Select an Inventory Entry

To edit an inventory entry, first select the entry in the table of database entries (Note: this screen capture has been anonymized, the entry highlighted in blue is named "Tutorial").


After selecting an entry to edit, click the Edit button (or double-click a row in the table) to open the inventory editor sheet.

The Inventory Editor Sheet

An inventory editor sheet will open. If you create the inventory as part of the recommended workflow related to preparing a treatment plan it should already be 'primed' for the appropriate (or default) physics file, patient name, total number of source placeholders N in the current plaque selection and the calibration assay date preset according to the plan's current surgical schedule settings. Buttons are also provided in this sheet as a convenience to simplify updating the inventory to the current plan parameters. This can be useful if the inventory was originally initialized for a different patient or treament schedule and you want to reuse the seeds at a later date in another plaque.

  • In the Radionuclide control group:
    • Physics file - if necessary, select a different source physics file from the menu.

    • Mfg. lot number - optionally enter the manufacturing lot number or any other identifying information such as the patient name.

    • Inventory name - enter a descriptive name for this inventory entry, typically this would be the name of the patient it is destined for (e.g. the patient is named 'Tutorial' in this example).

    • Comment - optionally enter any other comments here.

    • For plaque number - this is a set of plaque index number(s) (1..4) that can use these sources. This set defaults to the currently active plaque at the time the inventory was created. You may share an inventory amongst multiple plaques by expanding this set. For example, you can manually edit the set by clicking on the control or by simply loading sources into a plaque. Note: an inventory mismatch warning is generated in the status line of the plaque loading window when the active plaque index is not a member of the selected inventory's plaque set.

    • Number of sources - enter the current number of sources available and the total number of sources N in the lot. The total N may have been 'primed' based on the number of source placeholders in the current plaque selection when the inventory was initially created. You can override that count here. The popup menu fills both fields with a common initialization value in the range 1..42. The leftmost text field is the current seed count remaining in inventory, the text field closest to the popup menu is N. For a new entry, both entries should be initialized with the same number. The available count will decrease as seeds are pulled from the inventory and installed in a plaque. In this example no sources have yet been pulled from this inventory entry so there are 21 remaining. Note: PS does not enforce returning sources to an inventory when a treatment is completed so the indicated available count may be out-of-sync with the actual count if the seeds are used or reused across multiple plaques.

  • In the Calibration assay date control group:
    • Assay date - enter the assay date and time of the source strength either directly in the control, or optionally click the calendar button to open a calendar sheet. The buttons along the bottom of this group box allow you to lock the source calibration and/or update the calibration to the current implant date and time settings in the Rx Window. When you Calculate Sources in the Implant Calculator the calibration dates and strengths of sources loaded in a plaque and the inventories from which they were pulled are automatically updated unless the calibration is locked.

    • If you have existing sources with known absolute strengths and/or which you intend to recycle into subsequent patients, you might want to lock the calibration date of the inventory for those sources to prevent their being accidentally changed should you click Calculate Sources in the Implant Calculator instead of Calculate Implant Duration when using existing or recycled seeds.


Note: in this calendar example March 10th is highlighted to indicate a clock change due to the beginning of daylight saving time (DST) for locales that observe DST. Notable USA holidays are indicated using red text.

  • In the Source strength mode control group:
    • By default, Plaque Simulator pulls sources from an inventory using its averaging strength A. The value of A is the average absolute source strength on the calibration assay date. Averaging mode is the easiest and most flexible mode for managing source strengths because it allows for A to also be temporarily considered as a relative strength when calculating the strengths required to solve for a proposed treatment schedule using a plaque that contain sources pulled from one or more inventories.
    • For example, suppose you create an intensity modulated plaque that pulls sources from 2 or more inventories. When solving source strengths for the plaque, PS will treat all A as relative strengths and automatically maintain the pre-existing relationships of A between the multiple inventories and then assign a common calibration assay date to that group of inventories. Note that automatic solution of source strength(s) requires that all involved inventories use source strength averaging mode and that all calibration assay dates be unlocked. In the Radionuclide control group of Basic Preferences you can change the default mode for entering source strengths between either averaging, minimum and maximum or absolute strengths, but averaging is the recommended mode.

