Trial Outcomes & Findings for A Pilot Study Evaluating the Effect of 2D Antiscatter Grids on CBCT Image Quality (NCT NCT04565457)
NCT ID: NCT04565457
Last Updated: 2026-05-06
Results Overview
Median paired shift in Artifact Amplitude between research CBCT and standard clinical CBCT scans in participants receiving proton radiation therapy. Artifact Amplitude error was evaluated in corresponding regions of interest in paired scans. The Hodges-Lehmann estimate of the median shift and its 95% confidence interval were calculated, and paired differences were evaluated using a Wilcoxon signed-rank test.
COMPLETED
NA
43 participants
At time of CBCT imaging session (Day 1)
2026-05-06
Participant Flow
Out of 43 participants enrolled in the study, 42 were scanned with the research and the standard CBCT protocol. One participant in the proton therapy arm withdrew from the study before the research CBCT scan. 32 participants received photon and 10 participants received proton therapy. Outcomes of each therapy cohort was analyzed separately in two separate arms.
Participant milestones
| Measure |
Photon Therapy Participants
All photon radiotherapy participants were scanned with a CBCT system installed on a linac equipped with 2D antiscatter grid technology, referred to as research CBCT. Each participant was also scanned with a standard clinical CBCT as part of their standard clinical care, which served as the baseline, or control.
|
Proton Therapy Participants
All proton radiotherapy participants were scanned with a CBCT system installed on a proton therapy gantry equipped with 2D antiscatter grid technology, referred to as research CBCT. Each participant was also scanned with a standard clinical CBCT as part of their standard clinical care, which served as the baseline, or control.
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|---|---|---|
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Overall Study
STARTED
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32
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11
|
|
Overall Study
COMPLETED
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32
|
10
|
|
Overall Study
NOT COMPLETED
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0
|
1
|
Reasons for withdrawal
| Measure |
Photon Therapy Participants
All photon radiotherapy participants were scanned with a CBCT system installed on a linac equipped with 2D antiscatter grid technology, referred to as research CBCT. Each participant was also scanned with a standard clinical CBCT as part of their standard clinical care, which served as the baseline, or control.
|
Proton Therapy Participants
All proton radiotherapy participants were scanned with a CBCT system installed on a proton therapy gantry equipped with 2D antiscatter grid technology, referred to as research CBCT. Each participant was also scanned with a standard clinical CBCT as part of their standard clinical care, which served as the baseline, or control.
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|---|---|---|
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Overall Study
Withdrawal by Subject
|
0
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1
|
Baseline Characteristics
Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
Baseline characteristics by cohort
| Measure |
Photon Therapy Participants
n=31 Participants
Participants receiving photon radiation therapy, scanned with a novel CBCT technique, referred to as "Research CBCT". Each participant scanned twice, once with the research CBCT method under investigation and once with the standard of care CBCT. The novel Research CBCT technique incorporates a 2D antiscatter grid device.
Patients were accrued based on their treatment site: prostate/prostate bed, abdomen/pelvis, head and neck (H\&N).
.
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Proton Therapy Participants
n=10 Participants
Participants receiving proton radiation therapy scanned with a novel CBCT technique, referred to as "Research CBCT".
Each participant scanned twice, once with the research CBCT method under investigation and once with the standard of care CBCT. The novel Research CBCT technique incorporates a 2D antiscatter grid device.
Proton therapy patients treated for prostate or prostate bed cancers were accrued.
