IJMPCERO  Vol.2 No.2 , May 2013
Calculation of Dose in Healthy Organs, during Radiotherapy 4-Field Box 3D Conformal for Prostate Cancer, Simulation of the Linac 2300, Radiotherapy Room and MAX Phantom

In men, prostate cancer is one of the most frequent types, and radiotherapy is adopted as a form of treatment. Although there are efforts to minimize the dose in the healthy organ and tissues adjacent to the tumor during radiotherapy, these organs are affected by the secondary scattered and leakage radiation originating from the therapeutic beam and these doses deposited in the healthy organs, can induce the appearance of new focal points of cancer. The aim of this study is to calculate the equivalent and effective doses, due to photons and neutrons, in healthy organs of a patient submitted to radiotherapy treatment for prostate cancer. Computed simulation of radiotherapy treatment for prostate cancer was used to perform the dose calculations, adopting the treatment protocol used at INCA (Brazilian National Cancer Institute). The MCNPX code was employed in the simulation radiation transport while the male voxel MAX phantom was used to represent the patient's human anatomy. The results obtained in this study indicate that the organs close to the irradiated region are predominantly affected by the dose due to photons, with an impact on organs from different systems of the body, such as the bladder, colon, and testicles, besides bone structures such as the femur, pelvis and spinal column. The results obtained from the doses deposited due to neutrons suggest that tibia and fibula, mandible, cranium, brain and thyroid, had the highest dose deposited due to neutrons in relation to photons. The result obtained from the effective dose was 31.47 mSv due to photons, while the dose due to neutrons was 0.42 mSv. Note that the effective dose due to photons is significantly higher than the effective dose due to neutrons. The values calculated in this study were compared with the experimental values obtained in the literature, presenting reasonable concordance. Additionally, as described in the literature, it was verified that the dose due to photons decreases considerably with the increase in the distance of the target organ, while the dose due to neutrons is distributed homogeneously in the organs. It is concluded that the contribution of neutrons to the appearance of secondary cancers is more relevant in the organs furthest from the target volume, and that organs close to the tumor, are affected predominantly by the dose due to photons.

Cite this paper: J. Thalhofer, W. Rebello, S. Correa, A. Silva, E. Souza and D. Batista, "Calculation of Dose in Healthy Organs, during Radiotherapy 4-Field Box 3D Conformal for Prostate Cancer, Simulation of the Linac 2300, Radiotherapy Room and MAX Phantom," International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, Vol. 2 No. 2, 2013, pp. 61-68. doi: 10.4236/ijmpcero.2013.22009.

[1]   World Health Organization, 2013.

[2]   “Instituto Nacional de Cancer Section of prostate cancer: Estimativa de incidência de Cancer no Brasil,” 2012.

[3]   J. Fontenot, P. Taddei, Y. Zheng, D. Mirkovic, T. Jordan and W. Newhauser, “Equivalent Dose and Effective Dose from Stray Radiation during Passively Scattered Proton Radiotherapy for Prostate Cancer,” Physics in Medicine and Biology, Vol. 53, No. 6, 2008, pp. 1677-1688. doi:10.1088/0031-9155/53/6/012

[4]   Y. Tao, D. Lefkopoulos, D. Ibrahima, A. Bridier, M. P. Polizzi, P. Wibault, R. Crevoisier, R. Arriagada and J. Bourhis, “Comparison of Dose Contribution to Normal Pelvic Tissues among Conventional, Conformal and Intensity-Modulated Radiotherapy Techniques in Prostate Cancer,” Acta Oncologica, Vol. 47, No. 3, 2008, pp. 442-450. doi:10.1080/02841860701666055

[5]   X. G. Xu, B. Bednarz and H. Paganetti, “A review of dosimetry studies on external-beam radiation treatment with respect to second cancer induction,” Physics in Medicine and Biology, Vol. 53 No. 13, 2008, pp. 193-241. doi:10.1088/0031-9155/53/13/R01

[6]   B. Bednarz and G. X. Xu, “Monte Carlo Modeling of a 6 and 18 MV Varian Clinac Medical Accelerator for In-Field and Out-of-Field Dose Calculations: Development and Validation,” Physics in Medicine and Biology, Vol. 54, No. 4, 2009, pp. 43-57.

[7]   D. J. Brenner, R. E. Curtis, E. J. Hall and E. Ron, “Second Malignancies in Prostate Carcinoma Patients after Radiotherapy Compared with Surgery Cancer,” Cancer, Vol. 88, No. 2, 2000, pp. 398-406.

