New IMRT QA Detector Array The 2-Dimensional MapCHECK™ uses 445 detectors to electronically measure your treatment plan and dosimetrically compare to the calculated dose. The MapCHECK™ is a 2-dimensional therapy beam measurement system intended for quick and precise verification of the dose distribution resulting from an IMRT plan.  Beam measurement is accomplished using a matrix of 445 diode detectors that are housed between two sheets of solid acrylic. The MapCHECK measures the integrated dose at all detector locations, each of which has been corrected to the central detector sensitivity. This measured dose map can be normalized and compared to a normalized imported treatment plan dose map. Using a properly calibrated field, the detector array can be calibrated to measure ABSOLUTE dose.

The resulting dose map is then in dose units and can be directly compared to the dose values in the treatment plan dose map using the MapCHECK™ software. Using this approach for IMRT plan verification, a 5-field case may take approximately 15 minutes.

Physical Description
The MapCHECK™ is 2 dimensional matrix of 445 solid state diode detectors forming a high-density inner array and a low-density outer array. The high-density inner array measures 10 x 10 cm. The low-density outer array is 6cm wide and surrounds the inner 10 x 10 array. The detectors are treated for radiation hardness and numerically corrected for sensitivity.  The MapCHECK™ software communicates with the hardware via a single power/data cable.

Array Geometry (see figure)
Inner Array: 10 cm x 10 cm array: 7.07 mm diagonal, 1.0cm horizontal/vertical
Outer Array: 6 cm wide: 14.14 mm diagonal, 2.0cm horizontal/vertical
Axial and Transverse (X,Y) linear array length: 22 cm, 1.0 cm detector spacing
Diagonals linear array length: 25.4 cm, 7.07 mm Detector spacing
Active Detector area: 0.8 mm x 0.8 mm

Inherent Buildup
Total Buildup to Detector Junction: 2.0 ± 0.1 g/cm2
Linear Depth to detector junction from top of overlay: 1.35 ± 0.1 cm

Inherent Backscatter
Total Backscatter to Detector Junction: 2.7 ± 0.1 g/cm2
Linear Depth to detector junction from back of instrument plate: 1.94 ± 0.1 cm

Applications
The MapCHECK™ was designed specifically for the efficient and stringent QA of IMRT plans. The time required to measure all of the IMRT fields for any given case is only slightly longer than the time required for the machine to deliver the plan. Once the fields have been measured with the MapCHECK™, comparison is performed by quickly importing, via the MapCHECK™ software, a binary file of the 3-D calculated treatment plan. All major 3-D TPS vendors will be supported for this function.

Any 3-D plan can be imported, both MLC plans and tissue compensator plans are supported.

PC Communication
The MapCHECK™ communicates with a host computer via a single 25 M cable. The host computer is the comprehensive interface and storage device for the MapCHECK™. The MapCHECK™ uses the same power supply and cable as the PROFILER™ and DAILY QA CHECK™, meaning less cables to manage.

A pdf MapCHECK brochure is available, please click here