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T Strickert

Publications and source records attributed to T Strickert.

7 recordsLinked to original sources
PubMed2005

Fricke gel as a tool for dose distribution verification: optimization and characterization.

With the introduction of conformal techniques in radiation therapy, gel dosimetry plays an important role as a 3D dose verification system. There are two main types of gels in use for dosimetry: Fricke gels and polymer gels. The advantages of polymer gels are improved dose response and stability with no diffusion problems. However, the more complicated fabrication procedure and the greater cost compared to Fricke gels makes polymer gels less attractive in routine clinical use. Dose resolution has recently been introduced as a concept for comparing and optimizing the performance of different types of gel dosimeters. This parameter has not yet been investigated for Fricke gels. In this study, the effect on the dose resolution and the diffusion from different gelatine- and Fe2+-concentrations and different pH was evaluated. Increasing the concentration of gelatine from 6 wt% to 10 wt% influenced the diffusion coefficient the most, while reducing the pH from 2.0 to 1.5 had the largest effect on the dose resolution. For a gel consisting of 10 wt% gelatine, 1.0 mM Fe2+ and pH 1.5 the diffusion coefficient was found to be 1.5 mm2 h-1 and the dose resolution was about 4.1% (at 95% confidence level), for a dose of 40 Gy. By evaluating different dose gradients by the gamma-method, the diffusion was shown to have no clinically relevant impact on the dose distribution and plan acceptance within 3 h of irradiation. The results indicate a potential use of Fricke gels for IMRT verification.

Diffusion↗
PubMed2001

Late reactions after postoperative high-dose-rate intravaginal brachytherapy for endometrial cancer: a comparison of standardized and individualized target volumes.

PURPOSE: To compare retrospectively two treatment protocols for postoperative intravaginal brachytherapy as to frequency of late radiation reactions and vaginal recurrence of disease. METHODS AND MATERIALS: Two hundred seventeen patients with Stage I-II endometrial carcinoma underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy, followed by high-dose-rate (HDR) intracavitary irradiation, 5.5 Gy x 4 (22 Gy), to the upper 5 cm of the vagina. From 1988 to August 1991, the reference isodose was at 5 mm from the mucosal surface (standard treatment, 96 pts). From September 1991 to June 1996, the reference isodoses were chosen at 3 mm, 4 mm, or 5 mm depth depending on a clinical estimation of the mucosal thickness (individualized treatment, 121 pts). Maximum bladder and rectum doses were calculated from orthogonal X-ray films. RESULTS: The patients were followed for 3 to 10 years. The rate of late vaginal reactions Grade 1 and 2 were 26% and 8%, respectively, after standard treatment, vs. 17% and 1% after individualized treatment (p = 0.005). Bladder reaction rates were 9% Grade 1 and 1% Grade 2 after standard treatment vs. 1% Grade 1 after individualized treatment (p = 0.005). Rectum reactions Grade 1 were seen in 5% and 1%, respectively. No Grade 3 reactions were observed. The reactions appeared after a median time interval of 9 months and 11 months, respectively. The rate of vaginal reactions was strongly correlated to the dose on the surface of the vaginal applicator, and the bladder reaction rate correlated with the calculated maximum bladder dose. Local vaginal recurrences were seen in 1 patient (1.0%) in the standard treatment group and in 3 patients (2.5%) in the individualized treatment group (p = 0.78). CONCLUSIONS: By individualizing the depth of the reference dose in the vaginal mucosa according to its thickness and avoiding applicators with small diameters, the rate of reactions can be reduced without any significant increase in vaginal recurrences.

Adult↗
PubMed2001

10-Gy single-fraction pelvic irradiation for palliation and life prolongation in patients with cancer of the cervix and corpus uteri.

OBJECTIVE: The goal of this study was to evaluate the effects of single fractions of 10 Gy pelvic irradiation for palliation and life prolongation in patients with cancer of the uterine cervix or corpus. METHODS: A retrospective analysis was performed on 37 cervical cancer and 27 corpus cancer patients treated in the period 1988-1998. All patients had a life expectancy of less than 1 year. Due to stage of disease, age (median 82 years), or comorbidity they were considered unapt for surgery or conventional radiotherapy. Eleven patients with recurrence within irradiated field or early progression received one, 51 patients received two, and 2 patients received three fractions with a 4-week interval. RESULTS: Vaginal bleeding stopped in 90% and malodorous discharge in 39% of the patients. Among 46 patients with advanced disease treated for palliation, 10 (22%) showed complete tumor responses. Median time to progression was 6 months, and median survival, 9 months. Eighteen patients with early-stage disease and serious comorbidity were treated with life prolongation and symptom prevention as intention, and showed seven complete responses. Median survival was 13 months, and half the deaths were caused by intercurrent disease. Median hospital stay was 5 days and rehabilitation was easy. Fifty-six percent of the patients experienced no acute side effects and 33% had minor gastrointestinal problems. Three patients (6%) had serious late bowel complications, one with a fatal outcome, the symptoms appearing 9-10 months posttreatment. CONCLUSION: The 10-Gy single-fraction pelvic radiation regimen is an effective means of symptom palliation and is well tolerated. Tumor responses are obtained. The risk of late bowel complications is a concern for patients with a life expectancy greater than 9 months.

