image modalities by the radiation oncologist. However in most institutes the organs-at-risk (OARs) are delineated on a CT scan by the radiation technologist (RTT) during the treatment planning procedure. Defining strict guidelines on CT based information for OARs would reduce the inter-observer variability between institutes and allow for a more accurate comparison and evaluation of treatment results in multicentre trials.

A study was setup by the EORTC ROG-RTT group to define OARs guidelines to be used by RTTs and fellows / radiation oncologists involved in contouring OARs.

Aim of the Delineation Project

The aim of the study is to define clear anatomical guidelines using the uniform structure names for OARs which can then be used by RTTs / fellows / radiation oncologists in EORTC trials.

Once clear anatomical guidelines have been set and tested they can be incorporated in a delineation atlas. The atlas together with the anatomical guidelines can then be used to delineate OARs in EORTC trials.

Delineation Project Part 1:
OAR in the male Pelvic Region (completed 2014)

The EORTC ROG-RTT section setup a project group to realise this. The OARs in the male pelvic area were chosen for this project. Prior to commencing the study proper, logistics and evaluation methods were assessed in a pilot study using only one OAR (bladder) and a small group (5) of RTTs.

The same institutes participated in the second phase. In this phase general delineation guidelines were provided for each of the following OARs in the pelvic region (bladder, anus, rectum, sigmoid, femoral heads and penile bulb). The results were analysed and the guidelines were adjusted for those OARs that demonstrated large variations between observers.

The third phase involved a larger number of observers (16) with stricter guidelines for the same OARs. Furthermore we provided visual information of the structures to be delineated.

In the last phase we defined guidelines with bony anatomy and provided visual information of the structures to be delineated.The delineation was to be done on 4 new datasets by the same observers.

Results

The results of this delineation study were presented during the ROG-meeting in Bristol in March 2014.

Delineation Project Part 2:
Delineation of OAR within EORTC LungTech trial (now ongoing)

The primary objective of the EORTC LungTech trial is to evaluate the effectiveness of IG-SBRT in medically inoperable patients with small central tumours.

Secondary objectives are to assess the safety and evaluate toxicity. Toxicity reports are related to delineated volumes.

The role for the RTT-section is to improve the quality and consistency of the delineation of Organs At Risk (OAR) in the mediastinum according to LungTech trial protocol.

We are collecting data on the delineation by analysis of the delineated OAR’s in completed benchmark cases and collection of questionnaires, addressing the difficulty of delineation.

We will then give suggestions on how to improve the quality / consistency of the delineation of OAR (during trial!).

Current status

Early analysis of the returned benchmark cases (March 2015) showed that delineation of OAR was performed inconsistently, requiring adjustments in the delineation protocol.

Suggested improvement by the RTT-section (EGAM March ’15) was to organize a workshop on delineation of OAR in this LungTech-trial during the ROG-meeting in Las Palmas for participating institutes.

Delineation is to be redone thereafter, while the other group that will not be able to attend the workshop will be requested to redo delineation using the original guidelines (testing of learning curve).

If you as an RTT would like more information or wish to partake in this study please contact us.

On behalf of EORTC – ROG Technologists Section,

Bruno Speleers, Speleers.Bruno@uzgent.be

Maddalena Rossi, m.rossi@nki.nl

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