• Progress in Medical Physics
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• v.7 no.2
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• pp.3-17
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• 1996

Dose compensators have been widely used in radiotherapy fields. But, few reliable verification methods have been reported. We have developed the verification method for the evaluation of the effect of dose compensator using exit beam dose profile. The exit beam dose profiles were measured with and without dose compensator. For this purpose X-Omat V films and lead screened cassettes are used and dose distibutions are compared. Phantom data are collected using CT simulator(Picker, AcQ Sim) and compensator information can be obtained from Render Plan 3-D planning System. Aluminum Compensators are generated by computer controlled milling machine. The real dose distribution in the phantom and the exit beam dose profile can be obtained simultaneously with the films in the phantom and the opposite site of the beam. Dose compensations effects for oblique beam, parallel opposing beam and inhomogeneous human phantom can be obtained using above tools. And we could simate those effects with exit beam dose profile using the method that we have developed in this study.

• Progress in Medical Physics
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• v.18 no.1
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• pp.7-12
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• 2007

In the radiation therapy for breast cancer patients, wedge shaped compensators are essentially used to achieve appropriate dose distribution because of thickness difference according to breast shapes. Tangential Irradiation technique has usually been applied to radiation therapy for breast cancer patients treated with breast conservative surgery. When a primary beam is incident on wedge shaped compensators from medial direction In tangential irradiation technique, low energy scattered radiation is generated and gives additional dose to the breast surface. As a method to reduced additional dose to breast surface, the use of virtual wedge shaped compensator is possible. Eclipse radiation treatment planning (RTP) systems Installed at our institution have virtual wedge shaped compensator for radiation therapy treatment planning. The dose distributions of 15, 30, 45, 60 degree physical wedges and virtual wedges were measured and compared. Results showed that there was no significant differences In symmetry of $10{\times}10$ field among various wedge angles. When the transmission factor was compared, transmission factor Increased linearly as the wedge angle Increased. These results Indicates that the appilcation of virtual wedge in clinical use is appropriate.

• Radiation Oncology Journal
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• v.10 no.2
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• pp.147-153
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• 1992

It is ideal thing to compensate tissue deficit without skin contamination in curvatured irradiation field of high energy photon beam. The 3-dimensional compensating technique utilizing tissue equivalent materials to ensure an adequate dose distribution and skin sparing effect was described. This compensator was made of paraffin ($70\%$) and stearin wax ($30\%$) compound. The parameters for evaluation of the effect on skin dose in application of compensator were considered in the size of the field, the thickness of the compensator and the source-to-axis distance. The results are as follows; the skin doses were not changed even though application of the compensator, but depended on the field size and the source-to-axis distance, and the skin doses were only slightly changed within $1\%$ relative errors as increasing the thickness of the compensator in these experiments.

• 대한방사선방어학회:학술대회논문집
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• 2011.04a
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• pp.20-21
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• 2011

• Progress in Medical Physics
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• v.12 no.2
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• pp.185-191
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• 2001

The virtual compensator which are realized using a multileaf collimator(MLC) and three-dimensional radiation therapy Planning(3D RTP) system was designed. And the feasibility study of the virtual compensator was done to verify that it can do the function of the conventional compensator properly. As a model for the design of compensator, styrofoam phantom and mini water phantom were prepared to simulate the missing tissue area and the calculated dose distribution was produced through the 3D RTP system. The fluence maps which are basic materials for the design of virtual compensator were produced based on the dose distribution and the MLC leaf sequence file was made for the realization of the produced fluence map. Ma's algorithm were applied to design the MLC leaf sequence and all the design tools were programmed with IDL5.4. To verify the feasibility of the designed virtual compensator, the results of irradiation with or without a virtual compensator were analyzed by comparing the irradiated films inserted into the mini water phantom. The higher dose area produced due to the missing tissue was removed and intended regular dose distribution was achieved when the virtual compensator was applied.

• Progress in Medical Physics
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• v.16 no.2
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• pp.82-88
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• 2005

In this study, the physical compensator made with the high density material, Cerrobend, and the electronic compensator realized by the movement of a dynamic multileaf collimator were analyzed in order to verify the properness of a design function in the commercial RTP (radiation treatment planning) system, Eclipse. The CT images of a phantom composed of the regions of five different thickness were acquired and the proper compensator which can make homogeneous dose distribution at the reference depth was designed in the RTP. The frame for the casting of Cerrobend compensator was made with a computerized automatic styrofoam cutting device and the Millennium MLC-120 was used for the electronic compensator. All the dose values and isodose distributions were measured with a radiographic EDR2 film. The deviation of a dose distribution was $\pm0.99 cGy\;and\;\pm1.82cGy$ in each case of a Cerrobend compensator and a electronic compensator compared with a $\pm13.93 cGy$ deviation in an open beam condition. Which showed the proper function of the designed compensators in the view point of a homogeneous dose distribution. When the absolute dose value was analyzed, the Cerrobend compensator showed a $+3.83\%$ error and the electronic compensator showed a $-4.37\%$ error in comparison with a dose value which was calculated in the RTP. These errors can be admtted as an reasonable results that approve the accuracy of the compensator design in the RTP considering the error in the process of the manufacturing of the Cerrobend compensator and the limitation of a film in the absolute dosimetry.

