• Title/Summary/Keyword: High dose rate brachytherapy

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Feasibility Study of Source Position Verification in HDR Brachytherapy Using Scintillating Fiber

  • Moon, Sun Young;Jeong, EunHee;Lim, Young Kyung;Chung, Weon Kyu;Huh, Hyun Do;Kim, Dong Wook;Yoon, Myonggeun
    • Progress in Medical Physics
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    • v.27 no.4
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    • pp.213-219
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    • 2016
  • The position verification of the radiation source utilized in brachytherapy forms a critical factor in determining the therapeutic efficiency. Currently, films are used to verify the source position; however, this method is encumbered by the lengthy time interval required from film scanning to analysis, which makes real-time position verification difficult. In general, the source position accuracy is usually tested in a monthly quality assurance check. In this context, this study investigates the feasibility of the real-time position verification of the radiation source in high dose rate (HDR) brachytherapy with the use of scintillating fibers. To this end, we construct a system consisting of scintillating fibers and a silicon photomultiplier (SiPM), optimize the dosimetric software setup and radiation system characteristics to obtain maximum measurement accuracy, and determine the relative ratio of the measured signals dependent upon the position of the scintillating fiber. According to the dosimetric results based on a treatment plan, in which the dwell time is set at 30 and 60 s at two dwell positions, the number of signals is 31.5 and 83, respectively. In other words, the signal rate roughly doubles in proportion to the dwell time. The source position can also be confirmed at the same time. With further improvements in the spatial resolution and scintillating fiber array, the source position can be verified in real-time in clinical settings with the use of a scintillating fiber-based system.

Prediction of Late Rectal Complication Following High-dose-rate Intracavitary Brachytherapy in Cancer of the Uterine Cervix (자궁경부암 환자의 고선량률 강내치료 시행 시 직장합병증의 예측)

  • Lee, Jeung-Eun;Huh, Seung-Jae;Park, Won;Lim, Do-Hoon;Ahn, Yong-Chan
    • Radiation Oncology Journal
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    • v.21 no.4
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    • pp.276-282
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    • 2003
  • Purpose: Although high-dose-rate intracavitary radiotherapy (HDR ICR) has been used in the treatment of cervical cancer, the potential for increased risk of late complication, most commonly in the rectum, is a major concern. We have previously reported on 136 patients treated with HDR brachytherapy between 1995 and 1999. The purpose of this study is to upgrade the previous data and confirm the correlation between late rectal complication and rectal dose in cervix cancer patients treated with HDR ICR. Materials and Methods: A retrospective analysis was peformed for 222 patients with cevix cancer who were treated for curative intent with external beam radiotherapy (EBRT) and HDR ICR from July 1995 to December 2001. The median dose of EBRT was 50.4 (30.6$\~$56.4) Gy with a daily fraction size 1.8 Gy. A total of six fractions of HDR ICR were given twice weekly with fraction size of 4 (3$\~$5.5) Gy to A point by Iridium-192 source. The rectal dose was calculated at the rectal reference point using the barium contrast criteria. in vivo measurement of the rectal dose was peformed with thermoluminescent dosimeter (TLD) during HDR ICR. The median follow-up period was 39 months, ranging from 6 to 90 months. Results: Twenty-one patients (9.5$\%$) experienced late rectal bleeding, from 3 to 44 months (median, 13 months) after the completion of RT. The calculated rectal doses were not different between the patients with rectal bleeding and those without, but the measured rectal doses were higher in the complicated patients. The differences of the measured ICR rectal fractional dose, ICR total rectal dose, and total rectal biologically equivalent dose (BED) were statistically significant. When the measured ICR total rectal dose was beyond 16 Gy, when the ratio of the measured rectal dose to A point dose was beyond 70$\%$, or when the measured rectal BED was over 110 Gy$_{3}$, a high possibility of late rectal complication was found. Conclusion: Late rectal complication was closely correlated with measured rectal dose by in vivo dosimetry using TLD during HDR ICR. If data from in vivo dosimetry shows any possibility of rectal bleeding, efforts should be made to reduce the rectal dose.

