PalmOS PDA Applications: Along & Away

Another popular basis for brachytherapy QA are the Greenfield-Tichman-Norman (GTN) linear source implant tables (Greenfield MA, Tichman M and Norman A, Dosage tables for linear radium sources filtered by 0.5 and 1.0 mm of platinum. Radiology 1959; 73:418). It is common for the original tables to be modified to yield cGy/milligram-hour by dividing the original values by the factor C = 0.84 / (0.825 * 0.957) = 1.064 which corrects for the alteration of Γ for radium and converts exposure to dose to tissue. The tables can be adapted for HDR use by converting the original values to a more convenient form for Ir-192 (Γ = 0.469) HDR by dividing the original values by C and then again by H_GTN = (3600 * 0.825 / 0.469) = 6333 to yield cGy/mCi-sec. The HDR dwell time in seconds is calculated by dividing the tabulated cGy/mCi-sec values by the prescribed dose (in cGy) and multiplying by the current activity of the source (in mCi). Note: The reciprocal (ie mCi-sec/cGy) is actually displayed in this calculator to be consistent with the Paterson-Parker based companion application for linear sources.

Click here to download the .zip archive: Along & Away 1.0.0 (20K), last updated 9/16/03.

The total HDR dwell time is displayed in the bezel at the top of the form. Input fields for prescribed dose (in cGy) and source activity (in mCi) are just below the bezel. The source activity is automatically decayed to the current date whenever you enter this form, but can be changed if necessary. The current date (9/16/03 in this example) and the source calibration date (9/10/03 in this case) are displayed to the left of these fields. Buttons for source active length and distance along the source axis lie just below the activity field. A scrollable version of the modified linear source table occupies the bottom half of the form. To use the program, simply tap any cell in the row of the table which corresponds to the "away" distance.	HDR source calibration data is maintained from the Physics form.	Other information about this program is found in the Options menu.