Gamma Knife RadiosurgeryNCT02374983
Gamma Knife Dosimetric Differences, TMR 10 Versus Convolution Algorithm
An observational study of Gamma Knife Radiosurgery, run by University College, London at 1 site in United Kingdom.
Trial summary
Gamma Knife Radiosurgery (GKR) is a well established treatment modality for brain tumors and functional disorders of the brain. It relies on mathematical algorithms to predict dose distribution and to calculate the dose at arbitrary points in the head. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Gamma Knife Radiosurgery
- What is being tested?
- Gamma knife radiosurgery re-planning with convolution algorithm
- How many people
- 100 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- Oct 2013to Oct 2016
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: The population of the study is all adult patients receiving treatment at the Gamma Knife Centre at Queen Square Radiosurgery Centre (QSRC). The sample will consist of the first 100 patients (200 observations) receiving Gamma Knife treatment in QSRC who accomplish all the inclusion and exclusion criteria and consent to participate in the study. This study does not involve group allocation or randomization of patients.
Who may be able to join
- Adult patients receiving Gamma Knife treatment for any diagnosis in the Gamma Knife centre at QSRC.
- The subject consents to participate in the study and consent to have a stereotactic non contrast CT scan of the brain after GKR has finished.
Who cannot join
- Inability to consent
- Younger than 18 years of age: Children are not eligible to give consent by themselves and at the moment only adults are being treated at the QSRC.
- Patient is not suitable for CT scan: There are no absolute clinical contraindications for CT scan. However, for the purpose of the study, pregnancy is considered an absolute contraindication. Claustrophobia or anxiety disorders are considered a relative contraindication; however, this is more likely to affect the subject ability to tolerate Gamma Knife treatment and MRI scanning, which would make the patient not eligible or the study.
- Co-morbidity or previous treatment in the patient is not to be considered as exclusion criteria.
Trial locations and contacts
1 site in 1 country.
United Kingdom1 site, 1 recruiting
- Recruiting
The Gamma Knife Centre at Queen Square
London, London,City of, WC1N 3BG
Alvaro Villabona, +44 02034484076, a.villabona.11@ucl.ac.uk
Neil Kitchen, MD,FRCS(SN)
About this study
Official title: Evaluation of Dosimetric Differences Between the TMR 10 and Convolution Algorithm for Gamma Knife Radiosurgery Planning
Gamma Knife Radiosurgery (GKR) is a well established treatment modality for brain tumors and functional disorders of the brain. It relies on mathematical algorithms to predict dose distribution and to calculate the dose at arbitrary points in the head. For the last 25 years, doses applied using Gamma Knife Radiosurgery have been calculated using a simple algorithm, called the Tissue Maximum Ratio algorithm (TMR). Dose planning using this algorithm, relies on a number of approximations to enable fast isodose computation during treatment planning. One of the most significant of these is the approximation of the head to water-equivalent density. The increased electron density of brain and bone (relative to water) and the near-zero density of air cavities in the skull may make significant perturbations to isodose and beam-on time calculations.
With the advent of faster workstations, the effect of tissue in-homogeneities can finally be calculated in reasonable time during the treatment planning process; a newer, more modern algorithm known as convolution algorithm is now commercially available. It uses the values of density indicated in the CT scan to predict the dose distribution and is expected to more accurately calculate radiation dose, although it needs further investigation before clinical implementation. Inter- and intra-indication differences between the old and new algorithms need to be understood before this method can be confidently employed in a clinical setting. It is the aim of this study to understand the dosimetric differences between these dose calculation algorithms and to evaluate the implications of using the convolution algorithm for GKR. A large number of treatments will be re-planned using the convolution algorithm and compared to the TMR plans used to treat the patients. Beam-on-time, which is proportional to dose and a number of commonly used metrics for the targets such as coverage, selectivity, gradient index, and mean and maximum dose, will be estimated with both algorithms. Subgroup analysis will be done to assess whether any factor such as diagnosis, size of the head or location of the target could impact on the relative difference between the methods. The treatment plans will be compared and the potential implications on treatment planning will be elucidated.
