<title>Weanling piglet cerebellum: a surrogate for tolerance to MRT (microbeam radiation therapy) in pediatric neuro-oncology</title>

Prospects for microbeam radiation therapy of brain tumours in children to reduce neurological sequelae

“…The irradiated animals and their unirradiated litter-mates (27 rat pups and five piglets) were evaluated weekly thereafter for more than a year by Swiss farmers, scientists, and veterinarians experienced in porcine and rodent husbandry, until the animals were killed. These studies 17,18 are summarized as follows.…”

“…averaged 44% of their skin-entrance values (Fig. 1); 18 'stripes' were seen more than a year later throughout their cerebella. The sharpness of spatial fractionation of dose was not lost, even deep in the cerebellum, because cerebellar 'stripes' from dropout of neuronal and astroglial nuclei were observed up to the contralateral cerebellar surface, where peak doses had been attenuated after penetration of the quasiparallel microbeams through about 7.2cm of soft tissue from their skin-entrance values of 150Gy.…”

“…The cerebella of anaesthetized 42-or 48-day-old 5 to 12kg weanling Yorkshire piglets, which appeared mature and seemed so by optical microscopy, 18 and those of anaesthetized 11-to 13-day-old 20 to 38g suckling Sprague-Dawley rats, which were visibly and microscopically immature, were irradiated laterally through a multislit collimator by an array of multiple parallel, approximately 28µm wide (range 20-36µm), upright microbeams of synchrotron-wigglergenerated X-rays. 17 Peak skin-entrance doses for the weanling piglets were 150, 300, 425, or 600Gy ( Fig.…”

“…3). 18 Actually, slightly larger piglets (6-7wks old) were irradiated with peak skin-entrance microbeam doses of 150 to 600Gy. Early Monte Carlo dose computations showed that in-beam doses at the proximal cerebellar surface (3.4cm deep approx.)…”

Emerging neurosurgical applications of synchrotron-generated microbeams

“…MRT irradiation has been carried out to deliver very high radiation doses into tumours in a single fraction through an unidirectional approach [11,15]. Most of the experimental activity performed until now has been focused on the study of the effects of arrays of parallel microbeams [4,5,[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][28][29][30]. MRT has been applied to several tumor models including intracerebral gliosarcoma (9LGS) in rats [11,13,30], murine mammary carcinoma (EMT-6) [19] and human squamous-cell carcinoma (SCCVII) in mouse and rat [9,20].…”