• Radiation Oncology Journal
• /
• v.28 no.1
• /
• pp.39-49
• /
• 2010

Purpose: This aim of this study is to analyze the dosimetric difference between intensity-modulated radiation therapy (IMRT) using 3 or 5 beams and MSF in the radiotherapy of the left breast. Materials and Methods: We performed a comparative analysis of two radiotherapy modalities that can achieve improved dose homogeneity. First is the multistatic fields technique that simultaneously uses both major and minor irradiation fields. The other is IMRT, which employs 3 or 5 beams using a fixed multileaf collimator. We designed treatment plans for 16 early left breast cancer patients who had taken breast conservation surgery and radiotherapy, and analyzed them from a dosimetric standpoint. Results: For the mean values of $V_{95}$ and dose homogeneity index, no statistically significant difference was observed among the three therapies. Extreme hot spots receiving over 110% of the prescribed dose were not found in any of the three methods. A Tukey test performed on IMRT showed a significantly larger increase in exposure dose to the ipsilateral lung and heart than multistatic fields technique (MSF) in the low-dose area, but in the high-dose area, MSF showed a slight increase. Conclusion: In order to improve dose homogeneity, the application of MSF, which can be easily planned and applied more widely, is considered an optimal alternative to IMRT for radiotherapy of early left breast cancer.

• Radiation Oncology Journal
• /
• v.20 no.4
• /
• pp.303-308
• /
• 2002

Purpose : To determine the optimal radiation dose in a localized non-Hodgkin's lymphoma of the head and neck in the treatment setting for combined chemoradiotherapy. Materials an Methods :Fifty-three patients with stage I and II diffuse large ceil non-Hodgkin's lymphoma of the head and neck, who were treated with combined chemoradiotherapy between 1985 and 1998 were retrospectively reviewed. The median age was 49 years, and the male-to-female ratio was approximately 1.6. Twenty-seven patients had stage 1 disease and 26 had stage II. Twenty-three patients had bulky tumors $(\geq5\;cm)$ and 30 had non-bulky tumors (<5 cm). The primary tumors arose mainly from an extranodal organ $(70\%)$, most cases involving Waldeyer's ring $(90\%)$. All patients except one were initially treated with $3\~6$ cycles of chemotherapy, which was followed by radiotherapy. Radiation was delivered either to the primary tumor area alone $(9\%)$ or to the primary tumor area plus the bilateral neck nodes $(91\%)$ with a minimum dose of 30 Gy $(range\;30\~60\;Gy)$. The failure patterns according to the radiation field were analyzed, and the relationship between the dose and the in-field recurrence was evaluated. Results : The 10-year overall survival and the 10-year disease free survival rates were similar at $75\%\;and\;76\%$, respectively. A complete response (CR) after chemotherapy was achieved in 44 patients $(83\%)$. Subsequent radiotherapy showed a CR in all patients. Twelve patients $(23\%)$ had a relapse of the lymphoma after the initial treatment. Two of these patients had a recurrence inside the radiation field. No clear dose response relationship was observed and no significant prognostic factors for the in-field recurrences were identified because of the small number of in-field recurrences. However, for patients with tumors <5 cm in diameter, there were no in-field recurrences after a radiation dose 30 Gy. The 2 in-field recurrences encountered occurred in patients with a tumor $\geq5\;cm$. Conclusion .A dose of 30 Gy is sufficient for local control in patients with a non-bulky (<5 cm), localized, diffuse large cell non-Hodgkin's lymphoma when combined with chemotherapy. An additional boost dose in the primary site is recommended for patients with bulky tumors $(\geq5\;cm)$.

