This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for A Study Using Cone Beam CT for Head and Neck Cancer (NCT01661062), a na na study. The primary outcome is Rate of Movement of Normal Tissue.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01661062 |
| Phase | NA |
| Condition | Head and Neck Cancer |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 23 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Michigan Rogel Cancer Center |
| Results posted | Yes |
2. Clinical Question
Population
People with head and neck cancer receiving radiation therapy were eligible for this imaging study. The registry records enrollment of 23 participants. It does not report participant characteristics such as age, disease site, or other clinical features, so the population represented by the enrolled group cannot be described in more detail from this record.
Intervention
Participants received cone beam CT scans before individual radiation treatment sessions. The study description says scans were obtained every day throughout radiation therapy to examine whether daily imaging provided additional information compared with less frequent imaging. The scans were for research assessment; the information from them was not used to alter participants’ actual radiation treatment.
Comparator
This was a single-group study, not a randomized comparison. There was no separate control arm or assigned comparison group. The description frames the imaging question as whether daily scans provide additional information compared with scans performed less frequently, but the registry does not describe a randomized comparison of those imaging schedules.
Primary question
The primary aim was to characterize patient-specific movement of the radiation target and normal tissues during treatment. The primary outcome is titled “Rate of Movement of Normal Tissue,” with an approximately 7 weeks timeframe. The record does not report a numerical movement estimate, an uncertainty interval, or an analysis comparing movement across patients or time. The study also assessed image quality, radiation dose to the parotid gland, salivary output, swallowing, and quality of life, but results for these assessments are not reported in the registry record.
3. Trial Design
This completed pilot study enrolled 23 participants with head and neck cancer. It was sponsored by the University of Michigan Rogel Cancer Center and used cone beam CT imaging during radiation therapy. The registry gives the study phase and allocation as NA, identifies masking as NONE, and describes a single-group model. These details indicate that the study was not presented as a blinded, randomized treatment comparison.
Participants were to receive cone beam CT scans before individual radiation treatment sessions, with the arm description specifying daily scans for the length of radiation therapy. The imaging data were intended to help researchers study movement and changes in tumor and normal tissue, and to construct hypothetical radiation plans for future research. The registry explicitly states that scan data would not be used to change the actual radiation treatment delivered to enrolled participants.
The study began in 2009-01, reached primary completion in 2011-03, and has COMPLETED status. Its stated primary timeframe is approximately 7 weeks. The registry describes additional assessments of salivary output, swallowing, and quality of life, alongside outcomes concerning image quality and the median radiation dose delivered to the parotid gland. It lists four outcome measures, but outcome estimates and analysis results are not reported in the registry record. The record also does not describe a sample-size justification or a statistical analysis plan.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Cone Beam CT |
|---|---|
| STARTED | 23 |
| COMPLETED | 18 |
| NOT COMPLETED | 5 |
Reasons for not completing this period:
| Reason | Cone Beam CT |
|---|---|
| Completed Treatment Off Study | 3 |
| Withdrawal by Subject | 2 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
Population: Although 23 patients were enrolled, only 18 completed treatment.
| Characteristic | Unit | Cone Beam CT |
|---|---|---|
| Participants analysed | 18 | |
| Age, Continuous | years | 57 (50 to 76) |
| Sex: Female, Male: Female | Participants | 2 |
| Sex: Female, Male: Male | Participants | 16 |
| Disease Site: Base of Tongue | participants | 9 |
| Disease Site: Tonsil | participants | 9 |
| T Stage: T1 | participants | 2 |
| T Stage: T2 | participants | 10 |
| T Stage: T3 | participants | 5 |
| T Stage: T4 | participants | 1 |
| N Stage: N0 | participants | 1 |
| N Stage: N1 | participants | 0 |
| N Stage: N2a | participants | 1 |
| N Stage: N2b | participants | 10 |
| N Stage: N2c | participants | 4 |
| N Stage: N3 | participants | 2 |
| Pre-Treatment Weight | lb | 203 (105 to 308) |
6. Primary Endpoint
The registry lists the primary outcome as Rate of Movement of Normal Tissue, measured over approximately 7 weeks.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary outcome is titled “Rate of Movement of Normal Tissue.” The accompanying description says the study’s primary purpose was to characterize patient-specific movement of both the radiation target and normal tissue. This framing makes the endpoint a characterization question: it concerns how structures move during a course of radiation therapy, rather than a comparison of clinical outcomes between assigned treatments.