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Total
n=41 Participants
Total of all reporting groups
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|---|---|---|---|
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Age, Categorical
<=18 years
|
0 Participants
n=54 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
0 Participants
n=60 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
0 Participants
n=114 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
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Age, Categorical
Between 18 and 65 years
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17 Participants
n=54 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
1 Participants
n=60 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
18 Participants
n=114 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
|
Age, Categorical
>=65 years
|
14 Participants
n=54 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
9 Participants
n=60 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
23 Participants
n=114 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
|
Sex: Female, Male
Female
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6 Participants
n=54 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
0 Participants
n=60 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
6 Participants
n=114 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
|
Sex: Female, Male
Male
|
25 Participants
n=54 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
10 Participants
n=60 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
35 Participants
n=114 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
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|
Race (NIH/OMB)
American Indian or Alaska Native
|
0 Participants
n=54 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
0 Participants
n=60 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
0 Participants
n=114 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
|
Race (NIH/OMB)
Asian
|
0 Participants
n=54 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
0 Participants
n=60 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
0 Participants
n=114 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
|
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
|
0 Participants
n=54 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
0 Participants
n=60 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
0 Participants
n=114 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
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Race (NIH/OMB)
Black or African American
|
1 Participants
n=54 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
0 Participants
n=60 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
1 Participants
n=114 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
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|
Race (NIH/OMB)
White
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28 Participants
n=54 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
10 Participants
n=60 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
38 Participants
n=114 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
|
Race (NIH/OMB)
More than one race
|
0 Participants
n=54 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
0 Participants
n=60 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
0 Participants
n=114 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
|
Race (NIH/OMB)
Unknown or Not Reported
|
2 Participants
n=54 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
0 Participants
n=60 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
2 Participants
n=114 Participants • Forty-three participants were enrolled. One participant withdrew from the study before the intervention. Total of 42 participants were scanned. One of the participants scan was excluded from the analysis due to a technical issue during the CBCT scan. Therefore, baseline characteristics are reported for 41 participants.
|
|
Anatomical site
Prostate/Prostate bed
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10 Participants
n=54 Participants • In the proton therapy arm, only prostate or prostate bed cancer patients were accrued. In the photon therapy arm, patients with the following treatment sites were accrued: Prostate/prostate bed cancers, H\&N cancer, and pelvic/abdominal cancers.
|
10 Participants
n=60 Participants • In the proton therapy arm, only prostate or prostate bed cancer patients were accrued. In the photon therapy arm, patients with the following treatment sites were accrued: Prostate/prostate bed cancers, H\&N cancer, and pelvic/abdominal cancers.
|
20 Participants
n=114 Participants • In the proton therapy arm, only prostate or prostate bed cancer patients were accrued. In the photon therapy arm, patients with the following treatment sites were accrued: Prostate/prostate bed cancers, H\&N cancer, and pelvic/abdominal cancers.
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|
Anatomical site
Head and Neck
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11 Participants
n=54 Participants • In the proton therapy arm, only prostate or prostate bed cancer patients were accrued. In the photon therapy arm, patients with the following treatment sites were accrued: Prostate/prostate bed cancers, H\&N cancer, and pelvic/abdominal cancers.
|
0 Participants
n=60 Participants • In the proton therapy arm, only prostate or prostate bed cancer patients were accrued. In the photon therapy arm, patients with the following treatment sites were accrued: Prostate/prostate bed cancers, H\&N cancer, and pelvic/abdominal cancers.
|
11 Participants
n=114 Participants • In the proton therapy arm, only prostate or prostate bed cancer patients were accrued. In the photon therapy arm, patients with the following treatment sites were accrued: Prostate/prostate bed cancers, H\&N cancer, and pelvic/abdominal cancers.
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|
Anatomical site
Abdomen/Pelvis
|
10 Participants
n=54 Participants • In the proton therapy arm, only prostate or prostate bed cancer patients were accrued. In the photon therapy arm, patients with the following treatment sites were accrued: Prostate/prostate bed cancers, H\&N cancer, and pelvic/abdominal cancers.
|
0 Participants
n=60 Participants • In the proton therapy arm, only prostate or prostate bed cancer patients were accrued. In the photon therapy arm, patients with the following treatment sites were accrued: Prostate/prostate bed cancers, H\&N cancer, and pelvic/abdominal cancers.
|
10 Participants
n=114 Participants • In the proton therapy arm, only prostate or prostate bed cancer patients were accrued. In the photon therapy arm, patients with the following treatment sites were accrued: Prostate/prostate bed cancers, H\&N cancer, and pelvic/abdominal cancers.
