Primary objective:To investigate whether MR-only radiotherapy in prostate and rectal cancer patients is at least non-inferior in terms of position verification performed by a registration between the pCT and CBCT instead of the CT.Secondary…
ID
Source
Brief title
Condition
- Miscellaneous and site unspecified neoplasms malignant and unspecified
Synonym
Research involving
Sponsors and support
Intervention
Outcome measures
Primary outcome
In each of the 29 prostate cancer patients, a registration of fiducials will be
made for each of the 35 treatment fractions. In each of the 29 rectal cancer
patients, a registration based on bony anatomy will be made and the best
fitting plan will be selected from the LOP for each of the 25 fractions. Each
registration consists of a vector in x-, y-, and z-direction. These will be
noted and the standard deviation of all the registration vectors per patient
will be calculated. We will refer to this parameter as the variation in
registrations per patient.
In case a patient is not able to complete his treatment, he/she will be
replaced by another patient.
We will perform a noninferiority test (* = 0.05, 1-* = 0.80) on both the
variation of the registrations on fiducials in prostate patients and the
variation of the registrations based on bony anatomy in rectal patients. The
null hypothesis is that the standard deviation of the variation in the MR-only
workflow is higher and thus inferior to the conventional workflow.
We expect a common standard deviation of 0.8 mm for the registration on
fiducials in prostate cancer patients. We expect a common standard deviation of
0.55 mm for the registration based on bony anatomy in rectum cancer patients.
We reject the null hypothesis at a limit difference of 2/3 of the expected
standard deviation, thus 0.53 mm in the prostate cancer patients and 0.37 mm in
the rectal cancer patients.
Secondary outcome
The secondary parameter is the feasibility of the plan selection for the rectal
cancer patients. This evaluation is qualitative. The plan selected per fraction
in the MR-only workflow should be the same as in the conventional workflow.
Also, the RTT should experience this as equally difficult. This will be
qualified by the RTT*s from the research team as they perform the simulated
MR-only workflow. These RTT*s have extended clinical experience in plan
selection. They will report parameters such as time needed and certainty in
decision making.
Background summary
Radiation treatment starts with the imaging of the patient on a CT scanner.
This CT scan will be used throughout the treatment. The CT scan is first used
to determine and delineate the target volume and the organs at risk (OAR)
(sometimes supported by other imaging modalities), secondly to calculate the
dose of the treatment plan, and finally it is used as a reference for position
verification before each treatment fraction. For the latter, a cone-beam CT
(CBCT) is made of the patient on the treatment table. Position verification is
then performed by a registration between the CT and the CBCT.
Since MR images exceed the CT image in soft-tissue contrast, it is standard
procedure in patients with prostate cancer and in some patients with rectal
cancer to use both a CT image and an MR image for delineation. There are
several disadvantages of this procedure: first a patient must undergo two
separate scans. Furthermore, as the scans are made on different machines and
with a timespan of at least an hour, there will be a difference in the
patient*s anatomy and positioning between the scans. This introduces errors in
the delineation of the target volume and OAR*s as the images are both used but
contain conflicting information because of the imperfect registration between
them. The errors in the delineations need to be accounted for, typically by
introducing a treatment margin, which increases the volume of irradiated
healthy normal tissue.
With special MR imaging techniques it is now possible to make a so called
*pseudo CT* (pCT) . The pCT is proven to be suitable for dose calculations in
treatment planning. The pCT may also be suitable for position verification by a
registration between the pCT and CBCT. With the use of this MR technique, the
CT may no longer be needed and patients can be treated using only MR images:
the MR-only workflow. In this study we would like to investigate whether the
MR-only workflow can be clinically introduced in prostate and rectal cancer
patients with at least noninferiority in position verification by a
registration between pCT and CBCT. Therefore, we would like to compare the
conventional CT-based radiation treatment with an MR-only treatment simulation.
Study objective
Primary objective:
To investigate whether MR-only radiotherapy in prostate and rectal cancer
patients is at least non-inferior in terms of position verification performed
by a registration between the pCT and CBCT instead of the CT.
Secondary objective:
Feasibility of plan selection using the pCT instead of the CT for radiotherapy
in rectal cancer patients. This evaluation is qualitative. The plan selected
per fraction in the MR-only workflow should be the same as in the conventional
workflow. Also, the RTT should experience this as equally difficult.
Study design
The study is a prospective observational cohort study. To generate the pCT, an
extra MR sequence is added to the standard scan protocol, prolonging the scan
time by 10 minutes. The pCT will be used to simulate an MR-only radiotherapy of
the patient. The actual treatment of the patient is according to the
conventional clinical protocol.
Study burden and risks
An MR sequence is added to the normal MR scan protocol of the patients. This
will prolong the standard MR scan time of 30 to 45 minutes by 10 minutes. Since
MR imaging does not impose any ionizing radiation burden, patients are not
susceptible to radiation hazards or any other added risks. Furthermore,
patients are free to halt the procedure and withdraw from the extra MR sequence
at any time. Patients will not benefit from participation in this study.
It is only possible to investigate the differences between the conventional and
simulated MR-only treatment by comparing registrations between CT and CBCT*s
with registrations between pCT and CBCT*s. The CT scan and CBCT scans impose
ionizing radiation hazard, which are justified in context of the patient*s
radiation treatment. The acquisition of the pCT from MR scans does not impose
ionizing radiation burden. Therefore, our study design is the only way to
compare the two workflows without imposing patients to ionizing radiation
burden. The risk on side effects of the procedure are minimal (see risk
assessment form). The study does not include minors or incapacitated adults.
Meibergdreef 9
Amsterdam 1105 AZ
NL
Meibergdreef 9
Amsterdam 1105 AZ
NL
Listed location countries
Age
Inclusion criteria
* Patients have to be older than 18 years.
* They have to be diagnosed with prostate or rectal cancer and willing to
undergo a treatment with radiotherapy with curative intent at the AMC.
Exclusion criteria
* Incapacitated patients.
* Any 3T MRI contra-indications stated by the AMC MRI safety committee (see
appendix A)
* Patients with one or two hip prosthesis.
Design
Recruitment
Followed up by the following (possibly more current) registration
No registrations found.
Other (possibly less up-to-date) registrations in this register
No registrations found.
In other registers
| Register | ID |
|---|---|
| CCMO | NL65414.018.18 |