Developing an indigenous anthropomorphic heterogeneous female pelvic phantom for dosimetric audit in radiotherapy...

The aim of the present study was to create an indigenous anthropomorphic heterogeneous female pelvis (AHFP) phantom for quality assurance and dosimetric audits in advance radiotherapy centers.

The AHFP phantom was designed using paraffin wax, epoxy, water, polyvinyl chloride (PVC), and a hardener. A dosimetric audit was conducted using the fabricated phantom among four different hospitals. The hospitals were instructed to perform the procedure of treatment planning and delivery as per their institutional protocol. Each institute was asked to make optimized plans using available intensity-modulated radiation therapy (IMRT) and rapid arc (RA) delivery technique. Apart from this, additional plans were generated for using single field (1F), double field (2F), three field (3F), and four field (4F) for 5 cm × 5 cm and 10 cm × 10 cm geometry, 3dimensional conformal radiotherapy (3F, 4F), and IMRT (5F, 7F and 9F).

With regard to the measured radiological properties, the mean Hounsfield units (HUs) were 87.3 ± 39.45, 1122.5 ± 270.1, 1312.2 ± 232.5, 10.1 ± 58.5, and 20.2 ± 33.8; the mean relative electron densities (REDs) were 1.087 ± 0.04, 1.673 ± 0.16, 1.765 ± 0.14, 1.010 ± 0.06, and 1.021 ± 0.03 g/cc and the mean mass densities (MDs) were 1.074 ± 0.03, 1.673 ± 0.15, 1.765 ± 0.16, 1.011 ± 0.06, and 1.021 ± 0.03 g/cc for soft tissue, femoral head, bones, rectum, and bladder of AHFP phantom, respectively. The percentage deviations between measured and computed doses were within ± 3% for all measurements performed under the study in each hospital.

The fabricated AHFP phantom mimics the size, shape, and radiological properties of female pelvis. The dosimetric results from participant hospitals were within prescribed tolerance. The present study confirms the efficacy of the AHFP phantom as a trustworthy quality assurance tool in radiotherapy. Hence, it can be used for end-to-end validation and dosimetric audit of advanced radiation therapy centers.