Register Image
Oncentra MasterPlan v3.3_Radiation Commissioning and Quality Assurance
7. External Beam - Beam Data Tool
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Register Image
In an image series without DICOM data about acale and position, you can register these data to obtain a series usable for treatment planning.
You can also use it to create a new series out of an already existing series consisting of a smaller selection of the slices.
- Make sure the image slice you want to start from is display in the current view. It is recommendable to start with a slice positioned in treatment origin.
- Select Tools > Register Image to display the Registering image dialog.
- Select the 1st point row.
- Click on a first point in the image slice.
- Select the 2nd point row.
- Click on a second point in the image slice.
- Specify the distance between the two points.
- Specify the postion of the slice (for instance 0, if it is in the origin).
- Select image type for new series; CT or MR
- Click Done
A new image series constaining this first slice is now created. Register further images to this series, one after the other.
When registering image beyond the first one, you do not need to specify points and distance as all images in the series are presumed to have the same scale. You only have to state the position in relation to origin.
Algorithms
The Dose Calculation activity uses several dose calculation algorithms. The available algorithms are :
Pencil Beam or Collapsed Cone for photons,
and Voxel Monte Carlo for Electrons.
Hence, a selection of algorithms is available for photon beams, where the Collapsed Cone dose calculation algorithm is a more general algorithm to account for patient anatomy inhomogeneities.
It is therefore mort suitable to use than the Pencial Beam algorithm in conditions where accurate dose is essential close to a steep density gradient, e.g. for treatments involving lung, particularly at higher beam energies (>10MV)
Caution !
- Any dose calculation algorithm has limitations, and the user shall be aware that it is unsuitable to heavily rely on the exact dose values in high dose gradient regions,
- low dose regions (e.g under a shielding block or collimator),
- close to the patient external contour or in regions close to density interfaces (air cavities, bony structure or non-organic materials).
- It is particularly not recommended to prescribe the treatment dose, or normalize the isodose presentations, based on the dose value of any such region.
For more information on the advantages and disadvantages of different algorithms with respect to the clinical situation, see the 'Physics and Algorithm' manual.
25,07,2010
Creating Beams
By default, when you create a new beam, the width and length are to 10cm.
- The gantry,
- collimator and
- couch rotations are set to their default positions (depending on the unit).
The field settings and beam settings are displayed in the plan window. When you create a beam, it becomes the current beam.
The default field settings are as follows:
- 10*10 field size,
- with beam position at either geometric center of a specific ROI,
- center of current slice, or at a POI.
- The default matrix resolution is set in the Global Settings in Oncentra MasterPlan (System > Settings ... > External Beam tab),
- and the SSD and depth to the isocenter are reported for the current beam position.
Note! The SSD reports the distance from the source to the patient's surface; either from ROI type External (or bolus) to isocenter.
Note! The calculation of the geometric center considers only the outer edge of the ROI. This is also valid for ROIs that are split into several parts (e.g bifurcated volumes岔冊).
When you create an electron beam, the X and Z coordinate are set at the ROI type External or Bolus (SSD technique). The Y coordinate is set to the offset of the current slice (the slice display in the Main view) and the Y Offset is set to 0.
If you already have beams in your plan, you can create additional beams by duplicating or opposing the existing beams and thus re-use selected settings. The Digitally Reconstructed Radiograph (DDR) settings of the source beam are copied to the destination beam.
Creating a New Beam
- Click the New Beam button
(or choose Beam > New... from the menu; shortcut Ctrl +B) to display the New Beam dialog.
- Type a Beam Label.
- Select a Unit from the drop-down list. The list contains all treatment units in the treatment unit database.
- Selecte the Add MLC check box to add an MLC when the beams is created (only available if the treatment unit has an MLC).
- For photon beams, select a beam position (electron beams are placed at the ROI type External or Bolus丸 of the current slice):
- Geometric Center of places the beam isocenter at the three dimensional center of the ROI you select from the list.
- Center of Current Slice places the beam isocenter at the center of current slice (The slice displayed in the Main view).
