• The Journal of Korean Society for Radiation Therapy
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• v.26 no.1
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• pp.21-28
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• 2014

Purpose : For non-small cell lung cancer, if the treatment volume is large or the total lung volume is small, and the tumor is located in midline of patient's body, total lung dose tends to increase due to tolerance dose of spinal cord. The purpose of this study is to compare and evaluate the total lung dose of three dimensional conformal radiotherapy(3D CRT), intensity modulated radiotherapy(IMRT) and volumetric modulated arc therapy(VMAT) using restricted angle for non-small cell lung cancer patients. Materials and Methods : The treatment plans for four patients, being treated on TrueBeam STx($Varian^{TM}$, USA) with 10 MV and prescribed dose of 60 Gy in 30 fractions, 3D CRT, restricted angle IMRT and VAMT radiotherapy plans were established. Planning target volume(PTV), dose to total lung and spinal cord were evaluated using the dose volume histogram(DVH). Conformity index(CI), homogeneity index(HI), Paddick's index(PCI) for the PTV, $V_{30}$, $V_{20}$, $V_{10}$, $V_5$, mean dose for total lung and maximum dose for spinal cord was assessed. Results : Average value of CI, HI and PCI for PTV was $0.944{\pm}0.009$, $1.106{\pm}0.027$, $1.084{\pm}0.016$ respectively. $V_{20}$ values from 3D CRT, IMRT and VMAT plans were 30.7%, 20.2% and 21.2% for the first patient, 33.0%, 29.2% and 31.5% for second patient, 51.3%, 34.3% and 36.9% for third patient, finally 56.9%, 33.7% and 40.0% for the last patient. It was noticed that the $V_{20}$ was lowest in the IMRT plan using restricted angle. Maximum dose for spinal cord was evaluated to lower than the tolerance dose. Conclusion : For non-small cell lung cancer, IMRT with restricted angle or VMAT could minimize the lung dose and lower the dose to spinal cord below the tolerance level. Considering PTV coverage and tolerance dose to spinal cord, it was possible to obtain IMRT plan with smaller angle and this could result in lower dose to lung when compared to VMAT.

• The Journal of Korean Society for Radiation Therapy
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• v.24 no.1
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• pp.11-14
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• 2012

Purpose: Anisotropic Analytical Algorithm (AAA) provides more accurate dose calculation regarding impact on scatter and tissue inhomogeneity in comparison to Pencil Beam Convolution (PBC) algorithm. This study tries to analyze the difference of dose distribution according to PBC algorithm and dose calculation algorithm of AAA on breast cancer tangential plan. Materials and Methods: Computerized medical care plan using Eclipse treatment planning system (version 8.9, VARIAN, USA) has been established for the 10 breast cancer patients using 6 MV energy of Linac (CL-6EX, VARIAN, USA). After treatment plan of Conventional Radiation Therapy plan (Conventional plan) and Field-in-Field Intensity Modulated Radiation Therapy plan (FiF plan) using PBC algorithm has been established, MU has been fixed, implemented dose calculation after changing it to AAA, and compared and analyzed treatment plan using Dose Volume Histogram (DVH). Results: Firstly, as a result of evaluating PBC algorithm of Conventional plan and the difference according to AAA, the average difference of CI value on target volume has been highly estimated by 0.295 on PBC algorithm and as a result of evaluating dose of lung, $V_{47Gy}$ and $V_{45Gy}$ has been highly evaluated by 5.83% and 4.04% each, Mean dose, $V_{20Gy}$, $V_{5Gy}$, $V_{3Gy}$ has been highly evaluated 0.6%, 0.29%, 6.35%, 10.23% each on AAA. Secondly, in case of FiF plan, the average difference of CI value on target volume has been highly evaluated on PBC algorithm by 0.165, and dose on ipsilateral lung, $V_{47Gy}$, $V_{45Gy}$, Mean dose has been highly evaluated 6.17%, 3.80%, 0.15% each on PBC algorithm, $V_{20Gy}$, $V_{5Gy}$, $V_{3Gy}$ has been highly evaluated 0.14%, 4.07%, 4.35% each on AAA. Conclusion: When calculating with AAA on breast cancer tangential plan, compared to PBC algorithm, Conformity on target volume of Conventional plan, FiF plan has been less evaluated by 0.295, 0.165 each. For the reason that dose of high dose region of ipsilateral lung has been showed little amount, and dose of low dose region has been showed much amount, features according to dose calculation algorithm need to be considered when we evaluate dose for the lungs.

