Critical Factors of Dose Distribution in Breast Cancer Tomotherapy With Metallic Port Breast Tissue Expander: Image Correction, Delivery Mode, and Volume Impact.

Objectives: Breast reconstruction helps patients enhance their body image after mastectomy. Metallic ports in tissue expanders lead to dose attenuation during radiotherapy. Tissue expander volume shifts the metallic port position, possibly causing various dose alterations. This study aimed to evaluate the impact of the MAGNA-SITETM tissue expander volume on tomotherapy. Methods: Boluses and MAGNA-SITETM were placed on a Rando phantom to simulate the tissue expander under the pectoralis major. Computed tomography simulation images were transformed through replacing the electron density of (a) metallic artifact region only (Image metallic port) and (b) metallic port and artifact regions (Image Homo). Planning was calculated using fixed-beam and helical-mode techniques. Radiation was delivered with different volumes of the tissue expander. Results: Integrated 997 dose points were calculated. Planning with Image metallic port provided a calculated dose significantly closer to a realistic dose. The percentage of doses achieving the prescribed dose was significantly higher in the helical mode. In layer 2, the 100-mL tissue expander had a significantly lower measurement dose than all other volumes. Volume 150 mL had the highest increase in the measured dose difference from the plan dose at layer 2. Volume 250 mL had the highest percentage of measurement doses passing the 5% dose difference from plan dose. The coldest dose areas were noted in layers 1 and 2, especially in the metallic port-direct image mode. The average dose reduction of the measured cold areas was 6.03 ± 1.94%. Conclusion: Dose distribution was affected by the volume of the metallic port tissue expander. Tomotherapy with proper image heterogeneity correction and helical mode can reduce the attenuation from the metallic port. A tissue expander volume of 150 to 250 mL is suitable. Patients with high risk at the chest wall should be evaluated carefully to avoid underdosing. Radiation oncologists should closely cooperate with plastic surgeons to optimize treatment for each patient.

Sputter-prepared (001) BiFeO3 thin films with ferromagnetic L10-FePt(001) electrode on glass substrates.

Highly textured BiFeO3(001) films were formed on L10-FePt(001) bottom electrodes on glass substrates by sputtering at reduced temperature of 400°C. Good electric polarization 2Pr = 80 and 95 µC/cm2, comparable to that of the reported epitaxial films, and coercivity Ec = 415 and 435 kV/cm are achieved in the samples with 20-nm- and 30-nm-thick electrodes. The BiFeO3(001) films show different degrees of compressive strain. The relation between the variations of strain and 2Pr suggests that the enhancement of 2Pr resulted from the strain-induced rotation of spontaneous polarization. The presented results open possibilities for the applications based on electric-magnetic interactions.

Whole pelvic helical tomotherapy for locally advanced cervical cancer: technical implementation of IMRT with helical tomotherapy.

BACKGROUND: To review the experience and to evaluate the treatment plan of using helical tomotherapy (HT) for the treatment of cervical cancer. METHODS: Between November 1st, 2006 and May 31, 2009, 10 cervical cancer patients histologically confirmed were enrolled. All of the patients received definitive concurrent chemoradiation (CCRT) with whole pelvic HT (WPHT) followed by brachytherapy. During WPHT, all patients were treated with cisplatin, 40 mg/m2 intravenously weekly. Toxicity of treatment was scored according to the Common Terminology Criteria for Adverse Events v3.0 (CTCAE v3.0). RESULTS: The mean survival was 25 months (range, 3 to 27 months). The actuarial overall survival, disease-free survival, locoregional control and distant metastasis-free rates at 2 years were 67%, 77%, 90% and 88%, respectively. The average of uniformity index and conformal index was 1.06 and 1.19, respectively. One grade 3 of acute toxicity for diarrhea, thrombocytopenia and three grade 3 leucopenia were noted during CCRT. Only one grade 3 of subacute toxicity for thrombocytopenia was noted. There were no grade 3 or 4 subacute toxicities of anemia, leucopenia, genitourinary or gastrointestinal effects. Compared with conventional whole pelvic radiation therapy (WPRT), WPHT decreases the mean dose to rectum, bladder and intestines successfully. CONCLUSION: HT provides feasible clinical outcomes in locally advanced cervical cancer patients. Long-term follow-up and enroll more locally advanced cervical carcinoma patients by limiting bone marrow radiation dose with WPHT technique is warranted.

Total marrow irradiation with helical tomotherapy for bone marrow transplantation of multiple myeloma: first experience in Asia.

Three Asian patients with plasma cell myeloma stage IIIa with IgG predominant were selected for autologous hematopoietic cell transplantation (HSCT). Total marrow irradiation (TMI) tomotherapy planned with melphalan 140 mg/m2 as a preconditioning regimen of HSCT. Two image sets of computed tomography (CT) were scanned with 2.5 mm and 5 mm for the upper and lower part of the plan, respectively. The junction was determined and marked at 15 cm above knee on both thighs for upper and lower part of the plan. The clinical target volume (CTV) included the entire skeletal system. The planning target volume (PTV) was generated with with 0.8 cm for CTV(extremities) and with 0.5 cm margin for all other bones of CTV. A total dose of 800 cGy (200 cGy/fraction) was delivered to the PTV. Update to presentation, all of three patients post transplant without evidence of active disease were noted. During TMI treatment, one with grade 1 vomiting, two with grade 1 nausea, one with grade 1 mucositis, and three with grade 1 anorexia were noted. Toxicity of treatment was scored according to the Common Terminology Criteria for Adverse Events v3.0 (CTCAE v3.0). The average for upper part versus lower part of PTV (Bone marrow) of CI and H-index were 1.5 and 1.4 versus 1.2 and 1.2, respectively. The dose reduction of TMI tomotherapy to various OARs of head, chest, and abdomen relative to TBI varied from 31% to 74%, 21% to 51%, and 46% to 63%, respectively. The maximum average value of registration for upper torso versus lower extremities in different translation directions were 5.1 mm versus 4.1 mm for pretreatment and 1.5 mm versus 0.7 mm for post-treatment, respectively. The average treatment time for the upper versus lower part in beam-on time, setup time, and MVCT registration time took roughly 49.9, 23.3, and 11.7 min versus 11.5, 10.0, and 7.3 min, respectively. The margin of PTV could be less than 1 cm under good fixation and close position confirmation with MVCT. Antiemetics should be prescribed in the whole course of TMI for emesis prevention. TMI technique replaced TBI technique with 8 Gy as conditioning regiment for multiple myeloma could be acceptable for the Asian and the outcomes were feasible for the Asian.