- Point of Interest (POI) places the beam isocenter at the selected POI.
- Existing Isocenter places the new beam at the same isocenter position as a beam you select from the list.
- To create a gantry arc beam, click in the Gantry Arc check box and select Arc Direction from the drop-down list. Type values for Arc Start (degrees) and Arc Angle (degrees). The Arc Stop (degrees) is displayed in the last field.
- For an electron beam, you can select
- Applicator from the drop-down list
- Insert from the drop-down list.
- Click Ok to create the beam and close the dialog.
Duplicating a Beam
A duplicated beam is identical to the original beam, including any blocks, apertures, wedges and MLCs.
- Select the beam you want to duplicate.
- Click the Duplicate beam button (or choose Beam > Duplicate... from the menu) to display the Beam Label dialog.
- Type a beam label.
- Click Ok. The system creates the new beam and makes it the current beam (displayed in green)
Note! If you change the gantry angle of a duplicated beam, MLC and other settings might have to be re-made.
Creating an Opposing Beam
An opposed beam has the same isocenter position and field size as the original beam. Gantry angle, shields, apertures and MLCs are mirrored. When you oppose a beam with wedges, the wedges are copied onto the new (opposed) beam.
- Select the beam you want to oppose
- Click the Oppose beam button (or choose Beam > Oppose... from the menu) to display the Beam Label dialog.
- Type a beam label.
Note! If the collimator has a non-zero angle, it is rotated 360 minus the original collimator angle. For example, if the collimator angle is 90 degrees for the initial beam, the collimator angle of the opposed beam is 270 degrees. When entering the angle values manually, though, you can type-90. It automatically changes to 270.
- Click OK.
The New beam mirrors the field (and thus mirrors the settings of any MLCs, apertures or shields) of the initial beam and the gantry is rotated 180 degrees.
Caution! The mirroring of the field when making an opposed beam is not a dynamic setting. Whenever you make changes in original or mirror field, they are not perfect mirrors of each other any more. After the Oppose Beam operation, the two beams are not linked in any way.
Note! To set an opposed beam to use the SSD technique, set its Depth to 0.
Performing a Dose Calculation
To perform a dose calculation
- To open the Dose Calculation dialog, click the Dose Calculation button
- If dose exists only for some of the fields, marked as Incomplete (#/#), the Calculate All Beams check box can be ticked to enforce a complete re-calculation.
- If desired, click Options... to control and change calculation options. Close the Options dialog to continue.
- If desired, type a new Job label.
- When needed, changed the calculation job Priority from default Normal to Urgent. This means that the urgent job is performed before all queued jobs with priority Normal. An ongoing job is not affected, and always runs to completion before calculation starts on Urgent jobs.
- To send the job off to calculation, click Calculate. To exit DC without requesting a calculation, but saving the changes made in Options, click Close.
Note! The dose calculation for a plan defined by the Enhanced fluence calculation algorithm can only be performed in Oncentra MasterPlan 3.1 or later.
Dose Display [PA]
Dose is displayed in all views, except DRR views and RT image views. Dose is also displayed as ROI dose statistics in Case Explorer when Structure Set is selected. By default, absolute dose is displayed (Gy or cGy).
Relative dose can be selected by defining the relation between absolute and relative dose (dose "prescription")
Note!
- If no mass density is assigned to the external, the parts of the external draw outside the CT images are not considered in the dose calculation.
- If a mas density is specified for the external, these parts are considered during the dose calculation and dose is displayed outside the CT images. This is due to the fact that mass density has higher priority than CT data.
Note! When dose calculation has been performed on a limited selection of slices, the dose display is also limited to those slices. See further Dose Calculated for Subset of Slices.
To display relative dose, the absolute dose (Gy or cGy) corresponding to the relative dose (%) has to be defined. Since the selected value is used to display the dose independently of which plan is displayed, it is important to select a value valid for all plans.
- To define the relation between absolute dose and relative dose, select Plan > Relative dose ratio...
- Enter the absolute dose that corresponds to a certain relative dose, also to be entered. The default value is 100%
- Click Ok
When a relation between absolute and relative dose has been defined, you can switch the display by clicking the Relative/absolute button.
