Strategies to minimize X-ray exposure and enhance dosimetric quality in pediatric nephroblastoma

Abstract

Pediatric nephroblastoma is a rare kidney cancer occurring in children. This study investigates the impact of kidney shielding using a multileaf collimator compared with individual block techniques on dose-volume histograms (DVHs) of organs at risk (OARs) and on planning target volume (PTV) coverage during whole-abdominal irradiation with 6 MV beams in children with nephroblastoma. A computed tomography scan was performed in the supine position for five children with nephroblastoma. Treatment plans for both techniques—the conformal block technique (CFBT) and the conventional block technique (CVBT)—were created using the three-dimensional treatment planning system XIO version 4.8. Plans were compared based on dose conformity, homogeneity, and DVHs of OARs. Statistical analysis was performed using the t-test. The mean PTV conformity and homogeneity indices were 0.99 and 1.13 for CFBT, and 0.95 and 1.08 for CVBT, respectively. CFBT demonstrated superior target coverage, achieving 95% of the prescribed dose on 99.2% of the PTV compared to 95.0% for CVBT, which showed greater dose heterogeneity due to conventional kidney shielding and underdosing of adjacent abdominal regions. The average mean dose to the healthy kidney was 11.65 Gy (11.27-12.05) for CFBT and 11.44 Gy (11.09-11.75) for CVBT, with no significant differences in other OARs (p>0.05). CFBT represents an important advancement in three-dimensional conformal radiotherapy for children in developing countries, providing improved PTV homogeneity, enhanced treatment quality assurance, and a reduced potential for human error compared to CVBT. After the initial 10.5 Gy, the abdominal cavity was treated uniformly with CFBT.

Keywords

X-ray exposure / Nephroblastoma / Dose homogeneity / Dose volume histograms of organs at risk

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