• Journal of radiological science and technology
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• v.20 no.2
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• pp.79-82
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• 1997

Image-based three dimensional radiation treatment planning(3D RTP) has a potential of generating superior treatment plans. Advances in computer technology and software developments quickly make 3D RTP a feasible choice for routine clinical use. However, it has become clear that an evaluation of a 3D plan is more difficult than a 2D plan. A number of tools have been developed to facilitate the evaluation of 3D RTP both qualitatively and quantitatively. For example, beam's eye view(BEV) is one of the most powerful and time-saving method as a qualitative tools. Dose-volume histogram(DVH) has been proven to be one of the most valuable methods for a quantitative tools. But it has a limitation to evaluate several different plans for biological effects of the tissue and critical organ. Therefore, there is a strong interest in developing quantitative models which would predict the likely biological response of irradiated organs and tissues, such as tumor control probability(TCP) and normal tissue complication probability(NTCP). DVH and NTCP of hepatoma were evaluated for three dimensional conformal radiotherapy(3D CRT). Also, 3D RTP was analysed as a dose optimization based on beam arrangement and beam modulation.

• The Journal of Korean Society for Radiation Therapy
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• v.14 no.1
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• pp.1-5
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• 2002

I. 목적 : 방사선 치료 시 최적화된 체내 선량분포를 얻는 것은 정상조직의 장애를 줄이고 종양선량을 높여 치료 효율을 극대화하는데 매우 중요하다. 본원에서는 병변 부위가 한쪽으로 치우친 head&neck 환자 치료 시 정상조직(tongue)을 보호하기 위해 tongue displacer를 만들어 사용한다. 이에 본 저자는 tongue displacer사용의 치료 유용성을 평가 하고자 한다. II. 대상 및 방법 : head & neck 치료 환자 중 병변 부위가 인체의 정중선(MSP)을 기준으로 한쪽으로 치우친 환자를 대상으로 하였다. 사용된 실험재료로는 C-T (high speed advantage, GE,US), RTP System (3D RTP system, prowess, US), 치과용 인상제 주입기(caulk system, quixx, japan), tongue displacer 등이 있다. 실험 방법은 모의 치료나 planning C-T를 시행하기 전에 치료 환자에게 사용할 개인용 tongue displacer를 치과용 인상제로 자체 제작하였다. 제작 후 모의 치료를 시행하고 3D plan을 하기 위해 planning C-T를 촬영하게 되는데 이때 tongue displacer사용 유. 무에 따라 각각 촬영을 하였다. 촬영된 두 가지의 CT영상을 prowess를 이용하여 3D plan을 하게 되는데 이때의 plan parameter나 beam direction등 plan에서의 모든 조건은 모두 동일시하고 선량 분포 및 DVH(dose volume histogram)값을 비교하였다. III. 결과 : tongue displace의 사용 유. 무에 따른 3D plan상의 DVH 비교 결과 tumor volume 주위의 다른 organ들은 모두 비슷한 양상의 DVH를 보였으나 tongue에 있어서 큰 변화를 보였다. tongue displacer를 사용 시, 미 사용시 보다 tongue의 위치를 변화시켜 치료 부위 외의 tongue에 받는 방사선 피폭 면적을 줄일 수 있었고 그 결과 DVH상의 $50\%$ volume이 $16\%$ 정도 줄어드는 것이 확인되었다. IV. 결론 : tongue에 방사선을 조사하면 방사선 부작용으로 mucositis, ulcer, hemorrhage등의 pain(동통)이 수반되므로 치료환자의 음식물 섭취불량으로 체증감소 등 전신 쇠약으로 이어질 수 있다. head & neck 환자 중에서 병소 위치가 한쪽으로 치우쳐서 있을 경우 인상제를 이용하여 tongue displacer를 만들어서 사용하면 tongue 의 위치를 변화시켜 방사선 조사 야에서 제외시켜준다. 그러므로 방사선 치료 시 tongue의 부작용을 최소화 할 수 있고 환자의 방사선 치료 만족도를 높일 수 있다고 사료된다.

