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PURPOSE: The excellent treatment results obtained with traditional radiosurgery have stimulated attempts to broaden the range of intracranial disorders treated with radiosurgical techniques. For major users of radiosurgery this resulted in a gradual shift from treating vascular diseases in a single session to treating small, well delineated primary tumors on a fractionated basis. In this paper we present the technique currently used in Montreal for the fractionated stereotactic radiotherapy of selected intracranial lesions. METHODS AND MATERIALS: The regimen of six fractions given every other day has been in use for "fractionated stereotactic radiotherapy" in our center for the past 5 years. Our current irradiation technique, however, evolved from our initial method of using the stereotactic frame for target localization and first treatment, and a "halo-ring" with tattoo skin marks for the subsequent treatments. Recently, we developed a more precise irradiation technique, based on an in-house-built stereotactic frame which is left attached to the patient's skull for the duration of the fractionated regimen. Patients are treated with the stereotactic dynamic rotation technique on a 10 MV linear accelerator (linac). RESULTS: In preparation for the first treatment, the stereotactic frame is attached to the patient's skull and the coordinates of the target center are determined. The dose distribution is then calculated, the target coordinates are marked onto a Lucite target localization box, and the patient is placed into the treatment position on the linac with the help of laser positioning devices. The Lucite target localization box is then removed, the target information is tattooed on the patient's skin, and the patient is given the first treatment. The tattoo marks in conjunction with the target information on the Lucite target localization box are used for patient set-up on the linac for the subsequent 5 treatments. The location of the target center is marked with radio-opaque markers on the target localization box and verified with a computerized tomography scanner prior to the second treatment. The same verification is done prior to other treatments when the target center indicated by the target localization box disagrees with that indicated by the tattoo marks. The new position of the target center is then determined and used for treatment positioning. CONCLUSION: The in-house-built frame is inexpensive and easily left attached to the patient's skull for the 12 day duration of the fractionated regimen. Positioning with the Lucite target localization box verified with tattoo marks ensures a high level of precision for individual fractionated treatments.  相似文献   

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PURPOSE: To retrospectively evaluate the initial clinical results of stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (SRT) for pituitary adenomas with regard to tumor and hormonal control and adverse effects of the treatment. SUBJECTS AND METHODS: Forty-eight patients with pituitary adenoma who underwent SRS or SRT between September 1989 and September 1995 were analyzed. Of these, 18 received SRS and 30 received SRT. The median tumor volumes were 1.9 cm3 for SRS and 5.7 cm3 for SRT. Eleven of the SRS and 18 of the SRT patients were hormonally active at the time of the initial diagnosis. Four of the SRS and none of the SRT patients had a history of prior radiation therapy. Both SRS and SRT were performed using a dedicated stereotactic 6-MV linear accelerator (LINAC). The dose and normalization used for the SRS varied from 1000 cGy at 85% of the isodose line to 1500 cGy at 65% of the isodose line. For SRT patients, a total dose of 4500 cGy at 90% or 95% of the isodose line was delivered in 25 fractions of 180 cGy daily doses. RESULTS: Disease control-The three year tumor control rate was 91.1% (100% for SRS and 85.3% for SRT). Normalization of the hormonal abnormality was achieved in 47% of the 48 patients (33% for SRS and 54% for SRT). The average time required for normalization was 8.5 months for SRS and 18 months for SRT. Adverse effects-The 3-year rate of freedom from central nervous system adverse effects was 89.7% (72.2% for SRS and 100% for SRT). Three patients who received SRS for a tumor in the cavernous sinus developed a ring enhancement in the temporal lobe as shown by follow-up magnetic resonance imaging. Two of these cases were irreversible and were considered to be radiation necrosis. None of the 48 patients developed new neurocognitive or visual disorders attributable to the irradiation. The incidence of endocrinological adverse effects were similar in the two groups, resulting in 3-year rates of freedom from newly initiated hormonal replacement of 78.4% (77.1% for SRS and 79.9% for SRT). CONCLUSION: Considering the relatively high incidence of morbidity observed in the SRS group, we recommend SRT as the primary method of radiation therapy for pituitary tumors. When treating a lesion in the cavernous sinus with SRS, special attention should be paid to dose distribution in the adjacent brain parenchyma. Longer follow-up is necessary before drawing any conclusions about the advantages of these techniques over conventional external beam radiation therapy.  相似文献   

