In contrast, plaque brachytherapy places the source on the sclera beneath (adjacent to) the tumor. Thus, in the treatment of posterior choroidal melanomas, radiation must travel through the sclera before entering the tumor and through the eye before exiting through normal anterior ocular tissues (26). Primarily because of dose gradient and side-scatter effects, plaque brachytherapy delivers
comparatively more radiation to subjacent sclera and adjacent ocular structures (13). The ABS-OOTF recognizes (Level 1 Consensus) that in the treatment of posterior uveal melanomas, there is less resultant radiobiologic effect on normal anterior ocular structures using low-energy (103Pd, 125I) plaque brachytherapy compared with proton beam. This relative dose sparing may explain why clinical studies have Selleck INCB024360 revealed more anterior segment complications and secondary enucleations Natural Product Library after charged particle therapy , , , , ,  and . External beam radiation techniques (proton, helium ion, gamma knife, and stereotactic radiosurgery) are also complicated
by mobile target volume (eye movement). Since eye plaques are sewn to the eye wall beneath their target volume, when the eye moves so does the plaque. In contrast, when a target volume is externally created to extend within the eye (all EBRT techniques), mobility of the eye makes intraocular dose deposition less predictable. This is why during proton therapy, eye movements must be constantly monitored and the patient reminded (as needed) to fixate on a reference target. This is because eye movements cause misapplication of protons within the eye. In addition, should larger tumor-free safety margins become necessary, more normal tissues (anterior and posterior) fall within the cylindrical target volume. In addition, proton beam facilities are vastly more expensive (Table 4)  and . The ABS-OOTF survey indicates that proton beam has been used as an alternative to enucleation for tumors considered unsuitable for brachytherapy. This Oxymatrine includes tumors
that touch or surround the optic disc, for very large tumors and where 125I and 103Pd plaques are not available. In addition, a novel strategy tries to prevent secondary inflammation; “vitritis” or “toxic tumor syndrome” has been described after brachytherapy for large choroidal melanoma. Here, large uveal melanomas are first treated with proton beam and then removed by internal resection (102). There are only a few centers using this technique (ABS-OOTF Level 3 Consensus). Reporting the results of treatment is particularly challenging. Consider that when multiple centers use the same radionuclides source, they often differ in plaque construction, dosimetry, doses, and dose rate. Furthermore, until acceptance of the AJCC staging system, there existed no universal method to report the size of uveal melanomas.