Plan Quality and Optimized Treatment Planning Technique for Single-Isocenter VMAT Brain Stereotactic Radiosurgery/Radiotherapy Using Photon Optimizer

Document Type : Original Paper

Authors

1 Division of Physical Sciences, Karunya Institute of Technology and Sciences, Coimbatore, Tamilnadu, India. Department of Radiation Oncology, Yashoda Super Specialty Hospital and Cancer Institute. Ghaziabad, U.P. India.

2 Division of Physical Sciences, Karunya Institute of Technology and Sciences, Coimbatore, Tamilnadu, India.

3 Department of Radiation Oncology, Fortis Hospital, Mohali, Punjab, India.

4 Department of Radiation Oncology, Kidwai memorial institute of oncology center, Bengaluru, India.

5 1Division of Physical Sciences, Karunya Institute of Technology and Sciences, Coimbatore, Tamilnadu, India. 5Department of Radiation Oncology, Kovai Medical Center and Hospital, Coimbatore, Tamil Nadu, India.

6 1Division of Physical Sciences, Karunya Institute of Technology and Sciences, Coimbatore, Tamilnadu, India. 6Department of Radiation Oncology, Manipal hospital, bangalore, India.

10.22038/ijmp.2025.87088.2526

Abstract

Introduction: This study aims to analyze different dosimetric indices using various formulae in cranial Stereotactic Radiosurgery/Radiotherapy treatment planning.
Material and Methods: 42 targets were constructed from 23 patients with brain metastases (≤30 cc) treated at our institution, selected for this study. The PTVs were generated using a 3.0 mm isotropic margin from the CTV. Sequential boost prescriptions of 5-15 Gy were delivered using 6 MV FFF beams with full, partial, and non-coplanar arcs. The Acuros XB algorithm with a 1.25 mm grid size was optimized to calculate the dose distribution. The Conformity Index Homogeneity Index, and Gradient Index were evaluated using a DVH with different mathematical formulae.
Results: RTOG, Van’t Riet, and Paddick, and the Inverse of RTOG values were close to 1.0. Whereas Lomax & Scheib and SALT were 0.92 ± 0.06, 0.94±0.05, respectively, they achieved lower than 1.0. The results of different types of HI values achieved similar ideal values. For GI data scored, each target is in the case of multiple lesions. The effective radius and modified GI results for the dose GI are 4.61 ± 1.12 and 4.28 ± 1.24, respectively.
Conclusion: This study analyzed various CI, HI, and GI definitions to assess dose distribution quality in brain SRS/SRT plans. CI, HI, and GI are valuable tools for evaluating treatment plans by quantifying conformity, dose uniformity, and dose gradient. However, these indices have limitations. Future research should investigate these correlations, linking CI, HI, and GI with local control rates and toxicity outcomes.