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Twenty-seven acoustic tumors in 26 patients were treated with multiple fractionated linear-accelerator-based stereotactic radiotherapy (SRT). All patients with intact pretreatment facial nerve function with either small or large tumor volumes have thus far experienced no treatment-related facial neuropathy, including 9 patients with a mean follow-up of 22.4 +/- 1.6 months. The incidence of evaluable trigeminal neuropathy was 13%, and in 5 of 7 patients with serviceable pretreatment hearing, audiometry was unchanged in the immediate posttreatment period. Longer follow-up will be necessary to evaluate hearing preservation after SRT. Tumor response with central necrosis was seen in all assessable patients. SRT can be performed for cerebellopontine angle tumors with accuracy and reproducibility. It achieves a biological response similar to single fraction radiosurgery and may lower the incidence of facial and trigeminal neuropathies.  相似文献   

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Dose characteristics of a stereotactic radiotherapy unit based on a standard Varian Clinac 4/100 4 MV linear accelerator, in-house-built Lipowitz collimators and the SMART stereotactic radiotherapy treatment planning software have been determined. Beam collimation is constituted from the standard collimators of the linear accelerator and a tertiary collimation consisting of a replaceable divergent Lipowitz collimator. Four collimators with isocentre diameters of 15, 25, 35 and 45 mm, respectively, were constructed. Beam characteristics were measured in air, acrylic or water with ionization chamber, photon diode, electron diode, diamond detector and film. Monte Carlo simulation was also applied. The radiation leakage under the collimators was less than 1% at 50 mm depth in water. Specific beam characteristics for each collimator were imported to SMART and dose planning with five non-coplanar converging 140 degrees arcs separated by 36 degrees angles was performed for treatment of a RANDO phantom. Dose verification was made with TLD and radiochromic film. The in-house-built collimators were found to be suitable for stereotactic radiotherapy and patient treatments with this system are in progress.  相似文献   

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PURPOSE: To develop and test a system for high precision fractionated stereotactic radiotherapy that separates immobilization and localization devices. METHODS AND MATERIALS: Patient localization is achieved through detection and digital registration of an independent bite plate system. The bite plate is made and linked to a set of six infrared light emitting diodes (IRLEDs). These IRLEDs are detected by an infrared camera system that identifies the position of each IRLED within 0.1 to 0.15 mm. Calibration of the camera system defines isocenter and translational X, Y, and Z axes of the stereotactic radiosurgery subsystem and thereby digitally defines the virtual treatment room space in a computer linked to the camera system. Positions of the bite plate's IRLEDs are processed digitally using a computer algorithm so that positional differences between an actual bite plate position and a desired position can be resolved within 0.1 mm of translation (X, Y, and Z distance) and 0.1 degree of rotation. Furthermore, bite plate misalignment can be displayed digitally in real time with translational (x, y, and z) and rotational (roll, pitch, and yaw) parameters for an actual bite plate position. Immobilization is achieved by a custom head mold and thermal plastic mask linked by hook-and-loop fastener tape. The head holder system permits rotational and translational movements for daily treatment positioning based on the bite plate localization system. Initial testing of the localization system was performed on 20 patients treated with radiosurgery. The system was used to treat 11 patients with fractionated stereotactic radiotherapy. RESULTS: Assessment of bite plate localization in radiosurgery patients revealed that the patient's bite plate could be positioned and repositioned within 0.5 +/- 0.3 mm (standard deviation). After adjustments, the first 11 patients were treated with the bite plate repositioning error reduced to 0.2 +/- 0.1 mm. CONCLUSIONS: High precision stereotactic radiotherapy can be delivered using separate localization and immobilization systems. Treatment setup and delivery can be accomplished in 15 min or less. Advantages compared with standard systems require further study.  相似文献   

