• Journal of Radiation Protection and Research
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• v.36 no.3
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• pp.107-118
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• 2011

Conventional (SRS) and fractionated (FSRS) stereotactic radiosurgery necessarily require stringent overall target point accuracy and precision. We determine three-dimensional intracranial target point deviations (TPDs) in a whole treatment procedure using magnetic resonance image (MRI)-based polymer-gel dosimetry, and suggest a technique for overall system tests. TPDs were measured using a custom-made head phantom and gel dosimetry. We calculated TPDs using a treatment planning system. Then, we compared TPDs using mid bi-plane and three-dimensional volume methods with spherical and elliptical targets to determine their inherent analysis errors; finally, we analyzed regional TPDs using the latter method. Average and maximum additive errors for ellipses were 0.62 and 0.69 mm, respectively. Total displacements were 0.92 ${\pm}$ 0.25 and 0.77 ${\pm}$ 0.15 mm for virtual SRS and FSRS, respectively. Average TPDtotal at peripheral regions was greater than that at central regions for both. Overall system accuracy was similar to that reported previously. Our technique could be used as an overall system accuracy test that considers the real radiation field shape.

• The Journal of Korean Society for Radiation Therapy
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• v.22 no.2
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• pp.131-134
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• 2010

Purpose: TOMO therapy treatment for a relatively long run Beam time and temperature-sensitive detector, such as CT clinics in optimal temperature ($20~21^{\circ}$) to maintain a constant temperature in addition to its own Chamber Cooling system is activating. TOMO This clinic has been reduced in the patients' body temperature to keep the sheets and covers over the treated area. Therefore, these materials for any changes in the organization gives the dose were analyzed. Materials and Methods: To compare changes in the organization Dose Phantom cheese (Cheese Phantom) were used, CT-simulation taking the center point of the cheese phantom PTV (Planning Target Volume, treatment planning target volume) by setting Daily dose 200 cGy, 3 meetings planned treatment. PTV, PTV +7 cm, PTV +14 cm, the total count points on the phantom using the Ion chamber cover without any substance to measure the dose, and one of the most commonly used treatment, including the frequently used four kinds of bedding materials (febric 0.8 mm, gown 1.4 mm, rug, 3.3 mm, blanket 13.7 mm) and covered with a phantom and the dose measured at the same location were analyzed 3 times each. Results: PTV, PTV +7 cm, PTV +14 cm from the point of any substance measured in the state are covered with four kinds of materials (fabric, gown, rug, blanket) was measured in the covered states and compares their results, PTV respectively -0.17%, -0.44%, -0.53% and -0.9% change, PTV +7 cm, respectively -0.04%, +0.07%, +0.06%, +0.07%, were changed, PTV +14 cm, respectively 0%, -0.06%, -0.02%, +0.6%, respectively. Conclusion: These results TOMO treatment to patients to maintain their body mass by using PTV thickness of the material decreased in proportion to. PTV +7 cm, but showed slight changes in the point, PTV +14 cm at the point of the dose was increased a little. Sejijeom all the difference in treatment tolerance ${\pm}3%$ range, this is confirmed in the coming treatment will not affect the larger should be considered.

• The Journal of Korean Society for Radiation Therapy
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• v.25 no.2
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• pp.137-143
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• 2013

Purpose: We are to find out the difference of calculated dose of treatment planning system (TPS) and measured dose in case of inhomogeneous organ structure. Materials and Methods: Inhomogeneous phantom is made with solid water phantom and cork plate. CT image of inhomogeneous phantom is acquired. Treatment plan is made with TPS (Pinnacle3 9.2. Royal Philips Electronics, Netherlands) and calculated dose of point of interest is acquired. Treatment plan was delivered in the inhomogeneous phantom by ARTISTE (Siemens AG, Germany) measured dose of each point of interest is obtained with Gafchromic EBT2 film (International Specialty Products, US) in the gap between solid water phantom or cork plate. To simulate lung cancer radiation treatment, artificial tumor target of paraffin is inserted in the cork volume of inhomogeneous phantom. Calculated dose and measured dose are acquired as above. Results: In case of inhomogeneous phantom experiment, dose difference of calculated dose and measured dose is about -8.5% at solid water phantom-cork gap and about -7% lower in measured dose at cork-solid water phantom gap. In case of inhomogeneous phantom inserted paraffin target experiment, dose difference is about 5% lower in measured dose at cork-paraffin gap. There is no significant difference at same material gap in both experiments. Conclusion: Radiation dose at the gap between two organs with different electron density is significantly lower than calculated dose with TPS. Therefore, we must be aware of dose calculation error in TPS and great care is suggested in case of radiation treatment planning on inhomogeneous organ structure.

