The purpose
of this study is to investigate the potential use of Ir-192 as the source for
real time imaging during HDR (High Dose Rate) brachytherapy treatment. Phantom
measurement was performed to determine outside of the body dose. Monte Carlo
code, EGSnrcMP egs_inprz, was used for the simulation to calculate the outside
of the body x-ray signal for CT reconstruction. Matlab code was developed to
reconstruct the Ir-192 source and for 3D visualization in order to assess
reconstructed CT resolution, signal-to-noise ratio, and imaging dose
information. The measured dose was 0.67 ± 0.04 cGy, which was comparable to the
Monte Carlo simulation result 0.71 ± 0.20 cGy. The reconstructed source
diameter dimension was 1.3 mm compared with 1.1 mm for the real source dimension.
The signal-to-noise ratio was 19.91 db following de-noising. Source position
was within a 1 mm difference between programmed and simulated results. Although
the Ir-192 signal is weak for CT imaging, it is possible to use it as a CT
imaging x-ray source for HDR treatment localization, verification and dosimetry
purposes. Further study is needed for the detailed design of an outside of the
body CT-like device for use in brachytherapy imaging.
References
[1]
Ebert, M.A. (2002) Possibilities for Intensity-Modulated Brachytherapy: Technical Limitations on the Use of Non-Isotropic Sources. Physics in Medicine and Biology, 47, 2495-509. https://doi.org/10.1088/0031-9155/47/14/309
[2]
Hiatt, J., Hepel, J., Carol, M., Cardarelli, G., Wazer, D. and Sternick, E. (2008) Physical Principles of Intensity Modulated Electronic Brachytherapy (IMEB). Medical Physics, 35, 2732. https://doi.org/10.1118/1.2961778
[3]
Hiatt, J., Segala, J., Gardarelli, G. and Sternick, E. (2009) The Utility of Depth Dose Modulation (DDM) for Electronic Brachytherapy. Medical Physics, 36, 2423. https://doi.org/10.1118/1.3181075
[4]
Shi, C.Y., Guo, B.Q., Cheng, C.Y., Esquivel, C., Eng, T. and Papanikolaou, N. (2010) Three Dimensional Intensity Modulated Brachytherapy (IMBT): Dosimetry Algorithm and Inverse Treatment Planning. Medical Physics, 37, 3725-3737. https://doi.org/10.1118/1.3456598
[5]
Liu, Y., Flynn, R.T., Kim, Y., Yang, W. and Wu, X. (2013) Dynamic Rotating-Shield Brachytherapy. Medical Physics, 40, Article ID: 121703. https://doi.org/10.1118/1.4828778
[6]
Liu, Y., Flynn, R.T., Yang, W., Kim, Y., Bhatia, S.K., Sun, W. and Wu, X. (2013) Rapid Emission Angle Selection for Rotating-Shield Brachytherapy. Medical Physics, 40, Article ID: 051720. https://doi.org/10.1118/1.4802750
[7]
Liu, Y., Flynn, R.T., Kim, Y. and Wu, X. (2014) Asymmetric Dose-Volume Optimization with Smoothness Control for Rotating-Shield Brachytherapy. Medical Physics, 41, Article ID: 111709. https://doi.org/10.1118/1.4897617
[8]
Liu, Y., Flynn, R.T., Kim, Y., Dadkhah, H., Bhatia, S.K., Buatti, J.M., Xu, W. and Wu, X. (2015) Paddle-Based Rotating-Shield Brachytherapy. Medical Physics, 42, 5992-6003. https://doi.org/10.1118/1.4930807
[9]