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Parvovirus B19 (PV B19) infection was investigated in 29 pregnant women with fetal hydrops, after exclusion of feto-maternal incompatibility within red blood cell antigens, TORCH infections, feto-maternal hemorrhage and genetics reasons. The active viral infection was detected in 9 women (31%) by PCR amplification of DNA B19; in 2 of them IgM and IgG, in 1 IgM and in 4 IgG antibodies were also present. In 6 women (20%) IgG antibodies were only found, but not IgM and DNA B19, which confirmed infection in the past. In addition in 9 cases DNA B19 was evaluated in the fetal blood. The results in the mothers and their fetuses were concordant (4 positive, 5 negative). Our conclusion is that in nonimmune hydrops fetalis, PV B19 infection should be based on the viral DNA evaluation in the blood of mother (or fetus). IgM antibodies, in time of fetal disorders, might not be detected.  相似文献   

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PURPOSE: To assess the potential changes in the net costs of focal radiotherapy techniques at differing doses per fraction and interfraction intervals. METHODS: Linear quadratic radiobiological modeling is used with appropriate variations in the radiosensitivity and tumor cell proliferation parameters. The notional cost of treatment is calculated from the number of fractions, cost per fraction and the cost of treatment failure, which is itself related to (1-TCP) where TCP is the tumor cure probability. Additional Monte Carlo calculations from ranges of radiobiological parameters have been used to simulate the cost of treatment of tumor populations. RESULTS: The optimum dose per fraction (and optimum overall cost) for conventional (nonfocal) radiotherapy is generally at low doses of around 2 Gy per fraction. The use of hyperfractionated and accelerated radiotherapy in addition to focal radiotherapy techniques appear to be indicated for more radioresistant tumors and if tumor proliferation is extremely rapid, but the need for treatment acceleration is much reduced where effective focal techniques are used. CONCLUSIONS: Radiobiological and economic modeling can be used to guide clinical choices of dose fractionation techniques providing the key radiobiological parameters are known or if the ranges of likely parameters in a tumor population are known. Focal radiotherapy, by the introduction of changes in the physical dose distribution, produces an upward shift in the optimum dose per fraction and a reduced dependency on overall treatment time.  相似文献   

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Currently, the contribution of cellular apoptotic sensitivity to tumor response after radiation therapy remains controversial. To address this issue, the survival of Rat-1 fibroblasts containing a 4-hydroxytamoxifen-regulated c-Myc allele, c-MycER (T. D. Littlewood et al., Nucleic Acids Res., 23: 1686-1690, 1995), after single and fractionated doses of radiation was investigated. This model system allows pharmacological regulation of apoptosis sensitivity in the same cells in vitro and as xenograft tumors derived from these cells in vivo (G. I. Evan et al., Cell, 69: 119-128, 1992; R. M. Alarcon et al., Cancer Res., 56: 4315-4319, 1996). Activating c-MycER in vitro resulted in marked sensitization of Rat-1 fibroblasts to the effects of both single-dose and fractionated irradiation as measured by the induction of apoptosis and clonogenic survival. Overexpression of the antiapoptosis protein Bcl-2 suppressed the induction of apoptosis and increased clonogenic survival in cells with activated c-Myc after single-dose and fractionated radiation. Systemic time-release implant delivery of 4-hydroxytamoxifen to severe combined immunodeficient mice bearing Rat-1-MycER tumors over the course of either single-dose (10 Gy) or fractionated (five fractions of 2 Gy) radiotherapy resulted in prolonged tumor growth delay relative to identical tumors from mice that received placebo implants. Furthermore, tumors derived from Rat-1-MycER cells that overexpressed Bcl-2 exhibited shorter tumor growth delays relative to similarly treated Rat-1-MycER tumors. The length of tumor growth delay after single-dose or fractionated radiotherapy strongly correlated with the extent of radiation-induced apoptosis in the xenograft tumors as measured by terminal deoxynucleotidyl transferase-mediated nick end labeling. These in vivo results provide direct evidence that increasing the sensitivity of tumor cells to die by apoptosis increases the efficacy of fractionated radiotherapy by reducing tumor cell clonogenic survival.  相似文献   

