Clinical Comparison of Pencil Beam Convolution and Clarkson Algorithms for Dose Calculation

Abdulhamid Chaikh, Jean-Yves Giraud, Jacques Balosso

Joseph Fourier University, Grenoble, France.

DOI: 10.4236/jct.2013.410179                

Abstract

Purpose: The purpose of this work is to study and quantify the differences in calculated dose computed with two algorithms available in treatment planning systems: Pencil Beam Convolution and Clarkson. Material and Methods: Four different types of treatment cases were analyzed: lung, head and neck, brain and prostate. For each case, the volume definition was based on a clinical CT-scan acquisition. The patients were treated with 3-dimensional radiation therapy. For each patient, 2 treatment plans were generated using exactly the same configuration of beams. In plan 1 and plan 2, the dose was calculated using the Clarkson and Pencil Beam Convolution algorithms, respectively, without heterogeneity correction. To evaluate the treatment plans, the monitor units, isodose curves, dose volume histograms and quality index were compared. A statistical analysis was carried out using Wilcoxon signed rank test. Results: The difference observed for monitor unites was 1.2% for lung and less than 1% for head and neck, brain and prostate. Wilcoxon test showed that there was “no statically significant difference, (p > 0.05)”. The dosimetric parameters derived from dose volume histograms were higher for organs at risks using Clarkson compared to Pencil Beam Convolution algorithm inviting clinician to make “safer” prescriptions. For quality index there was no statistically significant difference between both algorithms for all quality indexes, (p > 0.05). Conclusion: The clinical evaluation of a treatment plan should be made regarding the calculation algorithm which, in turn, is linked to the experience of the clinician.

Keywords

Treatment Planning; Dose Distribution; Isodose; Monitor Unit; PBC; Clarkson

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Report of the Coordinated Research Project (CRP) on Development of Procedures for Quality Assurance of Dosimetry Calculations in Radiotherapy. Commissioning of Radiotherapy Treatment Planning Systems: Testing for Typical External Beam Treatment Techniques. IAEATECDOC-1583, 2008.
[2]	A. M. Morgan, T. Knoos, S. G. McNee, C. J. Evans and D. I. Thwaites, “Clinical Implications of the Implementation of Advanced Treatment Planning Algorithms for Thoracic Treatments,” Radiotherapy and Oncology, Vol. 86, No. 1, 2008, pp. 48-54. http://dx.doi.org/10.1016/j.radonc.2007.11.033
[3]	P. Lombardi, C. Fiorino, G. M. Cattaneo and R. Calandrino, “Monitor Unit Calculation in 6MV Irregularly Shaped Beam Accuracy in Clinical Practice,” The British Journal of Radiology, Vol. 70, 1977, pp. 638-644.
[4]	B. Fraass, K. Doppke, M. Hunt, G. Kutcher, G. Starkschall, R. Stern and J. Van Dyke, “AAPM Radiation Therapy Committee Task Group 53: Quality Assurance for Clinical Radiotherapy Treatment Planning,” Medical Physics, Vol. 25, No. 10, 1998, pp. 1773-1829. http://dx.doi.org/10.1118/1.598373
[5]	J. Chan, D. Russell, V. G. Peters and T. J. Farrell, “Comparison of Monitor Unit Calculations Performed with a 3D Computerized Planning System and Independent ‘‘Hand’’ Calculations: Results of Three Years Clinical Experience,” Journal of Applied Clinical Medical Physics, Vol. 3, No. 4, 2002, pp. 293-301. http://dx.doi.org/10.1120/1.1506379
[6]	International Commission on Radiation Units and Measurements, “ICRU Report No. 50: Prescribing, Recording and Reporting Photon Beam Therapy,” Bethesda, 1993.
[7]	International Commission on Radiation Units and Measurements, “ICRU Report No. 62: Prescribing, Recording and Reporting Photon Beam Therapy Supplement to ICRU Report 50,” Bethesda, 1999.
[8]	E. B. Bengt, R. Harunor and H. O. Ceferino, “Separation of Primary and Scatter Components of Measured Photon Beam Data,” Physics in Medicine and Biology, Vol. 34, No. 12, 1989, pp. 1939-1945. http://dx.doi.org/10.1088/0031-9155/34/12/017
[9]	A. Ahnesjo and M. M. Aspradakis, “Dose Calculations for External Photon Beams in Radiotherapy,” Physics in Medicine and Biology, Vol. 44, No. 11, 1999, pp. 99-155. http://dx.doi.org/10.1088/0031-9155/44/11/201
[10]	L. Feuvret, G. Noel, C. Nauraye, P. Garcia and J. J. Mazeron, “Conformal Index and Radiotherapy,” Cancer/Radiothérapie, Vol. 8, No. 2, 2004, pp. 108-119. http://dx.doi.org/10.1016/j.canrad.2003. 12.002
[11]	N. J. Lomax and S. G. Scheib, “Quantifying the Degree of Conformity in Radiosurgery Treatment Planning,” International Journal of Radiation Oncology, Biology, Physics, Vol. 55, No. 5, 2003, pp. 1409-1419. http://dx.doi.org/10.1016/S0360-3016(02)04599-6
[12]	I. Martel-Lafay “Best Practice Guide for Radiation Therapy of Non-Small Cell Bronchial Cancers,” Cancer/Radiothérapie, Vol. 13, No. 1, 2009, pp. 55-60.
[13]	L. Nadine, V. Dirk, V. A. Swana, V. Mia, B. Anette and S. Guy, “Evaluation of Dose Calculation Algorithms for Dynamic Arc Treatments of Head and Neck Tumors,” Radiotherapy and Oncology, Vol. 64, No. 1, 2002, pp. 85-95. http://dx.doi.org/10.1016/S0167-8140(02)00146-9