Preliminary Results of Concurrent Chemotherapy and Radiation Therapy using High-dose-rate Brachytherapy for Cervical Cancer (자궁경부암에 항암화학요법과 동시 병용요법으로 외부 방사선조사와 고선량률 강내조사의 예비적 치료 결과)

  • Lee, Kyung-Ja;Lee, Ji-Hye;Lee, Re-Na;Suh, Hyun-Suk
    • Radiation Oncology Journal
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    • v.24 no.3
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    • pp.171-178
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    • 2006
  • [ $\underline{Purpose}$ ]: To determine the efficacy and safety of concurrent chemotherapy and radiation therapy with high-dose-rate brachytherapy for cervical cancer. $\underline{Materials\;and\;Methods}$: From January 2001 to December 2002, 30 patients with cervical cancer were treated with concurrent chemotherapy (cisplatin and 5-FU) and definitive radiation therapy. The median age was 58 (range $34{\sim}74$) year old. The pathology of the biopsy sections was squamous cell carcinoma in 29 patients and one was adenocarcinoma. The distribution to FIGO staging system was as follows: stage IB, 7 (23%); IIA, 3 (10%); IIB, 12 (40%); IIIA, 3 (10%); IIIB, 5 (17%). All patients received pelvic external beam irradiation (EBRT) to a total dose of $45{\sim}50.4\;Gy$ (median: 50.4 Gy) over $5{\sim}5.5$ weeks. Ir-192 HDR intracavitary brachytherapy (ICBT) was given after a total dose of 41.4 Gy. HDR-ICBT was performed twice a week, with a fraction point A dose of 4 Gy and median dose to point A was 28 Gy (range: $16{\sim}32\;Gy$) in 7 fractions. The median cumulative biologic effective dose (BED) at point A (EBRT+ICBT) was $88\;Gy_{10}$ (range: $77{\sim}94\;Gy_{10}$). The median cumulative BED at ICRU 38 reference point (EBRT+ICBT) was $131\;Gy_3$ (range: $122{\sim}140\;Gy_3$) at point A, $109\;Gy_3$ (range: $88{\sim}125\;Gy_3$) at the rectum and $111\;Gy_3$ (range: $91{\sim}123\;Gy_3$) at the urinary bladder. Cisplatin ($60\;mg/m^2$) and 5-FU ($1,000\;mg/m^2$) was administered intravenously at 3 weeks interval from the first day of radiation for median 5 (range: $2{\sim}6$) cycles. The assessment was performed at 1 month after completion of radiation therapy by clinical examination and CT scan. The median follow-up time was 36 months (range: $8{\sim}50$ months). $\underline{: The complete response rate after concurrent chemoradiation therapy was 93.3%. The 3-yr actuarial pelvic control rate was 87% and 3-yr actuarial overall survival and disease-free survival rate was 93% and 87%, respectively. The local failure rate was 13% and distant metastatic rate was 3.3%. The crude rate of minor hematologic complications (RTOG grade 1-2) occurred in 3 patients (10%) and one patient had suffered from severe leukopenia (RTOG grade 4) during concurrent treatment. Acute minor enterocolitis (RTOG grade 1-2) occurred in 11 patients (37%) and one patient (3%) was suffered from colon perforation during radiation therapy. Late colitis of RTOG grade 1 occurred in 5 patients (15%). Acute cystitis of RTOG grade 1 occurred in 12 patients (40%) and late cystitis of RTOG grade 2 occurred in one patient (3%). No treatment related death was seen. $\underline{Conclusion}$: The results of this study suggest that the concurrent chemoradiation therapy with HDR brachytherapy could be accepted as an effective and safe treatment for cervical cancer.

Measurement of Ir-192 Source Activity for High Dose Rate Brachytherapy (고 선량률 근접치료시 사용되는 Ir-192 선원의 방사능 평가)

  • 최동락;허승재;안용찬;임도훈;김대용;우홍균
    • Progress in Medical Physics
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    • v.8 no.1
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    • pp.25-29
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    • 1997
  • Ir-192 source activity for high dose rate brachytherapy is measured using Farmertype ionization chamber. The source-to-chamber distance is 10 cm and the measured charge unit is converted to activity unit. The measured values are compared to the values provided from vendor. Because of time dependency of Ir-192 source activity, the activities are regularly checked and compared to calculated values. As the accuracy of Ir-192 source activity is depend on the mechanical measurement setup, we estimated the precision of remote controlled source dwell position using home-made device and film scanner. The difference between measured and predicted dwell position is within 1 mm. As a result, the errors of source activity are 0.7${\pm}$1.5 % for measured and vendor-provided values and 0.l${\pm}$1.2% for measured and time-dependent calculated vlaues. In conclusion, our measured activity has been comparable to the values provided from vendor and our brachytherapy unit has been very accurate until now. Regular quality control of brachytherapy is essential for successful treatment which depends on the accuracy of source position and activity.

