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

• Progress in Medical Physics
• /
• v.23 no.4
• /
• pp.269-278
• /
• 2012

Aquaplast Thermoplastic (AT) is a tissue-equivalent oral compensator that has been developed to improve dose uniformity at the common boundary and around the treated area during radiotherapy in patients with head and neck cancer. In order to assess the usefulness of AT, the degree of improvement in dose distribution and physical properties were compared to those of oral compensators made using paraffin, alginate, and putty, which are materials conventionally used in dental imprinting. To assess the physical properties, strength evaluations (compression and drop evaluations) and natural deformation evaluations (volume change over time) were performed; a Gafchromic EBT2 film and a glass dosimeter inserted into a developed phantom for dose verification were used to measure the common boundary dose and the beam profile to assess the dose delivery. When the natural deformation of the oral compensators was assessed over a two-month period, alginate exhibited a maximum of 80% change in volume from moisture evaporation, while the remaining tissue-equivalent properties, including those of AT, showed a change in volume that was less than 3%. In a free-fall test at a height of 1.5 m (repeated 5 times as a strength evaluation), paraffin was easily damaged by the impact, but AT exhibited no damage from the fall. In compressive strength testing, AT was not destroyed even at 8 times the force needed for paraffin. In dose verification using a glass dosimeter, the results showed that in a single test, the tissue-equivalent (about 80 Hounsfield Units [HU]) AT delivered about 4.9% lower surface dose in terms of delivery of an output coefficient (monitor unit), which was 4% lower than putty and exhibited a value of about 1,000 HU or higher during a dose delivery of the same formulation. In addition, when the incident direction of the beam was used as a reference, the uniformity of the dose, as assessed from the beam profile at the boundary after passing through the oral compensators, was 11.41, 3.98, and 4.30 for air, AT, and putty, respectively. The AT oral compensator had a higher strength and lower probability of material transformation than the oral compensators conventionally used as a tissue-equivalent material, and a uniform dose distribution was successfully formed at the boundary and surrounding area including the mouth. It was also possible to deliver a uniformly formulated dose and reduce the skin dose delivery.

• Radiation Oncology Journal
• /
• v.7 no.1
• /
• pp.133-140
• /
• 1989

Three-dimension paraffin compensator was designed to construct the tissue equivalent compensator for irregular body contours and obiliques beam incidence. The ratio of compensator thickness to tissue deficit was depended on field size, depth and air gap because the scattered dose loss. The ratio of compensator-tissue was optimized 0.79, 0.73, 0.61 and 0.56 in 6MV x-rays as function of field size $4{\times}4$, $10{\times}10$, $20{\times}20$ and $30{\times}30cm^2$ respectively. in our study. Using this tissue equivalent compensator, it can be got 2% difference of dose at same mid-plane in phantom study.

• The Journal of the Korea Contents Association
• /
• v.14 no.4
• /
• pp.249-255
• /
• 2014

Total body irradiation use one of the pre-treatment as hematopoietic stem cell transplantation in the treatment of leukemia. According to the study of Korean network for organ sharing 2013 report, continue to increase the number of hematopoietic stem cell transplantation. however, the current dose evaluation fall short before treatment. So purpose of this study is Surface dose and deep organ dose evaluation and then find the most ideal conditions when change of the thickness on tissue compensator in TBI. Result, surface dose in 4 MV, SSD 280 cm, compensators thickness 0.5 cm, was measured the highest dose 5.84 mGy/min. And the ideal dose showed when compensator thickness less than 1 cm.

• Radiation Oncology Journal
• /
• v.7 no.1
• /
• pp.123-132
• /
• 1989

A radiation beam incident on an irregular or sloping surface produces the non-uniformity of absorded dose. The use of a tissue compensator can partially correct this dose inhomogeneity. The tissue compensator is designed based on the patient's three dimensional contour. After required compensator thickness was determined according to tissue deficit at $25cm\pm25cm$ field size, 10cm depth for 6MV x-rays, tissue deficit was mapped by isoheight technique using laser beam system. Compensator was constructed along the designed model using 0.8mm lead sheet or 5mm acryl plate. Dosimetric verification were peformed by film dosimetry using humanoid phantom. Dosimetric measurements were normalized to central axis full phantom readings for both compensated and non-compensated field. Without compensation, the percent differences in absorbed dose ranged as high as $12.1\%$ along transverse axis, $10.8\%$ along vertical axis. With the tissue compensators in place, the difference was reduced to $0\~43\%$ Therefore, it can be concluded that the compensator system constructed by isoheihnt technique can produce good dose distribution with acceptible inhomogeneity, and such compensator system can be effectively applied to clinical radiotherapy.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2005.05a
• /
• pp.907-910
• /
• 2005

