Table 2. Dose limits of normal tissues under SBRT and CIRT for the treatment of prostate cancer.
| Organ | SBRT-CK (5 frequency) | CIRT (16 frequency) | |||
|---|---|---|---|---|---|
| Volume (cm3) | Dose (Gy) | Dmax (Gy) | Volume dose [Gy (RBE)] | ||
| Bladder | <15 | 18.3 | 38 | D50%≤50 | |
| Rectum | <20 | 25 | 38 | D40%≤50, D20%≤60 | |
| Bowel | <5 | 19.5 | 35 | D50%≤30, Dmax ≤45–50 | |
| Femoral heads | <10 | 30 | – | D5%≤50, D15%≤30 | |
SBRT-CK (5 frequency): for bladder, the volume with a dose of 18.3 Gy should not exceed 15 cm3, and the Dmax should not exceed 38 Gy; CIRT (16 frequency): bladder D50%, the exposure dose of 50% bladder volume should not exceed 50 Gy (RBE). SBRT-CK: in SBRT radiotherapy, the device used is the Cyberknife CK. SBRT, stereotactic body radiotherapy; CIRT, carbon-ion radiation therapy; CK, CyberKnife; RBE, relative biological effectiveness; Dmax, maximum irradiation dose.