• Radiation Oncology Journal
• /
• v.21 no.3
• /
• pp.183-191
• /
• 2003

Purpose: To suggest the optimal radiation fields after a surgical resection based on a nationwide survey on the principles of radiotherapy for rectal cancer in the Korean Patterns on Care Study. Materials and method: A consensus committee, composed of radiation oncologists from 18 hospitals in Seoul Metropolitan area, developed a survey format to analyze radiation oncologist's treatment principles for rectal cancer after a surgical resection. The survey format included 19 questions on the principles of defining field margins, and was sent to the radiation oncologists in charge of gastrointestinal malignancies in all korean hospitals (48 hospitals). Thirty three ($69\%$) oncologists replied. On the basis of the replies and literature review, the committee developed guidelines for the optimal radiation fields nor rectal cancer Results: The following guidelines were developed: superior border between the lower tip on the L5 vertebral body and upper sacroiliac joint; inferior border $2\~3$ cm distal to the anastomosis in patient whose sphincter was saved, and $2\~3$ cm distal to the perineal scar In patients whose anal sphincter was sacrificed; anterior margin at the posterior lip of the symphysis pubis or $2\~3$ cm anterior to the vertebral body, to include the internal iliac lymph node and posterior margin $1.5\~2$ cm posterior to the anterior surface of the surface, to include the presacral space with enough margin. Comparison with the guidelines, the replies on the superior margin coincided in 23 cases ($70\%$), the inferior margin after sphincter saving surgery in 13 ($39\%$), the inferior margin after adbominoperineal resection in 32 ($97\%$), the lateral margin in 32 ($97\%$), the posterior margins in 32 ($97\%$) and the anterior margin in 16 ($45\%$). Conclusion: These recommendations should be tailored to each patient according to the clinical characteristics such as tumor location, pathological and operative findings, for the optimal treatment. The adequacy of these guidelines should be proved be following the Korean Patterns of Care Study.

• Radiation Oncology Journal
• /
• v.18 no.3
• /
• pp.194-199
• /
• 2000

Purpose : Then determining the lower margin of post-operative pelvic radiation therapy field according to the traditional method (recommended by Gunderson), the organs located in the low pelvic cavity and the perineum are vulnerable to unnecessary radiation. This study evaluated the effect of individualized determination of the lower margin at 2 cm to 3 cm below the anastomotic site on the failure patterns. Materials and Methods . Authors included ぉ patients with modified Astler-Coiler (MAC) stages from B2 through C3, who received low anterior resection and post-operative pelvic radiation therapy from Sept. 1994 to May 1998 at Samsung Medical Center, Sungkyunkwan University. The numbers of male and female patients were 44 and 44, and the median age was 57 years (range: 32-81 years). Three field technique (posterior-anterior and bilateral portals) by 6, 10, 15 MV X-rays was used to deliver 4,500 cGy to the whole pelvis followed by Sn cGy's small field boost to the tumor bed over 5.5 weeks. Sixteen patients received radiation therapy by traditional field margin determination, and the lower margin was set either at the low margin of the obturator foramen or at 2 cm to 3 cm below the anastomotic site, whichever is lower. In 72 patients, the lower margin was set at 2 cm to 3 cm below the anastomotic site, irrespectively of the obturator foramen, by which the reduction of radiation volume was possible in 55 patients ($76\%$). Authors evaluated and compared survival, local control, and disease-free survival rates of these two groups. Results : The median follow-up period was 27 months (range : 7-58 months). MAC stages B2 in 32($36\%$), B3 in 2 ($2\%$), Cl in 2 ($2\%$), C2 in 50 ($57\%$), and C3 in 2 ($2\%$) Patients, respectively. The entire patients' overall survival rates at 2 and 4 years were $94\%$ and $68\%$, respectively, and disease-free survival rates at 2 and 4 years were $86\%$ and $58\%$, respectively. The first failure sites were local only in 4, distant only in 14, and combined local and distant in 1 patient, respectively. There was no significant difference with respect to local control and disease-free survival rates ( p=0.42, p=0.68) between two groups of different lower margin determination policies. Conclusion : The new concept in the individualized determination of the lower margin depending on the anastomotic site has led to the equivalent local control and disease-free survival rates, and is expected to contribute to the reduction of unnecessary radiation-related morbidity by reduction of radiation volume, compared with the traditional method of lower margin determination.

