Skip to main content

Advertisement

SpringerLink
Log in

Stereotactic radiotherapy for choroidal melanomas by means of HybridArc™

Physics and technique of linac-based photon beam therapy

Stereotaktische Radiotherapie von Aderhautmelanomen mittels HybridArc™

Physik und Technik der linearbeschleunigerbasierten Photonentherapie

  • Original Article
  • Published:
Strahlentherapie und Onkologie Aims and scope Submit manuscript

Abstract

Purpose

Stereotactic radiotherapy (SRT) is suitable to treat ocular tumours. The optimal beam geometry for SRT, however, has not been defined. Here we evaluate a combination technique with dynamic conformal arcs (DCAs) and intensity-modulated static fields (IMRT), known as HybridArc™ (HA).

Methods

For the first consecutive 25 cases with choroidal melanomas with volumes of 0.02 to 1.18 cm3 treated with 50 Gy in five fractions, the results with respect to dose conformity, homogeneity, and dose distributions were summarised. To describe the dose distribution at the planning target volume (PTV) boundary, we defined a spatially averaged dose gradient (SADG) and compared it with Paddick’s gradient index (GI). We made dosimetric comparisons between HA and other irradiation techniques.

Results

The PTVs ranged from 0.42 to 3.37 cm3. The conformity index (CI) was 1.25 ± 0.15, and the homogeneity index (HI) 0.08 ± 0.02. The SADG was (−3.5 ± 0.5) Gy/mm or (−7.0 ± 1.0) %/mm between the isodose levels 95 and 20%; local minima reached −11.5 Gy/mm or −22.9%/mm. The coefficient of determination for a nonlinear regression of GI on SADG was 0.072. After a median follow-up time of 19.6 months, local tumour control was 100% without any case of post-therapeutic enucleation. Two patients (8%) developed liver metastases.

Conclusion

SRT of ocular tumours by HA is highly appropriate, and HA is superior to intensity-modulated arc therapy (IMAT) concerning dose reduction in organs at risk (OARs). The novel gradient measure SADG is more informative than Paddick’s GI.

Zusammenfassung

Zielsetzung

Die stereotaktische Radiotherapie (SRT) ist zur Behandlung von Augentumoren geeignet. Jedoch ist bis jetzt noch keine Definition der optimalen Bestrahlungsgeometrie zur SRT erfolgt. Wir bewerten hier eine kombinierte Bestrahlungstechnik, bestehend aus dynamischen konformalen Rotationsfeldern (DCAs) und intensitätsmodulierten statischen Feldern (IMRT), die als HybridArc™ (HA) bekannt ist.

Methoden

Für die ersten 25 aufeinanderfolgenden Fälle mit Aderhautmelanomen in einem Volumenbereich von 0,02 bis 1,18 cm3, die mit 50 Gy in fünf Fraktionen bestrahlt wurden, wurden die Ergebnisse bezüglich Dosiskonformität, Dosishomogenität und Dosisverteilungen zusammengefasst. Zur Beschreibung der Dosisverteilung am Zielvolumenrand wurde ein räumlich gemittelter Dosisgradient (SADG) definiert und mit dem Gradientenindex (GI) nach Paddick verglichen. Wir stellten dosimetrische Vergleiche zwischen HA und anderen Bestrahlungstechniken an.

Ergebnisse

Die Planungszielvolumina (PTVs) lagen im Größenbereich von 0,42 bis 3,37 cm3. Für den Konformitätsindex (CI) und den Homogenitätsindex (HI) waren die Werte 1,25 ± 0,15 bzw. 0,08 ± 0,02. Der SADG betrug −3,5 ± 0,5 Gy/mm bzw. −7,0 ± 1,0 %/mm zwischen den Isodosenniveaus 95 und 20 %; lokale Minima erreichten −11,5 Gy/mm bzw. −22,9 %/mm. Der Determinationskoeffizient einer nichtlinearen Regression von GI über SADG war 0,072. Nach einem medianen Nachbeobachtungszeitraum von 19,6 Monaten lag die lokale Tumorkontrollrate bei 100 %, ohne einen einzigen Fall einer posttherapeutischen Enukleation. Zwei Patienten (8 %) entwickelten Lebermetastasen.