• Radiation Oncology Journal
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• v.24 no.4
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• pp.248-254
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• 2006

$\underline{Purpose}$: To evaluate acute toxicities in cervix cancer patients receiving intensity modulated whole pelvic radiation therapy (IM-WPRT). $\underline{Materials\;and\;Methods}$: Between August 2004 and April 2006, 17 patients who underwent IM-WPRT were analysed. An intravenous contrast agent was used for radiotherapy planning computed tomography (CT). The central clinical target volume (CTV) included the primary tumor, uterus, vagina, and parametrium. The nodal CTV was defined as the lymph nodes larger than 1 cm seen on CT and the contrased-enhanced pelvic vessels. The planning target volume (PTV) was the 1-cm expanded volume around the central CTV, except for a 5-mm expansion from the posterior vagina, and the nodal PTV was defined as the nodal CTV plus a 1.5 cm margin. IM-WPRT was prescribed to deliver a dose of 50 Gy to more than 95% of the PTV. Acute toxicity was assessed with common toxicity criteria up to 60 days after radiotherapy. $\underline{Results}$: Grade 1 nausea developed in 10 (58.9%) patients, and grade 1 and 2 diarrhea developed in 11 (64.7%) and 1 (5.9%) patients, respectively. No grade 3 or higher gastrointestinal toxicity was seen. Leukopenia, anemia, and thrombocytopenia occurred in 15 (88.2%). 7 (41.2%), and 2 (11.8%) patients, respectively, as hematologic toxicities. Grade 3 leukopenia developed in 2 patients who were treated with concurrent chemoradiotherapy. $\underline{Conclusion}$: IM-WPRT can be a useful treatment for cervix cancer patients with decreased severe acute toxicities and a resultant improved compliance to whole pelvic irradiation.

• Journal of radiological science and technology
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• v.40 no.2
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• pp.303-309
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• 2017

To evaluate the usefulness of 3-dimensional brachytherapy(BT) planning technique based on CT in cervical cancer. Patients with cervical cancer underwent 2-D BT treatment planning and then CT scan with HDR intracavitary applicators in place with same positions. Dose was prescribed to Point A with 5Gy per fraction on 2-D BT planning. For 3-D BT planning, and dose was prescribed to the High risk CTV for BT (HR CTV) with 5Gy. The 3-D BT planning goal was to cover at least 90% of the HR CTV with target 5Gy isodose surface while limiting the dose to $2cm^3$ of bladder to less than 7.5 Gy, and $2cm^3$ of rectum to less than 5Gy. In one patient of 10 patients, $D_{2cm3}$ of rectal dose was over 5Gy and 6patients at $D_{2cm3}$ of bladder dose on 2-D BT planning. There was a tendency to underestimate ICRU bladder dose than ICRU rectal dose. CT based 3-D BT planning for cervical cancer will enable evaluation of dose distributions for tumor and critical organs at risk. So, rectal and bladder morbidity as well as geographic miss will be reduced in case of the bulky disease or uterine malposition.

• Radiation Oncology Journal
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• v.27 no.4
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• pp.194-200
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• 2009

Purpose: This aim of this study was to evaluate changes in gastric volume and organ position as a result of delayed gastric emptying after a subtotal gastrectomy performed as part of the treatment of stomach cancer. Materials and Methods: The medical records of 32 patients who underwent concurrent chemoradiotherapy after a subtotal gastrectomy from March 2005 to December 2008 were reviewed. Of these, 5 patients that had more than 50 cc of residual gastric food detected at computed tomography (CT) simulation, were retrospectively enrolled in this study. Gastric volume and organ location was measured from CT images obtained before radiotherapy, twice weekly. In addition, authors evaluated the change of radiation dose distribution to planning the target volume and normal organ in a constant radiation therapy plan regardless of gastric volume variation. Results: A variation in the gastric volume was observed during the radiotherapy period (64.2~340.8 cc; mean, 188.2 cc). According to the change in gastric volume, the location of the left kidney was shifted up to 0.7 - 2.2 cm (mean, 1.2 cm) in the z-axis. Under-dose to planning target volume (V43, 79.5${\pm}$10.4%) and over-dose to left kidney (V20, 34.1${\pm}$12.1%; Mean dose, 23.5${\pm}$8.3 Gy) was expected, given that gastric volume change due to delayed gastric emptying wasn't taken into account. Conclusion: This study has shown that a great change in gastric volume and left kidney location may occur during the radiation therapy period following a subtotal gastrectomy, as a result of delayed gastric emptying. Detection of patients who experienced delayed gastric emptying and the application of gastric volume variation to radiation therapy planning will be very important.