• Journal of Radiation Protection and Research
• /
• v.25 no.1
• /
• pp.31-36
• /
• 2000

In radiotherapy, it may happen to radiate surrounding normal tissue because of inconsistent field size by changing patient position during treatment. We are going to analyze errors reduced by using immobilization device with Electonic portal imaging device(EPID) in this study. We had treated the twenty-one patients in pelvic region with 10 MV X-ray from Aug. 1998 to Aug. 1999 at Chungnam National University Hospital. All patients were treated at supine position during treatment. They were separated to two groups, 11 patients without device and 10 patients with immobilization device. We used styrofoam for immobilization device and measured the errors of anterior direction for x, y axis and lateral direction for z, y axis from simulation film to EPID image using matching technique. For no immobilization device group, the mean deviation values of x axis and y axis are 0.19 mm. 0.48 mm, respectively and the standard deviations of systematic deviation are 2.38 mm, 2.19 mm, respectively and of random deviation for x axis and y axis are 1.92 mm. 1.29 mm, respectively. The mean deviation values of z axis and y axis are -3.61 mm. 2.07 mm, respectively and the standard deviations of systematic deviation are 3.20 mm, 2.29 mm, respectively and of random deviation for z axis and y axis are 2.73 mm. 1.62 mm, respectively. For immobilization device group, the mean deviation values of x axis and y axis are 0.71 mm. -1.07 mm, respectively and the standard deviations of systematic deviation are 1.80 mm, 2.26 mm, respectively and of random deviation for x axis and y axis are 1.56 mm. 1.27 mm, respectively. The mean deviation values of z axis and y axis are -1.76 mm. 1.08 mm, respectively and the standard deviations of systematic deviation are 1.87 mm, 2.83 mm, respectively and of random deviation for x axis and y axis are 1.68 mm, 1.65 mm, respectively. Because of reducing random and systematic error using immobilization device, we had obtained good reproducibility of patient setup during treatment so that we recommend the use of immobilization device in pelvic region of radiation treatment.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2003.09a
• /
• pp.70-70
• /
• 2003

경피적관상동맥성형술(CPTCA)이나 스텐트삽입술 후에 발생하는 재협착을 방지하기 위한 방사선을 조사하는 방법 중에 베타 입자를 방출하는 액체 선원을 catheter풍선 내에 넣어 일정 시간 방사선 조사 시키는 방법이 있다. 조사시킬 혈관의 길이가 길어 한번의 방사선 조사가 어려울 경우 영역을 분할하여 두 번에 나누어 조사할 경우가 있다. 조사영역의 겹치는 부근의 흡수선량이 고선량이나 저선량이 되는가를 알기 위하여 두 풍선간의 접근 거리에 따른 혈관내벽의 흡수선량 분포를 알아보았다. 풍선내의 액체 선원은 Ho-l66을 이용하였고 Ho-l66의 물리적 반감기는 26.8시간이고 최대에너지 1.85 MeV, 평균에너지 0.69 MeV와 최대에너지 1.77 MeV, 평균에너지 0.65 MeV를 갖는 베타 입자를 방출한다. Ho-l66 의 방사선 흡수선량을 측정하기 위하여 GafChromic 필름(Nuclear Associates, Carle Place, NY, USA)을 이용하였고, 방사선이 조사된 필름의 optical density는 videodensitometer(Wellhofer, Schwarzen-bruck, Germany)를 이용하여 값을 읽었다. Catheter 풍선은 직경이 3 mm 이고 길이가 20 mm인 것을 이용하였다. 혈관 내벽의 최대 흡수선량을 표준화하여 겹치는 부분의 흡수선량 분포를 접근 거리에 따라 구하였다. 또한 몬테카를로 시abf레이션으로 확인하였다. 두 풍선의 겹치는 부근의 선량 분포는 풍선 중앙에서 중앙사이의 거리가 21 mm 일 때 중앙에서 20% 증가하였고, 거리가 22 mm일 때와 23 mm일 때 각각 10%와 40%의 감소를 보였다. 풍선 도자의 풍선 안에 베타입자 방출 액체 선원을 넣어 혈관내벽에 방사선 조사하는 방법은 비정거리가 짧아 혈관 내벽 부근에만 방사선을 조사시키고 그 외 중요 장기에는 영향을 덜 미치는 장점이 있다. 그러나 혈관 내벽 표면으로 부터의 거리에 따라 흡수선량이 급격히 떨어지는 분포를 이루기 때문에 두 개의 풍선이 겹치는 부근의 흡수선량은 아주 작은 접근 거리에서도 급격한 변화를 보였다. 따라서 시술 중에 겹치는 부분을 아주 적게 분할하여 정확하게 차례차례로 조사시키기 위해서는 신중한 거리 조정을 하여야 한다.

