SU-E-T-292: New Technique for Developing Proton Range Compensator Using Three-Dimensional Printer.

PURPOSE

A new system for manufacturing proton range compensator (PRC) was developed by using a three-dimensional printer (3DP). The physical accuracy and dosimetrical characteristics of the new PRC (PRC-3DP) was compared with conventional PRC (PRC-CMM) manufactured by computerized milling machine (CMM).

METHODS

A PRC for brain cancer treatment, with passive scattered proton beam, was calculated in the TPS (Eclipse, Varian, USA) and its data was converted into a new format for 3DP (Projet HD3000, 3D Systems, USA), using the in-house developed software. PRC-3DP was printed with UV curable acrylic plastic, while PRC- CMM was milled into PMMA using a CMM (V-CNC500, CINCINNATI, USA). We measured the 5 randomly selected points for its physical thickness of both PRCs to evaluate its physical accuracy. Stopping power ratio (SPR), spread-out bragg peak (SOBP, 90∼90%) and distal fall-off (DFO, 20∼80%) at the central axis, +2.5, and 2.5 cm in the lateral direction, and FWHM of dose profile in depth 6, 8, and 10 cm were measured to evaluate for its dosimetrical characteristics. All measured data was compared with TPS data.

RESULTS

There was no significant difference in the physical depths between the calculated and the measured value of both RPC-3DP and RPC-CMM (p<0.05). SPR of both PRC showed similarity in value (1.022) when compared with that of the water. Average difference of SOBP between the TPS and the measured data from both PRC was 0.3773±0.0075 and 0.2762±0.0235 cm, while DFO was 0.06±0.005 and 0.0471±0.0042 cm, respectively. Average differences of FWHM between the TPS and the measured data from PRC-3DP and PRC-CMM were 0.1799±0.025 and 0.137±0.0181 cm, respectively. There was no significant difference in dosimetrical characteristic between the RTP and both PRCs (p<0.05).

CONCLUSIONS

Physical accuracy and dosimetrical characteristics of the PRC-3DP were comparable to that of the conventional PRC-CMM, while significant system minimization was provided. This work was supported by the Technology Innovation Program, 10040362, Development of an integrated management solution for radiation therapy funded by the Ministry of Knowledge Economy (MKE, Korea). This idea was applied for a Korea patent (no. 10-2012-0010812).