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PRIMARY outcome
Timeframe: At time of CBCT imaging session (Day 1)Population: Out of 32 participants in the photon therapy group, 31 participants with evaluable paired CBCT scans (research CBCT with 2D antiscatter grid and standard clinical CBCT) were included in this analysis. One participant was excluded due to non-evaluable imaging data caused by a CBCT technical problem during the CBC T scan.
Ratio of HU error for standard clinical CBCT (iteratively reconstructed) relative to research CBCT with 2D antiscatter grid in photon therapy participants. HU error was assessed in corresponding regions of interest, and the ratio was estimated using a linear mixed-effects model. A ratio greater than 1 would indicate higher HU error in standard CBCT than in research CBCT. A ratio less than 1 would indicate higher HU error in research CBCT than in standard CBCT.
Outcome measures
| Measure |
Photon Therapy Participants
n=31 Participants
All photon radiotherapy participants will be scanned using the Research CBCT technique. Each participant will also be scanned with a standard clinical CBCT as part of their standard clinical care, which will serve as the baseline, or control.
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|---|---|
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Ratio of Standard CBCT to Research CBCT HU Error in Photon Therapy Participants
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1.768 Ratio (unitless)
Interval 1.466 to 2.132
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PRIMARY outcome
Timeframe: At time of CBCT imaging session (Day 1)Population: Proton therapy participants with standard CBCT and research CBCT scans were included in this analysis. All 10 participants in this arm were included in the analysis.
Median paired shift in Hounsfield Unit (HU) error between research CBCT and standard clinical CBCT scans in participants receiving proton radiation therapy. HU error was evaluated in corresponding regions of interest in paired scans. The Hodges-Lehmann estimate of the median shift and its 95% confidence interval were calculated, and paired differences were evaluated using a Wilcoxon signed-rank test.
Outcome measures
| Measure |
Photon Therapy Participants
n=10 Participants
All photon radiotherapy participants will be scanned using the Research CBCT technique. Each participant will also be scanned with a standard clinical CBCT as part of their standard clinical care, which will serve as the baseline, or control.
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|---|---|
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Median Shift in Hounsfield Unit (HU) Error Between Standard CBCT and Research CBCT in Proton Therapy Participants
|
-128.8 Change in HU error
Interval -137.9 to -123.3
|
PRIMARY outcome
Timeframe: At time of CBCT imaging session (Day 1)Population: 31 participants with evaluable paired CBCT scans (research CBCT with 2D antiscatter grid and standard clinical CBCT) were included in this analysis.
Ratio of artifact amplitude between standard clinical CBCT (iteratively reconstructed) and research CBCT scans in participants receiving photon radiation therapy. Artifact amplitude was measured in corresponding regions of interest. The ratio of artifact amplitude between standard CBCT and research CBCT was estimated using a linear mixed-effects model. Ratio greater than 1 would indicate that standard CBCT has greater artifact amplitude than research CBCT.
Outcome measures
| Measure |
Photon Therapy Participants
n=31 Participants
All photon radiotherapy participants will be scanned using the Research CBCT technique. Each participant will also be scanned with a standard clinical CBCT as part of their standard clinical care, which will serve as the baseline, or control.
|
|---|---|
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Ratio of Artifact Amplitude Between Standard CBCT and Research CBCT in Photon Therapy Participants
|
1.489 Ratio
Interval 1.255 to 1.767
|
PRIMARY outcome
Timeframe: At time of CBCT imaging session (Day 1)Population: All 10 proton therapy participants with paired standard CBCT and research CBCT scans were included in this analysis.
Median paired shift in Artifact Amplitude between research CBCT and standard clinical CBCT scans in participants receiving proton radiation therapy. Artifact Amplitude error was evaluated in corresponding regions of interest in paired scans. The Hodges-Lehmann estimate of the median shift and its 95% confidence interval were calculated, and paired differences were evaluated using a Wilcoxon signed-rank test.
