J Korean Neurosurg Soc.  2018 Nov;61(6):753-760. 10.3340/jkns.2018.0075.

Cyberknife Dosimetric Planning Using a Dose-Limiting Shell Method for Brain Metastases

Affiliations
  • 1Radiosurgery Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
  • 2Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
  • 3Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. yhyunc@amc.seoul.kr

Abstract


OBJECTIVE
We investigated the effect of optimization in dose-limiting shell method on the dosimetric quality of CyberKnife (CK) plans in treating brain metastases (BMs).
METHODS
We selected 19 BMs previously treated using CK between 2014 and 2015. The original CK plans (CKoriginal) had been produced using 1 to 3 dose-limiting shells : one at the prescription isodose level (PIDL) for dose conformity and the others at lowisodose levels (10-30% of prescription dose) for dose spillage. In each case, a modified CK plan (CKmodified) was generated using 5 dose-limiting shells : one at the PIDL, another at intermediate isodose level (50% of prescription dose) for steeper dose fall-off, and the others at low-isodose levels, with an optimized shell-dilation size based on our experience. A Gamma Knife (GK) plan was also produced using the original contour set. Thus, three data sets of dosimetric parameters were generated and compared.
RESULTS
There were no differences in the conformity indices among the CKoriginal, CKmodified, and GK plans (mean 1.22, 1.18, and 1.24, respectively; p=0.079) and tumor coverage (mean 99.5%, 99.5%, and 99.4%, respectively; p=0.177), whereas the CKmodified plans produced significantly smaller normal tissue volumes receiving 50% of prescription dose than those produced by the CKoriginal plans (p < 0.001), with no statistical differences in those volumes compared with GK plans (p=0.345).
CONCLUSION
These results indicate that significantly steeper dose fall-off is able to be achieved in the CK system by optimizing the shell function while maintaining high conformity of dose to tumor.

Keyword

Radiosurgery; Brain; Neoplasm metastasis

MeSH Terms

Brain*
Dataset
Methods*
Neoplasm Metastasis*
Prescriptions
Radiosurgery

Figure

  • Fig. 1. A schematic representation of the relationship between the gross tumor volume (GTV) and dose-limiting shells. RGTV is the equivalent spherical radius of the GTV, and RGTV×Mi is another equivalent spherical radius for an expanded volume of the GTV (shelli) achieved by applying an empirically determined multiplication factor of Mi.

  • Fig. 2. Comparison of dosimetric indices plotted against tumor diameters in all 19 cases. Each black circle, blue square, and red triangle represents the value in the CKoriginal, CKmodified, and GK plan, in terms of the conformity index (A), tumor coverage (B), and gradient index (C). CKoriginal : original CyberKnife plan, CKmodified : modified CyberKnife plan, GK : Gamma Knife plan.

  • Fig. 3. A representative case of optimized dose fall-off when using the modified CK planning technique. In the original CK plan (A), a single shell (green line) with a distance of 3 mm from the margin of the tumor volume (shaded in red; 14.8 cm3 in this case) was used (top). The multiple isodose lines presented in the planned dosimetric image (bottom). The isodose lines represent the percentage of the prescription dose. In the modified CK plan (B), 5 shells with distances of 2, 7, 18, 28, and 38 mm from the tumor margin were introduced and used (top). Note that the isodose lines are arranged more compactly in the planned image (bottom) than in the original plan. The value of the gradient index 3.4 in the original plan decreased to 2.5 in the modified plan in this case. In the GK plan (C), the value of the gradient index was 2.6. GTV : gross tumor volume, CK : CyberKnife.


