In order to provide more convenient irradiation regimens for patient comfort, radiation facility organization and health expenses, new hypofractionated protocols have been evaluated. Moderately (dose/fraction: 2.3 to 3 Gy), then ultra (dose/fraction: 5.2 to 6.1 Gy) hypofractionated irradiations were first validated. The current question is: is it possible to go forward using extreme hypofractionated regimens (EHR) based on 1 to 3 fractions. Different irradiation techniques are under investigation. However, brachytherapy remains the smartest way to deliver a high dose in a small volume. We report prospective and retrospective study results which evaluated EHR for breast and prostate brachytherapy. While oncological outcome and toxicity profile appear extremely encouraging for low-risk breast cancer after a 1 to 4 fractions (6.25 to 20 Gy/fraction), the use of a single fraction of 19 to 23 Gy appears debatable for prostate cancer. Brachytherapy represents an emblematic example of EHR but longer follow-up and more mature results are awaited in order to specify the right indications and refine the EQD2 calculation method including new biological and technical factors. 相似文献
: The aim of this work is to invetigate an unusually high rate of late rectal complications in a group of 43 patients treated with concomitant irradiation and chemotherapy for carcinoma of the cervix between December 1988 and April 1991, with a view to identifying predictive factors.
: The biologically effective dose received by each patient to the rectal reference point defined by the International Commission of Radiation Units and Measurements, Report 38, were calculated. Radiotherapy consisted of 46 Gy external beam irradiation plus three dose-rate intracavitary treatments of 10 Gy each prescribed to point A. Cisplatin 30 mg/m2 was given weekly throughout the duration of the irradiation. The results have been compared to data from 119 patients treated with irradiation alone to assess the cofounding effect of the cisplatin.
: The relationship between the biologically effective dose delivered to the rectal reference point and the development of late complications shows a strong dose-response with a threshold for complications occurring at aproximately the same biologically effective dose threshold as that found for external beam irradiation in the head and neck region. The date from the group of patients treated wihout cisplatin is comparable to the date from the first group of patients in the lower dose ranges; the higher doses were not used and thus are not available for comparison.
: Using the linear quadratic model applied to our clinical results, we have established a threshold for late rectal complications for patients treated with external beam irradiation and high dose-rate brachytherapy for carcinoma of the cervix. This threshold is consistent with similar data for external irradiation in the head and neck region. 相似文献
Prior findings in vitro of a TGF-β3 dependent mechanism induced by low dose-rate irradiation and resulting in increased radioresistance and removal of low dose hyper-radiosensitivity (HRS) was tested in an in vivo model. DBA/2 mice were given whole-body irradiation for 1 h at low dose-rates (LDR) of 0.3 or 0.03 Gy/h. Serum was harvested and added to RPMI (4% mouse serum and 6% bovine serum).This medium was transferred to reporter cells (T-47D breast cancer cells or T98G glioblastoma cells). The response to subsequent challenge irradiation of the reporter cells was measured by the colony assay. While serum from unirradiated control mice had no effect on the radiosensitivity in the reporter cells, serum from mice given 0.3 Gy/h or 0.03 Gy/h for 1 h removed HRS and also increased survival in response to doses up to 5 Gy. The effect lasted for at least 15 months after irradiation. TGF-β3 neutralizer added to the medium containing mouse serum inhibited the effect. Serum from mice given irradiation of 0.3 Gy/h for 1 h and subsequently treated with iNOS inhibitor 1400W did not affect radiosensitivity in reporter cells; neither did serum from the unirradiated progeny of mice given 1h LDR whole-body irradiation. 相似文献
The dose rate of atomic bomb (A-bomb) radiation to the survivors has still remained unclear, although the dose–response data of A-bomb cancers has been taken as a standard in estimating the cancer risk of radiation and the dose and dose-rate effectiveness factor (DDREF). Since the applicability of the currently used DDREF of 2 derived from A-bomb data is limited in a narrow dose-rate range, 0.25-75 Gy/min as estimated from analysis of DS86 dosimetry data in the present study, a non-tumor dose (Dnt) was applied in an attempt to gain a more universal dose-rate effectiveness factor (DREF), where Dnt is an empirical parameter defined as the highest dose at which no statistically significant tumor increase is observed above the control level and its magnitude depends on the dose rate. The new DREF values were expressed as a function of the dose rate at four exposure categories, i.e. partial body low LET, whole body low linear energy transfer (LET), partial body high LET and whole body high LET and provided a value of 14 for environmental level radiation at a dose rate of 10−9 Gy/min for whole body low LET. 相似文献
In this study, a mechanism in which low-dose hyper-radiosensitivity (HRS) is permanently removed, induced by low-dose-rate (LDR) (0.2–0.3 Gy/h for 1 h) but not by high-dose-rate priming (0.3 Gy at 40 Gy/h) was investigated. One HRS-negative cell line (NHIK 3025) and two HRS-positive cell lines (T-47D, T98G) were used. The effects of different pretreatments on HRS were investigated using the colony assay. Cell-based ELISA was used to measure nitric oxide synthase (NOS) levels, and microarray analysis to compare gene expression in primed and unprimed cells. The data show how permanent removal of HRS, previously found to be induced by LDR priming irradiation, can also be induced by addition of nitric oxide (NO)-donor DEANO combined with either high-dose-rate priming or exposure to prolonged cycling hypoxia followed by reoxygenation, a treatment not involving radiation. The removal of HRS appears not to involve DNA damage induced during priming irradiation as it was also induced by LDR irradiation of cell-conditioned medium without cells present. The permanent removal of HRS in LDR-primed cells was reversed by treatment with inducible nitric oxide synthase (iNOS) inhibitor 1400W. Furthermore, 1400W could also induce HRS in an HRS-negative cell line. The data suggest that LDR irradiation for 1 h, but not 15 min, activates iNOS, and also that sustained iNOS activation is necessary for the permanent removal of HRS by LDR priming. The data indicate that nitric oxide production is involved in the regulatory processes determining cellular responses to low-dose-rate irradiation. 相似文献
