The depth-dependent radiation response of human melanoma cells exposed to 65 MeV protons

Courdi, A.; Brassart, N.; Hérault, J.; Chauvel, P

doi:10.1259/0007-1285-67-800-800

Cited by 61 publications

(24 citation statements)

References 16 publications

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“…In France, human melanoma MV curves are presented in Table 1. cells were exposed to 65-MeV proton beams, with the results indiaes is seen following an increase in cating the RBE depended on depths in SOBP or changes of LET ton beams, ranging from 0.1993 to (Courdi et al, 1994). Very recently, the radiation response of the is seen in 1-values.…”

Section: Resultsmentioning

confidence: 99%

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Comparison of radiobiological effective depths in 65-MeV modulated proton beams

Tang

Inoue²,

Yamazaki³

et al. 1997

Br J Cancer

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Summary To assess the achievement of uniformity of radiobiological effectiveness at different depths in the proton spread-out Bragg peak (SOBP), Chinese hamster ovary (CHO) cells were exposed to 65-MeV modulated proton beams at the Research Center for Nuclear Physics (RCNP) of Osaka University. We selected four different irradiation positions: 2 mm depth, corresponding to the entrance, and 10, 18 and 23 mm depths, corresponding to different positions in the SOBP. Cell survival curves were generated with the in vitro colony formation method and fitted to the linear-quadratic model. With 137CS gamma-rays as the reference irradiation, the relative biological effectiveness (RBE) values for a surviving fraction (SF) level of 0.1 are 1.05, 1.10, 1.12 and 1.19 for depths of 2, 10, 18 and 23 mm respectively. A significant difference was found between the survival curves at 10 and 23 mm (P < 0.05), but not between 18 and 10 mm or between 18 and 23 mm. There was a significant dependence of RBE on depths in modulated proton beams at the 0.1 surviving fraction level (P< 0.05). Moreover, the rise of RBEs significantly depended on increasing SF level or decreased approximately in correspondence with irradiation dose (P = 0.0001). To maintain uniformity of radiobiological effectiveness for the target volume, careful attention should be paid to the influence of depth of beam and irradiation dose.Keywords: proton; spread-out Bragg peak; relative biological effectiveness; Chinese hamster ovary cellThe depth-dose curve for the single-energy proton beam has limited applications in clinical radiation therapy owing to the excessively narrow high-dose region. This region, also known as the Bragg peak, can be modulated by appropriate selection of a distribution of proton energies to produce a spread-out Bragg peak (SOBP) or a uniform region of full dose at the depth of interest. Dose uniformity across a target volume can be achieved with multiple X-ray beams. However, each X-ray beam features a greater dose in the entrance region than a corresponding proton beam, has a dose gradient across the target volume and delivers an undesirable dose to normal tissues distal to the target. Proton beams have none of these undesirable characteristics (Suit and Urie, 1992; Munzenrider and Crowell, 1994;Raju, 1996).Although SOBP produces an excellent physical dose distribution, there is a variation of linear energy transfer (LET) values at different depths in the SOBP, known as the LET gradient, from proximal to distal SOBP. The proton is a lower LET particle than other heavy-charged particles; for example, the mean LET values of the 65-MeV modulated proton beams (SOBP) are always less than 7 keV .m-' (Courdi et al, 1994).The achievement of uniformity of radiobiological effectiveness for target volumes is always a matter of concern. In fact, there is no uniformity of LET within target volumes. One study has suggested that DNA double-strand breaks, potentially lethal damage and sublethal damage, depend on LET and are closely

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Section: Resultsmentioning

confidence: 99%

“…The proton is a lower LET particle than other heavy-charged particles; for example, the mean LET values of the 65-MeV modulated proton beams (SOBP) are always less than 7 keV .m-' (Courdi et al, 1994).…”

mentioning

confidence: 99%

Comparison of radiobiological effective depths in 65-MeV modulated proton beams

Tang

Inoue²,

Yamazaki³

et al. 1997

Br J Cancer

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“…An increase in p with increase in LET has been previously reported (27)(28)(29)(30). If the quadratic term represents lethality due to interaction of 2DSB induced by 2 independent particles, the RBE of this kind of lethality can be derived by calculating , / $ neutrons/& photons (27).…”

Section: Discussionmentioning

confidence: 90%

The RBE of Fast Neutrons for in Vitro Inactivation of Human Tumour Cells Determined by the Ratio of Mean Inactivation Doses

et al. 1996

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“…Empirical evidence would indicate a dependence of RBE on linear energy transfer (LET) that is known to vary with depth along the proton track. Several investigations have measured variation in RBE with depth in a biological absorber for both in vitro 10,[18][19][20][21][22][23][24][25][26] and in vivo, [27][28][29][30][31] systems. Experimental conditions have used various cell lines with differences in sampling along the SOBP, initial beam energy, RBE calculation method, tissue type, and LET estimation.…”

Section: Discussionmentioning

confidence: 99%

“…Several published studies support this intuition that from the midpoint to the distal side of spread out Bragg peak (SOBP), the RBE increases to a maximum of as much as 3 just [10][11][12][13][14][15] beyond the distal dose falloff (DDF). The RBE value increases from 1.1 at the absorber entrance to as much as 1.6 at the midpoint of the SOBP 11 and to as much as 2.9 in the DDF.…”

Section: Introductionmentioning

confidence: 97%

Rapid RBE-Weighted Proton Radiation Dosimetry Risk Assessment

Qutub

Klein

Buchsbaum

2016

Technol Cancer Res Treat

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Proton therapy dose is affected by relative biological effectiveness differently than X-ray therapies. The current clinically accepted weighting factor is 1.1 at all positions along the depth-dose profile. However, the relative biological effectiveness correlates with the linear energy transfer, cell or tissue type, and the dose per fraction causing variation of relative biological effectiveness along the depth-dose profile. In this article, we present a simple relative biological effectiveness-weighted treatment planning risk assessment algorithm in 2-dimensions and compare the results with those derived using the standard relative biological effectiveness of 1.1. The isodose distribution profiles for beams were accomplished using matrices that represent coplanar intersecting beams. These matrices were combined and contoured using MATLAB to achieve the distribution of dose. There are some important differences in dose distribution between the dose profiles resulting from the use of relative biological effectiveness ¼ 1.1 and the empirically derived depth-dependent values of relative biological effectiveness. Significant hot spots of up to twice the intended dose are indicated in some beam configurations. This simple and rapid risk analysis could quickly evaluate the safety of various dose delivery schema.

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The depth-dependent radiation response of human melanoma cells exposed to 65 MeV protons

Cited by 61 publications

References 16 publications

Comparison of radiobiological effective depths in 65-MeV modulated proton beams

Comparison of radiobiological effective depths in 65-MeV modulated proton beams

The RBE of Fast Neutrons for in Vitro Inactivation of Human Tumour Cells Determined by the Ratio of Mean Inactivation Doses

Rapid RBE-Weighted Proton Radiation Dosimetry Risk Assessment

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