myQA iON - Independent Dose

On the Patient Plan Analysis page, an independent dose can be calculated on the Independent Dose tab.
Here, users can:

• View and change the Calculation Parameters, 3D Gamma settings, and Restart the calculations
• View the Secondary MU (Monitor Units) (RT only) and Gamma per Structure results

Launch of MC Simulation

Upon receiving the RT Ion Plan (PT), the patient RT plan (RT), or XML files for Cyberknife machines, myQA iON
automatically launches an independent dose calculation. 

For SciMoCa (RT only)

The MC dose engine requires the following to be able to function:

• A Beam Model Dictionary to be edited in the web interface using a Configuration account.
• An HU to Density file for converting CT images into density information.

For MCSquare (PT only)

The MC dose engine requires the following configuration files to be able to function:

• A BDL (beam data library) file modeling the treatment machine.
• A CT Scanner containing the HU to material and the HU to mass density conversions.

The myQA iON configuration contains the location of two folders in the path C:\ProgramData\IBA Dosimetry \myQA iON\mcsquare: 

• The first folder must contain the beam model of each treatment machine/room for MCSquare. Each
  beam model must be stored in a *.txt file with name “BDL_xxx.txt” where xxx is the treatment machine
  name for the beam model.

  Range shifters are specified in the BDL. Range shifter names in BDLs can only contain A-Z, 0-9, a period
  (.), a comma (,), and an underscore. For example, if the range shifter name in the DICOM file is “RS = 3
  cm”, the corresponding name in the BDL will be “RS3cm”. 

• The second folder must contain one sub-folder for each CT Scanner used for the patient CT simulation
  scans. Each sub-folder must have a name “Scanner_yyy” where yyy is the Station Name, Series
  Description, or Station Name and KVP for describing the CT scanner.

  Each scanner must contain two *.txt files named HU_Density_Conversion.txt and HU_Material_Conversion.txt.

  Note: The name of the scanner folder can be formatted in the application.yaml file. This setting is tied to the clinical signature and will be lost when the application.yaml is changed. See Section 2.3.3. Application Properties Configuration in the myQA iON Installation Guide for information on editing the application properties in the application.yaml file.

At the launch of the independent dose calculation, myQA iON reads the Treatment Machine Name (DICOM element [300A,00B2] in the Ion Beam sequence [300A,03A2]) defined in the patient treatment plan and associates it to the beam model in the BDL folder for MC computation. It will also read either the Station Name (DICOM element [0008,1010]), the Series Description [0008,103E] or the kVp (concatenation of STATION_NAME and KVP [0018,0060]) in the DICOM CT image files to associate the correct CT Scanner for the MC computation. 

IMPORTANT NOTICE
INCORPORATE THE PROTOCOL NAME ALONGSIDE THE STATION NAME AND SERIES
DESCRIPTION
When two CT calibrations share the same Station Name or Series Description, myQA iON is unable to accurately identify or locate the corresponding CT Scanner. The solution is to incorporate the Protocol Name (DICOM Tag [0018,1030]) alongside the Station Name and Series Description to assist in identifying the appropriate CT Scanner for MCSquare calculations.

Please note, DICOM tag [0008,1010] for the definition of the Station name is not a mandatory tag (even
though it is used by most TPS).

WARNING
CONTENT OF INPUT FILES FOR DOSE ENGINE

It is the user’s responsibility to be aware of the content of the beam model and scanners folder used by myQA iON.
The clinical commissioning and validation of the BDL and CT scanner calibration
curves are the user’s responsibility.

Calculation tab 

The Calculation tab allows the user to apply local parameters to the current patient for MCSquare (Section
3.2.3.1), Gate (Section 3.2.3.2), and SciMoCa (Section 3.2.3.3).

• Update the parameters.
• Click Save and Restart Calculations to apply the updated parameters to the current patient, or Cancel
  to discard any changes.
  Please note, when saved settings are changed, 3D Gamma will be recalculated for new parameters.

3D Gamma tab

3D Gamma parameters can also be edited in the 3D Gamma tab under the Independent Dose tab. Here the
user can choose to edit the parameters locally or globally.

• Select Local or Global (1) and update the parameters.
• Click Save (Global) or Save and Restart Analysis (Local) (2)
• Click the reset button (3) to reset all the parameters to the previously saved Global parameters.
• Individual values can be reset (4) independently from the rest of the parameters. 

Secondary MU tab

Beam information is available from SciMoCa under the Secondary MU tab.

The information displayed will depend on if a conventional LINAC or Cyberknife were used for the measurements.