Adams, Q.E., Xu, J., Breitbach, E.K., Li, X., Enger, S.A., Rochey, W.R., Kim, Y., Wu, X. and Flynn, R.T. (2014) Interstitial Rotating Shield Brachytherapy for Prostate Cancer. Medical Physics, 41, Article ID: 051703. https://doi.org/10.1118/1.4870441
[10]
Dadkhah, H., Kim, Y., Wu, X. and Flynn, R.T. (2015) Multihelix Rotating Shield Brachytherapy for Cervical Cancer. Medical Physics, 42, 6579-6588. https://doi.org/10.1118/1.4933244
[11]
Tanderup, K., Hellebust, T.P., Lang, S., Granfeldt, J., Potter, R., Lindegaard, J.C. and Kirisits, C. (2008) Consequences of Random and Systematic Reconstruction Uncertainties in 3D Image Based Brachytherapy in Cervical Cancer. Radiotherapy and Oncology, 89, 156-163. https://doi.org/10.1016/j.radonc.2008.06.010
[12]
Schindel, J., Zhang, W., Bhatia, S.K., Sun, W. and Kim, Y. (2013) Dosimetric Impacts of Applicator Displacements and Applicator Reconstruction-Uncertainties on 3D Image-Guided Brachytherapy for Cervical Cancer. Journal of Contemporary Brachytherapy, 5, 250-257. https://doi.org/10.5114/jcb.2013.39453
[13]
Thomadsen, B.R., Erickson, B.A., Eifel, P.J., Hsu, I.C., Patel, R.R., Petereit, G.D., Fraass, B.A. and Rivard, M.J. (2014) A Review of Safety, Quality Management and Practice Guidelines for High-Dose-Rate Brachytherapy: Executive Summary. Practical Radiation Oncology 4, 65-70. https://doi.org/10.1016/j.prro.2013.12.005
[14]
Xia, J., Waldron, T. and Kim, Y. (2014) A Real-Time Applicator Position Monitoring System for Gynecologic Intracavitary Brachytherapy. Medical Physics, 41, Article ID: 011703. https://doi.org/10.1118/1.4842555
[15]
Petasecca, M., Loo, K.J., Safavi-Naeini, M., Han, Z., Metcalfe, P.E., Meikle, S., Pospisil, S., Jakubek, J., Bucci, J.A., Zaider, M., Lerch, M.L.F., Qi, Y. and Rosenfeld, A.B. (2013) BrachyView: Proof-of-Principle of a Novel In-Body Gamma Camera for Low Dose-Rate Prostate Brachytherapy. Medical Physics, 40, Article ID: 041709. https://doi.org/10.1118/1.4794487
[16]
Safavi-Naeini, M., Han, Z., Cutajar, D., Guatelli, S., Petasecca, M., Lerch, M.L.F., Franklin, D.R., Jakubek, J., Pospisil, S., Bucci, J., Zaider, M. and Rosenfeld, A.B. (2013) BrachyView, A Novel Inbody Imaging System for HDR Prostate Brachytherapy: Design and Monte Carlo Feasibility Study. Medical Physics, 40, Article ID: 071715. https://doi.org/10.1118/1.4808360
[17]
Safavi-Naeini, M., Han, Z., Alnaghy, S., Cutajar, D., Petasecca, M., Lerch, M.L.F., Franklin, D.R., Bucci, J., Carrara, M., Zaider, M. and Rosenfeld, A.B. (2015) BrachyView, A Novel Inbody Imaging System for HDR Prostate Brachytherapy: Experimental Evaluation. Medical Physics, 42, 7098. https://doi.org/10.1118/1.4935866
[18]
Mowlavi, A.A., Cupardo, F. and Severgnini, M. (2008) Monte Carlo and Experimental Relative Dose Determination for an Iridium-192 Source in Water Phantom. International Journal of Radiation Research, 6, 37-42. http://ijrr.com/article-1-377-en.html
[19]
Duan, J., Macey, D.J., Pareek, P.N. and Brezovich, I.A. (2001) Real-Time Monitoring and Verification of in Vivo High Dose Rate Brachytherapy Using a Pinhole Camera. Medical Physics, 28, 167-173. https://doi.org/10.1118/1.1339882