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The Role of Intraluminal Brachytherapy in Management of Esophageal Cancer (식도암 치료에 있어 관내근접치료의 역할)

  • Lee Chang Geol;Suh Chang Ok;Kim Gwi Eon;Chu Sung Sil;Chung Eun Ji;Kim Woo Cheol
    • Radiation Oncology Journal
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    • v.13 no.4
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    • pp.331-338
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    • 1995
  • Purpose : To evaluate our clinical experience with the combination of teletherapy and intraluminal brachytherapy in patients with unresectable or inoperable esophageal cancers. Materials and Methods : From Nov 1989 to Mar 1993, twenty patients with esophageal cancer were treated with radical radiotherapy and intraluminal brachytherapy at Yonsei Cancer Center. All patients had squamous histolgy and stage distribution was as follows: stage II, 4($20{\%}$)patients; III, 15 ($75{\%}$)patients; IV, 1($5{\%}$)patients. A dose of S-12Gy/1-3weeks with intraluminal brachytherapy (3-5Gy/fraction) to 5mm from the outside of the esophageal tube using high dose rate Iridium-192 remotely afterloading brachytherapy machine was given 2 weeks after a total dose of 59-64Gy with external radiotherapy. Induction chemotherapy using cisplatin and 5-FU was performed in 13 patients with median 3 cycles(1-6 cycles), Response rate, local control rate, survival and complications were analysed retrospectively. Results : Two-year overall survival rate and median survival were $15.8{\%}$ and 13.5 months. Response rates were as follows complete remission(CR) 5($25{\%}$): partial remission a(PRa) 7($35{\%}$): partial remission b(PRb) 7($35{\%}$), no response(NR) 1($5{\%}$). Patterns of failure were as follows; local failure 13($65{\%}$), local and distant failure 3($15{\%}$), distant failure 0($0{\%}$). Ultimate local control rate was $20{\%}$. Treatment related complications included esophageal ulcer in two patients and esophageal stricture in one. Conclusion : Though poor local conrol rate, median survival was improved as compared with previous results of radiation therapy alone(8months) and chemoradiation combined treatment(11 months) in Yonsei Cancer Center High-dose-rate intraluminal brachytherapy following external irradiation is an effective treatment modality with acceptable toxicity in esophageal cancer.

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The Treatment of Uterine Cervical Cancer Using High Dose Rate Co-60 Sources (고선량율(高線量率) 강내조사법(腔內照射法)을 이용(利用)한 자궁경암(子宮頸癌) 방사선(放射線) 치료(治療))

  • Kim, G.E.;Suh, C.O.;Lee, D.H.;Park, C.Y.
    • Radiation Oncology Journal
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    • v.1 no.1
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    • pp.95-102
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    • 1983
  • The radical treatment of uterine cervical cancer by interacavitary radium or cesium, in combination with teletherapy are well known. Although the result of such treatment should not give rise to complacency, problem of radiation exposure to medical staff had not been resolved. Fortunately, many attempts have been made to reduce this hazard, most of which take the form of afterloading applicators with a suitably shielded radioisotope. In order to avoid hazardous radiation exposure to staffs concerned with brachytherapy, RALS using high intensity source of Co-60, have been employed at Yonsei Cancer Center since May, 1979. It allows rectal and bladder doses to be kept low, while maintaining a satifactory usual dose distribution of the other type of applicators, and the short treatment time allow four or five patients to be treated per hour. It also removes much patient's discomfort and the difficulties of nursing these patients. Since the first introduction in Korea, over seven hundred cases with various stage of uterine cervical cancer have been treated on a radical basis at this center last 4 years. These authors have strongly attracted attention to the results in terms of local control rate, survival s and morbidity compared with those of conventional low dose rate radiotherapy. Retrospective interim analysis of data was preliminarily accomplished through the labored follow-up study of 340 cases treated during initial 2 years and the radiobiologic standpoint of high dose rate intracavitary irradiation will be discussed.