• The Journal of Korean Society for Radiation Therapy
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• v.17 no.2
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• pp.95-103
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• 2005

Purpose : In the radiosurgery, to obtain CT image to find more accurate tumor position during respiration, and using them, to increase the accuracy of radiation treatment by applying image guided. Materials and Methods : Using the self-made vacuum cushion for the body SRS, CT images were obtained three for each patient during respiration (shallow, inhalation, exhalation). They were transformed to the RTP computer and then were fused. Global GTVs were delineated on the fused images and more appropriated treatment planning was established. Results : We can find the tumor position is moving toward cranio-caudal with max 10 mm margin and volume is transformed. As a result from the comparision of DVH (pre & post radio surgery), we observed about 100% dose to tumor. Conclusion : BSRS was skeptical due to the tumor movement during respiration. More accurate by the combination of the development of immobilization devices and BSRS based on Image Guide, it will be applied to more cases for BSRS.

• Progress in Medical Physics
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• v.16 no.4
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• pp.176-182
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• 2005

Stereotactic radiosurgery (SRS) is a technique to deliver a high dose to a target region and a low dose to a critical organ through only one or a few irradiation. The SRS must be planned exactly. Currently the surgery plan is peformed by trial and error method. There are many questions about the reliability and reproducibility of the plan result. This study Improve each step of the Oh's method based on heuristic target shaping to obtain the better result. The target was reconstructed using cylinders with same height and the neighbored cylinders were combined according to the difference of each center and diameter. Then, spheres were packed within each cylinders by the packing rules. Two virtual targets were used to compare this method with Oh's method. As a result, the numbers of isocenter were successfully reduced - more than $35\%$ and $26\%$ - without serious differences of proscription isodose to tumour volume ratio (PITV) and maximum dose to proscription dose ratio (MDPD). This technique using cylinder piling and sphere packing will be a helpful tool to planner in stereotactic radiosurgery.

• Journal of radiological science and technology
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• v.47 no.4
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• pp.271-278
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• 2024

This study aimed to evaluate the impact of changes in beam arrangement and arc counts on dosimetric factors in volumetric modulated arc therapy (VMAT) inverse radiation therapy planning for hippocampal-avoidance whole brain radiation therapy (HA-WBRT) by using the Elekta Monaco radiation therapy planning system (RTPs). For coplanar VMAT, both the arc per beam (APB) method and the beam determined arc(BDA) method, which is determined by the number of beams, were applied. For non-coplanar VMAT, the BDA method was utilized, and a total of 9 treatment plans were established by varying the arc counts. All radiation therapy plans met the radiation oncology group (RTOG) 0933 protocol standards, and 14 dosimetric factors were compared and analyzed. The results showed that the BDA-NC VMAT method demonstrated superior performance in terms of planning target volume (PTV) coverage and protection of normal organs, while APB-VMAT was advantageous in terms of hippocampal protection, monitor unit and delivery time. This study is expected to contribute to the efficient establishment of HA-WBRT plans considering the changes in beam arrangement and rotation arc numbers in Monaco RTPs.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.90-93
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• 2002

In particle radiotherapy, a shape of the beam to conform the irradiation field is statically defined by the compensator, collimator and potal devices at the outside of the patient body. However the target such as lung or liver cancer moves along with respiration. This increases the irradiated volume of normal tissue. Prior discussions about organ motions along with respiration have been mainly focused on inferior-superior movement that was usually perpendicular to beam axis. On the other hand, the change of the target depth along the beam axis is very important especially in particle radiotherapy, because the range end of beam (Bragg peak) is so sharp as to be matched to distal edge of the target. In treatment planning, the range of the particle beam inside the body is calculated using a calibration curve relating CT number and water equivalent path length (WEL) to correct the inhomogeneities of tissues. The variation in CT number along the beam path would cause the uncertainties of range calculation at treatment planning for particle radiotherapy. To estimate the uncertainties of the range calculation associated with patient breathing, we proposed the method using sequential CT images with respiration waveform, and analyzed organ motions and WELs at patients that had lung or liver cancer. The variation of the depth along the beam path was presented in WEL rather than geometrical length. In analyzed cases, WELs around the diaphragm were remarkably changed depending on the respiration, and the magnitude of these WEL variations was almost comparable to inferior-superior movement of diaphragm. The variation of WEL around the lung was influenced by heartbeat.