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Objective: The aim of our study was to evaluate the efficacy and safety of gefitinib combined with γ-ray stereotactic radiotherapy for senile patients with adenocarcinoma of lung as the first-line regimen. Methods: The 153 senile patients with adenocarcinoma of lung were divided into 4 groups according to the therapy method. Group A was the 35 patients treated with gefitinib combined with γ-ray stereotactic radiotherapy. Group B was the 45 patients treated with γ-ray stereotactic radiotherapy.Group C was the 42 patients treated with gefitinib. Group D was the 31 patients treated with best supportive therapy.The patients received gefitinib of 250 mg/d from the first day until disease progression or other reasons. The patients were treated six times every week. Results: All the patients were examined by enhanced double helix CT at the second month. The tumor response rate (RR) of group A was 68.6% (24/35). Disease control rate (DCR) was 88.6% (31/35). The median survival year survival rate was 40.0% (14/35). The main side effects included skin rash and diarrhea. The RR of group B was 51.1% survival rate was 15.6 % (7/45). The RR of group C was 40.5 % (17/42). DCR was 61.9% (26 /42). MST was 10.3 months overall 1-year survival rate was 0. The short-term therapeutic effects (RR) of group A was higher than group C (P = 0.014 <0.05, χ2 = 6.053) but has no significant difference with group B (P = 0.116 > 0.05, χ2 = 2.477). The long-term therapeutic effects (overall 1-year survival rate) of group A was higher than group B (P = 0.014 < 0.05, χ2 = 6.077) but has no significant difference with group C (P = 0.642 > 0.05, χ2 = 0.216). Conclusion: Gefitinib combined with γ-ray stereotactic radiotherapy is feasible and effective for treatment in senile patients with adenocarcinoma of lung as the first-line regimen.  相似文献   

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The parasites of the red rockfish Sebastes capensis off northern Chile are described quantitatively for the first time and compared with those of congeneric species of the Northern Hemisphere as well as of other Chilean marine fishes. Sixteen species were recorded, including 8 ectoparasites (2 copepods, 2 isopods, 1 turbellarian, and 3 monogeneans) and 8 endoparasites (2 acanthocephalans, 3 digeneans, and 3 nematodes). The ectoparasites Lepeophtheirus chilensis and Caligus cheilodactylus, and the endoparasites Pseudopecoelus sp. and Corynosoma sp. were predominant. Eighty percent of the fishes harbored 3-6 parasite species. Four parasite genera new to the genus Sebastes were found in S. capensis, which also shares several parasite genera with its congeneric species from other geographic areas. However, in contrast to its congeners, S. capensis exhibits a lower helminth species richness, although when all the metazoan fauna is considered the species number and diversity are similar. When compared with other demersal fishes of the Chilean coast, S. capensis shows a high number of species and high parasite abundance. Diphtherostomum sp. and Gnathia sp. are new generic records for the parasite fauna of Chilean coast fishes and the finding of Paramicrocotyle sp., Neobenedenia melleni, and Interniloculus chilensis in this study represents a new geographical record for these parasites.  相似文献   

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PURPOSE: Stereotactic radiotherapy (SRT) combines techniques of stereotactic radiosurgery (SRS) with radiation therapy fractionation schemes. Fractionation in SRT necessitates a relocatable immobilization system to precisely reproduce the patient's position at each treatment. The Gill-Thomas-Cosman (GTC) head frame is such an immobilization device compatible with the Brown-Roberts-Wells (BRW) stereotactic system. We describe this device, our modifications to the original design, the repeat position accuracy, and the daily verification procedure. METHODS AND MATERIALS: The original GTC frame was tested on volunteers. This testing led to an improved strapping system, the decision to construct the oral fixation appliance at our dental clinic, and the construction of a depth confirmation helmet to rapidly confirm the position of the frame on a daily basis. The GTC frame, at our institution, is not acceptable for children requiring anesthesia, and a new frame, the "Boston Childrens' Hospital" frame, was designed. This device uses the base ring of the GTC frame. Airway access is maintained through fixation on the nasal-glabellar region and the ear canal rather than the hard palate and upper gingiva. RESULTS: The modifications of the GTC frame and the verification protocol result in repeat positioning of the frame with respect to the patient anatomy, with a standard deviation of 0.4 mm for both the modified GTC frame and the Boston Childrens' Hospital frame. The relocatibility of the frames has been established in over 2,000 patient setups in over 60 patients to date. DISCUSSION: The GTC frame is a noninvasive and versatile fixation system that provides patient comfort, as well as accurate relocatibility for SRT. The frame is not appropriate for single fraction radiosurgery, as a large setup error (> 2 mm) for a single treatment cannot be excluded. The GTC frame is compatible with the BRW system, and treatment planning for SRT and SRS patients is identical. We currently treat 10-13 SRT patients per day with intracranial neoplasms on a dedicated stereotactic therapy unit. In addition, the Boston Childrens' Hospital frame allows the use of stereotactic therapy in the treatment of children under 6 years of age. This population will benefit especially from precise and highly focal cranial irradiation.  相似文献   