Adenocarcinoma↗
PubMed2000

Primary treatment of cervical carcinoma. Ten years experience from one Norwegian health region.

OBJECTIVE: To study the primary care of cervical carcinoma with regard to clinical and pathological factors, treatment decisions, complications and survival. DESIGN: A historical cohort comprising all women hospitalized with invasive cervical carcinoma (n=293) during the period 1987-1996. RESULTS: Median age was 52 years (range 23-90). FIGO stage distribution was 62%, 15%, 18% and 5% in stages I, II, III and IV, respectively. Early stage disease correlated with young age. Histologic types were: squamous cell carcinoma 84%, adenocarcinoma 11%, adenosquamous carcinoma 4% and small cell/anaplastic carcinoma 1%. Primary therapies were: surgery 188 women (64%), radiotherapy 99 women (34%), chemotherapy two women (0.7%); four women not treated (1.3%). Complications after surgery in 25 women (13%), none were fatal. Acute or late complications after primary or postoperative radiotherapy in 39 women (25%), seven (4.6%) were late serious complications. Three women died from complications related to radiotherapy. Mean follow-up of surviving patients was 58 months. Overall disease specific five-year survival was 70%. Five-year survival in stages IA, IB, II and III was 100%, 88%, 58% and 20%, respectively. One-year survival in stage IV was 31%. Median survival in stages III and IV according to curative or palliative aim of treatment was 20 and 6 months, respectively (p<0.005). CONCLUSION: Satisfactory quality of diagnosis and therapy have been maintained through regional care for cervical cancer patients.

Adenocarcinoma↗
PubMed1996

Changes in radiation sensitivity and steroid receptor content induced by hormonal agents and ionizing radiation in breast cancer cells in vitro.

Possible influences of tamoxifen and estradiol on in vitro radiation sensitivity and cellular receptor content after irradiation and/or tamoxifen treatment were studied in breast cancer cell lines; estrogen receptor (ER) and progesterone receptor (PgR) positive cell lines MCF-7 and MCF-7/TAM(R)-1 and the ER and PgR negative cell line MDA-MB-231. The tamoxifen resistant MCF-7/TAM(R)-1 cells were more resistant to ionizing radiation than the MCF-7 and MDA-MB-231 cells. Exposure to tamoxifen made the MCF-7 cells more radiation resistant, while estradiol made the MDA-MB-231 cells more radiation sensitive. A radiation dose of 6 Gy reduced the ER content in cytosol in both MCF-7 and MCF-7/TAM(R)-1 cells, but brought no alterations to the PgR content. In MCF-7/TAM(R)-1 cells tamoxifen exposure significantly increased the ER and reduced the PgR content, an effect not observed in the MCF-7 cells. To conclude, the present study indicates that irradiation and tamoxifen may modify the ER and PgR content in cytosol in breast cancer cells. Hormonal treatment may alter the radiation sensitivity, even in ER negative cells, suggesting that hormonal agents may act both via receptor and non-receptor binding mechanisms.

Antineoplastic Agents, Hormonal↗
PubMed1984

The value of complete lymphadenectomy in radical treatment of cancer of the cervix, Stage IB.

Two hundred ninety-three patients with Stage IB carcinoma of the uterine cervix were treated by intracavitary irradiation followed by radical hysterectomy and pelvic lymph node dissection in the 3-year period 1970 to 1972, inclusive. Preoperative lymphography was performed and intraoperative films were taken to obtain a lymphadenectomy that was as complete as possible. The number and location of remaining nodes were determined by postoperative films. No patients were lost to follow-up. The 5- and 10-year survival and recurrence rates were correlated to the number of remaining nodes. It is concluded that patients with four or more remaining nodes have a possible inferior prognosis compared with the rest of the patients. Meticulous and time-consuming search for a few remaining nodes was, however, not found to be justified.

Adenocarcinoma↗