  • Averaging - this is the default source strength mode.
    • Strength averaging is both an absolute, and, at times, a relative setting. Typically you will initialize the inventory to a relative strength of A = 1.0 and then use the Implant Calculator to solve the average source strength required at the time of implant to meet the surgical schedule. The units of A (e.g. mCi or U) are derived from the selected physics file settings. The Implant Calculator will calculate the required inventory averaging strength and assay date to fit the implant schedule whereupon A can thereafter be considered as an absolute strength on an absolute calibration date. As a convenience, the Std. menu lists standard strength values mentioned in the physics file.
    • Enter a percentage uncertainty range factor R for the averaging group. This typically defaults to ±2% for IsoAid seeds drawn from a single sorting batch but might be greater if there were insufficient sources in the primary batch and a few seeds from neighboring strength batches had to be used to fulfill an order.
    • Note: source averaging mode also allows you to exceed the seed total N if necessary and makes it easy to work with plaques that contain groups of intensity modulated sources. The relative strength of the different inventories used to load a plaque are maintained by the Implant Calculator when calulating source strengths.

  • Min & Max - By default, minimum and maximum strengths for the inventory are automatically calculated using the averaging source strength A and its uncertainty range factor R where min = A-R and max = A+R. Min and max are recalculated whenever the values of A and/or R are changed. You may also manually override the automatically calculated strengths. The leftmost text field is the minmum and the rightmost ('to') text field is the maximum.
    • A set S[N] of absolute source strengths (on the calibration date) randomly distributed over the range min ≤ S[N] ≤ max is regenerated every time you click the Min & max button. The set S[N] is tabulated, its histogram plotted, and statistics (min, max, mean and standard deviation) are listed in the Set of source strengths control group. Standard deviation (SD) is the average amount of variability in the data set. It tells us, on average, how far each measurement lies from the mean. Low standard deviation indicates the data are clustered around the mean, whereas high standard deviation indicates data are more spread out. In the example above, the standard deviation of 0.042 shows that on average the difference between the mean and individual strengths found in set S[N] is about 0.042 mCi. The relative standard deviation RSD ≅ 100 × (SD/mean) = 100 × (0.042/3.995) = 1.05%.
    • If the Randomize control is checked, whenever a source is pulled from an inventory in Min & max mode it will be randomly selected from the remaining members of set S[N] until the set is exhausted. Alternatively, if randomize is unchecked, the sources will be sequentially withdrawn from S[N] until the set is exhausted. Beware, in this mode you are limited to a maximum of N sources so if you run out of sources you must manually increase the value of N, which will, in turn, also regenerate an entirely new set S[N].

  • Absolute strengths - You can manually override the automatically generated set of absolute source strengths S[N] described above by selecting Absolute strengths mode.
    • In this mode the table in the Set of source strengths control group becomes selectable and editable.
    • Click on a table entry using the mouse cursor and then hit the Enter key to begin manual editing. To accept a manually edited value hit the Return key. The next entry in the table will be automatically selected and prepared for editing.
    • When you have completed editing the table, click the Lock button to terminate editing and prevent accidental changes to the set. For example, if you forget to lock the set, then accidentally clicking either the Averaging or Min & Max radio button will automatically regenerate a new set of absolute strengths based on the A and U values and you will lose the work you just entered.

For example, below (in red text) are individualized assay results for two lots of seeds from IsoAid with a total count of 17 seeds between the two lots. The two lots represent a pair source strengths intended for an intensity modulated plaque that holds 17 seeds. What follows is an example of creating an absolute source inventory for lot #202387393 which consists of eleven seeds.