Movement is relevant to radiation planning because the intended target and nearby normal tissues may not remain in exactly the same position or shape throughout treatment. As a general statistical point, measuring movement can help describe the variability that a planning approach may need to account for. This study also sought to use imaging information to create hypothetical radiation plans as a basis for future research. The registry says those hypothetical plans did not guide treatment delivered during the study.
The listed timeframe is approximately 7 weeks. The registry does not define the movement metric, its units, how scans were used to derive it, or how participant-specific estimates were combined. It also does not report a movement estimate, its distribution, or a confidence interval. Consequently, the endpoint’s intended subject is identifiable, but its operational definition and observed result are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry describes a pilot imaging study designed to characterize patient-specific movement of target and normal tissues during radiation therapy for head and neck cancer. Its primary endpoint is “Rate of Movement of Normal Tissue,” and its stated timeframe is approximately 7 weeks. The record reports enrollment of 23 participants, but it does not give an outcome estimate for tissue movement or an analysis of how movement varied across participants.
The registry lists four outcome measures and names secondary outcomes concerning image quality and the median delivered radiation dose to the parotid gland. It also describes salivary output, swallowing, and quality-of-life assessments. Numerical results for these outcomes, and inferential analyses of them, are not reported in the registry record. The record reports zero analyses. Thus, it does not support conclusions about the magnitude or precision of any imaging or tissue-motion findings.
The design limits what can be learned about comparative effects. This was a single-group study without a randomized or assigned comparison arm. Its description raises the question of whether daily scans provide additional information compared with less frequent scanning, but no group contrast, schedule comparison estimate, or uncertainty measure is reported. A descriptive study can characterize data collected within its participants; without a reported comparator and analysis, it cannot establish how those findings differ from an alternative imaging schedule.
The purpose was also distinct from changing treatment. The registry says cone beam CT data were not used to alter actual radiation treatment. The researchers planned to use the scans to examine movement and tissue changes and to develop hypothetical radiation plans for future research. Therefore, the record describes an imaging and characterization project, not a test of whether changing treatment in response to scan findings improves clinical outcomes.
The safety record lists 2 serious adverse events among 18 participants at risk and 9 other adverse events among 18 at risk in the Cone Beam CT group. Hyperkalemia and Renal Failure are each listed with 5.6%. These counts do not provide a comparison with an untreated or alternative-imaging group, and the registry does not report event attribution or a detailed event-level account. The death count is not reported in the registry record.
Overall, the posted information establishes the study’s aims, design, enrollment, and some safety counts, but does not provide analyzed primary or secondary outcome results. Any discussion of movement, image quality, dose, or participant-reported assessments therefore needs to remain at the level of the planned measurements, rather than claims about measured effects.
9. Statistical Methods Explained
Statistical interpretation depends on both the design and the way outcomes were measured. This study is described as single-group, with allocation NA and masking NONE. The registry identifies no randomized comparison, and reports zero analyses. It gives the primary outcome title and general purpose, but does not report the numerical outcome data or a statistical analysis plan. The interpretation must therefore distinguish the intended measurement from results that are not reported in the registry record.
What can a single-group design describe?
A single-group study can collect repeated observations and describe patterns within the enrolled participants. Here, cone beam CT was planned before radiation treatment sessions, with the arm description specifying daily scans during radiation therapy. Such imaging can be used to examine where tissues are positioned and how they change during treatment. As a general statistical point, repeated measures from the same participant are related: treating them as independent observations can understate uncertainty or give undue weight to participants with more measurements. The registry does not report how repeated scans were analyzed or whether observations were aggregated at the participant level.
