An evaluation of conformal and intensity-modulated radiotherapy in whole ventricular radiotherapy for localised primary intracranial germinomas.

AIMS: To evaluate different treatment techniques in whole ventricular radiotherapy (WVRT) for localised intracranial germinomas with respect to target volume and organ at risk (OAR) dose. As a second end point, a comparison of OAR doses between WVRT and whole brain radiotherapy was made. MATERIALS AND METHODS: Co-registered computed tomography-magnetic resonance images (MRI) of five patients were studied. Planning target volumes for whole ventricles (phase 1, PTV(1)) and boost to the primary tumour (phase 2, PTV(2)) were prescribed to 24 and 16 Gy. For phase 1, lateral parallel-opposed pairs (PP), non-coplanar three- and four-field (3F and 4F) and optimised four- and seven-field intensity-modulated radiotherapy (4FIMRT and 7FIMRT) plans were compared. A conformal non-coplanar six-field technique was used for phase 2. RESULTS: For phase 1, statistically significant high-dose sparing of normal brain was achieved with increasing treatment complexity for supratentorial brain (STB) minus PTV(1) (STB-PTV(1)) and infratentorial brain (ITB) minus PTV(1) (ITB-PTV(1)). Median pituitary gland dose sparing was 1 Gy with IMRT techniques (P=not significant). CONCLUSION: WVRT using 7FIMRT is the most conformal technique, which offers significant sparing of normal brain from high-dose irradiation, a mean reduction of 1 Gy in the pituitary gland (P<0.05) with no significant reduction in other OARs. Yet even with the most complex technique the absolute reduction in mean dose to normal brain tissue achieved was modest in clinical terms. Whether this could translate into a reduction in late sequelae in a predominantly adolescent patient population remains hypothetical.

Hipotension controlada con nitroprusiato de sodio en cirurgia de malformaciones vasculares cerebrales. / Controled hypotension with sodium nitroprusside in cerebrovascular malformation surgery

Se empleo solucion de nitroprusiato de sodio al 0,004% para producir hipotension controlada en 21 craneotomias para malformaciones arteriovenosas (3) y aneurismas (17). La muestra esta formada por 20 pacientes consecutivos entre 24 y 61 anos. Se realizo neuroleptoanestesia en condiciones de ventilacion hipocapnica, la hipotension se inicio una vez realizada la craneotomia y se suspendio al termino de la cirugia vascular. La dosis promedio de nitroprusiato fue de 1.258 kg/min.Se controlo PAM (presion arterial media),pulso -PVC- pH y gases. Los resultados de este estudio muestra: 1. no hubo dificultades en la obtencion de las cifras tensionales deseadas; 2. la hipotension obtenida (-x PAM 52,2 mm Hg) facilito en forma decisiva el manejo quirurgico de todos los pacientes y especialmente en 3 de ellos en que hubo rotura del aneurisma intraoperatorio; 3. los valores de pH y gases durante este periodo fueron satisfactorios; 4. en 4 pacientes hipertensos conocidos en tratamiento observamos hipertension arterial severa en el post-operatorio inmediato, la que cedio con propranolol