ABSTRACT
PURPOSE: To compare the numerous external radiotherapy (RT) techniques for the treatment of retinoblastoma, as well as an intensity-modulated RT (IMRT) technique. The latter was elaborated to evaluate the potential dose reduction in the surrounding tissue, as well as the potential avoidance of subdosage in the ora serrata retinae. METHODS AND MATERIALS: A 2-year-old patient with unilateral retinoblastoma underwent CT. With the aid of an ophthalmologist, the ocular structures were delimited, and 13 techniques described in published reports were reproduced on three-dimensional planning software and identified according to their authors. A technique with four noncoplanar fields using IMRT was also elaborated. These techniques were compared according to the dose to the ora serrata retinae, lens, orbit (volume that received a dose of >or=20 Gy), vitreous, optic nerve, lacrimal gland (volume that received a dose of >or=34 Gy), and cornea and according to their ease of reproducibility. RESULTS: The techniques that attained the therapeutic dose to the ora serrata retinae were the IMRT technique and the techniques of Haye, Cassady, Cormack, and al-Beteri. The Cormack technique had the lowest volume that received a dose of >or=20 Gy in the orbit, followed by the IMRT technique. The IMRT technique also achieved the lowest volume that received a dose of >or=34 Gy (14%) in the lacrimal gland. The Abramson/McCormick/Blach, Cassady, Reese, and Schipper techniques were the easiest to reproduce and the Chin the most complex. CONCLUSION: Retinoblastoma treatment with IMRT has an advantage over the other techniques, because it allows for the greatest reduction of dose to the orbit and lacrimal gland, while maintaining the therapeutic dose to the ora serrata retinae and vitreous.
Subject(s)
Retinal Neoplasms/radiotherapy , Retinoblastoma/radiotherapy , Child, Preschool , Humans , Lacrimal Apparatus/radiation effects , Lens, Crystalline/radiation effects , Optic Nerve/radiation effects , Radiation Injuries/prevention & control , Radiotherapy/methods , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted , Radiotherapy, Intensity-Modulated/methods , Reproducibility of Results , Retina/radiation effects , Retinal Neoplasms/diagnostic imaging , Retinoblastoma/diagnostic imaging , Tomography, X-Ray Computed , Vitreous Body/radiation effectsABSTRACT
A maioria dos corpos estranhos instala-se no trato gastrointestinal (92,5 por cento). Nos EUA, a incidência anual é de 120:100.00 habitantes, sendo responsável por 1.500 mortes anuais. Ocorre mais frequentemente em crianças com 1 e 3 anos. A ingesta pode ser intencional (Síndrome de Body-Paker) ou acidental. Cerca de 90 por cento dos corpos estranhos são eliminados espontaneamente, sem complicações. Apenas 1 por cento dos casos necessitam de procedimento cirúrgico. Os autres discutem a abordagem diagnóstica e terapêutica frente ao paciente com corpo estranho no trato gastrointestinal superior. A suspeita de corpo estranho baseia-se na história da ingestão de objetos. A sintomatologia mais comum é a odinofagia, disfagia, "engasgo", sialorréia, regurgitação, dor local e sensação de corpo estranho, a maioria dos quais é radiopaco. Os objetos radiotransparentes são diagnosticados por meio de esofagogastroduodenoscopia ou do exame com contraste hidrosolúvel. O tratamento varia de acordo com o tipo de corpo estranho e com sua localização