Biomedical subjects

Jorgen L Hansen

Publications and source records attributed to Jorgen L Hansen.

3 recordsLinked to original sources

PubMed2005

CT computer-optimized high-dose-rate brachytherapy with surface applicator technique for scar boost radiation after breast reconstruction surgery.

PURPOSE: Immediate breast reconstruction has become increasingly prevalent after mastectomy for breast cancer. Postoperative scar boost radiation for the reconstructed breast presents many planning challenges due to the shape, size, and curvature of the scar. High-dose-rate (HDR) surface applicator brachytherapy is a novel and effective method of delivering scar boost radiation. Two cases, one with a saline implant and one with a transverse rectus abdominis musculocutaneous flap reconstruction, illustrate the method and advantages of HDR optimization of surface applicators. METHODS AND MATERIALS: For 2 patients a mold of the breast was made with Aquaplast sheets. A reproducible system was used for arm positioning. Skin fiducials, including tattoos from external beam planning, were matched to fiducials on the mold. HDR catheters were sited on the mold at 1cm intervals, with the central catheter situated along the scar. Topographically, both scars demonstrated extreme curvature in both craniocaudal and mediolateral directions. A CT computer-optimized HDR plan was developed, with the reference dose prescribed at the skin surface. The dosimetry was compared to single-field and matched-field electron plans. RESULTS: This surface applicator technique provided a uniform skin dose of 100% to the entire clinical target volume (CTV) without hot spots in both patients. The patient position and surface applicator setup were consistently reproducible. The patients tolerated the treatment well with minimal skin erythema. In the single-field electron plan, skin dose was decreased to 50% at the periphery of the scar. Matching fields addressed this depth dose decrement, but resulted in large localized hot spots of more than 200% centrally in each field. CONCLUSION: CT computer-optimized HDR surface applicator brachytherapy provided a reproducible homogeneous method of treating highly curved scars on the reconstructed breast. Electron beam treatment would result in longer and more complex treatments yet still provide a less homogeneous dose than this surface applicator technique.

Brachytherapy↗

PubMed2005

Hyperthermia combined with radiation in treatment of locally advanced prostate cancer is associated with a favourable toxicity profile.

PURPOSE: Hyperthermia is used to treat several pelvic tumours. An important step in establishing a broader role for hyperthermia in treatment of prostate cancer is verification of an acceptable toxicity profile. In this report, short- and long-term toxicity profiles of a completed phase II trial of transrectal ultrasound hyperthermia combined with radiation in treatment of locally advanced prostate cancer are presented. METHODS AND MATERIALS: Thirty-seven patients enrolled on a phase II study of external beam radiation +/- androgen suppression with two transrectal ultrasound hyperthermia treatments were assessed for short- and long-term toxicity. Prostatic and anterior rectal wall temperatures were monitored. Rectal wall temperatures were limited to 40 degrees C (19 patients), 41 degrees C (three patients) and 42 degrees C (15 patients). Univariate logistic regression was used to estimate the log hazard of developing NCI CTC Grade 2 toxicity based on temperature parameters. Hazard ratios, 95% confidence intervals, p-values for statistical significance of each parameter and proportion of variability explained for each of the parameters were calculated. RESULTS: Median follow-up was 42 months. Both short- and long-term GI toxicity were limited to grade 2 or less. Acute grade 2 proctitis was greater for patients with allowable rectal wall temperature of >40 degrees C. Eleven of 18 patients in this group had acute grade 2 proctitis vs three of 19 patients with rectal wall temperatures limited to 40 degrees C (p = 0.004). Long-term grade 2 GI and GU toxicity occurred in 5% and 19% of patients. No late grade 3 or greater toxicity occurred. Late GI and GU toxicity were not associated with the allowable rectal wall temperature. CONCLUSION: Transrectal ultrasound hyperthermia combined with radiation for treatment of advanced clinically localized prostate cancer is safe and well tolerated.

Aged↗

PubMed2002

Association of rectal toxicity with thermal dose parameters in treatment of locally advanced prostate cancer with radiation and hyperthermia.

PURPOSE: Although hyperthermia has been used for more than two decades in the treatment of pelvic tumors, little is known about the potential impact of heat on rectal toxicity when combined with other treatment modalities. Because rectal toxicity is a concern with radiation and may be exacerbated by hyperthermia, definition of the association of thermal dose parameters with rectal toxicity is important. In this report, we correlate rectal toxicity with thermal dose parameters for patients treated with hyperthermia and radiation for prostate cancer. METHODS AND MATERIALS: Thirty patients with T2b-T3b disease (1992 American Joint Committee On Cancer criteria) enrolled in a Phase II study of external beam radiation +/- androgen-suppressive therapy with two transrectal ultrasound hyperthermia treatments were assessed for rectal toxicity. Prostatic and anterior rectal wall temperatures were monitored for all treatments. Rectal wall temperatures were limited to 40 degrees C in 19 patients, 41 degrees C in 3 patients, and 42 degrees C in 8 patients. Logistic regression was used to estimate the log hazard of developing National Cancer Institute Common Toxicity Criteria Grade 2 toxicity based on temperature parameters. The following were calculated: hazard ratios, 95% confidence intervals, p values for statistical significance of each parameter, and proportion of variability explained for each parameter. RESULTS: Gastrointestinal toxicity was limited to Grade 2. The rate of acute Grade 2 proctitis was greater for patients with an allowable rectal wall temperature of >40 degrees C. In this group, 7 of 11 patients experienced acute Grade 2 proctitis, as opposed to 3 of 19 patients in the group with rectal wall temperatures limited to 40 degrees C (p = 0.004). Preliminary assessment of long-term toxicity revealed no differences in toxicity. Hazard ratios for acute Grade 2 proctitis for allowable rectal wall temperature, average rectal wall Tmax, and average prostate Tmax were 9.33 (p = 0.01), 3.66 (p = 0.03), and 2.29 (p = 0.08), respectively. A model combining these three parameters explained 48.6% of the variability among groups. CONCLUSION: Rectal toxicity correlates with maximum allowable rectal wall temperature, average rectal wall Tmax, and average prostate Tmax for patients undergoing transrectal ultrasound hyperthermia combined with radiation for treatment of advanced clinically localized prostate cancer. Further definition of this association of thermal dose parameters with rectal toxicity in treatment of pelvic malignancies with hyperthermia should advance the goal of delivering thermal therapy in an effective yet safe manner.

Digestive System↗