Below, a new inventory was created via the Inventory window and then selected for editing. This inventory was automatically assigned the database ID 2A85EA5F based on its date and time of creation. The physics file was automatically set for IsoAid IAI-125 seeds based on PS preference settings. You could override the physics file here if necessary. The value #202387393 has been entered as the manufacturing (Mfg.) lot number. Tutorial has been entered as the inventory name. The default for the inventory name is the patient name. Entering a comment describing the inventory is optional.

The calibration assay date was automatically set to the plan's proposed treatment date of 10/18/2023. You could override the calibration here if necessary. Because these seeds already exist, the calibration assay date has been locked to prevent accidentally changing the assay date by calculating source strengths in the Implant Calculator window. The total number of seeds was automatically set to 17 seeds based on the number of seeds in the plaque and then manually overriden to 11 seeds to properly represent this particular lot.

The source strength mode was changed to Absolute strengths. This enables selection and editing of the S[N] table located in the Set of source strengths S[N] control group. The eleven measured strengths were then entered in the table. To begin data entry, select source N=1 by clicking the mouse cursor in its row. Press the enter key to begin editing. Be sure to press the return key to actually accept the value typed into the editable text field. Upon hitting the return key, the typed strength value will be accepted, the histogram updated, and the editable text field should automatically advance to the next table entry. Note: after entering the last strength (e.g. 11th in this example), the editable text field will loop back to the first table entry. If all the entered values look correct, proceed to lock the inventory source strengths.


Below, in the Radionuclide control group, the set of plaques has been expanded so that these sources can be used with plaques 1, 2 and 3 without generating an inventory mismatch warning.

In the Source strength mode control group, the mode has been locked to prevent accidentally changing the mode to Averaging or Min & Max which would automatically recalulate the set of source strengths S[N] based on the averaging and uncertainty settings. The randomize checkbox control determines how the set S[N] will be pulled from the inventory, either randomly or sequentially. Pulling seeds randomly is probably more representative of an actual preloaded plaque. Pulling sequentially allows you to precisely control which seed strength goes where in the plaque when manually loading seeds one-at-a-time by clicking on source placeholders in the Plaque window. A prospective 'next-available' source strength to be pulled from S[N] is listed in the Plaque window inventory status line. This 'next' value shown in the plaque status line will be correct if the inventory mode is averaging or if loading is performed sequentially for the absolute modes.


Updating the plaque

The sources in a plaque are snapshots of the state of an inventory entry at the moment the source was pulled from inventory and moved into the plaque.

Beginning with version 6.9.4 snapshots of all inventories used in a plan are also saved as part of the .iPlan6 treatment file package and can be used to completely regenerate missing source inventories at a later date or alternative planning location.

Note: Editing an inventory entry does NOT automatically propagate changes to the sources already in a plaque. If you edit an inventory entry (e.g. change its calibration or source strength mode) and any of the (up to 4) plaques currently under consideration in the current plan contain sources pulled from that inventory entry, you will be alerted when you close the inventory editor sheet and offered a one time opportunity to update the sources in the plaque(s) to match the current state of the inventory from which they were pulled.

Note: You will also NOT be alerted to update plaques containing this inventory entry that may be associated with another (e.g. prior) patient. In general, there is no need to edit the inventory settings of a prior patient. The rare exception would be if sources were manufactured and delivered with the wrong strength or calibration date and you need to recalculate dosimetry based on what was actually delivered. In such a case, to update the plaque(s) of a prior patient you must manually load that patient, select the inventory of interest, edit the inventory entry, update the plaque, and recalculate dosimetry.

In the example below, Plaque #1 contains eleven 1 mCi sources that were pulled from inventory ID 2A831344. At the time the sources were pulled that inventory was set for source strength averaging mode with an average strength of 1 mCi at the time of calibration. If you were to subsequently edit that inventory entry and change the strength from 1 mCi to 4 mCi (or change the calibration date), you would be presented an alert offering to update all of the 1 mCi sources in the plaque from inventory ID 2A831344 to the current average strength of 4 mCi.