A single group does not by itself provide a randomized contrast between imaging schedules. The description asks whether daily scanning provides additional information compared with less frequent scanning, but the record does not describe assignment to distinct scan-frequency groups or report a comparison estimate. A difference between measurements at different times, if observed, would not automatically isolate the effect of scanning frequency. Without a defined comparison and reported analysis, that question remains unanswered by the registry record.
What does an estimate and confidence interval communicate?
In general, an estimate is a numerical summary of the observed data under a specified definition and analysis. A confidence interval describes uncertainty around an estimate under the assumptions of the method used. A narrower interval generally indicates greater precision for that estimate, while a wider interval indicates less precision. Neither the primary outcome estimate nor a confidence interval is reported in the registry record, so the magnitude and precision of tissue movement cannot be evaluated from the posted results.
The endpoint’s operational details matter to interpretation. The registry does not define the movement unit, explain whether movement refers to a displacement, a rate over time, or another metric, or state how individual measurements were combined. It also does not identify a prespecified summary statistic for the primary outcome. Without those definitions, readers cannot assess whether a hypothetical movement estimate would represent a typical participant, an average across observations, or another feature of the data.
How should the planning illustration be read?
The stated planning illustration uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It frames the effect to detect as a stated fraction of the observed effect. For time-to-event outcomes, it describes total event counts; for other outcomes, participants per arm. These are planning assumptions, not a description of this trial’s design: the trial itself is single-group. The registry record does not report the observed effect needed to anchor such an illustration, nor does it report the resulting planning sample sizes. These planning quantities should not be interpreted as observed power, evidence of statistical significance, or the number of participants actually analyzed.
More generally, sample-size planning estimates the amount of information needed to detect a chosen effect under specified assumptions. It does not show that an effect exists, and it does not measure the precision achieved in a completed study. If the assumed effect differs from the effect that is relevant to researchers, the planning result may not address the intended scientific question. A planning calculation cannot replace the observed estimate and its uncertainty.
Why can over-dispersion matter?
As a general statistical concept, over-dispersion occurs when observed variability exceeds what a model assumes. For count outcomes, for example, a simple model may assume a particular relationship between the mean and variance; extra variation can make standard errors too small if the model is not adapted. The registry does not identify the primary endpoint as a count outcome, report a model, or discuss over-dispersion. This concept is therefore a general consideration, not a stated feature of this study’s analysis.
Likewise, model choice depends on the outcome scale and data structure. Movement measurements, repeated scans, dose summaries, and participant-reported measures may require different summaries or models. The registry does not identify a statistical model or analytic method for these outcomes. No particular model can be attributed to the investigators on the basis of this record.
Finally, descriptive results and inferential results answer different questions. A descriptive summary characterizes recorded observations; inferential analysis quantifies uncertainty or assesses a contrast under stated assumptions. The registry record contains no reported analysis results for the primary endpoint, and does not provide the methods needed to assess how any estimates were obtained. Interpretation should remain limited to the stated study aim and the data that are actually reported.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists four outcome measures, including the primary measure concerning tissue movement and secondary outcomes concerning image quality and median delivered dose of radiation to the parotid gland. The study description also mentions salivary output, swallowing, and quality-of-life questionnaires. When a study considers multiple outcomes, there may be more than one opportunity to observe an apparently notable result. As a general statistical principle, multiplicity methods can help control the interpretation of repeated statistical tests, but the appropriate approach depends on which outcomes and comparisons were prespecified.
The registry does not report a multiplicity adjustment, a hierarchy of outcomes beyond identifying the primary outcome, or a statistical analysis plan. It also does not report outcome estimates or test results. It is therefore not possible to determine whether multiplicity was addressed in the investigators’ analyses or how it would affect interpretation.
