• 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.