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Comparison of Treatment Planning on Dosimetric Differences Between 192Ir Sources for High-Dose Rate Brachytherapy (고선량률 근접치료에서 이리듐-192 선원의 선량특성 차이에 관한 치료계획 비교)

  • Yang, Oh-Nam;Shin, Seong Soo;Ahn, Woo Sang;Kim, Dae-Yong;Kwon, Kyung-Tae;Lim, Cheong-Hwan;Lee, Sang Ho;Choi, Wonsik
    • Journal of radiological science and technology
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    • v.39 no.2
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    • pp.163-170
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    • 2016
  • To evaluate whether the difference in geometrical characteristics between high-dose-rate (HDR) $^{192}Ir$ sources would influence the dose distributions of intracavitary brachytherapy. Two types of microSelectron HDR $^{192}Ir$ sources (classic and new models) were selected in this study. Two-dimensional (2D) treatment plans for classic and new sources were generated by using PLATO treatment planning system. We compared the point A, point B, and bladder and rectum reference points based on ICRU 38 recommendation. The radial dose function of the new source agrees with that of the classic source except difference of up to 2.6% at the nearest radial distance. The differences of anisotropy functions agree within 2% for r=1, 3, and 5 cm and $20^{\circ}$ < ${\theta}$ < $165^{\circ}$. The largest discrepancies of anisotropy functions reached up to 27% for ${\theta}$ < $20^{\circ}$ at r=0.25 cm and were up to 13%, 10%, and 7% at r=1, 3, and 5 cm for ${\theta}$ > $170^{\circ}$, respectively. There were no significant differences in doses of point A, point B, and bladder point for the treatment plans between the new and classic sources. For the ICRU rectum point, the percent dose difference was on average 0.65% and up to 1.0%. The dose discrepancies between two treatment plans are mainly affected due to the geometrical difference of the source and the sealed capsule.

Permanent Brachytherapy of Localized Prostate Cancer: Preliminary Results (국소 전립선암의 영구적 근접치료: 조기 결과)

  • Park, Hye-Li;Chang, Sei-Kyung;Kim, Ja-Young;Lee, Bo-Mi;Ko, Seong-Young;Kim, Sung-Joon;Shin, Hyun-Soo
    • Radiation Oncology Journal
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    • v.29 no.2
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    • pp.71-82
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    • 2011
  • Purpose: To evaluate the biochemical control rate and the rate of side effects after performing permanent brachytherapy of localized prostate cancer. Materials and Methods: 67 patients with localized prostate cancer were treated with brachytherapy between April 2007 and December 2008. Of these, 43 patients who were followed up and did not receive external radiotherapy were evaluated for the change in prostate specific antigen (PSA) level and the occurrence of side effects. In total, 18 patients were classified as low risk, 19 patients as intermediate risk, and 6 patients as high risk. The prescription dose was 145 Gy. Results: A PSA increase greater than 2 ng/mL occurred in 2 patients (4.7%). Radiation Therapy Oncology Group (RTOG) grade 1 and 2 acute urologic complications (UC) occurred in 40 and 3 patients, respectively. Further, 5 patients had RTOG grade 1 acute rectal complication (RC). The numbers of RTOG grade 1, 2, and 3 chronic UC were 1, 4, and 1, respectively. The numbers of RTOG grade 1, 2, and 4 chronic RC were 5, 10, and 3, respectively. The statistically significant risk factors (RF) of acute RC were the minimal dose in the most irradiated 0.1 cc volume ($D_{0.1cc}$, p=0.041) and absolute volume receiving 150% of the prescribed dose ($V_{150cc}$, p=0.038) in the entire rectum (ER). The percentage ($V_{100%}$, p=0.019) and absolute volume ($V_{100cc}$, p=0.047) in the involved rectum (IR) were also statistically significant. The RF of chronic RC were $V_{100%}$ (p=0.011) in the ER and the $D_{0.1cc}$ (p=0.049), $V_{100cc}$ (p=0.023) in the IR. The number of used seeds were related with acute UC (p=0.028). Conclusion: Permanent brachytherpy of localized prostate cancer showed a favorable short term biochemical control rate. As such, selective intermediate and high risk patients can be managed with permanent brachytherapy. The effort to reduce rectal complication is also necessary.