• Radiation Oncology Journal
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• v.20 no.1
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• pp.41-52
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• 2002

Purpose : 3D conformal radiotherapy, the optimum dose delivered to the tumor and provided the risk of normal tissue unless marginal miss, was restricted by organ motion. For tumors in the thorax and abdomen, the planning target volume (PTV) is decided including the margin for movement of tumor volumes during treatment due to patients breathing. We designed the respiratory gating radiotherapy device (RGRD) for using during CT simulation, dose planning and beam delivery at identical breathing period conditions. Using RGRD, reducing the treatment margin for organ (thorax or abdomen) motion due to breathing and improve dose distribution for 3D conformal radiotherapy. Materials and Methods : The internal organ motion data for lung cancer patients were obtained by examining the diaphragm in the supine position to find the position dependency. We made a respiratory gating radiotherapy device (RGRD) that is composed of a strip band, drug sensor, micro switch, and a connected on-off switch in a LINAC control box. During same breathing period by RGRD, spiral CT scan, virtual simulation, and 3D dose planing for lung cancer patients were peformed, without an extended PTV margin for free breathing, and then the dose was delivered at the same positions. We calculated effective volumes and normal tissue complication probabilities (NTCP) using dose volume histograms for normal lung, and analyzed changes in doses associated with selected NTCP levels and tumor control probabilities (TCP) at these new dose levels. The effects of 3D conformal radiotherapy by RGRD were evaluated with DVH (Dose Volume Histogram), TCP, NTCP and dose statistics. Results : The average movement of a diaphragm was 1.5 cm in the supine position when patients breathed freely. Depending on the location of the tumor, the magnitude of the PTV margin needs to be extended from 1 cm to 3 cm, which can greatly increase normal tissue irradiation, and hence, results in increase of the normal tissue complications probabiliy. Simple and precise RGRD is very easy to setup on patients and is sensitive to length variation (+2 mm), it also delivers on-off information to patients and the LINAC machine. We evaluated the treatment plans of patients who had received conformal partial organ lung irradiation for the treatment of thorax malignancies. Using RGRD, the PTV margin by free breathing can be reduced about 2 cm for moving organs by breathing. TCP values are almost the same values $(4\~5\%\;increased)$ for lung cancer regardless of increasing the PTV margin to 2.0 cm but NTCP values are rapidly increased $(50\~70\%\;increased)$ for upon extending PTV margins by 2.0 cm. Conclusion : Internal organ motion due to breathing can be reduced effectively using our simple RGRD. This method can be used in clinical treatments to reduce organ motion induced margin, thereby reducing normal tissue irradiation. Using treatment planning software, the dose to normal tissues was analyzed by comparing dose statistics with and without RGRD. Potential benefits of radiotherapy derived from reduction or elimination of planning target volume (PTV) margins associated with patient breathing through the evaluation of the lung cancer patients treated with 3D conformal radiotherapy.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.86-89
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• 2002