[8]   M. W. Skwarchuk, A. Jackson, M. J. Zelefsky, E. S. Venkatraman, D. M. Cowen, S. Levegrün, C. M. Burman, Z. Fuks, S. A. Leibel and C. C. Ling, “Late Rectal Toxicity after Conformal Radiotherapy of Prostate Cancer (I): Multivariate Analysis and Dose-Response,” International Journal of Radiation Oncology, Biology, Physics, Vol. 47, No. 1, 2000, pp. 103-113. doi:10.1016/S0360-3016(99)00560-X

[9]   S. L. Tucker, R. Cheung, L. Dong, H. H. Liu, H. D. Thames, E. H. Huang, D. Kuban and R. Mohan, “Dose-Volume Response Analyses of Late Rectal Bleeding after Radiotherapy for Prostate Cancer,” International Journal of Radiation Oncology, Biology, Physics, Vol. 59, No. 2, 2004, pp. 353-365. doi:10.1016/j.ijrobp.2003.12.033

[10]   K. Moon, G. J. Stukenborg, J. Keim and D. Theodorescu, “Cancer Incidence after Localized Therapy for Prostate Cancer,” Cancer, Vol. 107, No. 5, 2006, pp. 991-998. doi:10.1002/cncr.22083

[11]   N. Baxter, J. E. Tepper, S. B. Durham, D. A. Rothenberger and B. A. Virnig, “Increased Risk of Rectal Cancer after Prostate Radiation: A Population-Based Study,” Gastroenterology, Vol. 128, No. 4, 2005, pp. 819-824. doi:10.1053/j.gastro.2004.12.038

[12]   R. Kramer, J. W. Vieira, H. J. Khoury, F. R. A. Lima and D. Fuelle, “All about MAX: A Male Adult Voxel Phantom for Monte Carlo Calculations in Radiation Protection Dosimetry,” Physics in Medicine and Biology, Vol. 48, No. 10, 2003, pp. 1239-1262. doi:10.1088/0031-9155/48/10/301

[13]   R. Jeraj, P. Keall and P. Ostwald, “Comparison between MCNP, EGS4, and Experiment for Clinical Electron Beams,” Physics in Medicine and Biology, Vol. 44, No. 3, 1999, pp. 705-717. doi:10.1088/0031-9155/44/3/013

[14]   D. B. Pelowitz, “MCNPXTM User’s Manual,” Version 2.5.0., Los Alamos National Laboratory Report 2005, LA-CP-05-0369.

[15]   A. M. Larcher, S. M. BonetDurán and A. M. Lerner, “Dosis Ocupacional Debida a Neutrons en Aceleradores Lineales de uso Medico,” Autoridad Regulatoria Nuclear Buenos Aires, 2000.

[16]   A. Facure, A. X. Silva and R. C. Falcao, “Monte Carlo Simulation of Scattered and Thermal Photoneutron fluences inside a Radiotherapy Room. Radiation Protection Dosimetry, Vol. 123, No. 1, 2007, pp. 56-61. doi:10.1093/rpd/ncl080

[17]   W. F. Rebello, A. X. Silva and A. Facure, “Multileaf Shielding Design against Neutrons Produced by Medical Linear Accelerators,” Radiation Protection Dosimetry, 2008, Vol. 128, No. 2, pp. 227-233. doi:10.1093/rpd/ncm312

[18]   A. J. Giordani, R. S. Dias, H. R. C. Segreto and R. A. Segreto, “Acurácia na Reprodutibilidade do Posicionamento diáRio de Pacientes Submetidos a Radioterapia Conformada (RT3D) para Cancer de próStata,” Radiologia Brasileira, Vol. 43, No. 4, 2010, pp. 236-240. doi:10.1590/S0100-39842010000400007

[19]   S. C. A. Correa, E. M. Souza, A. X. Silva, H. Yoriyaz and R. T. Lopes, “AP and PA Thorax Radiographs: Dose Evaluation Using the FAX Phantom. International Journal of Low Radiation, Vol. 5, No. 3, 2008, pp. 237-255. doi:10.1504/IJLR.2008.020253

[20]   S. C. A. Correa, E. M. Souza, A. X. Silva, H. Yoriyaz and R. T. Lopes, “Dose and Risk Evaluation in Thoracic Radiology Using Male and Female Voxels Phantom,” International Journal of Low Radiation, Vol. 7, No. 2, 2010, pp. 81-97. doi:10.1504/IJLR.2010.032812

[21]   S. C. A. Correa, J. O. Aquino, E. M. Souza and A. X. Silva, “Evaluation of the Dose and the Risk of Cancer Induction Associated with the Use of Transmission X-Ray Body Scanners Using the Monte Carlo MCNPX code,” International Journal of Low Radiation, Vol. 8, No. 5-6, 2011, pp. 340-354. doi:10.1504/IJLR.2011.047180

[22]   International Commission on Radiological Protection, “The 2007 Recommendations of the International Commission on Radiological Protection,” Annals of the ICRP, 2007.

[23]   R. M. Howell, N. E. Hertel, Z. Wang, J. Hutchinson and G. Fullerton, “Calculation of Effective Dose from Measurements of Secondary Neutron Spectra and Scattered Photon Dose from Dynamic MLC IMRT for 6 MV, 15 MV, and 18 MV Beam Energies,” Medical Physics, Vol. 33, No. 2, 2006, pp. 360-368. doi:10.1118/1.2140119