Implementing a tantalum wire mesh to increase the skin dose in low-energy electron irradiation of the chest wall.

Radiation treatment of the post-mastectomy chest wall is performed in our institution by straight-on electron irradiation. The chest-wall thickness is measured and the beam energy is chosen so that the chest wall is treated to therapeutic doses, while sparing the underlying lung tissue. The most commonly chosen energies are 6 and 9 MeV. The skin dose should be 90% of the dose prescribed to the chest wall, which is higher than can be achieved with 6- and 9-MeV beams because of the low surface dose. The addition of a bolus slab during part of the treatment can correct for this; however, the added depth means that a higher energy has to be chosen, which will increase the lung dose (the higher the electron energy, the slower the falloff of the electron depth-dose curve). A mesh of a high-Z material above the skin gives rise to obliquely scattered and low-energy electrons that effectively spoil the buildup zone. Dosimetric measurements of a Tantalum (Ta) mesh were performed using a dose scanner in a water tank and a film inserted in a humanoid phantom during a simulated treatment. Measurements were also done for the clinically relevant cases of oblique beam incidence and with the mesh placed 1 cm above the surface. The measurements demonstrate the spoiling of the buildup zone, while having only a moderate influence on the dose distribution beyond the dose maximum. The mesh also changes the absolute dose. In a fractionated regime, the first part of the treatment would be without the mesh, adding it only during the latter fractions. The total dose distribution gives 90% to the skin, while leaving the depth-dose characteristics beyond the dose maximum virtually unchanged.

[Breast conservation: safe for early breast cancer].

Between 1981-1993 581 women with primary breast cancer were treated by breast conservation. Their mean age was 56 +/- 12 years and 63% were postmenopausal and 37% pre- or perimenopausal. The median follow-up time was 56 months. 45% had pathological Stage I disease, 49% Stage II, 2.5% Stage III and 3.5% clinical Stage I-II disease. 54% of lesions were excised with good margins, 10% with close margins (< 0.5 cm), 9% with microscopic residual, 3% with macroscopic residual, and in 24% margins were not reported. Adjuvant therapy, consisting of combination chemotherapy and/or hormones, was given to 69%. Radiotherapy, usually 50 Gy tangential photon irradiation to the whole breast, was given to 564 (97%); an electron or photon "boost" to the tumor with a median dose of 17.5 Gy was given to 378 (65%). Most of those with positive nodes received 50 Gy to the lymphatic drainage system. 1 year after radiotherapy cosmetic results were rated as "good" or "excellent" in 80%, "moderate" in 17% and "poor" in 3%. The 5-year actuarial survival was 97% in Stage I and 88% in Stage II. 37 patients (6.5%) developed breast recurrence; 11 of these (2%) had simultaneous distant metastases. 5 (< 1%) developed axillary or supraclavicular lymph node metastases, and 81 (14%) developed distant metastases. Most local recurrences were in those younger than 40, and in those with primary tumors > 1.75 cm. The satisfactory level of local control achieved is attributed to the high doses of radiation (up to 75 Gy) administered to those with high risk lesions.

Metastatic spinal cord compression as initial presentation of follicular thyroid carcinoma.

Follicular thyroid carcinoma, initially presenting as spinal cord compression due to metastatic lesions, is a less reported event. We present two cases of well-differentiated thyroid carcinoma that led to spinal cord compression. A thorough search of the literature revealed only five similar cases. We summarize the clinical characteristics of these cases, the therapeutic measures used, their outcome, and the prognosis.