Bioevaluation studies of 32P incorporated mould brachytherapy sources for potential application in treatment of superficial tumors.
OBJECTIVE
To prepare 32P-based user-friendly mould brachytherpy sources for the treatment of superficial tumors.


METHODS
32P as orthophosphoric acid was adsorbed on 15-25 mm (diameter) circular sheets of cellulose-based adsorbent paper to prepare sources containing approximately 37-74 MBq of 32P per cm of strip. The sources were immobilized between plastic sheets of 40 microm thickness. Autoradiography studies were carried out to determine the uniformity of 32P deposition in the source. Dosimetric evaluation of the sources was also carried out. Bioevaluation studies were carried out in C57BL6 mice bearing melanoma using 37-74 MBq sources.


RESULTS
Cellulose-based sources containing 37-74 MBq of 32P per cm2 could be prepared from which no radioactivity leakage could be detected in water or saline. Autoradiography studies revealed 32P to be uniformly distributed in these sources. Dosimetric evaluation showed that the contact dose imparted was 10 Gy/h, sufficient for treatment of superficial tumors. In mice bearing melanoma, complete tumor regression could be achieved with two applications of 37-74 MBq sources, at an interval of 3 days. Histopathological examination of the skin tissue from the treated area proved the absence of tumor as compared with the controls.


CONCLUSIONS
Preparation of P sources of various shapes and sizes (based on the tumor size) having uniform 32P activity distribution could be achieved. Efficacy of these sources in treating melanoma tumors could be established in the animal model.
Pandey
Usha
U
Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai, India.
Saxena
Sanjay Kumar
SK
Sarma
Haladhar Dev
HD
Tandon
Pankaj
P
Ram
Ramu
R
Samuel
Grace
G
Dash
Ashutosh
A
Venkatesh
Meera
M