The purpose is to develop a system to reduce the organ movement from the respiration during the 3DCRT or IMRT. This research reports the experience of utilizing personally developed system for mobile tumors. The patients clinical database was structured for 10 mobile tumors and patient setup error measurement and immobilization device effects were investigated. The RMRD system is composed of the respiratory motion reduction device utilized in prone position and abdominal strip device(ASD) utilized in the supine position, and the analysis program, which enables the analysis on patients setup reproducibility. Dose to normal tissue between patients with RMRDs and without RMRDs was analyzed by comparing the normal tissue volume, field margins and dose volume histogram(DVH) using fluoroscopy and CT images. And, reproducibility of patients setup verify by utilization of digital images. When patients breathed freely, average movement of diaphragm was 1.2 cm in prone position in contrast to 1.6 cm in supine position. In prone position, difference in diaphragm movement with and without RMRDs was 0.5 cm and 1.2 cm, respectively, showing that PTV margins could be reduced to as much as 0.7 cm. With RMRDs, volume of the irradiated normal tissue (lung, liver) reduced up to 20 % in DVH analysis. Also by obtaining the digital image, reproducibility of patients setup verify by visualization using the real-time image acquisition, leading to practical utilization of our software. Internal organ motion due to breathing can be reduced using RMRDs, which is simple and easy to use in clinical setting. It can reduce the organ motion-related PTV margin, thereby decrease volume of the irradiated normal tissue.

• Radiation Oncology Journal
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• v.19 no.1
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• pp.53-65
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• 2001

Purpose : To improve the local control of patients with nasopharyngeal cancer, we have implemented 3-D conformal radiotherapy and forward intensity modulated radiation therapy (IMRT) to used of compensating filters. Three dimension conformal radiotherapy with intensity modulation is a new modality for cancer treatments. We designed 3-D treatment planning with 3-D RTP (radiation treatment planning system) and evaluation dose distribution with tumor control probability (TCP) and normal tissue complication probability (NTCP). Material and Methods : We have developed a treatment plan consisting four intensity modulated photon fields that are delivered through the compensating tilters and block transmission for critical organs. We get a full size CT imaging including head and neck as 3 mm slices, and delineating PTV (planning target volume) and surrounding critical organs, and reconstructed 3D imaging on the computer windows. In the planning stage, the planner specifies the number of beams and their directions including non-coplanar, and the prescribed doses for the target volume and the permissible dose of normal organs and the overlap regions. We designed compensating filter according to tissue deficit and PTV volume shape also dose weighting for each field to obtain adequate dose distribution, and shielding blocks weighting for transmission. Therapeutic gains were evaluated by numerical equation of tumor control probability and normal tissue complication probability. The TCP and NTCP by DVH (dose volume histogram) were compared with the 3-D conformal radiotherapy and forward intensity modulated conformal radiotherapy by compensator and blocks weighting. Optimization for the weight distribution was peformed iteration with initial guess weight or the even weight distribution. The TCP and NTCP by DVH were compared with the 3-D conformal radiotherapy and intensitiy modulated conformal radiotherapy by compensator and blocks weighting. Results : Using a four field IMRT plan, we have customized dose distribution to conform and deliver sufficient dose to the PTV. In addition, in the overlap regions between the PTV and the normal organs (spinal cord, salivary grand, pituitary, optic nerves), the dose is kept within the tolerance of the respective organs. We evaluated to obtain sufficient TCP value and acceptable NTCP using compensating filters. Quality assurance checks show acceptable agreement between the planned and the implemented MLC(multi-leaf collimator). Conclusion : IMRT provides a powerful and efficient solution for complex planning problems where the surrounding normal tissues place severe constraints on the prescription dose. The intensity modulated fields can be efficaciously and accurately delivered using compensating filters.

• Progress in Medical Physics
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• v.9 no.4
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• pp.227-245
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• 1998

A most appropriate model of 3-D conformal radiotherapy has been induced by clinical evaluation and animal study, and therapeutic gains were evaluated by numerical equation of tumor control probability(TCP) and normal tissue complication probability (NTCP). The radiation dose to the tumor and the adjacent normal organs was accurately evaluated and compared using the dose volume histogram(DVH). The TCP and NTCP was derived from the distribution of given dosage and irradiated volume, and these numbers were used as the biological index for the assessment of the treatment effects. Ten patients with liver disease have been evaluated and 3 dogs were sacrificed for this study. Based on the 3-D images of the tumor and adjacent organs, the optimum radiation dose and the projection direction which could maximize the radiation effect while minimizing the effects to the adjacent organs could be decided. 3). The most effective collimation for the normal adjacent organs was made through the beams eye view with the use of multileaf collimator. When the dose was increased from 50Gy to 70Gy, the TCP for the conventional 2-port radiation and the 5-port multidimensional therapy was 0.982 and 0.995 respectively, while the NTCP was 0.725 and 0.142 respectively, suggesting that the 3-D conformal radiotherapy might be the appropriate therapy to apply sufficient radiation dose to the tumor while minimizing the damages to the normal areas of the liver. Positive correlation was observed between the NTCP and the actual complication of the normal liver in the animal study. The present study suggest that the use of 3-D conformal radiotherapy and the application of the mathematical models of TCP and NTCP may provide the improvements in the treatment of hepatoma with enhanced results.

