Dual Energy CT - a Tool for Delineation of Tumor and Organs at Risk in Radiotherapy

Condition(s) studied

Investigational drug(s) / intervention(s)

Dual-energy CT (DECT): Additional DECT scan performed for tumor and OAR delineation.

Iodine-based contrast agent: Administered intravenously with DECT for enhanced imaging.

Magnetic Resonance Imaging (MRI): Additional MRI scan performed for tumor and OAR delineation.

Gadolinium-based contrast agent: Administered intravenously with MRI for enhanced imaging.

Study summary

The primary aim of this clinical study, 'Dual Energy CT - a tool for delineation of tumor and organs at risk in radiotherapy' (DART) is to evaluate whether dual-energy CT (DECT) is at least as effective as magnetic resonance imaging (MRI) in delineating both tumors and organs at risk (OARs) in patients referred for radiotherapy (RT). This primary aim will be explored in patient groups where the performance of DECT for RT has been described in the literature (but mostly based on signal-to-noise ratio and/or contrast-to-noise ratio), such as brain metastases (sub-cohort 'DART Brain') and head and neck cancer (sub-cohort 'DART H\&N'). Additionally, DART will explore diagnoses not yet studied in the literature, such as bone metastases (sub-cohort 'DART Bone'). If DECT could be demonstrated to achieve delineations for RT in both tumors and OARs that are equally accurate as those based on MRI, it could offer significant advantages by being faster and more cost-effective, making DECT a valuable alternative to MRI in clinical practice. As a secondary aim, the study will evaluate whether DART offers benefits when added to standard RT imaging for tumor and OAR delineation: (1) For lung cancer patients (sub-cohort 'DART Lung'), where MRI scans are typically not valuable due to tumor motion caused by breathing, 'DART Lung' will assess whether DECT performed in breath-hold provides added value compared to the single-energy CT (SECT) scan conducted during free breathing, as used in current clinical practice. (2) For head and neck cancer patients, 'DART H\&N' will evaluate whether DECT offers added value compared to the positron emission tomography (PET)/CT scan currently used in clinical practice.

Eligibility

Primary outcome measure(s)

• Inter-observer variability (geometric differences in volume and surface) of manual tumor and OAR delineations on DECT compared with SECT/MRI. — Baseline (time of imaging before radiotherapy planning)
  For patients enrolled in cohorts 'DART Brain', 'DART Bone' and 'DART H\&N', the accuracy of manual delineations of tumors and OARs on DECT scans will be compared to those manually performed on a combination of SECT and MRI scans for each patient. For patients enrolled in 'DART H\&N' the comparison will also be done to the PET/CT scan. A reduction in inter-observer variability in delineations will serve as an indicator of improved contour accuracy for both tumors and OARs. Inter-observer variability for tumor and OAR delineations on DECT and SECT/MRI scans, respectively, will be measured as geometric differences between individual manual delineations and consensus structures for each tumor and OAR. Consensus structures will be generated on both DECT and SECT/MRI scans using the STAPLE function with a 50% agreement threshold. Variations relative to the consensus structures will be reported using various metrics, including volume and surface differences.

Trial sites (3)

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