The endocrinological function of the ovary during and after curative intracavitary high dose-rate irradiation has been studied by determining the peripheral plasma levels of P, E1, E2, FSH, LH and PROL in 8 patients aged 37 ± 7 yr (± SD). In addition, the concentrations of E1 and E2 in ovarian venous blood during the estimated ovulatory phase after irradiation were determined. The functional structure of the ovary was studied histochemically using 3β-hydroxysteroid dehydrogenase (HSD) and ultrastructurally and histologically with routine methods. The results during and after irradiation were compared to those before irradiation. In addition, 28 postmenopausal patients were used as controls.At the end of the irradiation course, which lasted from the premenstrual to the ovulatory phase, 3 out of 4 patients with cervical carcinoma had normal plasma P levels; the menstrual cycles of these patients was previously ovulatory. The normal P levels as well as a rise in E1 and E2 concentrations indicate ovulation. During the next menstrual cycle these values and the ratio in peripheral venous blood decreased and the levels of FSH and LH rose to the postmenopausal values. In patients with endometrial carcinoma, the menstrual cycle was anovulatory both before and after radiotherapy; in estrogen and gonadotrophin levels, similar changes were observed as in patients having ovulatory cycles.In ovarian venous blood, the E2 plasma levels and the ratios were in both groups significantly higher at the time of the second potential ovulatory phase than the corresponding postmenopausal values. As in the postmenopausal women, both E1 and E2 levels in irradiated patients were higher in ovarian effluent blood than peripherally. The ovarian/cubital E1 ratios did not differ between these groups. For E2, this ratio was, however, significantly higher in irradiated patients than in postmenopausal controls.The morphological findings — both by light and electron microscopy — as well as the enzymehistochemical studies support the chemical results reflecting a decreased yet significant estrogen production in the ovaries after irradiation. 相似文献
Two hundred and ninety-one patients with invasive carcinoma of the cervix uteri were treated by a combination of external beam therapy (telecobalt or 4 Mv Linear accelerator) and a high dose-rate afterloading intracavitary apparatus (the Cathetron). All patients have been followed for a minimum of 3 1/2 years. The five year survival rates are: all patients 55%; Stage I, 81%; Stage IIA, 74%; Stage IIB, 40%; Stage III, 27%. Death was directly attributed to treatment in five patients. We found a serious complication rate of 3% for all patients treated, the major problem being radiation ileitis. It is concluded that high dose-rate treatment offers comparable results to conventional radium therapy; the choice between high and lose dose-rate afterloading systems depends on the number of patients needing treatment and associated economic factors rather than any intrinsic radiobiological advantage of either system. 相似文献
Purpose: To generate a statistical model for personalizing a patient’s occlusion therapy regimen.
Methods: Statistical modelling was undertaken on a combined data set of the Monitored Occlusion Treatment of Amblyopia Study (MOTAS) and the Randomized Occlusion Treatment of Amblyopia Study (ROTAS). This exercise permits the calculation of future patients’ total effective dose (TED)—that predicted to achieve their best attainable visual acuity. Daily patching regimens (hours/day) can be calculated from the TED.
Results: Occlusion data for 149 study participants with amblyopia (anisometropic in 50, strabismic in 43, and mixed in 56) were analyzed. Median time to best observed visual acuity was 63 days (25% and 75% quartiles; 28 and 91 days). Median visual acuity in the amblyopic eye at start of occlusion was 0.40 logMAR (quartiles 0.22 and 0.68 logMAR) and at end of occlusion was 0.12 (quartiles 0.025 and 0.32 logMAR). Median lower and upper estimates of TED were 120 hours (quartiles 34 and 242 hours), and 176 hours (quartiles 84 and 316 hours). The data suggest a piecewise linear relationship (P = 0.008) between patching dose-rate (hours/day) and TED with a single breakpoint estimated at 2.16 (standard error 0.51) hours/day, suggesting doses below 2.16 hours/day are less effective.
Conclusion: We introduce the concept of TED of occlusion. Predictors for TED are visual acuity deficit, amblyopia type, and age at start of occlusion therapy. Dose-rates prescribed within the model range from 2.5 to 12 hours/day and can be revised dynamically throughout treatment in response to recorded patient compliance: a personalized dosing strategy. 相似文献
To evaluate biochemical control and treatment related toxicity of patients with localized adenocarcinoma of the prostate treated with high dose-rate brachytherapy (HDRB) combined with conventional 2D or 3D-conformal external beam irradiation (EBI).
Material and methods
Four-hundred and three patients treated between December 2000 and March 2004. HDRB was delivered with three fractions of 5.5-7 Gy with a single implant, followed by 45 Gy delivered with 2D or 3D conformal EBI.
Results
The median follow-up was 48.4 months. Biochemical failure (BF) occurred in 9.6% according to both ASTRO and Phoenix consensus criteria. Mean time to relapse was 13 and 26 months, respectively. The 5-year BF free survival using the ASTRO criteria was 94.3%, 86.9% and 86.6% for the low, intermediate and high risk groups, respectively; using Phoenix criteria, 92.4%, 88.0% and 85.3%, respectively. The only predictive factor of BF in the multivariate analysis by both ASTRO and Phoenix criteria was the presence of prostate nodules detected by digital palpation, and patients younger than 60 years presented a higher chance of failure using Phoenix criteria only.
Conclusions
Treatment scheme is feasible and safe with good efficacy. 相似文献