• Journal of Radiation Protection and Research
• /
• v.26 no.2
• /
• pp.113-117
• /
• 2001

The energy band method for NaI spectrum calculates only the exposure rate due to natural radiation because it calculates exposure rate using energy spectrum of $1300{\sim}3000keV$. However, the total energy method includes in its calculation the exposure rate due to man-made radiation because it uses the energy spectrum of $150{\sim}3400keV$. Therefore, the resulting difference of extracting the exposure rate calculated by the energy band method from the exposure rate calculated by the total energy method is apparently the exposure rate due to man-made radiation. In this study, we measured the NaI spectrum during the period of significant changes of the exposure rate in the area without a man-made radiation. As the results, we found the exposure rates calculated by those two methods are equal within the statistical variation of ${\pm}0.3{\mu}R\;h^{-1}$. Consequently, if the difference between the exposure rates calculated by the two methods exists, it may be due to the man-made radiation exposure rate.

• Radiation Oncology Journal
• /
• v.20 no.3
• /
• pp.199-205
• /
• 2002

Purpose : This study was peformed to determine the optimal radiation therapy field for the treatment of malignant astrocytoma and glioblastoma multiforme. Materials and Methods : From Jan. 1994 to Mar. 2000, 21 patients with malignant astrocytoma and glioblastoma multiforme, confirmed as recurrent by follow up MRI after surgery and radiation therapy, were analyzed. The distance from the margin of the primary lesion to the recurrent lesion was measured. The following factors were analyzed to Investigate the influence of these factors to recurrence pattern; tumor size, degree of edema, surgical extent, gamma knife radiosurgery and multiple lesions. Results : Among the 21 patients, 18 $(86\%)$ were recurred within 2 cm from the primary lesion site. 12 within 1 cm, 6 between 1 and 2 cm. The other 3 patients all with multiple lesions, were recurred at 3, 4, 5 cm, from the primary lesion site. The recurrence pattern was not influenced by the factors of tumor size, extent of edema, surgical extent, or gamma knife radiosurgery. However, patients with multiple lesions showed a tendency of recurrence at sites further from the primary lesion. Conclusions : Most $(86\%)$ of the recurrences of malignant astrocytoma and glioblastoma multiforme occurred within 2 cm from the primary lesion site. The width of treatment field does not need to be changed according to tumor size, degree of edema, surgical extent, or gamma knife radiosurgery. However, the treatment field for multiple lesions appears to be wider than that for a single lesion.