Missing-data methods and analysis populations are also not described. The record gives enrollment of 23 participants, while the adverse-event group lists 18 at risk for each adverse-event category. It does not explain the difference between those figures, identify the number contributing to each efficacy outcome, or state how incomplete scans or assessments were handled. The record does not describe an intention-to-treat, per-protocol, or other named analysis population. No conclusions about missingness or the handling of incomplete observations can be drawn from the registry record.
As a general statistical matter, missing data can affect estimates when the probability of being missing is related to participant characteristics or outcomes. The impact depends on the amount, reasons, and pattern of missingness, as well as the analysis method. None of those details is reported for this study. The absence of a reported method should not be taken as evidence that no missing data occurred or that missingness had no effect.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Cone Beam CT | 2 | 18 | 11.1% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Cone Beam CT | 9 of 18 |
Most frequent serious adverse event terms
| Event term | Organ system | Cone Beam CT |
|---|---|---|
| Hyperkalemia | Metabolism and nutrition disorders | 1 of 18 |
| Renal Failure | Renal and urinary disorders | 1 of 18 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Cone Beam CT |
|---|---|---|
| xerostomia | Gastrointestinal disorders | 9 of 18 |
| Dysphagia | Gastrointestinal disorders | 9 of 18 |
| Mucositis/Stomatitis (upon exam) | Investigations | 9 of 18 |
| Dysgeusia | Gastrointestinal disorders | 9 of 18 |
| Dehydration | Metabolism and nutrition disorders | 8 of 18 |
| Esophagitis | Gastrointestinal disorders | 8 of 18 |
| Chemoradiation Rash | Skin and subcutaneous tissue disorders | 7 of 18 |
| Salivary Gland Changes | Gastrointestinal disorders | 7 of 18 |
| Nausea | Gastrointestinal disorders | 3 of 18 |
| Radiation Rash | Skin and subcutaneous tissue disorders | 2 of 18 |
Serious events with the highest arm-level rate: hyperkalemia (5.6%), renal failure (5.6%).
The registry reports adverse events for the Cone Beam CT group, with 18 participants at risk for serious events and 18 at risk for other events. It records 2 serious adverse events and 9 other adverse events. These are counts, not comparative risk estimates. The record does not provide a separate control group, so the figures do not establish how event occurrence compares with another imaging approach or with no imaging.
Hyperkalemia and Renal Failure are each listed among the most frequent serious adverse-event terms, at 5.6%. The registry does not report event-level counts alongside those terms in the information available for this analysis, nor does it describe whether the events were considered related to the imaging procedure, cancer, radiation therapy, or another cause. The terms should therefore be read as recorded safety categories, not as evidence of causation.
The death count is not reported in the registry record. It should not be interpreted as a count of zero. More broadly, adverse-event summaries depend on the definitions used, the observation period, and how events were collected; those details are not reported. The counts describe the posted safety record but do not by themselves establish comparative safety.
12. What the Result Does, and Does Not, Mean
The study addresses a technical and measurement question: how target and normal tissues move during radiation therapy for head and neck cancer, as assessed using cone beam CT. The registry describes scans before individual treatment sessions and says the scans were not used to alter actual treatment. It also describes the use of imaging data to construct hypothetical radiation plans for future research. This is a characterization aim, rather than a randomized test of treatment strategies.
The posted record does not report an estimate of normal-tissue movement, a confidence interval, or an analysis of variation between participants. It also does not report results for image quality, parotid gland dose, salivary output, swallowing, or quality of life. As a result, the record supports a description of what researchers intended to measure, but not a quantitative conclusion about the results of those measurements.
The study cannot establish whether daily scanning is better than less frequent scanning from the information reported. The single-group design is not a randomized comparison of scan schedules, and the registry reports no schedule-specific outcome estimates. Similarly, the study does not show whether using imaging to change treatment improves outcomes: the description says the scan data were not used to alter participants’ actual radiation treatment.
The safety counts are also limited in scope. They document serious and other adverse events in the Cone Beam CT group, but there is no randomized comparator and no reported attribution analysis. They cannot establish whether an event was caused by imaging or whether its frequency differs from another approach.