Schlussfolgerung

Die SRT von Augentumoren mittels HA ist äußerst gut geeignet. HA ist der intensitätsmodulierten Rotationstherapie (IMAT) bezüglich der Dosiseinsparung in Risikoorganen (OARs) überlegen. Das neu eingeführte Gradientenmaß SADG besitzt gegenüber dem GI nach Paddick mehr Informationsgehalt.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3

Similar content being viewed by others

References

  1. Gesellschaft der Epidemiologischen Krebsregister in Deutschland und Robert Koch-Institut (2017) Krebs in Deutschland für 2013/2014, 11th edn. Robert Koch-Institut, Berlin

  2. American Brachytherapy Society—Ophthalmic Oncology Task Force (2014) The American Brachytherapy Society consensus guidelines for plaque brachytherapy of uveal melanoma and retinoblastoma. Brachytherapy 13(1):1–14

    Article  Google Scholar 

  3. Krause L, Mladenova A, Bechrakis NE, Kreusel KM, Plath T, Moser L, Foerster M (2009) Treatment modalities for conjunctival melanoma. Klin Monbl Augenheilkd 226(12):1012–1016

    Article  CAS  Google Scholar 

  4. Collaborative Ocular Melanoma Study Group (2006) The COMS randomized trial of iodine 125 brachytherapy for choroidal melanoma: V. Twelve-year mortality rates and prognostic factors: COMS report no. 28. Arch Ophthalmol 124(12):1684–1693

    Article  Google Scholar 

  5. Hrbacek J, Mishra KK, Kacperek A, Dendale R, Nauraye C, Auger M, Herault J, Daftari IK, Trofimov AV, Shih HA, Chen YL, Denker A, Heufelder J, Horwacik T, Swakoń J, Hoehr C, Duzenli C, Pica A, Goudjil F, Mazal A, Thariat J, Weber DC (2016) Practice patterns analysis of ocular proton therapy centers: the international OPTIC survey. Int J Radiat Oncol Biol Phys 95(1):336–343

    Article  Google Scholar 

  6. Modorati G, Miserocchi E, Galli L, Picozzi P, Rama P (2009) Gamma knife radiosurgery for uveal melanoma: 12 years of experience. Br J Ophthalmol 93(1):40–44

    Article  CAS  Google Scholar 

  7. Dunavoelgyi R, Dieckmann K, Gleiss A, Sacu S, Kircher K, Georgopoulos M, Georg D, Zehetmayer M, Poetter R (2011) Local tumor control, visual acuity, and survival after hypofractionated stereotactic photon radiotherapy of choroidal melanoma in 212 patients treated between 1997 and 2007. Int J Radiat Oncol Biol Phys 81(1):199–205

    Article  Google Scholar 

  8. Eibl-Lindner K, Fürweger C, Nentwich M, Foerster P, Wowra B, Schaller U, Muacevic A (2016) Robotic radiosurgery for the treatment of medium and large uveal melanoma. Melanoma Res 26(1):51–57

    Article  CAS  Google Scholar 

  9. Kreusel KM, Bechrakis N, Riese J, Krause L, Wachtlin J, Foerster MH (2006) Combined brachytherapy and transpupillary thermotherapy for large choroidal melanoma: tumor regression and early complications. Graefes Arch Clin Exp Ophthalmol 244(12):1575–1580

    Article  Google Scholar 

  10. Jang BS, Chang JH, Oh S, Lim YJ, Kim IH (2017) Surgery vs. radiotherapy in patients with uveal melanoma: Analysis of the SEER database using propensity score matching and weighting. Strahlenther Onkol 193(11):931–942

    Article  Google Scholar 

  11. Bekkering GE, Rutjes AW, Vlassov VV, Aebersold DM, von Bremen K, Jüni P, Kleijnen J (2009) The effectiveness and safety of proton radiation therapy for indications of the eye: a systematic review. Strahlenther Onkol 185(4):211–221

    Article  Google Scholar 

  12. Lin AJ, Rao YJ, Acharya S, Schwarz J, Rao PK, Grigsby P (2017) Patterns of care and outcomes of proton and eye plaque brachytherapy for uveal melanoma: review of the National Cancer Database. Brachytherapy 16(6):1225–1231

    Article  Google Scholar 

  13. Beliveau-Nadeau D, Callejo S, Roberge D (2016) Technique for robotic stereotactic irradiation of choroidal melanoma. Cureus 8(4):e582

    PubMed  PubMed Central  Google Scholar 

  14. Klingenstein A, Kufeld M, Wowra B, Muacevic A, Fürweger C, Schaller UC (2012) CyberKnife radiosurgery for the treatment of orbital metastases. Technol Cancer Res Treat 11(5):433–439

    Article  CAS  Google Scholar 

  15. Haas A, Pinter O, Papaefthymiou G, Weger M, Berghold A, Schröttner O, Müllner K, Pendl G, Langmann G (2002) Incidence of radiation retinopathy after high-dosage single-fraction gamma knife radiosurgery for choroidal melanoma. Ophthalmology 109(5):909–913

    Article  Google Scholar 

  16. Robar JL, Thomas C (2012) Hybridarc: a novel radiation therapy technique combining optimized dynamic arcs and intensity modulation. Med Dosim 37(4):358–368

    Article  Google Scholar 

  17. Paddick I, Lippitz B (2006) A simple dose gradient measurement tool to complement the conformity index. J Neurosurg 105(Suppl):194–201