• Radiation Oncology Journal
• /
• v.16 no.3
• /
• pp.233-243
• /
• 1998

Purpose : To evaluate the effects of X-irradiation on prenatal deaths, i.e., preimplantation deaths, embryonic deaths and fetal deaths, and on external malformations in precompacted preimplantation ddy mice Materials and Methods : Pregnant mice (n=85) obtained by limiting the mating time to from 6 to 9 A.M., were segregated into 11 groups. The first five groups (n=26) were irradiated with X-ray doses of 0.1 0.5, 0.75, 1.5, and 3 Gy, respectively, at 24 h post conception (p.c.) of the preimplantation Period. The second five (n=27) groups were irradiated at the same X-ray doses, respectively, but at 48 h p.c. of the preimplantation period. The last group (n=32) was the control group. The uterine contents were examined on the 18th day of gestation for prenatal deaths and external malformations. Results : 1) A statistically significant increase in preimplantation deaths with increasing dose was observed in the experimental groups irradiated at 24 h p.c. and in the groups irradiated at 48 h p.c., as compared to the control group. The threshold dose was close to 0.05 Gy and 0.075 Gy for the irradiations at 24 h p.c. and 48 h p.c. respectively. 2) A statistically significant increase in embryonic deaths with increasing dose was observed in all irradiation groups, except the group irradiated with a dose of 0.1 Gy at 48 h p.c.. 3) No fetal deaths were found in any experimental group. 4) In the experimental groups irradiated at 24 h p.c. anomalies increased with statistical significance, as compared with the control group : 2 exencephalies, 2 open eyelids, 3 anophthalmias, 2 cleft Palates, 2 gastroschisis, 1 abdominal wall defect. 1 leg defect, and 2 short tail anomalies: the threshold dose for external malformations was close to 0.2 Gy at 24 h p.c.. In the groups irradiated at 48 h p.c., 1 open eyelid and 2 short tail anomalies were observed, but there was no statistical significance in those malformations. Conclusion : The results of this study reveal that X-irradiation of precompacted preimplantation ddy mice causes not only preimplantation deaths and embryonic deaths but also external malformations. In addition, external malformations were observed in our experiments at diagnostic doses, including 0.1 and 0.5 Gy. For this reason, we recommend that irradiation should be avoided during the preimplantation period by applying Rugh's 10-day rule.

• Radiation Oncology Journal
• /
• v.28 no.3
• /
• pp.177-183
• /
• 2010

Purpose: Simulation using computed tomography (CT) is now widely available for radiation treatment planning for breast cancer. It is an important tool to help define the tumor target and normal tissue based on anatomical features of an individual patient. In Korea, most patients have small sized breasts and the purpose of this study was to review the margin of treatment field between conventional two-dimensional (2D) planning and CT based three-dimensional (3D) planning in patients with small breasts. Materials and Methods: Twenty-five consecutive patients with early breast cancer undergoing breast conservation therapy were selected. All patients underwent 3D CT based planning with a conventional breast tangential field design. In 2D planning, the treatment field margins were determined by palpation of the breast parenchyma (In general, the superior: base of the clavicle, medial: midline, lateral: mid - axillary line, and inferior margin: 2 m below the inframammary fold). In 3D planning, the clinical target volume (CTV) ought to comprise all glandular breast tissue, and the PTV was obtained by adding a 3D margin of 1 cm around the CTV except in the skin direction. The difference in the treatment field margin and equivalent field size between 2D and 3D planning were evaluated. The association between radiation field margins and factors such as body mass index, menopause status, and bra size was determined. Lung volume and heart volume were examined on the basis of the prescribed breast radiation dose and 3D dose distribution. Results: The margins of the treatment field were smaller in the 3D planning except for two patients. The superior margin was especially variable (average, 2.5 cm; range, -2.5 to 4.5 cm; SD, 1.85). The margin of these targets did not vary equally across BMI class, menopause status, or bra size. The average irradiated lung volume was significantly lower for 3D planning. The average irradiated heart volume did not decrease significantly. Conclusion: The use of 3D CT based planning reduced the radiation field in early breast cancer patients with small breasts in relation to conventional planning. Though a coherent definition of the breast is needed, CT-based planning generated the better plan in terms of reducing the irradiation volume of normal tissue. Moreover it was possible that 3D CT based planning showed better CTV coverage including postoperative change.