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Table 1 RBE versus SOBP

From: New insights in the relative radiobiological effectiveness of proton irradiation

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