Keywords

Main Subjects

References

  1. Lauko A, Rauf Y, Ahluwalia MS. Medical management of brain metastases. Neuro-oncology advances. 2020 Jan;2(1):vdaa015.
  2. Lin X, DeAngelis LM. Treatment of brain metastases. Journal of clinical oncology. 2015 Oct 20;33(30):3475-84.
  3. Kocher M, Wittig A, Piroth MD, Treuer H, Seegenschmiedt H, Ruge M, et al. Stereotactic radiosurgery for treatment of brain metastases: a report of the DEGRO Working Group on Stereotactic Radiotherapy. Strahlentherapie und Onkologie. 2014 Jun;190(6):521-32.
  4. Andrews DW, Scott CB, Sperduto PW, Flanders AE, Gaspar LE, Schell MC, et al. Whole brain radiation therapy with or without stereotactic radiosurgery boost for patients with one to three brain metastases: phase III results of the RTOG 9508 randomised trial. The Lancet. 2004 May 22;363(9422):1665-72.
  5. Leksell L. The stereotaxic method and radiosurgery of the brain. Acta chir scand. 1951;102:316-9.
  6. Thomas E, Popple R, Clark G, Fiveash JB. Comparison of plan quality and delivery time between volumetric arc therapy (VMAT) and gamma knife radiosurgery for patients with≥ 4 cranial metastases. Journal of Radiosurgery & SBRT. 2013 Mar 2;2.
  7. Thomas EM, Popple RA, Wu X, Clark GM, Markert JM, Guthrie BL, et al. Comparison of plan quality and delivery time between volumetric arc therapy (RapidArc) and Gamma Knife radiosurgery for multiple cranial metastases. Neurosurgery. 2014 Oct 1;75(4):409-18.
  8. Jones D. ICRU report 50—prescribing, recording and reporting photon beam therapy.
  9. Morgan-Fletcher SL. Prescribing, recording and reporting photon beam therapy (Supplement to ICRU Report 50), ICRU Report 62. ICRU, pp. ix+ 52, 1999 (ICRU Bethesda, MD) $65.00 ISBN 0-913394-61-0.
  10. Zare M, Lashkari M, Ghalehtaki R, Ghasemi A, Manshadi HD, Mir A, et al. The comparison of 5-field conformal radiotherapy techniques for the treatment of prostate cancer: The best for femoral head sparing. Medical Dosimetry. 2016 Dec 1;41(4):296-9.
  11. International Commission on Radiation Units and Measurements. ICRU report 83 prescribing, recording, and reporting intensity-modulated Photon-Beam therapy (IMRT). J Int Comm Radiat Units Meas. 2010;10(1):1-06.
  12. Wilke L, Andratschke N, Blanck O, Brunner TB, Combs SE, Grosu AL, et al. ICRU report 91 on prescribing, recording, and reporting of stereotactic treatments with small photon beams: Statement from the DEGRO/DGMP working group stereotactic radiotherapy and radiosurgery. Strahlentherapie und Onkologie. 2019 Mar 1;195(3):193-8.
  13. Feuvret L, Noël G, Mazeron JJ, Bey P. Conformity index: a review. International Journal of Radiation Oncology* Biology* Physics. 2006 Feb 1;64(2):333-42.
  14. Ohtakara K, Hayashi S, Hoshi H. Dose gradient analyses in Linac-based intracranial stereotactic radiosurgery using Paddick's gradient index: consideration of the optimal method for plan evaluation. Journal of radiation research. 2011 Sep;52(5):592-9.
  15. Shaw E, Kline R, Gillin M, Souhami L, Hirschfeld A, Dinapoli R, et al. Radiation Therapy Oncology Group: radiosurgery quality assurance guidelines. International Journal of Radiation Oncology* Biology* Physics. 1993 Dec 1;27(5):1231-9.
  16. Shaw E, Scott C, Souhami L, Dinapoli R, Kline R, Loeffler J, et al. Single dose radiosurgical treatment of recurrent previously irradiated primary brain tumors and brain metastases: final report of RTOG protocol 90-05. International Journal of Radiation Oncology* Biology* Physics. 2000 May 1;47(2):291-8.
  17. Knöös T, Kristensen I, Nilsson P. Volumetric and dosimetric evaluation of radiation treatment plans: radiation conformity index. International Journal of Radiation Oncology* Biology* Physics. 1998 Dec 1;42(5):1169-76.
  18. Dejean C, Lefkopoulos D, Foulquier JN, Schlienger M, Touboul E. Automatic definition of prescription isodose for stereotaxic radiation of arteriovenous malformations. Cancer Radiotherapie: Journal de la Societe Francaise de Radiotherapie Oncologique. 2001 Apr 1;5(2):138-49.
  19. Grandjean P, Platoni K, Lefkopoulos D, Merienne L, Schlienger M. Use of a general inverse technique for the conformational stereotactic treatment of complex intracranial lesions. International Journal of Radiation Oncology* Biology* Physics. 1998 Apr 1;41(1):69-76.
  20. Lomax NJ, Scheib SG. Quantifying the degree of conformity in radiosurgery treatment planning. International Journal of Radiation Oncology* Biology* Physics. 2003 Apr 1;55(5):1409-19.
  21. Van't Riet A, Mak AC, Moerland MA, Elders LH, Van Der Zee W. A conformation number to quantify the degree of conformality in brachytherapy and external beam irradiation: application to the prostate. International Journal of Radiation Oncology* Biology* Physics. 1997 Feb 1;37(3):731-6.
  22. Wu QR, Wessels BW, Einstein DB, Maciunas RJ, Kim EY, Kinsella TJ. Quality of coverage: conformity measures for stereotactic radiosurgery. Journal of applied clinical medical physics. 2003 Sep;4(4):374-81.
  23. Park JM, Park SY, Ye SJ, Kim JH, Carlson J, Wu HG. New conformity indices based on the calculation of distances between the target volume and the volume of reference isodose. The British journal of radiology. 2014 Nov 1;87(1043):20140342.