방사선치료에서 결손조직의 보호를 위해 사용되는 기존의 결손조직 보상체는 체표윤곽을 얻기위해 컴퓨터단층촬영영상이나 자기공명촬영영상등의 의료영상을 이용해 왔다. 하지만 이러한 촬영을 위해서는 고가의 비용이 소요되고 방사선치료에 따른 체표윤곽의 변화에 적절히 대응하지 못하는 등의 단점이 지적되고 있다. 따라서 본 연구에서는 사용이 간편한 디지털 카메라로 환자를 촬영한 후 얻은 2차원 이미지를 이용하여 결손조직 보상체를 제작하고 이의 유용성 평가를 위해 기하학적, 선량학적 평가를 수행하였다. 그 결과, 조직결손을 보정하고 정상조직을 보호할 수 있어 임상적용의 가능성을 확인 할 수 있었다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.06a
• /
• pp.10-12
• /
• 2006

U-Health에 대한 연구는 환자, 의료장비에 대한 위치 추적을 통한 의료업무 지원관리 분야로 집중되고 있다. 본 논문에서는 RFID Tag를 의료 측정에 적용한다. 즉, RFID Tag를 이용하여 방사선치료에서 사용되는 결손조직 보상체의 체표 윤곽을 모델링하는 방법을 제안한다. 기존의 모델링 방법은 환자의 체표 윤곽을 컴퓨터단층촬영이나 자기공명촬영을 사용한 의료영상을 이용해왔다. 이러한 방법은 고가의 비용이 소요되고 방사선치료에 따른 체표윤곽의 변화에 대응하지 못한다. 본 연구에서는 U-Health에서 기본적으로 사용하는 RFID Tag를 환자의 체표윤각에 고정하여 3차원 위치정보를 획득한다. 체표윤곽에 위치한 RFID의 상대적 위치를 통해 결손조직 보상체를 제작하고 이의 유용성 평가를 위해 기하학적, 선량학적 평가를 수행하였다.

• Journal of The Korean Radiological Technologist Association
• /
• v.29 no.1
• /
• pp.6-11
• /
• 2003

목적 : 전신방사선조사(TBI)시 균등한 선량을 조사할 목적으로 사용되는 각 신체부위별 보상체(compensator) 두께의 결정은 열형광선량계(TLD)를 이용하여 표면선량(surface dose)을 측정하고, 심부선량(depth dose)으로 환산하는 방법을 주로 이용한다. 그러나 이와 같은 방법은 골(bone) 조직에 대한 선량감쇠(dose attenuation)의 영향이 고려되지 않아 신체중심부에서의 정확한 심부선량을 알 수가 없다. 이에 본 연구

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

• The Journal of Korean Society for Radiation Therapy
• /
• v.25 no.1
• /
• pp.15-24
• /
• 2013

Purpose: In Asan Medical Center, Two parallel opposite beams are employed for total body irradiation. Patients are required to be in supine position where two arms are attached to mid axillary line. Normally, physical compensators are required to compensate the large dose difference for different parts of body due to the different thicknesses compared to the umbilicus separation. There was the maximum dose difference up to 30% in lung and chest wall compared to the prescription dose. In order to resolve the dose discrepancy occurring on different body regions, the feasibility of using Fieid-in-Field Technique is investigated in this study. Materials and Methods: CT scan was performed to The RANDO Phantom with fabricated two arms and sent to Eclipse treatment planning system (version 10.0, Varian, USA). Conventional plan with physical lead compensator and new plan using Field-in-Field Technique were established on TPS. AAA (Anisotropic Analytical Algorithm) dose calculation algorithm was employed for two parallel opposite beams attenuation. Results: The dose difference between two methods was compared with the prescription dose. The dose distribution of chest and anterior chest wall uncovered by patient arms was 114~124% for physical lead compensator while Field-in-Field Technique gave 106~107% of the dose distribution. In-vivo dosimetry result using TLD showed that the dose distribution to the same region was 110~117% for conventional physical compensator and 104~107% for Field-in-Field Technique. Conclusion: In this study, the feasibility of using FIF technique has been investigated with fabricated arms attached Rando phantom. The dose difference was up to 17% due to the attached arms. It is shown that the dose homogeneity is within ${\pm}10%$ with the CT based 3-dimensional 4 step FIF technique. The in-vivo dosimetry result using TLD was showed that 95~107% dose distribution compared to prescription dose. It is considered that CT based 3-dimensional Field-in-Field Technique for the total body irradiation gives much homogeneous dose distribution for different body parts than the conventional physical compensator method and might be useful to evaluate the dose on each part of patient body.