Fig 1.
CT number-to-RSP curve created with stoichiometric calibration.
(a) Relationship between head and body cancer cases—solid lines: head case; dashed lines: body case; dotted lines with crosses: errors. Comparison of curves obtained using our method and using a polybinary tissue model for (b) head and (c) body; the circles show the polybinary tissue model. Comparison between the calculated stopping-power ratio and those measured for materials representing (d) head and (e) body—circles: milk; triangles: lard; squares: chicken; diamonds: beef.
Fig 2.
In-air spot sizes and profiles for selected energies.
(a) The beam size defined by one sigma in the isocenter plane (z = 0) vs. energy—solid line: calculated spot size in the x-direction; dotted line: calculated spot size in the y-direction; circles: measured spot size in the x-direction; triangles: calculated spot size in the y-direction; red solid line: error in the spot size in the x-direction; red dotted line: error in the spot size in the y-direction. The lateral in-air dose profiles are shown for a pencil beam at selected energies and different positions. The selected energies are (b) 140.0 MeV/u, (c) 302.1 MeV/u, and (d) 430.0 MeV/u. The lateral in-air dose profiles are measured at z = +200 mm (circles), 0 mm (triangles), and −200 mm (squares), whereas they are calculated at z = +200 mm (dotted lines), 0 mm (solid lines), and −200 mm (dashed lines).
Fig 3.
Comparison of IDDs from the TPS calculations and measurements for 100 energies.
The circles and solid lines show the measured and calculated IDDs, respectively. IDDs were selected for ease of viewing. The lower graph shows the differences in R90 in units of millimeters for all energies.
Fig 4.
Lateral-dose profiles in water at selected energies and different positions.
The profiles are for pencil beams with energies of 140.0, 302.1, and 430.0 MeV/u (a–c, respectively). Pencil-beam profiles at an energy of 430.0 MeV/u for cases with RS thicknesses of 3.0, 12.0, and 24.0 mm (d–f, respectively).
Fig 5.
Comparison of the absolute doses from the TPS and measurement in units of Gy mm2/MU for 100 energies.
The circles, solid lines, and dotted lines with triangles show the measured absolute dose, calculated absolute dose, and errors in the calculation relative to the measurement, respectively.
Fig 6.
Doses measured in the irradiation of frame patterns A–C for a pencil beam. Point doses for a pencil beam with an energy of 430.0 MeV/u at energies (a–c) 140.0, 302.1, and 430.0 MeV/u, (a–c, respectively), and with an RS of 3.0, 12.0, and 24.0 mm (d–f, respectively). The measured absolute doses are shown for patterns A (circles), B (triangles), and C (squares), whereas the TPS-calculated absolute doses are shown for patterns A (dotted lines), B (solid lines), and C (dashed lines). The errors in the calculation relative to the measurement are shown for patterns A (red dotted lines), B (red solid lines), and C (red dashed lines). (g) Three selected frame patterns.
Fig 7.
Comparison between the TPS-calculated and -measured absolute point doses at the field center, and the SOBP for selected volumetric dose distributions as functions of field size ranging from 20 × 20 mm2 to 200 × 200 mm2.
The circles, solid lines, and dotted lines with triangles represent the measured absolute dose, calculated absolute dose, and errors in the calculation relative to the measurement (a) for an 80-mm range with a 40-mm SOBP, (b) for an 80-mm range with a 200-mm SOBP, and (c) for a 300-mm range with a 100-mm SOBP.
Fig 8.
Comparison of the TPS-calculated and measured dose profiles for a field size of 100 × 100 mm2 with a 6-mm SOBP.
(a) The depth–dose profile along the central axis; the vertical dashed line represents the position of the measured lateral profile. (b) The lateral-dose profile at 156-mm depth; the circles and solid lines are the measured and calculated profiles, respectively.
Fig 9.
Results of the scanned-beam model compared with measurements in heterogeneous media.
(a) The heterogeneous phantom and measurement setup; the yellow arrow represents the incident beam’s direction. (b) The depth–dose profile penetrating each material; the circle, triangle, and square represent measurements in the acrylic, bone, and lung materials, respectively. The orange, blue, and green solid lines are the calculated profiles in acrylic, bone, and lung materials, respectively. The color in the legend of calculations changes according to the number of beam splittings. The vertical black dashed lines represent the measured lateral profile positions. (c and d) Lateral-dose profiles at 66 and 105 mm, respectively; the circles represent the measured profile, whereas the sky blue, blue, green, light yellow, yellow, orange, and pink solid lines are the calculated profiles with no splitting and with beam splittings 3 × 3 (default), 4 × 4, 5 × 5, 7 × 7, 9 × 9, and 15 × 15, respectively. The right vertical axis indicates the gamma value of 1D local-gamma-index analysis at a distance-to-agreement of 2 mm and a dose difference of 2%, with a 10% threshold.
Table 1.
Comparison of the dosimetric parameters of lateral-dose profiles penetrating the heterogeneous materials shown in Fig 9(C) and 9(D).
Fig 10.
RBE for the selected volumetric dose distribution of CIBs with a field size of 60 × 60 mm2 and a range of 150 mm as a function of SOBP size from 30 to 120 mm.
The RBE values calculated using VQA Plan and Xio-N and the difference between the two are shown as a solid line with circles, dashed line with squares, and dotted line with triangles, respectively.
Fig 11.
PSQA performed in our institute.
(a) Measurement device combined with a 2D ionization chamber array and an accordion-type water phantom. (b) Typical results for PSQA. The upper and lower panels show the PC and HNC cases, respectively. The arrows on the dose distribution indicate the dose profile’s direction. (c) The gamma passing rate in the clinical cases.
Fig 12.
Comparison of clinical and physical dose distributions from the mixed beam and MK models.
The PC case is prescribed to receive 51.6 Gy (RBE) in 12 fractions. This figure shows the dose distribution calculated with the (a) mixed beam model and (b) MK model. (c) The dose profiles, with differences between the RBE models, are shown by the yellow arrows. The liver case is prescribed to receive 60 Gy (RBE) in four fractions. The dose distributions shown are calculated with the (d) mixed beam model and (e) MK model. (f) The dose profiles with differences between the RBE models are shown by the yellow arrows.