Innovative education method for a more effective, faster, and valued training in radiation therapy treatment planning

Purpose: Because of the automation of radiation therapy, competencies of radiation technologists (RTTs) change, and training methods are challenged. This study aims to develop, and pilot test an innovative training method based on lean management principles. Methods and Materials: A new training method was developed for lung cancer treatment planning (TP). The novelty is summarized by including a stable environment and an increased focus on the how and why of key decision making. Trainees have to motivate their decisions during TP process, and to argue their choices with peers. Six students and 6 RTTs completed this training for lung cancer TP. Effects of the training were measured by (1) quality of TP, using doses in organs at risk and target volumes, (2) perceived experiences (survey), measured at baseline (T0); after peer session (T1); and 6 months later (T2). Finally, training throughput time was measured. Results: At T0, RTTs showed a larger intragroup interquartile range (IIR) (2.63Gy vs 1.51Gy), but lower mean doses to heart and esophagus than students (6.79Gy vs 8.49Gy; 20.87Gy vs 24.62Gy). At T1, quality of TPs was similar between RTTs and students (IIR: 1.39Gy vs 1.33Gy) and no significant differences in mean dose to heart and esophagus (4.48Gy vs 4.69Gy; 17.75Gy vs 18.47Gy). At T2, students still performed equal to RTTs (IIR: 1.07Gy vs 1.45Gy) and achieved lower maximum dose to esophagus (44.75Gy vs 46.45Gy). The training method and peer sessions were experienced positive: at baseline (T0): 8 score on a scale 1-10, directly after the peer sessions; (T1): 8 by the students and 7 by the RTTs, after 9 months; (T2): 9 by the students and 7 by the RTTs. Training throughput time decreased from 12 to 3 months. Conclusions: This training method based on lean management principles was successfully applied to training of RTTs for lung cancer TP. Training throughput time was reduced dramatically and TP quality sustained after 6 months. This method can potentially improve training efficiency in diverse situations with complex decision-making.</p

The concept of a 'virtual patient': Transformation of multiple lung cancer patients to a common spatial configuration using non-rigid registration, a way to simplify large datasets and to generate new hypotheses

Purpose: To investigate the use of non-rigid registration for transforming and fusing data from multiple lung cancer patients into a common spatial reference ("Virtual Patient' ) in order to perform spatial-based statistics. This allows us to study the eflects ot radiotherapy by comparing the spatial distribution of data such as PET and dose distribution for multiple patients with or without a complication or a relapse. Furthermore, the reverse transformation can be applied on the reference contours in order to automatically segment the patient anatomy. Materials: CT imaging was performed for 6 lung cancer patients . One patient was taken as reference and the lungs and spinal cord were delineated. The 5 other patients were also delineated for validation purposes. An intensity based affine alignment followed by a log-domain phase-based non-rigid registration were applied on these data, producing for each patient a deformation field representing the transformation from the reference to the patient, and its inverse. For each patient, the tumor was delineated and ignored during the deformation field computation. The direct transformation was used to deform each patient CT towards the reference anatomy. while the inverse transformation was used to deform the reference contours towards the patient anatomy. These contours were compared to manual contours for each patient In order to validate the registration process. Results: CT, PET and dose distribution were successfully deformed towards the reference configuration ("Virtual Patient") using the deformation fields resulting from registration (see Figure 1). After registration, the DICE coefficient, used as a measurement of overlap between deformed reference contours and manual contours of the lungs was of 92 ± 3% (1SO). Conclusions: These preliminary results showed that non-rigid registration was able to match accurately the lung contours of the reference with the lung contours of the patients. The resulting transformations can then be used to deform the CT, PET and dose distribution accordingly, in order to transform the individual patient information into a common spatial configuration for performing spatial-based statistical analysis on two populations (e.g. with and without complications) inside two ("Virtual") reference patients summarizing respectively the PET images and dose distribution of patients with and without a complication. This approach allows to "simplify" large complex datasets or randomized trials and to generate new hypotheses

Is contrast enhancement required to visualize a known breast tumor in a pre-operative CT scan?

AbstractBackground and purposeA pre-operative CT scan with contrast enhancement (CE) has recently been proposed to improve tumorbed delineation in breast conserving therapy. However, it is not clear whether CE is required for visualization of a known breast tumor. The main aims of this study were to compare the sensitivity of a CE-CT scan with a native CT scan (i.e. without CE) and to identify characteristics predictive for the requirement of CE.Patients and methodsBoth a CE-CT and a native CT were made in 58 breast cancer patients (age 37–75yr), prior to breast conserving surgery. Visibility of the tumor on CT was scored by three observers (clearly visible/doubtful/not visible). Age, tumor size, palpable tumor yes/no, histology, and visibility on mammography were analyzed with respect to the visibility of the tumor on the native CT.ResultsThe sensitivity for tumor detection was better for CE-CT (95%) than for native CT (83%) (p<0.001). Only mammographic visibility scores appeared to be significantly correlated with the visibility of the tumor on the native CT (p=0.013).ConclusionIn most patients CE is not required to visualize a known breast tumor. Mammographic visibility is a good parameter to decide on the use of CE

Reducing interobserver variation of boost-CTV delineation in breast conserving radiation therapy using a pre-operative CT and delineation guidelines

Clinical Oncolog