• The Journal of Korean Society for Radiation Therapy
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• v.17 no.2
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• pp.147-153
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• 2005

Purpose : We should use a computed tomography-simulator for the body measure and compensator manufacture process was practiced with TBI's positioning in process and to estimate the availability.,Materials and Methods : Patient took position that lied down. and got picture through computed tomography-simulator. This picture transmitted to Somavision and measured about body measure point on the picture. Measurement was done with skin, and used the image to use measure the image about lungs. We decided thickness of compensator through value that was measured by the image. Also, We decided and confirmed position of compensator through image. Finally, We measured dosage with TLD in the treatment department.,Results : About thickness at body measure point. we could find difference of $1{\sim}2$ cm relationship general measure and image measure. General measure and image measure of body length was seen difference of $3{\sim}4$ cm. Also, we could paint first drawing of compensator through the image. The value of dose measurement used TLD on head, neck, axilla, chest(lungs inclusion), knee region were measured by $92{\sim}98%$ and abdomen, pelvis, inquinal region, feet region were measured by $102{\sim}109%$.,Conclusion : It was useful for TBI's positioning to use an image of computed tomography-simulator in the process. There was not that is difference of body thickness measure point, but measure about length was achieved definitely. Like this, manufacture of various compensator that consider body density if use image is available. Positioning of compensator could be done exactly. and produce easily without shape of compensator is courted Positioning in the treatment department could shortened overall $15\{sim}20$ minute time. and reduce compensator manufacture time about 15 minutes.

• Radiation Oncology Journal
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• v.20 no.1
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• pp.24-33
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• 2002

Purpose : In order to improve dose homogeneity and to reduce acute toxicity in tangential whole breast radiotherapy, we evaluated two treatment techniques using multiple static fields or universal compensators. Materials and Methods : 1) Multistatic field technique : Using a three dimensional radiation treatment planning system, Adac Pinnacle 4.0, we accomplished a conventional wedged tangential plan. Examining the isodose distributions, a third field which blocked overdose regions was designed and an opposing field was created by using an automatic function of RTPS. Weighting of the beams was tuned until an ideal dose distribution was obtained. Another pair of beams were added when the dose homogeneity was not satisfactory. 2) Universal compensator technique : The breast shapes and sizes were obtained from the CT images of 20 patients who received whole breast radiation therapy at our institution. The data obtained were averaged and a pair of universal physical compensators were designed for the averaged data. DII (Dose Inhomogeneity Index : percentage volume of PTV outside $95\~105\%$ of the prescribed dose) $D_{max}$ (the maximum point dose in the PTV) and isodose distributions for each technique were compared. Results : The multistatic field technique was found to be superior to the conventional technique, reducing the mean value of DII by $14.6\%$ (p value<0.000) and the $D_{max}$ by $4.7\%$ (p value<0.000). The universal compensator was not significantly superior to the conventional technique since it decreased $D_{max}$ by $0.3\%$ (p value=0.867) and reduced DII by $3.7\%$ (p value=0.260). However, it decreased the value of DII by maximum $18\%$ when patients' breast shapes fitted in with the compensator geometry. Conclusion : The multistatic field technique is effective for improving dose homogeneity for whole breast radiation therapy and is applicable to all patients, whereas the use of universal compensators is effective only in patients whose breast shapes fit inwith the universal compensator geometry, and thus has limited applicability.

• Progress in Medical Physics
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• v.19 no.1
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• pp.35-41
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• 2008

The main benefit of proton therapy over photon beam radiotherapy is the absence of exit dose, which offers the opportunity for highly conformal dose distributions to target volume while simultaneously irradiating less normal tissue. For proton beam therapy two patient specific beam modifying devices are used. The aperture is used to shape the transverse extension of the proton beam to the shape of the tumor target and a patient-specific compensator attached to the block aperture when required and used to modify the beam range as required by the treatment plan for the patient. A block of range shifting material, shaped on one face in such a way that the distal end of the proton field in the patient takes the shape of the distal end of the target volume. The mechanical quality assurance of range compensator is an essential procedure to confirm the 3 dimensional patient-specific dose distributions. We proposed a new quality assurance method for range compensator based on image processing using X-ray tube of proton therapy treatment room. The depth information, boundaries of each depth of plan compensatorfile and x-ray image of compensator were analyzed and presented over 80% matching results with proposed QA program.

• Journal of radiological science and technology
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• v.38 no.1
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• pp.17-21
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• 2015

Total body irradiation(TBI) and chemotherapy are the pre-treatment method of a stem cell transplantations of the childhood leukemia. in this study, we evaluate the Quantitative human body dose prior to the treatment. The MCNPX simulation program evaluated by changing the material of the tissue compensators with imitation material of pediatric exposure in a virtual space. As a result, first, the average skin dose with the material of the tissue compensators of Plexiglass tissue compensators is 74.60 mGy/min, Al is 73.96 mGy/min, Cu is 72.26 mGy/min and Pb 67.90 mGy/min respectively. Second, regardless of the tissue compensators material that organ dose were thyroid, gentile, digestive system, brain, lungs, kidneys higher in order. Finally, the ideal distance between body compensator and the patient were 50 cm aparting each other. In conclusion, tissue compensators Al, Cu, Pb are able to replace of the currently used in Plexiglass materials.