- Conditions
- Gamma Knife Radiosurgery
- Being tested
- Gamma knife radiosurgery re-planning with convolution algorithm
- Keywords
- Gamma Knife Radiosurgery, Radiation Dosimetry
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Gamma knife radiosurgery re-planning with convolution algorithmOther
The convolution algorithm, which uses the correlation between CT imaging density in Hounsfield units (HU) and electron density (ρe) of the tissues as input to predict dose distribution, can provide a better simulation of real delivered dose for GKR. By more accurately predicting the dose delivered, a better prediction of clinical effects can be made, increasing the potential clinical efficacy of treatment.
Convolution algorithm is now available in Leksell GammaPlan® 10 but there is not enough clinical data to support its use over TMR 10, which is the current clinical standard. Using convolution algorithm to recalculate the dose for the otherwise unaltered TMR 10 plan will provide valuable insight and understanding of the dosimetric differences between these planning algorithms.
| Study group | Role | What they receive |
|---|---|---|
| Research group | The group will consist of 100 patients (200 observations) receiving Gamma Knife treatment. Radiosurgery treatments will be re-planned using the convolution algorithm and compared to the TMR plans used to treat the patients. Receives: Other: Gamma knife radiosurgery re-planning with convolution algorithm |
What is being measured
The primary outcome is the main question the study is designed to answer.
Beam-on time (difference in the Beam-on-time of the treatment plans obtained using TMR 10 and convolution algorithm for each lesion treated)
The difference in the Beam-on-time of the treatment plans obtained using TMR 10 and convolution algorithm for each lesion treated will be the primary outcome of the study
Measured: Beam-on time obtained with the TMR 10 algorithm at the time of treatment (baseline) vs Beam-on time observed when the treatment is re-planned with the convolution algorithm, that being a few hours after the actual treatment is delivered (maximum 1 day)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Mar 2015 (estimated)
- Study startOct 2013
- Primary completionOct 2015 (estimated)
- Study completionOct 2016 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Gamma Knife RadiosurgeryStudies of the same condition, open and under way.
- More trials run by University College, LondonThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Time perspective
- Prospective
- Enrolment
- 100 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University College, London
- Sponsor type
- University, hospital or other
- Collaborators
- University College London Hospitals
- Responsible party
- Sponsor
- Investigators
- Neil Kitchen, Study chair, National Hospital for Neurology and Neurosurgery
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT02374983
- Sponsor's protocol ID
- 13/0188
- Other IDs
- 13/LO/085, 128269
- Status last verified
- Feb 2015
- First submitted
- 16 Feb 2015
- Last updated
- 2 Mar 2015
- Results posted
- No
- Data monitoring committee
- No
Study at a glance
From the registry record, last updated by the sponsor on 2 Mar 2015. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Evaluation of Dosimetric Differences Between the TMR 10 and Convolution Algorithm for Gamma Knife Radiosurgery Planning
- ClinicalTrials.gov ID
- NCT02374983
- Acronym / sponsor ID
- 13/0188
- Conditions
- Gamma Knife Radiosurgery
- Keywords
- Gamma Knife Radiosurgery, Radiation Dosimetry
- Study type
- Observational
- Recruitment status
- Unknown status
- Enrolment
- 100 participants (estimated)
- Lead sponsor
- University College, LondonUniversity, hospital or other
- Collaborators
- University College London Hospitals
- Study start
- Oct 2013
- Primary completion
- Oct 2015 (estimated)
- Study completion
- Oct 2016 (estimated)
- First posted
- 2 Mar 2015 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Gamma Knife Radiosurgery (GKR) is a well established treatment modality for brain tumors and functional disorders of the brain. It relies on mathematical algorithms to predict dose distribution and to calculate the dose at arbitrary points in the head. For the last 25 years, doses applied using Gamma Knife Radiosurgery have been calculated using a simple algorithm, called the Tissue Maximum Ratio algorithm (TMR). Dose planning using this algorithm, relies on a number of approximations to enable fast isodose computation during treatment planning. One of the most significant of these is the approximation of the head to water-equivalent density. The increased electron density of brain and bone (relative to water) and the near-zero density of air cavities in the skull may make significant perturbations to isodose and beam-on time calculations.