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PURPOSE: It has been shown that thermochemotherapy (TC) given prior to radiation reduces the number of clonogens, with a resultant decrease in the tumor control radiation dose. The purpose of this article was to investigate using an animal tumor model how this clonogen reduction affects subsequent fractionated radiotherapy, including repopulation of surviving clonogens, and whether the induction TC can increase the therapeutic gain factor (TGF). METHODS AND MATERIALS: The single-cell suspensions prepared from the fourth-generation isotransplants of a spontaneous fibrosarcoma, FSa-II, were transplanted into the C3Hf/Sed mouse foot. TC was given by heating tumors at 41.5 degrees C for 30 min immediately after an intraperitoneal injection of cyclophosphamide (200 mg/kg) when tumors reached an average diameter of 4 mm. Fractionated radiotherapy (R) with equally graded daily doses was initiated 24 h after TC either in air (A) or under hypoxic conditions (H). The 50% tumor control dose (TCD50) and the radiation dose to induce a score 2.0 reaction (complete epilation with fibrosis) in one-half of irradiated animals, RD50(2.0), were obtained, and the TGF was calculated. Our previous results on the fractionated radiotherapy using the same tumor system served as controls. RESULTS: The TCD50(A, single dose) and TCD50(H, single dose) following TC+R were 52.2 and 57.3 Gy, respectively, which were 14.0 and 20.4 Gy lower than those following radiation alone. The TCD50(A, TC+R) increased only slightly when the number of fractions was increased from one to 10 doses, and all TCD50s were significantly lower than the TCD50(A, R alone). Both TCD50(H, TC+R) and TCD50(H, R alone) increased consistently from a single dose to 20 doses, but all TCD50(H, TC+R) were significantly lower than the TCD50(H, R alone). Regarding the normal tissue reaction, the RD50 values both following TC+R and R alone increased consistently from a single dose to 20 daily doses. However, the RD50(TC+R) and RD50(R alone) for each corresponding number of fractions was not significantly different, resulting in the TGFs significantly > 1.0 for combined TC+R treatments, with the exception of 20 daily doses given in air. CONCLUSION: The induction TC decreased the TCD50 values substantially without altering the RD50 for a late reaction, resulting in an significant increase in the TGF. These results encourage the use of TC as an induction treatment prior to fractionated radiotherapy.  相似文献   

