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.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
OTHER
Masking
NONE
Enrollment
41
One or two CBCT images are acquired on the novel CBCT imaging system.
Maastricht Radiation Oncology
Maastricht, Limburg, Netherlands
Image Quality
For this objective, the image noise level was evaluated in regions of interest representing different tissue types (muscle and fat) in both CT simulation images and HyperSight CBCT images. Image noise is the variation in image intensity, which is measured in Hounsfield Units (HU), in a region that should have uniform intensity without the presence of noise. Image noise is measured as the standard deviation of HU within the defined regions of interest. Higher noise values indicate poorer image quality. HyperSight images can be reconstructed from raw data using different reconstruction algorithms. For this analysis, both the standard Feldkamp-Davis-Kress (FDK) algorithm and an iterative metal artifact reduction (MAR) algorithm were evaluated.
Time frame: Within 1 month from the start of treatment
Accuracy of Radiation Dose Calculation on HyperSight CBCT
The accuracy of dose calculation on HyperSight CBCT was evaluated by re-calculating a participant's clinical treatment plan on one of their HyperSight images and comparing the doses delivered to target structures and organs at risk (OARs). The lower the difference in dose metrics between a HyperSight CBCT-based plan and a CT simulation-based plan, the more accurate the dose calculation on HyperSight CBCT. Both the maximum dose delivered to OARs and the mean dose delivered to OARs were compared between HyperSight-based plans and CT simulation-based plans. We report the worst overall accuracy, i.e. maximum difference in dose metrics across all OARs from across all patients. Similarly, the maximum dose delivered to the target, the mean dose delivered to the target and the minimum dose delivered to 95% of the target were compared between HyperSight CBCT-based plans and CT simulation-based plans. We report here the maximum difference across all dose metrics from across all patients.
Time frame: Within 1 month from the start of treatment
Qualitative Assessment of Novel CBCT Images for Contouring Organs at Risk
CT simulation images and HyperSight CBCTs from subjects were randomly presented to expert reviewers, who were blinded to the type of image they were looking at and who were asked to rate their confidence level for contouring organs at risk (OARs) on the images using a 5-point Likert scale (very high, high, moderate, low, very low). The percentage of times that a reviewer rated their confidence level for contouring OARs on HyperSight CBCT as moderate, high, or very high was recorded. A higher percentage means a more favorable assessment for OAR contouring on HyperSight CBCT. The percentage of times the reviewer's confidence level for contouring on a HyperSight CBCT was equal to or higher than their confidence level on the corresponding CT simulation image was also recorded, where again a higher percentage means a better assessment for OAR contouring on HyperSight CBCT. The HyperSight iterative metal artifact reconstruction (MAR) algorithm was used in this analysis.
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Time frame: Within 1 month from the start of treatment