Prog Med Phys.  2020 Sep;31(3):63-70. 10.14316/pmp.2020.31.3.63.

Stereotactic Radiosurgery

• Chung HT
• Lee DJ

• KMID: 2507479
• DOI: http://doi.org/10.14316/pmp.2020.31.3.63

Abstract

Stereotactic radiosurgery is one of the most sophisticated forms of modern advanced radiation therapy. Unlike conventional fractionated radiotherapy, stereotactic radiosurgery uses a high dose of radiation with steep gradient precisely delivered to target lesions. Lars Leksell presented the principle of radiosurgery in 1951. Gamma Knife^® (GK) is the first radiosurgery device used in clinics, and the first patient was treated in the winter of 1967. The first GK unit had 179 cobalt 60 sources distributed on a hemispherical surface. A patient could move only in a single direction. Treatment planning was performed manually and took more than a day. The latest model, Gamma Knife^® Icon^TM , shares the same principle but has many new dazzling characteristics. In this article, first, a brief history of radiosurgery was described. Then, the physical properties of modern radiosurgery machines and physicists’ endeavors to assure the quality of radiosurgery were described. Intrinsic characteristics of modern radiosurgery devices such as small fields, steep dose distribution producing sharp penumbra, and multi-directionality of the beam were reviewed together with the techniques to assess the accuracy of these devices. The reference conditions and principles of GK dosimetry given in the most recent international standard protocol, International Atomic Energy Agency TRS 483, were shortly reviewed, and several points needing careful revisions were highlighted. Understanding the principles and physics of radiosurgery will be helpful for modern medical physicists.

Keyword

Gamma Knife; Radiosurgery; Dosimetry; Standard protocol

Figure

• 

  Fig. 1 Modern stereotactic machines. (a) Gamma Knife, (b) Novalis Tx, and (c) CyberKnife.

Reference

References

1. Wilson RR. 1946; Radiological use of fast protons. Radiology. 47:487–491. DOI: 10.1148/47.5.487. PMID: 20274616.

2. Lawrence JH, Tobias CA, Born JL, Sangalli Fr, Carlson RA, Linfoot JH. 1962; Heavy particle therapy in acromegaly. Acta Radiol. 58:337–347. DOI: 10.3109/00016926209169575. PMID: 3319599.

3. Leksell L. 1951; The stereotaxic method and radiosurgery of the brain. Acta Chir Scand. 102:316–319.

4. Leksell L. 1971; Sterotaxic radiosurgery in trigeminal neuralgia. Acta Chir Scand. 137:311–314. PMID: 4948331.

5. Backlund EO. 2007; Gamma knife- the early story: memoirs of a privileged man. Prog Neurol Surg. 20:XXI–XXXII.

6. Mack A, Czempiel H, Kreiner HJ, Dürr G, Wowra B. 2002; Quality assurance in stereotactic space. A system test for verifying the accuracy of aim in radiosurgery. Med Phys. 29:561–568. DOI: 10.1118/1.1463062. PMID: 11991128.

7. Chung HT, Park JH, Chun KJ. 2017; Verification of dose profiles generated by the convolution algorithm of the gamma knife® radiosurgery planning system. Med Phys. 44:4880–4889. DOI: 10.1002/mp.12347. PMID: 28513854.

8. International Atomic Energy Agency. 2017. Dosimetry of small static fields used in external beam radiotherapy: an international code of practice for reference and relative dose determination. International Atomic Energy Agency;Vienna:

9. Chung HT, Park WY, Kim TH, Kim YK, Chun KJ. 2018; Assessment of the accuracy and stability of frameless gamma knife radiosurgery. J Appl Clin Med Phys. 19:148–154. DOI: 10.1002/acm2.12365. PMID: 29862671. PMCID: PMC6036398.

10. Andrews DW, Bednarz G, Evans JJ, Downes B. 2006; A review of 3 current radiosurgery systems. Surg Neurol. 66:559–564. DOI: 10.1016/j.surneu.2006.08.002. PMID: 17145309.

11. Rahimian J, Chen JC, Rao AA, Girvigian MR, Miller MJ, Greathouse HE. 2004; Geometrical accuracy of the Novalis stereotactic radiosurgery system for trigeminal neuralgia. J Neurosurg. 101 Suppl 3:351–355. DOI: 10.3171/sup.2004.101.supplement3.0351. PMID: 15537189.

12. Yin FF, Zhu J, Yan H, Gaun H, Hammoud R, Ryu S, et al. 2002; Dosimetric characteristics of Novalis shaped beam surgery unit. Med Phys. 29:1729–1738. DOI: 10.1118/1.1494830. PMID: 12201420.

13. Antypas C, Pantelis E. 2008; Performance evaluation of a CyberKnife G4 image-guided robotic stereotactic radiosurgery system. Phys Med Biol. 53:4697–4718. DOI: 10.1088/0031-9155/53/17/016. PMID: 18695294.

14. Zoros E, Moutsatsos A, Pappas EP, Georgiou E, Kollias G, Karaiskos P, et al. 2017; Monte Carlo and experimental determination of correction factors for gamma knife perfexion small field dosimetry measurements. Phys Med Biol. 62:7532–7555. DOI: 10.1088/1361-6560/aa8590. PMID: 28796643.

15. Mirzakhanian L, Benmakhlouf H, Tessier F, Seuntjens J. 2018; Determination of kQmsr,Q0fmsr,fref factors for ion chambers used in the calibration of Leksell Gamma Knife Perfexion model using EGSnrc and PENELOPE Monte Carlo codes. Med Phys. 45:1748–1757. DOI: 10.1002/mp.12821. PMID: 29468677.

16. International Atomic Energy Agency. 2000. Absorbed dose determination in external beam radiotherapy: an international code of practice for dosimetry based on standards of absorbed dose to water. International Atomic Energy Agency;Vienna:

17. Mirzakhanian L, Sarfehnia A, Seuntjens J. 2020; Experimental validation of recommended msr-correction factors for the calibration of Leksell Gamma Knife® Icontm unit following IAEA TRS-483. Phys Med Biol. 65:065003. DOI: 10.1088/1361-6560/ab6953. PMID: 31914427.

18. Schaarschmidt T, Kim TH, Kim YK, Yang HJ, Chung HT. 2018; GEANT4-based Monte Carlo simulation of beam quality correction factors for the Leksell Gamma Knife® PerfexionTM. J Korean Phys Soc. 73:1814–1820. DOI: 10.3938/jkps.73.1814.