• The Journal of Korean Society for Radiation Therapy
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• v.23 no.2
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• pp.103-108
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• 2011

Purpose: Opposing portal irradiation with helmet field shape that has been given to a patient with brain metastasis can cause excess dose in patient's scalp, resulting in hair loss. For this reason, this study is to quantitatively analyze scalp dose for effective prevention of hair loss by comparing opposing portal irradiation with scalp-shielding shape and tomotherapy designed to protect patient's scalp with conventional radiation therapy. Materials and Methods: Scalp dose was measured by using three therapies (HELMET, MLC, TOMO) after five thermo-luminescence dosimeters were positioned along center line of frontal lobe by using RANDO Phantom. Scalp dose and change in dose distribution were compared and analyzed with DVH after radiation therapy plan was made by using Radiation Treatment Planning System (Pinnacle3, Philips Medical System, USA) and 6 MV X-ray (Clinac 6EX, VARIAN, USA). Results: When surface dose of scalp by using thermo-luminescence dosimeters was measured, it was revealed that scalp dose decreased by average 87.44% at each point in MLC technique and that scalp dose decreased by average 88.03% at each point in TOMO compared with HELMET field therapy. In addition, when percentage of volume (V95%, V100%, V105% of prescribed dose) was calculated by using Dose Volume Histogram (DVH) in order to evaluate the existence or nonexistence of hotspot in scalp as to three therapies (HELMET, MLC, TOMO), it was revealed that MLC technique and TOMO plan had good dose coverage and did not have hot spot. Conclusion: Reducing hair loss of a patient who receives whole brain radiotherapy treatment can make a contribution to improve life quality of the patient. It is expected that making good use of opposing portal irradiation with scalp-shielding shape and tomotherapy to protect scalp of a patient based on this study will reduce hair loss of a patient.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.17
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• pp.7795-7801
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• 2015

The aim of the present research was to establish primary characteristics of electron beams for a Varian 2100C/D linear accelerator with recently developed PRIMO Monte Carlo software and to verify relations between electron energy and dose distribution. To maintain conformity of simulated and measured dose curves within 1%/1mm, mean energy, Full Width at Half Maximum (FWHM) of energy and focal spot FWHM of initial beam were changed iteratively. Mean and most probable energies were extracted from validated phase spaces and compared with related empirical equation results. To explain the importance of correct estimation of primary energy on a clinical case, computed tomography images of a thorax phantom were imported in PRIMO. Dose distributions and dose volume histogram (DVH) curves were compared between validated and artificial cases with overestimated energy. Initial mean energies were obtained of 6.68, 9.73, 13.2 and 16.4 MeV for 6, 9, 12 and 15 nominal energies, respectively. Energy FWHM reduced with increase in energy. Three mm focal spot FWHM for 9 MeV and 4 mm for other energies made proper matches of simulated and measured profiles. In addition, the maximum difference of calculated mean electrons energy at the phantom surface with empirical equation was 2.2 percent. Finally, clear differences in DVH curves of validated and artificial energy were observed as heterogeneity indexes were 0.15 for 7.21 MeV and 0.25 for 6.68 MeV. The Monte Carlo model presented in PRIMO for Varian 2100 CD was precisely validated. IAEA polynomial equations estimated mean energy more accurately than a known linear one. Small displacement of R50 changed DVH curves and homogeneity indexes. PRIMO is a user-friendly software which has suitable capabilities to calculate dose distribution in water phantoms or computerized tomographic volumes accurately.