Output Measurements of Monte Carlo, Collapse Cone and Pencil Beam Algorithms in Homogeneous and Inhomogeneous Phantom

Abstract

Accuracy of small field measurements and calculation algorithms is critical for accurate calculation of dose distribution in Radiotherapy. In inhomogeneous and homogeneous phantoms, measurements (1x1, 2x2, 3x3, 4x4, 5x5cm² field sizes) were made with CC04 and CC01 Razor ion chambers using 6MV, 6MV-FFF, 10MV and 10MV-FFF energies. In the Monaco treatment planning system, dose distribution was calculated by Monte Carlo-Dose to Medium (MC-Dm), Monte Carlo-Dose to Water (MC-Dw), Collapse Cone (CC) and Pencil Beam (PB) algorithms and compared with measurements. The homogeneous phantom water equivalent was generated from RW3 solid phantoms, and the inhomogeneous phantom was created using a water-equivalent RW3 solid phantom and a lung equivalent balsa phantom. When both the homogeneous and inhomogeneous phantom measurements were evaluated with CC04 and CC01Razor ion chambers, results consistent with MC-Dm, MC-Dw, CC and PB were obtained. The greatest differences in both phantoms were obtained in 1x1cm² fields. When the results in the inhomogeneous phantom were compared with the results in the homogeneous phantom, the compliance ratio was observed to be better in the homogeneous phantom. The CC01 Razor ion chamber has a volume of 0.01cm³ and its central electrode is graphite. With the CC01 Razor ion chamber, reliable results were obtained. As the field size becomes smaller, the differences between measurements and calculations increase.

Keywords

• Inhomogeneity,Monte Carlo,CC01 Razor ion chamber

Monte Carlo, Collapse Cone ve Pencil Beam Algoritmalarının Homojen ve İnhomojen Fantomda Açık Alan Ölçümleri

Abstract

Radyoterapide doz dağılımının doğru hesaplanması için küçük alan ölçümleri ve hesaplama algoritmalarının doğruluğu kritik öneme sahiptir. İnhomojen ortamlarda küçük alan dozimetrisindeki belirsizlikler ve zorluklar daha da artmaktadır. Bu çalışmada inhomojen ve homojen fantomlarda 6MV, 6MV-FFF, 10MV ve 10MV-FFF enerjileri ile 1x1, 2x2, 3x3, 4x4, 5x5cm² alan boyutlarında CC04 ve CC01 Razor iyon odaları ile ölçümler alındı. Ölçümler ile Monaco tedavi planlama sisteminde Monte Carlo-Dose to Medium (MC-Dm), Monte Carlo-Dose to Water (MC-Dw), Collapse Cone (CC) ve Pencil Beam (PB) algoritmaları ile yapılan hesaplamalar karşılaştırıldı. Homojen fantom su eşdeğeri RW3 katı fantomlardan,  inhomojen fantom ise su eşdeğeri RW3 katı fantom ve akciğer eşdeğeri balsa fantom kullanılarak oluşturuldu. CC04 ve CC01 Razor iyon odaları ile hem homojen hem de inhomojen fantomda ölçümler değerlendirildiğinde, MC-Dm, MC-Dw, CC ve PB ile uyumlu sonuçlar elde edildi. Her iki fantomda da en büyük farklar 1x1cm² alanlarda olduğu görüldü. İnhomojen fantomdaki sonuçlar homojen fantomdaki sonuçlarla karşılaştırıldığında uyum oranının homojen fantomda daha iyi olduğu görüldü. CC01 Razor iyon odası 0.01cm³ hacme sahip ve merkezi elektrodu grafittir. Bu özellikleri ile CC01 Razor iyon odası ile yeterince güvenilir sonuçlar elde edilmiştir. Alan boyutu küçüldükçe ölçümler ve hesaplamalar arasındaki farklar artmaktadır.