Note! A plan normalized to a user-defined value (the User Defined option) in OTP 1.3, is considered unnormalized in MasterPlan................................
Dose Display [BM]
By default, dose is displayed in view as isolines; lines that connect all dose points that have the same dose value. Using the Isoline Setup dialog, you determine what levels of dose are displayed as isolines in the views.
Dose can also be displayed as isoshapes, which represent the dose by coloring each pixel from red (hot-high dose) to blue (code-low dose). Unlike isolines, the color range cannot be modified.
The resolution and area of the dose display set for the calculation is set using the Dose Presentation Matrix option in Beam Modeling.
Note! If no mass density is assigned to the external, the parts of the external draw outside the CT images are not considered in the dose calculation. If a mass density is specified for the external, these parts are considered during the dose calculation and dose is displayed outside the CT images. This is due to the fact that mass density has higher priority than CT data.
Dose Calculation Per Beam
In MasterPlan, dose is calculated per beam. The dose matrices are kept in the system's runtime cache and database until there is a change that affects the dose. In many situations a change to a plan only affects one beam, and for most of these cases the system only invaidates the dose for the changed beams; thus
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Dose Display [PE]
By default, dose is displayed in views as isolines; lines that connect all dose points that have the same value. Using the Isoline Setup dialog, you determine what levels of dose are displayed as isolines in the views.
Dose can also be displayed as isoshades, which represent the dose by coloring each pixel from red to blue.
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Dose Calculation Concept
In Oncentra MasterPlan, dose is calculated by the same underlying calculation facility, wherever the calculation settings have been made. Calculation parameters can be set in
- Beam Modeling [BM]
- Plan Optimization [PO] (Optimizer)
- Dose Calculation Activity [DC]. The Dose calculation in the Dose Calculation Activity is for external beam plans.
After plan adjustments in PO for IMRT planning, a final dose calculation is made.
Note! Plan Optimization is not part of Dose Calculation standard functionality. To access the Plan Optimization, you need a separate Plan Optimization license.
Outline of calculation workflow:
- Plan information from BM, PO.
- Calculation settings in BM,PO,DC.
- Background dose calculation.
- Calculation result displayed in BM, PE, PO, PA.
- When necessary, plan and optimization adjustments in BM, PO, DC and recalculation.
- Validation in PE and PA.
Volume Rendering Activity
VR display 3D rendered image series, structure sets, beams and dose. Data display can be switched on or off and be modified in a number of different ways:
- Images:
- rendering parameters: opacity, blending mode, lighting, etc.
- cut planes: display reconstructed image slices in one or several different directions.
- transformation functions: density values mapped to opacity
- Structures:
- ROIs (Regions of Interest):solid, transparent
- Points:
- POIs (Points of Interest): selectable size
- Beams:
- transparent or wirefram
- labels, wedges, rotation
- Dose:
- surface and/or volumetric rendering
- opacity, blending mode,etc.
Oncentra MasterPlan v3.3_Radiation Commissioning and Quality Assurance
6. External Beam - Line Dose Guide
6.1 Introduction
6.2 Input File: Description and Examples
6.3 Output File: Description and Examples
6.4 Output from the Density Matrix Dump
6.1 Introduction
The scope of this guide is to help a reasonably experienced Oncentra MasterPlan user to generate and export Line Dose files containing calculated dose along specified lines.
It can be used for examining details of the dose calculations when unexpected dose results are obtained.它可以用於研究 的詳情劑量計算結果時，得到意想不到的劑量。
Note:
- For comparison between measured and Oncentra MasterPlan calculated data, the Beam Data Tool (see Chapter 7) is more flexible as it automatically generates comparison plots.
- Line Dose is accessed from the DC activity. It acts on all static beam segments in the current plan.
- The dose output is presented as output factor normalized劑量輸出是作為輸出因子正常化, i.e. dose per monitor unit for the actual field divided by the dose per monitor unit for the calibration field at the calibration point.
