Precious 4DCT Reconstruction Algorithm Using Motion Curve and Comparison with Phase-Based Resorting method

The 5th KOREA-JAPAN Joint Meeting on Medical Physic

Four-dimensional layer-stacking carbon-ion beam dose distribution by use of a lung numeric phantom.

To extend layer-stacking irradiation to accommodate intrafractional organ motion, we evaluated the carbon-ion layer-stacking dose distribution using a numeric lung phantom. We designed several types of range compensators. The planning target volume was calculated from the respective respiratory phases for consideration of intrafractional beam range variation. The accumulated dose distribution was calculated by registering of the dose distributions at respective phases to that at the reference phase. We evaluated the dose distribution based on the following six parameters: motion displacement, direction, gating window, respiratory cycle, range-shifter change time, and prescribed dose. All parameters affected the dose conformation to the moving target. By shortening of the gating window, dose metrics for superior-inferior (SI) and anterior-posterior (AP) motions were decreased from a D95 of 94 %, Dmax of 108 %, and homogeneity index (HI) of 23 % at T00-T90, to a D95 of 93 %, Dmax of 102 %, and HI of 20 % at T40-T60. In contrast, all dose metrics except the HI were independent of respiratory cycle. All dose metrics in SI motion were almost the same in respective motion displacement, with a D95 of 94 %, Dmax of 108 %, Dmin of 89 %, and HI of 23 % for the ungated phase, and D95 of 93 %, Dmax of 102 %, Dmin of 85 %, and HI of 20 % for the gated phase. The dose conformation to a moving target was improved by the gating strategy and by an increase in the prescribed dose. A combination of these approaches is a practical means of adding them to existing treatment protocols without modifications

Simplification of the patient set up in radiotherapy with guideline using epipolar geometry

Computer Assisted Radiology and Surgery (CARS) 201

A treatment planning strategy for heavy-charged-particle radiotherapy of lung cancer by the use of computed tomography with projection data-based temporal maximum-intensity projection

To design a range-compensating bolus for heavy-charged-particle radiotherapy of lung cancer, we propose an image-processing method that uses CT projection data for treatment planning. We studied six lung cancer patients in 4DCT mode. Three types of range-compensating bolus were designed with use of (1) each bolus for 4DCT images, (2) image-based maximum-intensity projection data (4DIM), and (3) CT images reconstructed by the use of maximum-attenuation projection data (4DPM) along the time axis around exhale (=respiratory-gated treatment). Carbon-ion dose distributions were calculated by the use of these designed range-compensating boluses and were compared. The dose distribution with 4DIM caused overdosing beyond the target. However, the dose distribution with 4DPM was similar to that with a composite of the range-compensating bolus (CCB) designed for the respiratory phases. Furthermore, the volume of the receiving dose for >95% (D95) for CTV and the volume of the lung receiving dose for >20 GyE (V20) with 4DPM were similar to that with the CCB. The range-compensating bolus with 4DPM provides dose distributions similar to that with the CCB in peripheral lung cancer and improves the calculating efficiency over CCB

Development of GPU-based Multi-threaded Software Application to Calculate Digitally Reconstructed Radiographs for Radiotherapy

To provide faster calculation of digitally reconstructed radiographs (DRRs) in patient-positioning verification, we developed and evaluated a GPU (graphic processing unit)-based DRR software application and comparison with a CPU (central processing unit)-based application. The evaluation metrics were calculation speed and image quality with various slice thicknesses. The results showed that GPU-based DRR computation was an average of 50 times faster than the CPU-based methodology, whereas the image quality was very similar. This excellent performance may increase the accuracy of patient positioning and improve the patient treatment-throughput time

Simplification of the patient set up in radiotherapy with guideline using epipolar geometry

Computer Assisted Radiology and Surger

Simplification of the patient set up in radiotherapy with guideline using epipolar geometry

Computer Assisted Radiology and Surger