Evaluation of a Cone-beam CT Scanner for Image Guided Radiotherapy (CONFIGURE)

This is a feasibility study investigating the image quality of a new, high-performance cone beam CT (CBCT) used for on-couch imaging during radiotherapy treatments.

This study will examine the image quality generated by a new cone-beam CT (CBCT) imaging system integrated into an external beam radiation treatment delivery platform. Normally, CBCT images are acquired at the start of a daily radiation delivery treatment to align the patient with the images that were used to generate their radiation treatment plan. This alignment increases the precision of radiation delivery. This study will assess whether the improvements in image quality expected from the novel CBCT imaging system are sufficient for the images to be used for more than just patient alignment. The study will enroll patients who will be treated with external beam radiation therapy for the following conditions: head and neck cancers, stage I lung cancer, stage II to IV lung cancer, cancer in the left breast, tumors in the abdomen, and tumors in the pelvic region. Each patient will undergo one additional imaging session with the novel CBCT imaging system during which 1 or 2 CBCT images will be acquired. The number of novel CBCT images acquired depends on the location and type of the patient's tumor. The additional imaging session will occur on the same day as one of the patient's scheduled treatment delivery sessions to minimize impact on the patient's schedule. The patient's cancer treatment will not be affected by participation in this study. The methodology for the subject's treatment setup, CT simulation, treatment planning, image guidance and treatment delivery will be determined by the subject's treatment team. The images acquired by the novel CBCT imaging system will be compared to standard CBCT images acquired as part of the patient's treatment and to the CT simulation images used to define the patient's radiation treatment plan.

This is a single-site study designed to generate data describing the quality and applicability of a novel on-couch CBCT imaging system for anatomy visualization and radiation treatment dosimetry planning.

Comparison of image quality produced by the novel cone-beam CT imaging system to the quality of standard cone-beam CT imaging and to that of conventional CT images used for radiotherapy planning purposes. For this objective, the image contrast-to-noise ratio (CNR) will be evaluated. CNR is frequently used to measure image quality.

For this objective, targets and organs at risk will be delineated on the novel CBCT images acquired for each subject. The treatment plan created for the patient on the planning CT scan will be registered to the novel cone-beam CT dataset, the dose will be recalculated on the standard CBCT as well as the novel cone-beam CT. The delineations of target and OARs will either be copied, deformed or manually delineated on the CBCT images, the radiotherapy dose metrics for specific structures relevant for the anatomical site that is imaged will be compared to dose metrics from the original treatment plan.

Qualitative assessment of the novel CBCT images will be obtained by presenting individual novel CBCT images as well as head-to-head comparisons of novel and standard CBCT images from the same patient to radiation oncologists and radiation therapists. The reviewers will be asked to evaluate the images on their suitability for anatomical contouring and patient positioning. Qualitative assessments will be determined using a 5-point Likert scale.

Inclusion Criteria: The patient will be treated with external beam photon radiotherapy at Maastro for head-and-neck cancer, stage I lung cancer, stage II-IV lung cancer, left breast cancer, or tumours in the abdominal or pelvic region. Age ≥ 18 years Ability to understand the requirements of the study and to give written informed consent, as determined by the treating physician Provision of written informed consent Exclusion Criteria: Patient is pregnant