  24. Semenenko VA, Reitz B, Day E, Qi XS, Miften M, Li XA. Evaluation of a commercial biologically based IMRT treatment planning system. Medical physics. 2008 Dec;35(12):5851-60.
  25. Yoon M, Park SY, Shin D, Lee SB, Pyo HR, Kim DY, et al. A new homogeneity index based on statistical analysis of the dose–volume histogram. Journal of applied clinical medical physics. 2007 Mar;8(2):9-17.
  26. Paddick I, Lippitz B. A simple dose gradient measurement tool to complement the conformity index. Journal of neurosurgery. 2006 Dec 1;105(Supplement):194-201.
  27. Ohtakara K, Hayashi S, Hoshi H. Dose gradient analyses in Linac-based intracranial stereotactic radiosurgery using Paddick's gradient index: consideration of the optimal method for plan evaluation. Journal of radiation research. 2011 Sep;52(5):592-9.
  28. Agostinelli S, Garelli S, Gusinu M, Zeverino M, Cavagnetto F, Pupillo F, et al. Dosimetric analysis of Tomotherapy-based intracranial stereotactic radiosurgery of brain metastasis. Physica Medica. 2018 Aug 1;52:48-55.
  29. Benedict SH, Yenice KM, Followill D, Galvin JM, Hinson W, Kavanagh B, et al. Stereotactic body radiation therapy: the report of AAPM Task Group 101. Medical physics. 2010 Aug;37(8):4078-101.
  30. Clark GM, Popple RA, Prendergast BM, Spencer SA, Thomas EM, Stewart JG, et al. Plan quality and treatment planning technique for single isocenter cranial radiosurgery with volumetric modulated arc therapy. Practical radiation oncology. 2012 Oct 1;2(4):306-13.
  31. Fogliata A, Nicolini G, Clivio A, Vanetti E, Cozzi L. Dosimetric evaluation of Acuros XB Advanced Dose Calculation algorithm in heterogeneous media. Radiation oncology. 2011 Jul 19;6(1):82.
  32. Liu H, Sintay B, Pearman K, Shang Q, Hayes L, Maurer J, et al. Comparison of the progressive resolution optimizer and photon optimizer in VMAT optimization for stereotactic treatments. Journal of applied clinical medical physics. 2018 Jul;19(4):155-62.
  33. Sundaram V, Khanna D, Vasudeva T. Comparison of Progressive Resolution Optimizer and Photon Optimizer algorithms in RapidArc delivery for head and neck SIB treatments. Reports of Practical Oncology and Radiotherapy. 2023;28(5):623-35.
  34. UK SABR Consortium. (2019). UK SABR consortium guidelines : A Resource. Version 6.1. 2019, https://www.sabr.org.uk/wp-content/uploads/2019/04/SABRconsortium-guidelines-2019-v6.1.0.pdf
  35. Reynolds TA, Jensen AR, Bellairs EE, Ozer M. Dose gradient index for stereotactic radiosurgery/radiation therapy. International Journal of Radiation Oncology* Biology* Physics. 2020 Mar 1;106(3):604-11.
  36. Oliver M, Chen J, Wong E, Van Dyk J, Perera F. A treatment planning study comparing whole breast radiation therapy against conformal, IMRT and tomotherapy for accelerated partial breast irradiation. Radiotherapy and oncology. 2007 Mar 1;82(3):317-23.
  37. Clark GM, Popple RA, Young PE, Fiveash JB. Feasibility of single-isocenter volumetric modulated arc radiosurgery for treatment of multiple brain metastases. International Journal of Radiation Oncology* Biology* Physics. 2010 Jan 1;76(1):296-302.
  38. Cui Y, Gao H, Zhang J, Kirkpatrick JP, Yin FF. Retrospective quality metrics review of stereotactic radiosurgery plans treating multiple targets using single‐isocenter volumetric modulated arc therapy. Journal of Applied Clinical Medical Physics. 2020 Jun;21(6):93-9.
  39. Ballangrud Å, Kuo LC, Happersett L, Lim SB, Beal K, Yamada Y, et al. Institutional experience with SRS VMAT planning for multiple cranial metastases. Journal of applied clinical medical physics. 2018 Mar;19(2):176-83.
  40. Menon SV, Paramu R, Bhasi S, Gopalakrishnan Z, Bhaskaran S, Nair RK. Dosimetric comparison of iPlanⓇ Pencil Beam (PB) and Monte Carlo (MC) algorithms in stereotactic radiosurgery/radiotherapy (SRS/SRT) plans of intracranial arteriovenous malformations. Medical Dosimetry. 2020 Sep 1;45(3):225-34.
  41. Stanley J, Breitman K, Dunscombe P, Spencer DP, Lau H. Evaluation of stereotactic radiosurgery conformity indices for 170 target volumes in patients with brain metastases. Journal of applied clinical medical physics. 2011 Mar;12(2):245-53.
  42. Cao T, Dai Z, Ding Z, Li W, Quan H. Analysis of different evaluation indexes for prostate stereotactic body radiation therapy plans: conformity index, homogeneity index and gradient index. Precision Radiation Oncology. 2019 Sep;3(3):72-9.
  43. Kihara S, Ohira S, Kanayama N, Ikawa T, Inui S, Isono M, et al. Effects of institutional experience on plan quality in stereotactic radiotherapy using HyperArc for brain metastases. in vivo. 2025 Jan 1;39(1):210-7.
  44. Ho HW, Lee SP, Lin HM, Chen HY, Huang CC, Wang SC, et al. Dosimetric comparison between RapidArc and HyperArc techniques in salvage stereotactic body radiation therapy for recurrent nasopharyngeal carcinoma. Radiation Oncology. 2020 Jul 8;15(1):164.

 

 

Iranian Journal of Medical Physics
Volume 22, Issue 4 - Serial Number 4
July and August 2025
Pages 247-260

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History

  • Receive Date: 31 March 2025
  • Revise Date: 30 September 2025
  • Accept Date: 07 October 2025

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