Reference

References

1. Blonigen BJ, Steinmetz RD, Levin L, Lamba MA, Warnick RE, Breneman JC. Irradiated volume as a predictor of brain radionecrosis after linear accelerator stereotactic radiosurgery. Int J Radiat Oncol Biol Phys. 77:996–1001. 2010.
Article
2. Chin LS, Ma L, DiBiase S. Radiation necrosis following gamma knife surgery: a case-controlled comparison of treatment parameters and long-term clinical follow up. J Neurosurg. 94:899–904. 2001.
Article
3. Cho YH, Lee JM, Lee D, Park JH, Yoon K, Kim SO, et al. Experiences on two different stereotactic radiosurgery modalities of Gamma Knife and Cyberknife in treating brain metastases. Acta neurochir (Wien). 157:2003–2009. discussion 2009. 2015.
Article
4. Fahrig A, Ganslandt O, Lambrecht U, Grabenbauer G, Kleinert G, Sauer R, et al. Hypofractionated stereotactic radiotherapy for brain metastases--results from three different dose concepts. Strahlenther Onkol. 183:625–630. 2007.
Article
5. Feuvret L, Vinchon S, Martin V, Lamproglou I, Halley A, Calugaru V, et al. Stereotactic radiotherapy for large solitary brain metastases. Cancer Radiother. 18:97–106. 2014.
Article
6. Gevaert T, Levivier M, Lacornerie T, Verellen D, Engels B, Reynaert N, et al. Dosimetric comparison of different treatment modalities for stereotactic radiosurgery of arteriovenous malformations and acoustic neuromas. Radiother Oncol. 106:192–197. 2013.
Article
7. Giubilei C, Ingrosso G, D'Andrea M, Benassi M, Santoni R. Hypofractionated stereotactic radiotherapy in combination with whole brain radiotherapy for brain metastases. J Neurooncol. 91:207–212. 2009.
Article
8. Jiang XS, Xiao JP, Zhang Y, Xu YJ, Li XP, Chen XJ, et al. Hypofractionated stereotactic radiotherapy for brain metastases larger than three centimeters. Radiat Oncol. 7:36. 2012.
Article
9. Kaul D, Badakhshi H, Gevaert T, Pasemann D, Budach V, Tuleasca C, et al. Dosimetric comparison of different treatment modalities for stereotactic radiosurgery of meningioma. Acta Neurochir (Wien). 157:559–563. discussion 563-564. 2015.
Article
10. Kim YJ, Cho KH, Kim JY, Lim YK, Min HS, Lee SH, et al. Single-dose versus fractionated stereotactic radiotherapy for brain metastases. Int J Radiat Oncol Biol Phys. 81:483–489. 2011.
Article
11. Korytko T, Radivoyevitch T, Colussi V, Wessels BW, Pillai K, Maciunas RJ, et al. 12 Gy gamma knife radiosurgical volume is a predictor for radiation necrosis in non-AVM intracranial tumors. Int J Radiat Oncol Biol Phys. 64:419–424. 2006.
Article
12. Kwon AK, Dibiase SJ, Wang B, Hughes SL, Milcarek B, Zhu Y. Hypofractionated stereotactic radiotherapy for the treatment of brain metastases. Cancer. 115:890–898. 2009.
Article
13. Ma L, Sahgal A, Descovich M, Cho YB, Chuang C, Huang K, et al. Equivalence in dose fall-off for isocentric and nonisocentric intracranial treatment modalities and its impact on dose fractionation schemes. Int J Radiat Oncol Biol Phys. 76:943–948. 2010.
Article
14. Massager N, Maris C, Nissim O, Devriendt D, Salmon I, Levivier M. Experimental analysis of radiation dose distribution in radiosurgery. II. Dose fall-off outside the target volume. Stereotact Funct Neurosurg. 87:137–142. 2009.
Article
15. Meeks SL, Buatti JM, Bova FJ, Friedman WA, Mendenhall WM. Treatment planning optimization for linear accelerator radiosurgery. Int J Radiat Oncol Biol Phys. 41:183–197. 1998.
Article
16. Minniti G, Clarke E, Lanzetta G, Osti MF, Trasimeni G, Bozzao A, et al. Stereotactic radiosurgery for brain metastases: analysis of outcome and risk of brain radionecrosis. Radiat Oncol. 6:48. 2011.
Article
17. Minniti G, D'Angelillo RM, Scaringi C, Trodella LE, Clarke E, Matteucci P, et al. Fractionated stereotactic radiosurgery for patients with brain metastases. J Neurooncol. 117:295–301. 2014.
Article
18. Murai T, Ogino H, Manabe Y, Iwabuchi M, Okumura T, Matsushita Y, et al. Fractionated stereotactic radiotherapy using CyberKnife for the treatment of large brain metastases: a dose escalation study. Clin Oncol (R Coll Radiol). 26:151–158. 2014.
Article
19. Paddick I, Lippitz B. A simple dose gradient measurement tool to complement the conformity index. J Neurosurg. 105 Suppl:194–201. 2006.
Article
20. Sio TT, Jang S, Lee SW, Curran B, Pyakuryal AP, Sternick ES. Comparing Gamma Knife and CyberKnife in patients with brain metastases. J Appl Clin Med Phys. 15:4095. 2014.
Article
21. Solberg TD, Balter JM, Benedict SH, Fraass BA, Kavanagh B, Miyamoto C, et al. Quality and safety considerations in stereotactic radiosurgery and stereotactic body radiation therapy: executive summary. Pract Radiat Oncol. 2:2–9. 2012.
Article
22. Wagner TH, Bova FJ, Friedman WA, Buatti JM, Bouchet LG, Meeks SL. A simple and reliable index for scoring rival stereotactic radiosurgery plans. Int J Radiat Oncol Biol Phys. 57:1141–1149. 2003.
Article
23. Wowra B, Muacevic A, Tonn JC. Quality of radiosurgery for single brain metastases with respect to treatment technology: a matched-pair analysis. J Neurooncol. 94:69–77. 2009.
Article
24. Yu C, Jozsef G, Apuzzo ML, Petrovich Z. Dosimetric comparison of CyberKnife with other radiosurgical modalities for an ellipsoidal target. Neurosurgery. 53:1155–1162. discussion 1162-1163. 2003.
Article
25. Zeverino M, Jaccard M, Patin D, Ryckx N, Marguet M, Tuleasca C, et al. Commissioning of the leksell Gamma Knife® Icon™. Med Phys. 44:355–363. 2017.
Full Text Links
  • JKNS
Actions
Cited
CITED
export Copy
Close
Share
  • Twitter
  • Facebook
Similar articles
Copyright © 2024 by Korean Association of Medical Journal Editors. All rights reserved.     E-mail: koreamed@kamje.or.kr