Comparison of dose calculations between pencil-beam and Monte Carlo algorithms of the iPlan RT in arc therapy using a homogenous phantom with 3DVH software

Radiation Oncology

Seok Hyun Son¹  Soo-Min Chae³  Chul Seung Kay¹  Hun-Joo Shin¹  Jin Ho Song² 

[1] Department of Radiation Oncology, Incheon St. Mary’s hospital, College of Medicine, The Catholic University of Korea, Incheon, Korea;Department of Radiation Oncology, Seoul St. Mary’s hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea;Department of Radiation Oncology, Cheju Halla General Hospital, Jeju, Korea

关键词: Pencil-beam;    Monte Carlo;    3DVH;    Arc therapy;   

Others  :  829511
DOI  :  10.1186/1748-717X-8-284

 received in 2013-04-23, accepted in 2013-11-24,  发布年份 2013

【 摘 要 】

Background

To create an arc therapy plan, certain current general calculation algorithms such as pencil-beam calculation (PBC) are based on discretizing the continuous arc into multiple fields to simulate an arc. The iPlan RT™ treatment planning system incorporates not only a PBC algorithm, but also a more recent Monte Carlo calculation (MCC) algorithm that does not need beam discretization. The objective of this study is to evaluate the dose differences in a homogenous phantom between PBC and MCC by using a three-dimensional (3D) diode array detector (ArcCHECK™) and 3DVH software.

Methods

A cylindrically shaped ‘target’ region of interest (ROI) and a ‘periphery ROI’ surrounding the target were designed. An arc therapy plan was created to deliver 600 cGy to the target within a 350° rotation angle, calculated using the PBC and MCC algorithms. The radiation doses were measured by the ArcCHECK, and reproduced by the 3DVH software. Through this process, we could compare the accuracy of both algorithms with regard to the 3D gamma passing rate (for the entire area and for each ROI).

Results

Comparing the PBC and MCC planned dose distributions directly, the 3D gamma passing rates for the entire area were 97.7% with the gamma 3%/3 mm criterion. Comparing the planned dose to the measured dose, the 3D gamma passing rates were 98.8% under the PBC algorithm and 100% under the MCC algorithm. The difference was statistically significant (p = 0.034). Furthermore the gamma passing rate decreases 7.5% in the PBC when using the 2%/2 mm criterion compared to only a 0.4% decrease under the MCC. Each ROI as well as the entire area showed statistically significant higher gamma passing rates under the MCC algorithm. The failure points that did not satisfy the gamma criteria showed a regular pattern repeated every 10°.

Conclusions

MCC showed better accuracy than the PBC of the iPlan RT in calculating the dose distribution in arc therapy, which was validated with the ArcCHECK and the 3DVH software. This may suggest that the arc step of 10° is too large in the PBC algorithm in the iPlan RT.

