Dose distribution assessment in human eye proton therapy by Monte Carlo method 1 Department of Physics, Faculty of Science, University of Isfahan, Isfahan, Iran. 2* Department of Biomedical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, Iran M. Tavakol 1, A. Karimian 2*, S.M. Mostajab Aldaavati 1 10/10/20151

10/10/20152 Eye and its anatomic structure

Eye TumorsEye Tumors  Tumors in the eye usually are secondary tumors caused by cancers that have spread from other parts of the body, especially the breast, lung, bowel or prostate.  Two types of primary tumors arise within the eye itself and are known as retinoblastoma in children and melanoma in adults 10/10/

Retinoblastoma  Retinoblastoma is a cancer of the retina. This most common childhood eye cancer usually strikes children under age five, affecting 500 to 600 in the United States each year. In nearly a third of the cases, retinoblastoma occurs in both eyes. 10/10/

melanoma  Malignant melanoma occurs most frequently in adults 60 to 65 years of age, arising from uncontrolled growth of cells called melanocytes. From 1,500 to 2,000 new cases are diagnosed annually in the United States 10/10/20155

Eye tumors affectsEye tumors affects  In addition to damaging vision, eye tumors can spread to the optic nerve, the brain and the rest of the body.  Melanoma tends to spread via blood vessels to distant organs  Therefore, early diagnosis and treatment are extremely important. 10/10/20156

Eye tumor treatment methodsEye tumor treatment methods  There are various ways to treat eye tumors, depending on the size and aggressiveness of the tumor, and other factors.  Surgery, Radiation Therapy, laser and cryosurgery may use for eye tumor treatment 10/10/20157

Radiation therapy Internal radiation therapy Proton therapy 10/10/2015 Tele-therapy (LINAC, …) plaque therapy Brachytherapy 8

Advantags of proton particles Noninvasive Small dimensions Focal Proton Particles Energetic but controlled Rather short-range Suitable Bragg Peak 10/10/20159

Individual mask Block-Bite [ Nozzle 10/10/201510

In spite of the advantages of proton therapy, during treatment, the tumor and also other components of vision like optic nerve, cornea, lens, anterior chamber are subjected to the radiation. Malignant melanomas appear most commonly in the choroid 10/10/201511

 In this research, one proton therapy system belonging to the Laboratori Nazionali del Sud- INFN as well as the human eye and its components were simulated by Monte Carlo method. Maximum proton energy beam = 250 MeV Proton beam radius = 0.5 cm Modifier thickness = 1.5 cm Number of particles per second = 1.25 E+10 In this research: Energy for eye = ( 50 – 65 ) MeV Proton beam radius = ( ) cm Modifier thickness = ( ) cm 10/10/201512

To assess the absorbed dose in different parts of eye, the proton therapy system, the nuzzle aperture, modifier, different parts of eye such as choroid and sclera, retina and etc, also vision sense parts such as optic nerve, cornea, lens and anterior chamber were simulated by Monte Carlo method. The eye was simulated by considering real materials and densities of eye components such as lens, cornea, retina, anterior chamber. 10/10/201513

Optic nerve Vitreous Lens Anterior chamber Cornea 10/10/201514

10/10/2015 Optic Nerve 15

10/10/ Treatment view of choroid and sclera cancer

 The study was done in the following two stages, by changing the thickness of modifier in the range of 1.0 – 1.9 cm : I. A tumor with the radius of 0.28 cm in choroid region (cell 23) II. A tumor with the radius of 0.26 cm in choroid region and close to optic nerve (cell 27) 10/10/201517

Radius tumor = 0.28 cm Volume tumor = cm /10/201518

23 cell No.23 Radius tumor = 0.28 cm Volume tumor = cm 3 proton energy beam = 53.5 MeV Modifier thickness = 1.5 cm proton beam radius = 0.8 cm 10/10/2015 Dose (Gy) Cell No 19

The calculated total dose (Gy) in this study for the tumor in the choroid and sclera regions (cell No.23) Cells /10/201520

Radius tumor = 0.26 cm Volume tumor = cm /10/201521

27 cell No.27 Radius tumor = 0.26 cm Volume tumor = cm 3 proton energy beam = 65 MeV modifier thickness = 1.5 cm proton beam radius = 0.5 cm Dose (Gy) Cell No 10/10/201522

The calculated total dose (Gy) in this study for the tumor in the choroid and sclera regions (cell No.27) Cells /10/201523

10/10/ This research showed in spite of the benefits of proton therapy in eye cancer treatment, the absorbed dose of healthy parts of eye specially the closed parts to the tumor are considerable and needs to reduce as much as possible. The absorbed dose depends on the energy of proton beam, modifier thickness, size and location of tumor, radiation angle, etc, Which can modify and improve by Monte Carlo method. proton energy beam modifier thickness proton beam radius Radius tumor Position tumor MeV 65cm 1.5cm 0.5cm 0.26Cell No.27 MeV 53.5cm 1.5cm 0.8cm 0.28Cell No.23 Conclusion

10/10/ Thank you