Outcome measures
| Measure |
Photon Therapy Participants
n=10 Participants
All photon radiotherapy participants will be scanned using the Research CBCT technique. Each participant will also be scanned with a standard clinical CBCT as part of their standard clinical care, which will serve as the baseline, or control.
|
|---|---|
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Median Shift in Artifact Amplitude (Measured in Hounsfield Units) Between Standard CBCT and Research CBCT in Proton Therapy Participants
|
-235.9 Change in HU
Interval -269.1 to -182.4
|
PRIMARY outcome
Timeframe: At time of CBCT imaging session (Day 1)Population: 31 participants with evaluable paired CBCT scans (research CBCT with 2D antiscatter grid and standard clinical CBCT) were included in this analysis.
Ratio of CNR between standard clinical CBCT and research CBCT scans in participants receiving photon radiation therapy. CNR was quantified in corresponding regions of interest in paired standard and research CBCT scans of each participant. The ratio of CNR between standard CBCT and research CBCT was estimated using a linear mixed-effects model.
Outcome measures
| Measure |
Photon Therapy Participants
n=31 Participants
All photon radiotherapy participants will be scanned using the Research CBCT technique. Each participant will also be scanned with a standard clinical CBCT as part of their standard clinical care, which will serve as the baseline, or control.
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|---|---|
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Ratio of Contrast-To-Noise Ratio (CNR) Between Standard CBCT and Research CBCT in Photon Therapy Participants
|
1.199 Ratio
Interval 1.082 to 1.329
|
PRIMARY outcome
Timeframe: At time of CBCT imaging session (Day 1)Population: Proton therapy participants were included in this analysis. Data of 10 participants were analyzed.
Median paired shift in CNR between research CBCT and standard clinical CBCT scans in participants receiving proton radiation therapy. CNR was evaluated in corresponding regions of interest in paired scans. The Hodges-Lehmann estimate of the median shift and its 95% confidence interval were calculated, and paired differences were evaluated using a Wilcoxon signed-rank test.
Outcome measures
| Measure |
Photon Therapy Participants
n=10 Participants
All photon radiotherapy participants will be scanned using the Research CBCT technique. Each participant will also be scanned with a standard clinical CBCT as part of their standard clinical care, which will serve as the baseline, or control.
|
|---|---|
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Median Shift in Contrast to Noise Ratio (CNR) Between Standard CBCT and Research CBCT in Proton Therapy Participants
|
0.56 Unitless
Interval 0.44 to 0.73
|
SECONDARY outcome
Timeframe: At time of CBCT imaging session.Population: 31 photon therapy participants were enrolled. Five participants were excluded from the secondary outcome analysis because the required segmentation data were not suitable for analysis due to severe artifacts in the CBCT images. Mean difference in Dice similarity coefficient (standard CBCT minus research CBCT) was analyzed. Negative values would indicate higher Dice similarity and auto-delineation accuracy for research CBCT.
Similarity between anatomical structures delineated by auto-segmentation software and expert observer contours in research CBCT and standard clinical CBCT images was evaluated using the Dice similarity coefficient. The pairwise difference in Dice coefficients between standard clinical CBCT and research CBCT images was calculated. Higher Dice coefficients indicate greater similarity between auto-segmented and expert-drawn contours and higher accuracy in automated tissue delineation.
Outcome measures
| Measure |
Photon Therapy Participants
n=26 Participants
All photon radiotherapy participants will be scanned using the Research CBCT technique. Each participant will also be scanned with a standard clinical CBCT as part of their standard clinical care, which will serve as the baseline, or control.
|
|---|---|
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Accuracy of Automated Tissue Delineation in CBCT Images for Photon Therapy Participants. Difference in Dice Similarity Coefficient Between Research CBCT and Standard CBCT
|
-0.065 Difference in Dice coefficients
Interval -0.099 to -0.032
|
Adverse Events
Photon Therapy Participants
Proton Therapy Participants
Serious adverse events
Adverse event data not reported
Other adverse events
Adverse event data not reported
Additional Information
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place