In addition to total dose other dosimetric details such as dose components (primary, scatter), energy fluence etc. are presented for each point in the scan. - Two co-ordinate systems are supported for input and output: the IEC system and the HELAX_TMS system.
The IEC co-ordinate system is a right-handed orthogonal system as shown in the left pane of Figure 6-1.The z-axis is directed along the central axis of the beam, from the isocenter towards the beam sources.
The y-axis is parallel to the axis of rotation of the gantry and directed into the gantry.
The x-axis is is in the plane of the gantry rotation and oriented such that the co-ordinate system becomes right-handed.
The HELAX_TMS co-ordinate system is also a right-handed orthogonal system as shown in the right pane of Figure 6-1. It has the same x-axis as the IEC system, but the y- and z-axes are opposed to those of the IEC system.
Both system co-rotate with the gantry such that the z-axis is always in the beam direction.
Note:
- The coordinate systems used in Line Dose do not co-rotate with the collimator.
- The origin of the systems could be set at any point along the beam axis but the default in both cases is at the point where the beam axis intersects the phantom surface; i.e. at the source-to-surface distance, SSD. The depth in the phantom is then described by the z co-ordinate, if the HELAX_TMS system is used, or the negative z co-ordinate, if the IEC system is used. (the down image is right-hand orthogonal system)
6.2 Input File: Description and Examples
Generation of line Dose output can be scripted through use of an input file selected in the Line Dose facility. An input file specifies an arbitrary number of scans where each scan will result in a Line Dose output file.
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Oncentra MasterPlan v3.3_Radiation Commissioning and Quality Assurance
7. External Beam - Beam Data Tool
7.1 Introduction
7.2 Main Workflows
7.3 Starting the Beam Data Tool
7.4 Importing and Customizing Dose Profiles
7.5 Performing Calculations of Dose Profiles
7.6 Comparing Measured and Calculated Dose Profiles
7.7 Selecting Collimator Model
7.8 Defining Interleaf Leakage
7.9 Defining Beam Source Size Parameters
7.10 Committing Changes
7.11 Defining and Committing VMAT Parameters
7.12 Data Limits BDT
7.13 References
7.14 Supported Scan Formats - Examples
7.1 Introduction
The new fluence calculation algorithm, introduced in Oncentra MasterPlan v3.1, is particularly suited for IMRT dose calculations.
The algorithm relies on beam charaterization parameters obtained for the original dose calculation algorithms, with a few exceptions: the algorithm requires separately fitted source size parameters, an interleaf插頁 leakage parameter, and detailed specifications of the treatment unit collimators.
With Oncentra MasterPlan the user can define these parameters, and thereby it will be faster to bring the new fluence calculation algorithm into clinical operation.
To aid in this process, the Beam Data Tool is provided with Oncentra MasterPlan.
- The Beam Data Tool (BDT) is intended for definition and updating of the characterization parameters relevant for the enhanced fluence calculation algorithm,
- but it can also be used for requesting multiple water phantom dose calculations with any supported dose calculation algorithm, 要求多水假體劑量計算與任何支持的劑量計算算法，
- and it can be used for comparing measured and calculated dose profiles from a number of different sources.
The Beam Data Tool is currently not able to perform electron beam calculations.
Caution:
- Do not run treatment device administration tools (RDStore, TDC, BDT) while dose planning is being performed.
- Be aware that請注意 the system dose not block concurrent use of Oncentra MasterPlan clients while these tools are used.
- As updates to the treatment device data can change the intended behavior of the dose calculation and beam modeling characteristics, it is strongly advised that the user manually ensures exclusive use of the entire Oncentra MasterPlan system while editing treatment device data.
- Open the Server Information service via Windows Start Menu>....>Server Information.
- On the Server Information page, choose License Module and then Active Users. Make sure no active users are listed.
7.2 Main Workflows
7.2.1 Defining New Parameters for a Machine in the Database
To bring the new fluence calculation algorithm into operation for a treatment machine that already exists in physics database, the workflow described below is suitable (if a treatment unit is not yet stored in the database, first follow the instructions for storing the unit with RD Store in Section 5.2, and customizing and verifying the unit with Treatment Device Configuration, TDC, in Section 5.3).
