Mucheck Monitor Unit Validation Program

In a radiation therapy department a course of patient treatment is prescribed by a written directive from the radiation oncologist. Certain parameters from this directive are used by the medical dosimetrist and/or medical physicist along with x-rays or CT scans where applicable to plan a course of treatment. Typically a radiation treatment planning system is used to properly define the precise location and dose distribution for the beam therapy. As part of the planning process, a monitor unit setting will be calculated which determines the machine duration of beam exposure. The primary radiation treatment planning software may or may not calculate the monitor unit setting. Regardless, the dosimetrist or physicist will either perform a manual calculation or perhaps use an in-house developed spreadsheet or program to calculate the monitor unit setting.

A manual calculation will involve the dosimetrist looking up beam data factors from a booklet of measured beam data provided by the physicist. These beam data factors are unique to each machine and must be measured by the physicist. The beam data booklet can contain 50 or more pages for a typical machine consisting of 2 photon beams and 5 electron beams. These factors are plugged into a standardized worksheet and a calculator is used to compute the monitor unit setting. This can be a tedious, time consuming process as well as error prone. The dosimetrist may have to search through multiple pages of data to find the correct factors to use. They will then have to be written down on the worksheet to be used for the final monitor unit calculation. Ideally they should be double checked for accuracy.

The muCheck Monitor Unit Validation Program (the device under review) makes this process much faster and more accurate. Initially, all of the beam data factors for each beam energy are entered into the system one time and stored in a database as part of the pre-installation process. After entry these factors are then plotted on a graph and printed along with tables of actual values entered to verify accuracy of data entry. To use the program, the dosimetrist simply enters the key data parameters as prompted by the program. As the parameters are entered into the system, beam factors are looked up and are automatically used by the program to calculate the correct monitor unit setting. All of the pertinent calculation data is displayed on the screen in worksheet form. This worksheet can be printed out and stored in the patients chart for permanent documentation. There are many user mput-edits incorporated into the system during the pre-installation process to insure the accuracy of the calculation. It must be stressed that this program does not provide the primary treatment calculation. It merely serves as quality assurance as part of good treatment protocol to have a second means to verify the accuracy of the primary calculation.