【 授权许可】

   
2013 Song et al.; licensee BioMed Central Ltd.

【 图 表 】

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【 参考文献 】

• [1]Feygelman V, Zhang G, Stevens C, Nelms BE: Evaluation of a new VMAT QA device, or the “X” and “O” array geometries. J Appl Clin Med Phys 2011, 12:3346.
• [2]Shepard DM, Cao D, Afghan MK, Earl MA: An arc-sequencing algorithm for intensity modulated arc therapy. Med Phys 2007, 34:464-470.
• [3]Yu CX, Tang G: Intensity-modulated arc therapy: principles, technologies and clinical implementation. Phys Med Biol 2011, 56:R31-R54.
• [4]Morales-Paliza MA, Coffey CW, Ding GX: Evaluation of the dynamic conformal arc therapy in comparison to intensity-modulated radiation therapy in prostate, brain, head-and-neck and spine tumors. J Appl Clin Med Phys 2011, 12:3197.
• [5]Chow JC, Wong E, Chen JZ, Van Dyk J: Comparison of dose calculation algorithms with Monte Carlo methods for photon arcs. Med Phys 2003, 30:2686-2694.
• [6]Petoukhova AL, van Wingerden K, Wiggenraad RG, van de Vaart PJ, van Egmond J, Franken EM, van Santvoort JP: Verification measurements and clinical evaluation of the iPlan RT Monte Carlo dose algorithm for 6 MV photon energy. Phys Med Biol 2010, 55:4601-4614.
• [7]Garnica-Garza HM: A monte carlo comparison of three different media for contrast enhanced radiotherapy of the prostate. Technol Cancer Res Treat 2010, 9:271-278.
• [8]Krieger T, Sauer OA: Monte Carlo- versus pencil-beam-/collapsed-cone-dose calculation in a heterogeneous multi-layer phantom. Phys Med Biol 2005, 50:859-868.
• [9]Petoukhova AL, van Egmond J, Eenink MG, Wiggenraad RG, van Santvoort JP: The ArcCHECK diode array for dosimetric verification of HybridArc. Phys Med Biol 2011, 56:5411-5428.
• [10]Fragoso M, Wen N, Kumar S, Liu D, Ryu S, Movsas B, Munther A, Chetty IJ: Dosimetric verification and clinical evaluation of a new commercially available Monte Carlo-based dose algorithm for application in stereotactic body radiation therapy (SBRT) treatment planning. Phys Med Biol 2010, 55:4445-4464.
• [11]Li G, Zhang Y, Jiang X, Bai S, Peng G, Wu K, Jiang Q: Evaluation of the ArcCHECK QA system for IMRT and VMAT verification. Phys Med 2013, 29:295-303.
• [12]Neilson C, Klein M, Barnett R, Yartsev S: Delivery quality assurance with ArcCHECK. Med Dosim 2013, 38:77-80.
• [13]Bedford JL, Lee YK, Wai P, South CP, Warrington AP: Evaluation of the Delta4 phantom for IMRT and VMAT verification. Phys Med Biol 2009, 54:N167-N176.
• [14]Yan G, Lu B, Kozelka J, Liu C, Li JG: Calibration of a novel four-dimensional diode array. Med Phys 2010, 37:108-115.
• [15]Low DA, Harms WB, Mutic S, Purdy JA: A technique for the quantitative evaluation of dose distributions. Med Phys 1998, 25:656-661.
• [16]Ezzell GA, Burmeister JW, Dogan N, LoSasso TJ, Mechalakos JG, Mihailidis D, Molineu A, Palta JR, Ramsey CR, Salter BJ, et al.: IMRT commissioning: multiple institution planning and dosimetry comparisons, a report from AAPM Task Group 119. Med Phys 2009, 36:5359-5373.
• [17]Nelms BE, Opp D, Robinson J, Wolf TK, Zhang G, Moros E, Feygelman V: VMAT QA: measurement-guided 4D dose reconstruction on a patient. Med Phys 2012, 39:4228-4238.
• [18]Olch AJ: Evaluation of the accuracy of 3DVH software estimates of dose to virtual ion chamber and film in composite IMRT QA. Med Phys 2012, 39:81-86.
• [19]Fippel M: Fast Monte Carlo dose calculation for photon beams based on the VMC electron algorithm. Med Phys 1999, 26:1466-1475.
• [20]Kawrakow I, Fippel M, Friedrich K: 3D electron dose calculation using a Voxel based Monte Carlo algorithm (VMC). Med Phys 1996, 23:445-457.
• [21]Carrasco P, Jornet N, Latorre A, Eudaldo T, Ruiz A, Ribas M: 3D DVH-based metric analysis versus per-beam planar analysis in IMRT pretreatment verification. Med Phys 2012, 39:5040-5049.
• [22]Zhen H, Nelms BE, Tome WA: Moving from gamma passing rates to patient DVH-based QA metrics in pretreatment dose QA. Med Phys 2011, 38:5477-5489.
• [23]Shepard DM, Olivera G, Angelos L, Sauer O, Reckwerdt P, Mackie TR: A simple model for examining issues in radiotherapy optimization. Med Phys 1999, 26:1212-1221.
• [24]Kozelka J, Robinson J, Nelms B, Zhang G, Savitskij D, Feygelman V: Optimizing the accuracy of a helical diode array dosimeter: a comprehensive calibration methodology coupled with a novel virtual inclinometer. Med Phys 2011, 38:5021-5032.
• [25]Jabbari K: Review of fast monte carlo codes for dose calculation in radiation therapy treatment planning. J Med Signals Sens 2011, 1:73-86.
• [26]Fippel M, Haryanto F, Dohm O, Nusslin F, Kriesen S: A virtual photon energy fluence model for Monte Carlo dose calculation. Med Phys 2003, 30:301-311.
• [27]Fippel M: Efficient particle transport simulation through beam modulating devices for Monte Carlo treatment planning. Med Phys 2004, 31:1235-1242.
• [28]Tudor GS, Thomas SJ: Impact of the fixed gantry angle approximation on dosimetric accuracy for helical tomotherapy plans. Med Phys 2013, 40:011711.
• [29]Stasi M, Bresciani S, Miranti A, Maggio A, Sapino V, Gabriele P: Pretreatment patient-specific IMRT quality assurance: a correlation study between gamma index and patient clinical dose volume histogram. Med Phys 2012, 39:7626-7634.