In general, a pilot study can help describe procedures and generate questions for later research. That general role should not be confused with evidence of a comparative effect. The registry record establishes that the study was completed and enrolled 23 participants, while leaving the central outcome estimates and their precision unreported. Conclusions about the amount of tissue movement or the value of a particular imaging schedule would require results and analyses not reported in the registry record.
13. Why This Trial Matters Statistically
This study is statistically notable because its main aim is to characterize movement and change over time within participants, rather than to compare assigned treatments. That distinction affects both the analysis and the claims that the data could support. Repeated imaging can produce many measurements, but those observations are linked to the participant and treatment course from which they came. In general, analysis needs to account for that structure rather than treating each scan as if it came from a different person.
The study description also makes clear that the imaging data were intended to inform hypothetical plans for future research, not to change the treatment delivered during the study. This separates measurement and planning work from an intervention trial. The distinction is important when interpreting any stated aim: collecting information that may inform later research is not the same as testing whether an imaging-guided treatment strategy changes clinical outcomes.
The registry’s planning assumptions illustrate another design issue. They specify equal allocation between two arms even though the study is described as single-group. Such assumptions can be useful for a hypothetical planning exercise, but they do not describe the completed trial’s allocation or analysis. The registry does not report the observed effect used for the planning illustration or its resulting sample-size values, so the illustration cannot be interpreted as evidence about the study’s achieved precision.
Finally, the gap between stated aims and reported results is itself important for statistical reading. The registry provides a primary outcome title, timeframe, and study description, but no outcome analyses. Readers can identify the intended scientific question without claiming that the posted record resolves it. Clear separation of study purpose, design, planning assumptions, and observed estimates is essential to avoid overstating what a pilot record can establish.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The most direct limitation is that the registry record does not report analyzed primary or secondary outcome results. There is no numerical estimate of tissue movement, no uncertainty interval, and no reported analysis of image quality, parotid gland dose, salivary output, swallowing, or quality of life. The number of outcome measures is recorded as four, but outcome definitions and results are not reported in sufficient detail to interpret the full set.
The primary endpoint description is broad. The registry does not report the movement metric’s units, measurement procedure, or method for summarizing repeated scans. The timeframe is approximately 7 weeks, but the record does not clarify the timing or completeness of observations within that interval. These omissions limit the ability to assess what a movement estimate would mean or how comparable it would be across participants.
The study is single-group and has no randomized comparator. Although the description raises a question about daily versus less frequent scanning, the registry does not report a comparison between scan schedules. The fact that the actual radiation treatment was not altered using the scan data also means the record does not evaluate an imaging-guided change in treatment.
The registry does not report a statistical analysis plan, sample-size justification, multiplicity approach, missing-data method, or analysis population. It does not explain why 23 participants were enrolled while 18 were listed at risk for each adverse-event category. The safety summary does not report event attribution, detailed event-level counts for the listed terms, or a death count. These reporting limits leave important design, analysis, and safety details unresolved.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study Using Cone Beam CT for Head and Neck Cancer — NCT01661062.
- Registry record last updated 2016-08-29; status last verified 2016-07.
- Results first posted 2014-10-31.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT01661062, titled “A Study Using Cone Beam CT for Head and Neck Cancer,” is a completed pilot study sponsored by the University of Michigan Rogel Cancer Center. It enrolled 23 participants, began in 2009-01, and reached primary completion in 2011-03. The registry describes a single-group study with masking NONE and phase NA.
The study used cone beam CT scans before radiation treatment sessions to characterize patient-specific target and normal-tissue movement and tissue changes during treatment. The scan data were not used to alter actual treatment. The primary outcome is titled “Rate of Movement of Normal Tissue,” with an approximately 7 weeks timeframe. Numerical outcome estimates and analysis results are not reported in the registry record.
The safety record lists 2 serious and 9 other adverse events among 18 participants at risk in the Cone Beam CT group. Hyperkalemia and Renal Failure are each listed at 5.6%. The death count is not reported in the registry record.