• Radiation Oncology Journal
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• v.28 no.3
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• pp.177-183
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• 2010

Purpose: Simulation using computed tomography (CT) is now widely available for radiation treatment planning for breast cancer. It is an important tool to help define the tumor target and normal tissue based on anatomical features of an individual patient. In Korea, most patients have small sized breasts and the purpose of this study was to review the margin of treatment field between conventional two-dimensional (2D) planning and CT based three-dimensional (3D) planning in patients with small breasts. Materials and Methods: Twenty-five consecutive patients with early breast cancer undergoing breast conservation therapy were selected. All patients underwent 3D CT based planning with a conventional breast tangential field design. In 2D planning, the treatment field margins were determined by palpation of the breast parenchyma (In general, the superior: base of the clavicle, medial: midline, lateral: mid - axillary line, and inferior margin: 2 m below the inframammary fold). In 3D planning, the clinical target volume (CTV) ought to comprise all glandular breast tissue, and the PTV was obtained by adding a 3D margin of 1 cm around the CTV except in the skin direction. The difference in the treatment field margin and equivalent field size between 2D and 3D planning were evaluated. The association between radiation field margins and factors such as body mass index, menopause status, and bra size was determined. Lung volume and heart volume were examined on the basis of the prescribed breast radiation dose and 3D dose distribution. Results: The margins of the treatment field were smaller in the 3D planning except for two patients. The superior margin was especially variable (average, 2.5 cm; range, -2.5 to 4.5 cm; SD, 1.85). The margin of these targets did not vary equally across BMI class, menopause status, or bra size. The average irradiated lung volume was significantly lower for 3D planning. The average irradiated heart volume did not decrease significantly. Conclusion: The use of 3D CT based planning reduced the radiation field in early breast cancer patients with small breasts in relation to conventional planning. Though a coherent definition of the breast is needed, CT-based planning generated the better plan in terms of reducing the irradiation volume of normal tissue. Moreover it was possible that 3D CT based planning showed better CTV coverage including postoperative change.

• Radiation Oncology Journal
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• v.19 no.1
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• pp.74-80
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• 2001

Purpose : Irradiation cones by using backscatter electrons are made for the treatment of superficial small lesions of skin, oral cavity, and rectum where a significant dose gradient and maximum surface dose is desired. Methods and Materials : Backscatter electrons are produced from the primary electron beams from the linear accelerators. The design consists of a cylindrical cone that has a thick circular plate of high atomic number medium (Pb or Cu) attached to the distal end, and the plate can be adjusted the reflected angle. Primary electrons strike the metal plate perpendicularly and produce backscatter electrons that reflect through the lateral hole for treatment. Using film and a parallel plate ion chamber, backscatter electron dose characteristics are measured. Results : The depth dose characteristic of the backscatter electron is very similar to that of the hard x-ray beam that is commonly used for the intracavitary and superficial lesions. The basckscatter electron energy is nearly constant and effectively about 1.5 MeV from the clinical megavoltage beams. The backscatter electron dose rate of $35\~85\;cGy/min$ could be achieved from modern accelerators without any modification. and the depth in water of $50\%$ depth dose from backscatter electron located at 6mm for $45^{\circ}$ angled lead scatter. The beam flatness is dependent on the slit size and the depth of treatment, but is satisfactory to treat small lesions. Conclusions : The measured data for backscatter electron energy, depth dose flatness dose rate and absolute dose indicates that the backscatter electrons are suitable for clinical use.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.103-109
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• 2005

Isolation and primary culture technique of rabbit oral keratinocytes, and the study for effect of environmental factors on the cell growth were carried out in T75-flask. $1.92{\pm}0.59{\times}10^6$ viable cells were isolated by trypsin enzymatic digestion method from $0.25cm^2$ biopsy of rabbit oral mucosa. Primary culture with 10 mL of K-SFM containing 50 mg/L BPE, $5.0{\mu}g/L$ EGF and 0.15 mM $Ca^{2+}$ showed confluence after 8 days and doubling time was 2.54 days. Effect of medium types, medium volume and supplement types on the cell growth was investigated after the cultured keratinocytes had been harvested from primary confluence. Serum addition showed adverse effect and the increase of serum concentration didn't have an effect on the cell growth. The increase of medium volume decreased the cell growth. The increase of calcium concentration increased the cell growth and 2.0 mM was optimum value. In conclusion, when rabbit oral keratinocytes was cultured in T75-flask, the most effective conditions was to use 10 mL of K-SFM containing 50 mg/L BPE, $5.0{\mu}g/L$ EGF and 2.0 mM $Ca^{2+}$, and doubling time was 1.32 days. This study can provide the useful informations to develop a process and design a bioreactor for the culture of keratinocytes in human body like skin and cornea, as well as mucosa.