The eligibility of the dose spillage in stereotactic radiotherapy evaluated with an in-house-written program

The eligibility of the dose spillage in stereotactic radiotherapy evaluated with an in-house-written program Jeno Palvolgyi Abstract. The dvhanal in-house written program developed previously, which allows the user to examine the dose coverage of the PTV and the dose limits of the OARs from the DVH file, and to evaluate whether the radiotherapy plan meets the protocol prescriptions. For the evaluation of the dose spillage in SRS planning, the dhvanal program was modified, and the dvhsrs add-on was written. Introduction The dvhanal program was written to evaluate the DVH files of RT plans prepared with the Monaco 5.11 treatment planning system (Elekta, Sweden) [1]. The program runs under Windows 11, it was written in QB64, and the GUI was implemented in Python 3.11. The absolute DVH file of the RT plan is exported from the TPS. The program also requires a protocol prescription file, which stores the list of tasks for collecting the quantities from the DVH data file, the per-protocol, and acceptable variation values. Materials and Methods For evaluation of the dose spillage in stereotactic (SRS) planning, additional data are required as follows: the Prescription dose, the maximal (D(0,03ccm)) dose in the PTV, the maximal dose at 2 cm apart from the PTV, the maximal dose out of the PTV. Volume of the 50% isodose surface, Table 1. illustrates the mandatory tasks and the added commands (C,P). Lung SRS 50=5*10Gy PP VA cGy cGY PTV D 0,03 ccm < 6000 7500 cGy PTV V 5000 cGy > 98 95 % PTV P 5000 cGy < 0 0 cGy PTV C 0 ccm < 0 0 ccm PTV N 0 ccm > 4500 0 cGy PTV V 5000 cGy > 0 0 ccm PTV V 2500 cGy > 0 0 ccm Pat-PTV+2 D 0,03 ccm < 0 0 cGy Pat-PTV D 0,03 ccm < 0 0 cGy V_50 C 0 ccm < 0 0 ccm Table 1. The mandatory tasks (sample) in the protocol prescription file for evaluation of the dose spillage Command P: sets the Prescription dose, Command C: writes the value of the PTV volume, Command N: writes the minimal dose value in the PTV structure Pat-PTV: External contour - PTV, structure Pat-PTV+2 is the External contourPTV extended with 2cm in all directions, structure V_50 is the isodose surface generated with the 50% of the Prescription dose. (The latter three structures should be also included in the exported DVH.txt file) According to the RTOG 0813 and RTOG 0915 protocols, the per-protocol and acceptable variation values depend on the PTV volume. Two additional files: psrsd2cm.csv and psrsrR50.csv were created with the protocol prescription file format to store the per-protocol and acceptable variation values with different PTV volumes as seen in Table 3. and 4. in the Appendix. The dvhsrs program reads the Report.csv file generated by the dvhanal program, and also reads the psrsd2cm.csv and psrsr5.csv files, selects the per-protocol and acceptable variation values on the PTV volume, and generates the srsreport.csv file illustrated in Table 2. However, the per protocol and acceptable variation values are pertinent to the Lung cases: they can be applied for other locations[2]. The GUI was also updated. Prescription dose 5000 cGy max dose 6501 cGy maxdos/prescription dose 1,3002 max dose at 2cm 3279 cGy max dose at 2cm/presd 50 57 65,58 % uv PTV_volume 31 ccm V_50_volume 162 ccm V_50/PTV volume 5,9 7,5 5,225806 pp Table 2. The SRS plan dose spillage report (uv: unacceptable, va: acceptable variation, pp: per protocol). Installation Unzip the dvhanalsrs.zip file, create the C:\dvhanal folder with r/w attributes, copy the extracted folders work and protocols to the dvhanal map. Run the qui.exe program. Disclaimer. The program comes without any warranty, and has not been approved for clinical use by any regulatory bodies. Use at your own risk. Appendix Table 3. The srsrd2cm.csv file srs_max dose at 2cm PP VA PTV 2 1 ccm < 50 57 % PTV 2 18 ccm < 50 57 % PTV 2 38 ccm < 50 57 % PTV 2 74 ccm < 50 58 % PTV 2 132 ccm < 50 58 % PTV 2 220 ccm < 54 63 % PTV 2 340 ccm < 58 68 % PTV 2 500 ccm < 62 77 % PTV 2 700 ccm < 66 86 % PTV 2 950 ccm < 70 89 % PTV 2 1260 ccm < 73 91 % Table 4. The psrsr50.csv file References 1. Palvolgyi, J. (2025). A simple in-house-written program for examination of eligibility of the radiotherapy plans for the protocol prescriptions. Zenodo. https://doi.org/10.5281/zenodo.16285650 2. Linda H. SBRT Treatment Planning: Practical Considerations https://amos3.aapm.org/abstracts/pdf/68-19774-234349-85603.pdf PP*10 VA *10 PTV R 1 ccm < 59 75 PTV R 18 ccm < 59 75 PTV R 38 ccm < 55 65 PTV R 74 ccm < 51 60 PTV R 132 ccm < 47 58 PTV R 220 ccm < 45 55 PTV R 340 ccm < 43 53 PTV R 500 ccm < 40 50 PTV R 700 ccm < 35 48 PTV R 950 ccm < 33 44 PTV R 1260 ccm < 31 40 PTV R 1630 ccm < 29 37