For Healthcare Professional
Questions
How is DVS® Used?DVS is intended for use in radiation therapy to verify treatment planning and radiation dose to tissue and organs in or near the irradiated areas of the patient.
Can it be implanted in any organ or tissue?
DVS is indicated to measure photon beam therapy and as an adjunct to treatment planning to permit measurement of the in vivo radiation dose received at the site of implant; for example, tumor periphery, tumor bed and/or surrounding normal tissues for validation of the prescribed dose. DVS currently is cleared for use in breast and prostate cancer. The prescribing physician will determine the appropriate use for DVS in his or her patients.
Can DVS be used for localization as a part of IGRT?
DVS can be used for localization with many systems such as kV images, ultrasound, CBCT, and TomoTherapy®, Resonant Medical, and the Cyberknife® Synchrony System. Sicel Technologies can provide image examples upon request.
How do I interpret DVS dose measurements?
In actual patient use, daily DVS dose measurements are reviewed on the basis of a comparison to the planned dose using the same approach now used for surface dosimetry.
The interpretation of the results is based on clinic defined ranges. In the DVS package insert, guidelines are provided to instruct the clinician to look at trends in daily dose measurements deviating >7% of the planned dose that occur over a number of fractions suggesting systematic or random errors. Single dose measurements deviating > 10% prompt direct review of several variables to identify the source for deviation.
Is DVS reimbursed by insurance?
There are codes that can be used in the submission of claims for reimbursement when DVS is prescribed. Sicel Technologies has partnered with The Pinnacle Health Care Group to address questions regarding coding, reimbursement potential, and to assist clients during the reimbursement process.
What is the retention mechanism made of?
The retention mechanism is made of surgical grade polyester.
Some prostate patients may be physically large. How can we read these dosimeters?
Twelve centimeters is the maximum depth at which DVS can be read. Larger patients may be read from the posterior surface or through the perineum.
Is DVS affected by prostate seed implants?
Radioactive seeds that are implanted prior to external radiation treatment would deliver radiation to the prostate and could have an effect on DVS performance.
If external beam irradiation is delivered after 10 half-lives time of the implanted radioactive material, the effect should be negligible.
DVS will not affect brachytherapy treatment if it is delivered after external beam radiation. Several patients in the clinical trial had brachytherapy after external beam radiation. DVS positioning should be considered if brachytherapy will follow external beam radiation.
If a patient has had a prior radioactive implant, i.e. prostate seeds, will the DVS dosimeter pick up dose from the implant?
It depends on how long ago the prostate implant was done. If more than 2 years have elapsed, there will be negligible dose left in the implanted seeds. If the implant was performed within 2 years, the dosimeter will detect some dose, although the amount or effect has not been determined.
What is the accuracy of DVS?
0-20 Gy: <5.5% (2 sigma), 0-74Gy: < 6.5% (2 sigma)
This value represents accuracy observed over multiple lots. Lot specific accuracy is published in the calibration certificate included with each kit.
What effect, if any, do long treatment times have on dosimeter performance?
(For example, some prostate IMRT treatments take 30-35 minutes to treat.)
There should be no effect on dosimeter performance for IMRT treatments. Significant effects of fade do not occur until about 20 minutes or more after the completion of the entire treatment.
Due to the fade phenomenon of MOSFETS, dosimeters must be read within 10 minutes of irradiation to obtain an accurate reading (2-3 minutes is optimal). On average, the signal decays ≤2% after twenty minutes.
Can the DVS dosimeter be implanted in the prostate with a biopsy needle at the time of biopsy?
The DVS dosimeter should be inserted through the perineum using the DVS insertion tool provided. The instructions for implantation are included in the DVS Instructions for Use and supplemented with a DVS Implantation Demonstration.
If a patient receives external beam therapy, gets an HDR boost, then resumes external beam therapy, what is the impact to DVS?
HDR doses can be very high. If the HDR catheter is close (<1cm) to the implanted DVS dosimeter and performed prior to or in between external beam therapy, the dosimeter could be saturated and may not read.
The DVS will not affect the HDR treatment, but the HDR treatment could affect the ability of DVS to measure dose for external beam therapy. DVS positioning should be considered if HDR therapy is performed prior to or in between external beam therapy.
Why must dosimeters be implanted at least 3cm from the skin surface?
- Ensures adequate build-up, especially at higher energies
- Helps maintain a consistent temperature to the device, thus a more precise reading
- Minimizes potential for mechanical damage
- Increases patient comfort.
How does tissue attenuate signal?
There is no tissue effect. If the dosimeter is too deep (>12cm), it simply will not read.
What is the effect of temperature on dosimeters?
Dosimeter performance is validated at 37oC and performs well within + 5oC of validation temperature.
Correction factors are available for room temperature phantom measurements.
Is there data on angular dependence of the DVS detector readings?
Yes, angular dependence averages about 1% for all beam incident directions except for a beam parallel to the dosimeter. In this case, the angular dependence is about 5%. We recommend that the dosimeter is implanted within 30o parallel to the vertical axis of the body to maintain the 1% isotropy behavior.