Defining new or updating characterization parameters for the new fluence calculation algorithm through the Beam Data Tool can only be performed at the Oncentra MasterPlan server.
The Beam Data Tool is available also on Oncentra MasterPlan clients, but can then not be used for modifying the characterization data修改特徵數據, only for evaluating measured and calculated dose profiles.
To successfully define a complete set of characterization parameters for the new fluence algorithm for one treatment unit and beam quality, perform the following steps within the Beam Data Tool:
- Import a set of measurements that can be used for matching measured and calculated penumbra匹配測量和計算半影 when determining the interleaf leakage and source size parameters(Section 7.4).
- Select MLC model and enable associated rectangular jaw models (Section 7.7).
- Define (potentially through iterative fitting) the fractional interleaf leakage parameter (Section 7.8).
- Define source size parameters in the cross-plane and in-plane directions through manual or automated fitting of the penumbra for a set of measured and calculated lateral dose profiles (Section 7.8.3)
- Review and commit the modifications to enable dose calculation with the enhanced algorithm for the treatment machine and beam quality in question (Section 7.10)
Note:
- Dose calculation with the Enhanced algorithm requires that an explicit明確的 MLC model is selected for the treatment unit.
- Dose calculation with the Enhanced algorithm will not be performed if no MLC model is assigned分配.
- Therefore it is required that an MLC model is selected before fitting of the interleaf leakage and source size parameters can be performed.
Caution:
- When deactivating 失能激活and subsequently 新啟re-activating a treatment unit or beam quality through RDStore (see Section 5.2.3), any changes made on the original database entry of this unit or quality using the Beam Data Tool will not be transferred to the new database entry.
- Before de-activating, use the Beam Data Tool to identify these changes (see Sections 7.7 to 7.8.3), or examine the BDREPORT.XML file located in OTP_DATA\BDT on the Oncentra MasterPlan server.
- After successful re-activation through RDStore, run the Beam Data Tool and re-enter the requested parameters.
- Verify that the entered parameters together with the re-activated unit or beam quality data provides a sufficient fit with measurements, otherwise trim修剪 the parameters to provide a sufficient fit.
7.2.2 Comparing Measured and Calculated Dose Profiles
The Beam Data Tool is also suitable for comparing measured and calculated dose profiles, for example at commissioning when receiving beam characterization data.
The Beam Data Tool provides a direct link to the Oncentra MasterPlan dose calculation components, relieving紓緩 the user from most of the repetitive work for setting up and performing so-called"line dose calculations" (see Chapter 6) in a water phantom.
To compare measured and calculated dose profiles, perform the following steps within the Beam Data Tool:
- Import a set of measurements, e.g. the set used to generate the beam characterization data (Section 7.4)
- Request dose calculation corresponding to the measurements for the desired combination of fluence and dose algorithms (Section 7.5).
- When calculation is completed, display measured dose profiles alongside並肩 the corresponding calculated doe profiles and evaluate devitions using the gamma property (Section 7.6).
7.2.3 Converting PLATO RTS Calculated Dose Profiles to "Beam Data" Format
Treatment units modeled in PLATO RTS can with limited effort be transitioned過渡 to Oncentra MasterPlan.
PLATO RTS and Oncentra MasterPlan require different sets of measurements for beam modeling,
but by using PLATO RTS to calculate the dose profiles required for Oncentra MasterPlan's photon beam data charaterization (see Section 2.4.4),
a MasterPlan beam data set corresponding to the original PLATO RTS beam data can be prepared by Nucletron physics support personnel物理支援人員.
To obtain a complete set of PLATO RTS calcualted dose profile applicable for characterization of Oncentra MasterPlan photon beam data, perform the following steps:
- Calculated the required dose profiles and output factors in water using PLATO RTS (Section 7.2.3.1)
- Import the calculated dose profiles into the Beam Data Tool and customize
- Accelerator design data
- Air fluence profiles
- Depth doses and dose profile in water
- Absolute dose measurement
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