    PubMed  Google Scholar 

  18. Kaiser PK, Friedman NJ, Pineda R (2014) The massachusetts eye and ear infirmary—illustrated manual of ophthalmology, 4th edn. Elsevier Saunders, New York

    Google Scholar 

  19. Miralbell R, Caro M, Weber DC, Elizalde J, Perez-Ochoa A, Villà S, IgnacioToscas J, Martinez P, Linero D, Nouet P, Escudé L (2007) Stereotactic radiotherapy for ocular melanoma: initial experience using closed eyes for ocular target immobilization. Technol Cancer Res Treat 6(5):413–417

    Article  Google Scholar 

  20. International Commission on Radiation Units and Measurements (2014) ICRU Report 91: prescribing, recording, and reporting of stereotactic treatments with small photon beams. J Int Comm Radiat Unit Meas 14(2):1–160. https://doi.org/10.1093/jicru/ndx017

    Article  Google Scholar 

  21. Landberg T, Chavaudra J, Dobbs J, Gerard JP, Hanks G, Horiot JC, Johansson KA, Möller T, Purdy J, Suntharalingam N, Svensson H (1999) ICRU Report 62: prescribing, recording and reporting photon beam therapy (Supplement to ICRU Report 50). J Int Comm Radiat Units Meas 32(1):1–52

    Google Scholar 

  22. Ohtakara K, Hayashi S, Hoshi H (2012) The relation between various conformity indices and the influence of the target coverage difference in prescription isodose surface on these values in intracranial stereotactic radiosurgery. Br J Radiol 85(1014):e223–e228

    Article  CAS  Google Scholar 

  23. International Commission on Radiation Units and Measurements (2010) ICRU Report 83: prescribing, recording, and reporting intensity-modulated photon-beam therapy (IMRT). J Int Comm Radiat Units Meas 10(1):1–106

    Google Scholar 

  24. Weber DC, Bogner J, Verwey J, Georg D, Dieckmann K, Escudé L, Caro M, Pötter R, Goitein G, Lomax AJ, Miralbell R (2005) Proton beam radiotherapy versus fractionated stereotactic radiotherapy for uveal melanomas: a comparative study. Int J Radiat Oncol Biol Phys 63(2):373–384

    Article  Google Scholar 

  25. Podgorsak EB (2005) Radiation oncology physics: a handbook for teachers and students. International Atomic Energy Agency, Vienna

    Google Scholar 

  26. Lipski AC, Lakotka N, Riechardt AI, Willerding GD, Heufelder J, Türkmen S, Keilholz U, Moser UL, Joussen AM (2013) Diagnostik und Therapie choroidaler Melanome. Klin Monbl Augenheilkd 230(10):1005–1019

    Article  CAS  Google Scholar 

  27. Landberg T, Chavaudra J, Dobbs J, Hanks G, Johansson KA, Möller T, Purdy J (1993) ICRU Report 50: prescribing, recording and reporting photon beam therapy. J Int Comm Radiat Units Meas 26(1):1–72

    Google Scholar 

  28. International Electrotechnical Commission (2007) Radiotherapy equipment—coordinates, movements and scales (IEC 61217:1996 plus A1:2000 plus A2:2007). VDE Verlag GmbH, Berlin

  29. Gevaert T, Verellen D, Tournel K, Linthout N, Bral S, Engels B, Collen C, Depuydt T, Duchateau M, Reynders T, Storme G, De Ridder M (2012) Setup accuracy of the Novalis ExacTrac 6DOF system for frameless radiosurgery. Int J Radiat Oncol Biol Phys 82(5):1627–1635

    Article  Google Scholar 

  30. Ciernik IF, Wösle M, Krause L, Krayenbuehl J (2018) Optimizing radiosurgery with photons for ocular melanoma. Phys Imag Radiat Oncol 6:83–88. https://doi.org/10.1016/j.phro.2018.06.001

    Article  Google Scholar 

  31. Höcht S, Stark R, Seiler F, Heufelder J, Bechrakis NE, Cordini D, Marnitz S, Kluge H, Foerster MH, Hinkelbein W (2005) Proton or stereotactic photon irradiation for posterior uveal melanoma? A planning intercomparison. Strahlenther Onkol 181(12):783–788

    Article  Google Scholar 

  32. Herrmann T, Baumann M, Dörr W (2005) Klinische Strahlenbiologie—kurz und bündig, 4th edn. Elsevier Urban & Fischer, München, Jena

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Klinik für Strahlentherapie und Radioonkologie, Städtisches Klinikum Dessau, Auenweg 38, 06847, Dessau-Roßlau, Germany

    Markus Wösle M. Sc., Shanthala Sreenivasa & Ilja F. Ciernik

  2. Klinik für Augenheilkunde und Zentrum für Refraktive Chirurgie, Städtisches Klinikum Dessau, Auenweg 38, 06847, Dessau-Roßlau, Germany

    Lothar Krause

  3. Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, Magdeburger Straße 8, 06108, Halle (Saale), Germany

    Shanthala Sreenivasa

  4. Universitätsklinik und Poliklinik für Strahlentherapie, Universitätsklinikum Halle (Saale), Ernst-Grube-Straße 40, 06120, Halle (Saale), Germany

    Dirk Vordermark

Authors
  1. Markus Wösle M. Sc.
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Lothar Krause
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Shanthala Sreenivasa
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Dirk Vordermark
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Ilja F. Ciernik
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Markus Wösle M. Sc..