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BACKGROUND: During the course of AIDS, 25 to 44% of homosexual patients infected with the human immunodeficiency virus develop Kaposi's sarcoma. Main manifestation is the skin. Response rates of 80 to 100% can be achieved with total dosage up to 50 Gy. Nevertheless, remissions can also be attained with 20 Gy of fractionated radiotherapy. As clinical data on low dose conventional fractionated radiotherapy are insufficient we analysed the response rates of an overall dose of 20 Gy in conventional fractionation. PATIENTS AND METHODS: From June 1991 to June 1993, 43 patients with 111 HIV-associated Kaposi's sarcoma of the skin or oral cavity were treated. Lesions were irradiated with 5 to 12 MeV electrons or 60Co gamma-rays. The fractionation scheme was 5 times 2 Gy/week for skin and endoral lesions with a total reference dosage of up to 20 Gy. Side effects were assessed during therapy and the therapeutic result 6 weeks after end of treatment. RESULTS: Thirty-eight out of 111 lesions were judged as complete response (CR) (34%), 61/111 as partial response (PR) (55%) and 12/111 were judged as no change (NC) (11%). Overall response (CR + PR) was 89%. Two patients with lesions of oral cavity suffered from RTOG grade-IV mucositis after 10 and 14 Gy. In 71/106 skin lesions (67%), radiation induced RTOG grade-1 reactions were observed. CONCLUSION: In patients with HIV associated Kaposi's sarcoma effective palliation can be achieved by means of radiotherapy with an overall dose of 20 Gy in conventional fractionation. Yet, the fraction of patients with complete responses is with 34 to 47% lower compared with doses above 20 Gy (66 to 100%). With reference to the reported data our results point to a dose-response relationship for Kaposi's sarcoma. Therefore higher total reference doses, e.g. 30 Gy with weekly 5 times 2 Gy or 24 Gy with 5 times 1.6 Gy for mucous lesions, respectively, are suggested as by this mean the complete response rate can be doubled.  相似文献   

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为提高自身的产品竞争力,作者所在公司提出新建一座RH炉,采用Rockwell公司的ControlLogix 1756-L6PLC平台作为一级自动化控制系统处理器,利用ControlNet,DeviceNet和Profibus总线实现远程PLC站、智能电机控制中心与主PLC的通信。本文简要介绍梅山钢铁股份有限公司炼钢厂新建RH炉的工艺和控制系统组成,叙述RH炉建设过程中EIC三电系统的设备调试过程。对于三电设备安装调试中遇到的问题,按照设计、设备和应用三个方面提出了解决方案以及今后项目建设中应该注意的问题。  相似文献   

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BACKGROUND: The clinical outcome of patients with ovarian serous tumors of low malignant potential (LMP) remains controversial, especially for those with extraovarian disease. We retrospectively reviewed our experience to study this question further, to assess the safety of conservative management of patients with limited disease, and to determine whether exophytic ovarian surface tumor was predictive of tumor recurrence. METHODS: The clinical and pathologic records of 76 patients with ovarian serous LMP tumors accessioned at the Cleveland Clinic Foundation from 1979 to 1990 were reviewed. International Federation of Gynecology and Obstetrics (FIGO) staging was retrospectively assigned, follow-up information obtained, and clinicopathologic correlations made. RESULTS: An exophytic ovarian surface component was present in 39 of 76 patients (51%). Stage II or III disease was present in 28 of 74 staged patients (38%). Follow-up information was available on 66 patients, ranging from 8 to 264 months (mean, 99 months). Twenty-five patients of 66 patients with follow-up information (38%) received adjuvant therapy. Only 1 patient (1.5%) developed progressive disease; she died of widespread invasive serous carcinoma. Two of 18 conservatively managed patients (11%) developed "recurrent" disease, including 1 patient with a second primary serous LMP tumor of the preserved ovary and 1 patient with an incidentally discovered microscopic serosal implant. There were no other recurrences in the study group, which included four patients with stromal microinvasion and one with lymph node involvement. CONCLUSIONS: The long term outcome of serous LMP tumors is extremely favorable. Exophytic ovarian surface tumor did not serve as a predictor for subsequent peritoneal implants. Conservative surgical management in young patients with localized disease is supported and the use of adjuvant therapy in the initial management of patients with advanced tumors is further questioned.  相似文献   

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A semilongitudinal study was designed to follow-up the course of anxiety and depression in patients undergoing coronary artery bypass graft (CABG) surgery. The focus was on possible effects of gender and age on variations in both mean level and interindividual differences over time. At two timepoints before and two after surgery, 217 patients completed self-report questionnaires. Multivariate testing revealed an overall decrease in mean levels of anxiety and depression in the postoperative period but different trends for men and women. Compared with men, women reported more anxiety and depression, both pre- and postoperatively, but showed a relatively stronger decrease in the early postoperative period. Regarding variations in interindividual differences over time, multivariate testing revealed different trends of depression for men and women. Women appeared to be most homogeneous in the early days after surgery, whereas interindividual differences for men showed a stable trend.  相似文献   

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