Table 1.
RBE versus SOBP
| Reference | Biological system | Biological endpoint | Beam [MeV] | SOBP [cm] | RBE (position of SOBP) | Ref. radiation |
|---|---|---|---|---|---|---|
| Calugaru et al., 2011 [16] | Human cervix cancer cells HeLa/Head and neck squamous cancer cells SQ20B | Cell survival SF = 0.37 | 76 201 |
3 20 |
1.07/1.09 (entrance), 1.14/1.17 (mid-SOBP), 1.33/1.30 (distal) No variation with depth along SOBP for 201-MeV energy beam |
137Cs γ-rays |
| Wouters et al., 2015 [24] | Chinese hamster cells V-79 | Cell survival A) SF = 0.34 B) SF = 0.71 |
160 230 |
10 | A) 1.07 (entrance), 1.10 (prox. half), 1.17 (distal half) and 1.21 (distal edge) Similar effects also for 230 MeV beam B) 1.13 (entrance), 1.15 (prox. half), 1.26 (distal half), 1.30 (distal edge) |
60Co γ-rays |
| Cuaron et al., 2016 [12] | U2OS | DNA damage repair A) 3 h B) 24 h |
152 | 10 | RBE increases as a function of depth along the Bragg peak A) RBE > 2 (entrance), RBE > 4.0 (distal) B) RBE > 2 (entrance), RBE > 6.0 (distal) |
6 MV X-rays |
| Britten et al., 2013 [10] | Human laryngeal cancer cells Hep2/ Chinese hamster cells V79 | Cell survival SF = 0.10 |
87 200 |
1.46/1.23 (mid), 2.1/1.46 (distal), 2.3/1.78 (dose fall-off) Similar D0.1 isoeffect RBE values as for 200 MeV proton beam irradiation |
60Co γ-rays | |
| Chaudhary et al., 2014 [11] | Human fibroblasts AG01522 and glioma cells U87 | Cell survival | 62 | RBE increases for both cell lines and SF = 0.50, SF = 0.10 and SF = 0.01 as a function of depth of the SOBP | 225 kVp X-rays | |
| Matsumoto et al., 2014 [13] | Human salivary gland tumor cells HSG | Cell survival A) SF = 0.10 B) SF = 0.60 |
190 | 5 | A) 1.24 (150 mm- middle), 1.5 (180 mm - distal) B) 1.20 (150 mm- middle), 1.86 (180 mm - distal) |
6 MV X-rays |
| Bettega et al., 2000 [50] | Human squamous cell carcinoma of the tongue SCC25 | Cell survival SF = 0.10 |
65 | 0.99 (2 mm) – entrance 1.04 (15.6 mm) and 1.22 (25 mm) – in the SOBP 1.34 (27.2 mm) and 1.98 (27.8 mm) – distal declining edge |
60Co γ-rays | |
| Petrovic et al., 2010 [51] | HTB140 melanoma | Cell survival | 62 | 1.68–2.84 at the distal end of SOBP 7.14 at its distal declining edge |
Middle of the SOBP | |
| Hojo et al., 2017 [52] | Human esophageal cancer cell lines OE21/KYSE450 |
Cell survival A) SF = 0.10 B) SF = 0.37 |
235 | A) 1.06/1.03 (entrance), 1.17/1.06 (proximal), 1.22/1.20 (middle), 1.24/1.24 (distal) B) 1.16/1.02 (entrance), 1.33/1.09 (proximal), 1.31/1.21 (middle), 1.40/1.27 (distal) |
6 MV X-rays | |
| Slabbert et al., 2015 [54] | Ex vivo murine jejunum | Regeneration of intestinal crypts | 200 | A) 3 B) 7 |
A) RBE increase of 5% ± 3% from the middle to the intermediate position, and an RBE increase of 9% ± 4% from the middle to the end of the SOBP B) RBE increase of 10% ± 4% from the middle to the end of the SOBP |
60Co γ-rays |
| Marshall et al., 2016 [55] | Human skin fibroblasts AG01522 | Cell survival as a function of total dose delivered in a single (A) and triple exposure (B) SF = 0.10 |
219.65 | A: 1.02 (entrance), 1.13 (proximal), 1.25 (center), 1.40 (distal) B: 1.11 (entrance), 1.31 (proximal), 1.40 (center), 2.01 (distal) |
225 kVp X-rays | |
| Chaudhary et al. 2016 [56] | Human skin fibroblasts AG01522 | DNA damage repair | 60 | Modulated SOBP and monoenergetic proton beam | Modulated SOBP: increased complexity of DNA lesions at the distal end of SOBP and slower repair kinetics Pristine beam: Significantly increased number of foci at Bragg peak position 24 h after irradiation |
225 kVp X-rays |
| Guan et al., 2015 [57] | Non-small cell lung cancer cells H460 and H1437 (p53 mutant) | Cell survival SF = 0.10 |
79.7 | Monoenergetic scanning beam with 4.8 cm range in water | Increased RBE at and beyond the Bragg peak. Non-linear relationship between RBE and LET for both cell lines, RBE scaled in a biphasic maner |
137Cs γ-rays |