Conventional LINAC Secondary MU tab 

Beam information is available from SciMoCa under the Secondary MU tab. Click on the Geometry, Dose Check, and Complexity Scores tabs different tabs to view the information. The top of the Secondary MU tab displays information from the TPS: 

• The number of fractions
• Prescription dose
• Beam name, energy (MV), and type 

The Geometry tab displays angle information and number of control points from the TPS.

The Dose Check tab displays:

• Beam and density dose specification points.
• TPS and SciMoCa beam dose and the beam dose percentage difference between the two.
• TPS and SciMoCa MU and the difference between the two.

The beam dose percentage difference (%) values will be displayed in different colors to indicate the pass /
fail criteria:

• Green if below 3% (beam dose percentage difference is acceptable)
• Orange between 3 to 10%
• Red if above 10% 

Please note, that myQA does not give an error if the difference is too great. It is the responsibility of the user
to check all values. 

The Complexity Scores tab displays the plan complexity score (PCS). A PCS is a number that expresses the complexity of an intensity modulated treatment plan and can be designated to stress different aspects of the plan, for example field shape, modulation degree or dynamic properties of leaves, gantry, and dose rate.

Please note, if more than one beam is present in the plan, the maximal value for each field is highlighted in blue.

Table 5.3. Plan Complexity Scores 

PCS	Range	Formula	Description
Field irregularity	1 (all fields are circular) to infinity.		The deviation of the field shape from a circle. It is the average overall field shapes of the plan, weighted with their relative MU.
Leaf travel variability	0 (all leaves move in sync) to infinity.		Measures how much the leaves move in a synchronized fashion from one control point to the next. It is the average over all standard deviations of leaf movement, weighted with their relative MU.
Leaf gantry synchronization	0 (no leaf travel) to infinity (diminishing gantry rotation).		Measures how much leaf travel dominates gantry rotation. It is the average overall control points, weighted with their relative MU.
Small field contribution	1 (all fields have the same size) to infinity.		The ratio of MU delivered by small fields. It is the average over the inverse of all field areas of the plan, weighted with their relative MU.
Off axis contribution	1 (all fields have the same size and are centered on the central axis) to infinity.		The ratio of MU delivered by small fields, weighted with the distance from the central beam axis. It is the average over the inverse of all field areas of the plan, weighted with their relative MU.
Max leaf travel per monitor unit	0 (no leaf travel) to infinity (diminishing dose rate).		Maximum leaf movement per MU and is therefore an indicator of how much the leaf movement dominates the dose rate.
Max gantry rotation per monitor unit	0 (no gantry rotation) to infinity (diminishing dose rate).		Maximum gantry rotation per MU and is therefore an indicator of how much the gantry rotation dominates the dose rate.
Beam delivered energy	-	(MU*cm^2)	Measures the amount of MU delivered to a specific area.

Table 5.4. PCS Formula Terms and Definitions

Cyberknife Secondary MU tab

Beam information is available from SciMoCa under the Secondary MU tab. The top of the Secondary MU tab (1) displays information from the TPS:

• Number of fractions
• Prescription dose
• Prescription percentage
• Max dose 

Beams tab:

Click on the arrow (2) to expand the Beams tab. At the top of the Beams tab the user can see:

• Beam dose specification point (X, Y, Z)
• Dose gradient at specific point
• Density at specification point
• Density gradient at specification point
• Total number of beams

To display a specific beam from the list, type in the beam ID in the Beam ID field (3). The beam will be highlighted in the list (4). 

The list of beams provides the following information to the user: 

• Beam ID
• TPS and SciMoCa beam dose and the beam dose percentage difference between the two.
• TPS and SciMoCa MU and the difference between the two.

The beam dose percentage difference (%) values will be displayed in different colors (5) to indicate the pass / fail criteria:

• Green if below 3% (beam dose percentage difference is acceptable)
• Orange between 3 to 10%
• Red if above 10% 

Please note, that myQA does not give an error if the difference is too great. It is the responsibility of the user to check all values.

Gamma / Structure tab

The Passing Rate (1) shows the overall passing rate for the calculation volume delimited by the structure
with DICOM type External or by the external density threshold value).

The Gamma per Structure represents the individual gamma analysis results for each ROI within the contour with DICOM type External. To assess the impact of each structure in comparison to the TPS, the Gamma / Structures tab lists the individual results of all the structures present in the body of the patient (2). It is the responsibility of the user to check all values and ensure they are acceptable based on the structure and patient.

The Gamma / Structures tab is available for both the Independent Dose and Irradiation Logs.