Ethics declarations

Conflict of interest

M. Wösle, L. Krause, S. Sreenivasa, D. Vordermark and I.F. Ciernik declare that they have no competing interests.

Ethical standards

Informed consent was obtained from all individual participants included in the study.

Appendix

Appendix

Benchmark experiment for evaluating treatment plan quality

A good benchmark to compare dose conformity, homogeneity, gradient measures and the dose ratio Dout/Dnom is SRS of brain metastases. This thought experiment is simple, and all physicians and medical physicists with stereotaxy experience are able to ascertain it.

For this experiment we generated treatment plans for spherical PTVs with highly conformal dose distributions. Three different PTVs were of equal size as the minimal, mean and maximal PTV in the cohort of 25 patients with choroidal melanomas. The results of our benchmark experiment to evaluate the novel dose gradient measure SADG according to Eq. 9 were summarised in Table 5. In Table 5, we also saw an unexpected characteristic of GI according to Eq. 10 on the PTV size: With increasing size of PTV, GI became better and SADG worsened. But only the characteristic of SADG is right, because with increasing field size the total physical penumbra broadens and as a result, the dose gradient at PTV boundary worsens.

Table 5 Benchmark data of stereotactic radiosurgery for brain metastases for assessment purposes concerning treatment plan quality criteria in stereotactic radiotherapy for choroidal melanomas by means of HybridArc™ (BRAINLAB AG, Feldkirchen, Germany)
Full size table

The values of the criterion CI95% according to Eq. 2 of our series in Table 2 were worse than the results for SRS obtained from assessments of the benchmark in Table 5: 1.25 ± 0.15 versus CI80% = 1.13 ± 0.11. That is not surprising because in the benchmark, the convenient geometric and anatomical conditions—spherical PTV without adjacent OARs—allow almost ideal values for CI. However, the values for HI according to Eq. 3 of our series were twice as good as the values of the benchmark: 0.08 ± 0.02 versus 0.20 ± 0.01. Thus, the achieved values of CIx% and HI were undoubtedly clinically acceptable in the present series. The corresponding values for the dose gradient measures SADG and GI were of the same order: (−11.9 ± 2.1)%/mm versus (−13.3 ± 4.6)%/mm and 2.9 ± 0.3 versus 2.7 ± 0.1, respectively. The advantage for the benchmark in both gradient measures is—as stated before—a consequence of the more convenient geometric conditions. The values for Dout/Dnom according to Eq. 5 relating to the dose fraction applied by DCA in Table 2 were also confirmed by the benchmark experiment: 1.45 ± 1.10 versus 1.48 ± 0.08.

Comparison of treatment planning results with gold standard

In Table 6 we compared our treatment planning results with published results of the gold standard methods PBT and linac-based SRT [24] by means of the criteria CIICRU according to Eq. 1 and IC according to Eq. 4.

Table 6 Tumour size, planning target volume size, conformity index and inhomogeneity coefficient for four choroidal melanomas from Table 1 in comparison with four virtual tumours of the treatment planning study [24]
Full size table

HA yields better plan qualities concerning dose conformity at the PTV boundary than the previously reported photon beam techniques, which have until now defined the standard in linac-based SRT. HA also seems competitive to PBT, because in the present series, the median of CIICRU for all four cases is 1.09, and thus closest to the optimum of 1.00. Undoubtedly, good conformity is one necessary precondition for dose sparing in normal tissue and OARs.

Another aspect is the maximum dose and dose inhomogeneity within the PTV. In the comparative study by Weber et al., the range was 109.0 to 130.0% for photon beam therapy and 101.0 to 115.0% for PBT [24]. Our maximum dose values with HA never exceeded 105.1% of the prescribed tumour dose. Expressed with values of IC, our median value 0.12 is closer to the optimum of 0.00 than any previously reported value for any photon beam technique.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Wösle, M., Krause, L., Sreenivasa, S. et al. Stereotactic radiotherapy for choroidal melanomas by means of HybridArc™. Strahlenther Onkol 194, 929–943 (2018). https://doi.org/10.1007/s00066-018-1349-4

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00066-018-1349-4

Keywords

Schlüsselwörter

Search

Navigation