With the advent of faster workstations, the effect of tissue in-homogeneities can finally be calculated in reasonable time during the treatment planning process; a newer, more modern algorithm known as convolution algorithm is now commercially available. It uses the values of density indicated in the CT scan to predict the dose distribution and is expected to more accurately calculate radiation dose, although it needs further investigation before clinical implementation. Inter- and intra-indication differences between the old and new algorithms need to be understood before this method can be confidently employed in a clinical setting. It is the aim of this study to understand the dosimetric differences between these dose calculation algorithms and to evaluate the implications of using the convolution algorithm for GKR. A large number of treatments will be re-planned using the convolution algorithm and compared to the TMR plans used to treat the patients. Beam-on-time, which is proportional to dose and a number of commonly used metrics for the targets such as coverage, selectivity, gradient index, and mean and maximum dose, will be estimated with both algorithms. Subgroup analysis will be done to assess whether any factor such as diagnosis, size of the head or location of the target could impact on the relative difference between the methods. The treatment plans will be compared and the potential implications on treatment planning will be elucidated.
Study design
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Research group | – | Other: Gamma knife radiosurgery re-planning with convolution algorithmThe group will consist of 100 patients (200 observations) receiving Gamma Knife treatment. Radiosurgery treatments will be re-planned using the convolution algorithm and compared to the TMR plans used to treat the patients. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- The population of the study is all adult patients receiving treatment at the Gamma Knife Centre at Queen Square Radiosurgery Centre (QSRC). The sample will consist of the first 100 patients (200 observations) receiving Gamma Knife treatment in QSRC who accomplish all the inclusion and exclusion criteria and consent to participate in the study. This study does not involve group allocation or randomization of patients.
Key inclusion criteria (2 listed)
- Adult patients receiving Gamma Knife treatment for any diagnosis in the Gamma Knife centre at QSRC.
- The subject consents to participate in the study and consent to have a stereotactic non contrast CT scan of the brain after GKR has finished.
Key exclusion criteria (4 listed)
- Inability to consent
- Younger than 18 years of age: Children are not eligible to give consent by themselves and at the moment only adults are being treated at the QSRC.
- Patient is not suitable for CT scan: There are no absolute clinical contraindications for CT scan. However, for the purpose of the study, pregnancy is considered an absolute contraindication. Claustrophobia or anxiety disorders are considered a relative contraindication; however, this is more likely to affect the subject ability to tolerate Gamma Knife treatment and MRI scanning, which would make the patient not eligible or the study.
- Co-morbidity or previous treatment in the patient is not to be considered as exclusion criteria.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Gamma knife radiosurgery re-planning with convolution algorithmThe convolution algorithm, which uses the correlation between CT imaging density in Hounsfield units (HU) and electron density (ρe) of the tissues as input to predict dose distribution, can provide a better simulation of real delivered dose for GKR. By more accurately predicting the dose delivered, a better prediction of clinical effects can be made, increasing the potential clinical efficacy of treatment. Convolution algorithm is now available in Leksell GammaPlan® 10 but there is not enough clinical data to support its use over TMR 10, which is the current clinical standard. Using convolution algorithm to recalculate the dose for the otherwise unaltered TMR 10 plan will provide valuable insight and understanding of the dosimetric differences between these planning algorithms. | Other | Research group |
Primary outcome
Beam-on time (difference in the Beam-on-time of the treatment plans obtained using TMR 10 and convolution algorithm for each lesion treated)
Time frame: Beam-on time obtained with the TMR 10 algorithm at the time of treatment (baseline) vs Beam-on time observed when the treatment is re-planned with the convolution algorithm, that being a few hours after the actual treatment is delivered (maximum 1 day)
The difference in the Beam-on-time of the treatment plans obtained using TMR 10 and convolution algorithm for each lesion treated will be the primary outcome of the study
Results and safety
Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 2 Mar 2015.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Neil Kitchen study chair
National Hospital for Neurology and Neurosurgery
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Gamma Knife Radiosurgery, run by University College, London at 1 site in United Kingdom.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: status not confirmed, as of the sponsor's last update on 2 Mar 2015. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Results are not available in the source record.
How can a doctor refer a patient or contact the research team?
Contact Alvaro Villabona (+4402034484076, a.villabona.11@ucl.ac.uk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Beam-on time (difference in the Beam-on-time of the treatment plans obtained using TMR 10 and convolution algorithm for each lesion treated) (time frame: Beam-on time obtained with the TMR 10 algorithm at the time of treatment (baseline) vs Beam-on time observed when the treatment is re-planned with the convolution algorithm, that being a few hours after the actual treatment is delivered (maximum 1 day)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 2 Mar 2015.