Late Rectal Complication in Patients treated with High Dose Rate Brachytherapy for Stage IIB Carcinoma of the Cervix (FIGO병기 IIB 자궁경부암에서 고선량 강내 방사선치료후의 후기 직장 합병증)

  • Chung, Eun-Ji;Kim, Gwi-Eon;Suh, Chang-Ok;Keum, Ki-Chang;Kim, Woo-Cheol
    • Radiation Oncology Journal
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    • v.14 no.1
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    • pp.41-52
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    • 1996
  • Purpose : This paper reports a dosimetric study of 88 patients treated with a combination of external radiotherapy and high dose rate ICR for FIGO stage IIB carcinoma of the cervix. The purpose is to investigate the correlation between the radiation doses to the rectum, external radiation dose to the whole pelvis, ICR reference volume, TDF BED and the incidence of late rectal complications, retrospectively. Materials and Methods : From November 1989 through December 1992, 88 patients with stage IIB cervical carcinoma received radical radiotherapy at Department of Radiation Oncology in Yonsei University Hospital. Radiotherapy consisted of 44-54 Gy(median 49 Gy) external beam irradiation plus high dose rate intracavitary brachytherapy with 5 Gy per fraction twice a week to a total dose of 30 Gy on point A. The maximum dose to the rectum by contrast(r, R) and reference rectal dose by ICRU 38(dr, DR) were calculated. The ICR reference volume was calculated by Gamma Dot 3.11 HDR planning system, retrospectively The time-dose factor(TDF) and the biologically effective dose (BED) were calculated. Results : Twenty seven($30.7\%$) of the 88 patients developed late rectal complications:12 patients($13.6\%$) for grade 1, 12 patients($13.6\%$) for grade 2 and 3 patients($3.4\%$) for grade 3. We found a significant correlation between the external whole pelvis irradiation dose and grade 2, 3 rectal complication. The mean dose to the whole pelvis for the group of patients with grade 2, 3 complication was Higher, $4093.3\pm453.1$ cGy, than that for the patients without complication, $3873.8\pm415.6$ (0.05$7163.0\pm838.5$ cGy, than that for the Patients without rectal complication, $0772.7\pm884.0$ (p<0.05). There was no correlation of the rate of grade 2, 3 rectal complication with the iCR rectal doses(r, dr), ICR reference volume, TDF and BED. Conclusion : This investigation has revealed a significant correlation between the dose calculated at the rectal dose by ICRU 38(DR) or the most anterior rectal dose by contrast(R) dose to the whole pelvis and the incidence of grade 2, 3 late rectal complications in patients with stage IIB cervical cancer undergoing external beam radiotherapy and HOR ICR. Thus these rectal reference points doses and whole pelvis dose appear to be useful Prognostic indicators of late rectal complication in high dose rate ICR treatment in cervical carcinoma.

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Development of Source Template ICRT Dose Planning Software for Uterine Cervix Using the HDR: $^{192}Ir$ (강내조사를 위한 고선량률 근접조사 선원맞춤형 선량계획)

  • Choi, Tae-Jin;Oh, Young-Kee;Kim, Jin-Hee;Kim, Ok-Bae
    • Progress in Medical Physics
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    • v.20 no.2
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    • pp.112-118
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    • 2009
  • The source position and source dwelling time in a given source arrangement in the applicators is very high effect to determine the expose time which in general is derived from the brachytherapy planning system. In high dose rate (HDR) intracavitary radiation therapy (ICRT), the treatment is often performed in based out-patient during the whole fractionation irradiations. However, the patient should be waited on coutch for ICR treatment in first start fraction as unconvinent and immobilized state until perform the dose plannings. In our experiments, the HDR source contributed dose for$55.89{\pm}4.20%$ for straight tandem source, $38.14{\pm}4.46%$ for the right ovoid soucre on the fornix and$5.97{\pm}0.50%$ for left ovoid source. It also showed the $60.33{\pm}6.53%$ for the tandem, $33.10{\pm}6.74%$ for right ovoid and $6.58{\pm}0.30%$ for the left ovoid source in 10 degrees of applicator. The authors designed the source template dose planning software for ICRT of uterine cervix results average $-0.55{\pm}2.15%$ discrepancy of the full charged brachytherapy dose planning. Developed Source temperate ICRT plaanning software guide a minimized the complains and operating times within a ${\pm}3%$ of dose discrepancies.

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