BACKGROUND Carbon ion radiotherapy(CIRT)is currently used to treat prostate cancer.Rectal bleeding is a major cause of toxicity even with CIRT.However,to date,a correlation between the dose and volume parameters of th...BACKGROUND Carbon ion radiotherapy(CIRT)is currently used to treat prostate cancer.Rectal bleeding is a major cause of toxicity even with CIRT.However,to date,a correlation between the dose and volume parameters of the 12 fractions of CIRT for prostate cancer and rectal bleeding has not been shown.Similarly,the clinical risk factors for rectal bleeding were absent after 12 fractions of CIRT.AIM To identify the risk factors for rectal bleeding in 12 fractions of CIRT for prostate cancer.METHODS Among 259 patients who received 51.6 Gy[relative biological effectiveness(RBE)],in 12 fractions of CIRT,15 had grade 1(5.8%)and nine had grade 2 rectal bleeding(3.5%).The dose-volume parameters included the volume(cc)of the rectum irradiated with at least x Gy(RBE)(Vx)and the minimum dose in the most irradiated x cc normal rectal volume(Dx).RESULTS The mean values of D6cc,D2cc,V10 Gy(RBE),V20 Gy(RBE),V30 Gy(RBE),and V40 Gy(RBE)were significantly higher in the patients with rectal bleeding than in those without.The cutoff values were D6cc=34.34 Gy(RBE),D2cc=46.46 Gy(RBE),V10 Gy(RBE)=9.85 cc,V20 Gy(RBE)=7.00 cc,V30 Gy(RBE)=6.91 cc,and V40 Gy(RBE)=4.26 cc.The D2cc,V10 Gy(RBE),and V20 Gy(RBE)cutoff values were significant predictors of grade 2 rectal bleeding.CONCLUSION The above dose-volume parameters may serve as guidelines for preventing rectal bleeding after 12 fractions of CIRT for prostate cancer.展开更多
The average absorbed dose in glandular tissue is the most appropriate parameter for the assessment of the radiation-induced risk during breast imaging. The aims of this work concern:(1) the investigation of the variat...The average absorbed dose in glandular tissue is the most appropriate parameter for the assessment of the radiation-induced risk during breast imaging. The aims of this work concern:(1) the investigation of the variation effect of any related update to photon cross-section data-bases on the computation of the normalized glandular dose(Dg N) for mammography quality control tests and(2) the proposition of a parameterization method leading to provide Dg N values function of the breast thickness(T) and the particle energy(E) instead of E alone, as normally known. We analyzed the change effect of the photon cross-section data-bases on the computation of Dg N. Those coefficients, generated using the Geant4 Monte Carlo toolkit, were studied over a range of compressed breast thickness of 2–8 cm for monoenergetic(1–120 ke V by 1 ke V intervals) and polyenergetic(23–35 k Vp by 2 k Vp intervals) X-ray beams. Moreover, breast tissue composition ranging from about0% glandular(about 100% adipose) to 100% glandular(0% adipose) was also covered. The successful parameterization of Dg N look-up table function of the breast thickness and energy, will compact its analytical form without loss of accuracy. All parameterization fits resulted in r2 values of 0.999 or better.展开更多
Lead has been recognized as a high risk toxic for most organisms including human. The effects of Pb in non-mammalian vertebrates are oprly known, particularly in anuran amphibians. The purpose of this study was to det...Lead has been recognized as a high risk toxic for most organisms including human. The effects of Pb in non-mammalian vertebrates are oprly known, particularly in anuran amphibians. The purpose of this study was to determine the effect of this metal on some hematological parameters of adult Bufo arenarum. It was found that all parameters remained unaltered within normal ranges, with the exception of reticulocyte counts which was significantly increased compared to the in controls (3. 7% vs. 0. 2 % ). It is suggested that the selective change found in reticulocyte count might be considered as an early response of a biomarker to sublethal exposition of Bufo arenarum to lead.展开更多
文摘BACKGROUND Carbon ion radiotherapy(CIRT)is currently used to treat prostate cancer.Rectal bleeding is a major cause of toxicity even with CIRT.However,to date,a correlation between the dose and volume parameters of the 12 fractions of CIRT for prostate cancer and rectal bleeding has not been shown.Similarly,the clinical risk factors for rectal bleeding were absent after 12 fractions of CIRT.AIM To identify the risk factors for rectal bleeding in 12 fractions of CIRT for prostate cancer.METHODS Among 259 patients who received 51.6 Gy[relative biological effectiveness(RBE)],in 12 fractions of CIRT,15 had grade 1(5.8%)and nine had grade 2 rectal bleeding(3.5%).The dose-volume parameters included the volume(cc)of the rectum irradiated with at least x Gy(RBE)(Vx)and the minimum dose in the most irradiated x cc normal rectal volume(Dx).RESULTS The mean values of D6cc,D2cc,V10 Gy(RBE),V20 Gy(RBE),V30 Gy(RBE),and V40 Gy(RBE)were significantly higher in the patients with rectal bleeding than in those without.The cutoff values were D6cc=34.34 Gy(RBE),D2cc=46.46 Gy(RBE),V10 Gy(RBE)=9.85 cc,V20 Gy(RBE)=7.00 cc,V30 Gy(RBE)=6.91 cc,and V40 Gy(RBE)=4.26 cc.The D2cc,V10 Gy(RBE),and V20 Gy(RBE)cutoff values were significant predictors of grade 2 rectal bleeding.CONCLUSION The above dose-volume parameters may serve as guidelines for preventing rectal bleeding after 12 fractions of CIRT for prostate cancer.
基金Supported by the National Plan for Science,Technology and Innovation(MAARIFAH)King Abdulaziz City for Science and Technology,Kingdom of Saudi Arabia(No.1827)
文摘The average absorbed dose in glandular tissue is the most appropriate parameter for the assessment of the radiation-induced risk during breast imaging. The aims of this work concern:(1) the investigation of the variation effect of any related update to photon cross-section data-bases on the computation of the normalized glandular dose(Dg N) for mammography quality control tests and(2) the proposition of a parameterization method leading to provide Dg N values function of the breast thickness(T) and the particle energy(E) instead of E alone, as normally known. We analyzed the change effect of the photon cross-section data-bases on the computation of Dg N. Those coefficients, generated using the Geant4 Monte Carlo toolkit, were studied over a range of compressed breast thickness of 2–8 cm for monoenergetic(1–120 ke V by 1 ke V intervals) and polyenergetic(23–35 k Vp by 2 k Vp intervals) X-ray beams. Moreover, breast tissue composition ranging from about0% glandular(about 100% adipose) to 100% glandular(0% adipose) was also covered. The successful parameterization of Dg N look-up table function of the breast thickness and energy, will compact its analytical form without loss of accuracy. All parameterization fits resulted in r2 values of 0.999 or better.
文摘Lead has been recognized as a high risk toxic for most organisms including human. The effects of Pb in non-mammalian vertebrates are oprly known, particularly in anuran amphibians. The purpose of this study was to determine the effect of this metal on some hematological parameters of adult Bufo arenarum. It was found that all parameters remained unaltered within normal ranges, with the exception of reticulocyte counts which was significantly increased compared to the in controls (3. 7% vs. 0. 2 % ). It is suggested that the selective change found in reticulocyte count might be considered as an early response of a biomarker to sublethal exposition of Bufo arenarum to lead.