Keywords

• İnhomojenite,Monte Carlo,CC01 Razor İyon Odası

References

1. Almond P. R., Biggs P. J., Coursey B. M., Hanson W. F., Huq M. S., Nath R., Rogers D. W. O., 1999. AAPM’s TG-51 Protocol for Clinical Reference Dosimetry of High Energy Photon and Electron Beams. Med. Phys. 26 (9).
2. Bruinvis I. A. D., Keus R. B., Lenglet W. J. M., Meijer G. J., Mijnheer B. J., 2005. NCS Report 15: Quality Assurance of 3-D Treatment Planning Sysytems for External Photon and Electron Beams. From https://radiationdosimetry.org/ncs/documents/ncs-15-3d-tps-for-external-photon-and-electron-beams
3. Chen H., Lohr F., Fritz P., Wenz F., Dobler B., Lorenz F., Muhlnickel W., 2010. Stereotactic, Single-Dose Irradiation Of Lung Tumors: A Comparison Of Absolute Dose And Dose Distribution Between Pencil Beam And Monte Carlo Algorithms Based On Actual Patient CT Scans. International Journal Of Radiation Oncology Biology Physics. 78 (3): 955-963.
4. Chetty I. J., Devpura S., Liu D., Chen D., Li H., Wen N. W., Kumar S., Fraser C., Siddiqui M. S., Ajlouni M., Movsas B., 2013. Correlationofdose Computed Using Different Algorithms With Local Control Following Stereotactic Ablative Radiotherapy (SABR)-Based Treatment Of Non-Small-Cell Lung Cancer. Radiother Oncol. 109:498–504.
5. Das I. J., Ding G. X., Ahnesjö A., 2008. Small Fields: Nonequilibrium Radiation Dosimetry. Med. Phys. 35 (1).
6. Das I. J., Cheng C. W., Ahnesjö A., Gibbons J., Li X. A., Lowenstein J., Mitra R. K., Simon W. E., Zhu T. C., 2008. Accelerator Beam Data Commissioning Equipmwnt and Procedures: Report of the TG-106 of Therapy Physics Committee of the AAPM. Med. Phys.35 (9).
7. Dobler B., Walter C., Knopf A., Fabri D., Loeschel R., Polednik M., Schneider F., Wenz F., Lohr F., 2006. Optimization Of Extracranial Stereotactic Radiation Therapy Of Small Lung Lesions Using Accurate Dose Calculation Algorithms. Radiat Oncol. 1:45.
8. Fraass B., Doopke K., Hunt M., Kutcher G., Strakschall G., Dyke J. V., 1998. American Association of Physicists in Medicine Radiation Therapy Committee Task Group 53: Quality Assurance for Clinical Radiotherapy Treatment Planning. Med. Phys. 25 (10).

9. IAEA, 2017. Dosimetry of Small Static Fields Used in External Beam Radiotherapy. IEAE Technical reports series, Report 483.,ISSN 0074–1914; no. 483.
10. IAEA, 2004. Commissioning and Quality Assurance Computerized Planning Systems for Radiation Treatment of Cancer. IEAE Technical reports series, Report 430ISSN 0074–1914; no 430.
11. ICRU, 2017. Journal of the International Commission on Radiation Units and Measurements. Report 91.14 (2): 1–160. from https://doi.org/10.1093/jicru/ndx017
12. Khan F. M., 2010. The Physics Of Radiation Therapy 3rd Edition. Lippincott Williams & Wilkins Company, USA.
13. Kim S. J., Kim S. K. & Kim D. H., 2015. Journal Of The Korean Physical Society. 67: 153.Https://Doi.Org/10.3938/Jkps.67.153
14. Latifi K., Oliver J., Baker R, Dilling T. J., Stevens C. W., Kim J., Yue B., Demarco M., Zhang G., G., Fevgelman V., 2014. Study Of 201 Nonsmall Cell Lung Cancer Patients Given Stereotactic Ablative Radiation Therapy Shows Local Control Dependence On Dose Calculation Algorithm. Int. J. Radiat. Oncol. Biol. Phys. 88:1108–13.
15. Lax I., Panettieri V., Wennberg B., Duch M. A., Näslund I., Baumann P., Gagliardi G., 2006. Dose Distributions In SBRT Of Lung Tumors: Comparison Between Two Different Treatment Planning Algorithms And Monte-Carlo Simulation Including Breathing Motions. Acta Oncologica. 45(7) :978-988.
16. Lu L., 2013. Dose Calculation Algorithms İn External Beam Photon Radiation Therapy. Int J Cancer Ther Oncol. 1:01025.
17. Ma C. M., Li J. S., Deng J., Fan J., 2008. Implementation Of Monte Carlo Dose Calculation For Cyberknife Treatment Planning. Journal of Physics. 102 (1).
18. Wilcox E. E., Daskalov G. M., 2008. Accuracy of Dose Measurements and Calculations Within and Beyond Heterogeneous Tissues For 6 MV Photon Fields Smaller Than 4 cm Produced by Cyberknife. Med Phys. 35: 2259-2266.