• Progress in Medical Physics
• /
• v.17 no.4
• /
• pp.232-237
• /
• 2006

The aim of this study was to develop the calculation algorithm of source strength of Ir-192 source In terms of the absorbed dose to water instead of an apparent activity (Ci). For this work the Multi Purpose Brachytherapy Phantom(MPBP) was developed, which was designed to locate the source and the chamber precisely at a specific position Inside the water phantom. The reference point of measurement was set at the 5 cm distance along the transverse axis of the source. For a brachytherapy source calibration, the absorbed dose to water calibration factor ($N_{D.W.Q}$) of an lonization chamber were determined and then apply standard protocols of absorbed dose to water. The calibration factor ($N_{D.W.Q}$) of the ion chamber (TM30013, PTW, Germany) was determined using the EGSnrcCPP Monte Carlo Code. The calculated calibration factor ($N_{D.W.Q}$) was 5.28 cGy/nC. The calculated factor was then used to determine the absorbed dose to water from which the air kerma strength for an Ir-192 source can be easily derived at the reference point (5 cm). The calculated air kerma strength showed discrepancies of -0.6% to +1.8% relative to the air kerma strength provided by the vendor, In this work we demonstrated that the air kerma strength ($S_k$) could be determined from the absorbed dose to water calibration factor for Ir-192 source. In audition, this source calibration method could be applied directly to the dose Calculation formalism of AAPM report TG-43.

• Radiation Oncology Journal
• /
• v.25 no.3
• /
• pp.177-184
• /
• 2007

Purpose: To evaluate the palliative effect of endobronchial brachytherapy (EBB) for patients with lung cancer that previously received external beam radiotherapy (EBRT). Materials and Methods: From July 1992 to May 2003, 29 patients with a recurrent or persistent lung cancer were treated with palliative EBB at our institute. EBB consisted of three fractions (once a week) of a dose of 5 Gy using the high dose-rate remote afterloader. Symptomatic improvement was assessed subjectively, and patients were divided into two groups according to whether symptoms were improved or not. Factors such as age, performance status, duration from EBRT to EBB and the location of the tumor were compared between the improved and unimproved groups of patients. Results: Overall symptomatic improvement was found in 27 out of 52 symptoms (52%). Improvement as to the type of symptoms was seen in 41 %, 50%, 82% and 33% of patients with cough, dyspnea, hemoptysis, and obstructive pneumonia respectively. The rate of improvement of hemoptysis was more than that of cough (p<0.05). The median time to symptom relapse was 5 months. The improved patient group (n=17, 59%) had a better performance status and longer duration from EBRT to EBB than the unimproved patient group (p<0.05). Lesions located in the distal trachea and/or main bronchus were found more frequently in the improved group of patients than in the unimproved group of patients, but the difference was not statistically significant (p=0.06). Fatal complications developed in two patients (7%), which were a hemoptysis and bronchopleural fistula respectively. Conclusion: Symptom improvement was found in 60% of patients after EBB and improvement was maintained for 5 months. Palliative EBB, even when EBRT was given previously, can be effective for a patient that has an endobronchial symptom, such as hemoptysis, and for a patient with good performance and a long duration from previous EBRT to EBB.

• The Journal of Korean Society for Radiation Therapy
• /
• v.16 no.1
• /
• pp.73-77
• /
• 2004

Purpose of the radio-therapy is maximize the radiation dose to the tumor while minimizing the dose to the critical organ. Carcinoma of the uterine cervix treatment are external irradiation or an interstitial brachtheraphy make use of isotope. Brachytherapy is a method of radiotherapy in advantage to achieve better local control with minimum radiation toxicity in comparison with external irradiation because radiation dose is distributed according to the inverse square low of gamma-ray emitted from the implanted sources. Authors make use of the patients data which 192Ir gives medical treatment intrcavity. Intracavitary radiation of the uterine cervix cancer, critical organ take $20\%$ below than exposure dose of A point in the ICRU report. None the less of the advice, Radiation proctitis and radiation cystitis are frequent and problematic early complications in patients treated with radiation for the uterine cervix cancer. In brachytherapy of uterine cervical cancer using a high dose rate remote afterloading system, it is of prime importance to deliver a accurate dose in each fractionated treatment by minimizing the difference between the pre-treatment planned and post-treatment calculated doses. Use of packing to reduce late complications intracavitary radiation of the uterine cervix cancer. Bladder and rectum changes exposure dose rate by radiotherphy make use of packing.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.9
• /
• pp.3891-3893
• /
• 2014

Background: Most patients with endometrial cancer have stage I disease. Adjuvant therapy in stage IB (formerly IC) endometrial cancer is controversial, treatment options including observation or brachytherapy/radiotherapy in grade 1-3 patients with or without chemotherapy. The purpose of this study was to assess the outcomes of our patients with stage IB endometrioid endometrial cancer. Materials and Methods: Sixty two patients with stage IB endometrial cancer and endometrioid histology were retrospectively evaluated. All patients were initially treated surgically by the same surgeon with comprehensive staging, i.e. total abdominal hysterectomy, bilateral salphingooopherectomy, bilateral pelvic and paraaortic lymph node dissection and omentectomy. Adjuvant radiotherapy was discussed with patients and utilized by those who accepted. Adjuvant chemotherapy was not given to any of the patients. Results: Median age was 62 (range, 42-95). Ninety percent of the patients had grade 1-2 disease. Thirteen patients (21%) received intra vaginal brachytherapy (IVBT) and one received whole pelvic radiotherapy (WPRT). Median follow-up time was 46 months (range, 9-77 months). Three patients experienced recurrence (4.8%), two of them died on follow-up and one was still alive at last visit. Two patients with recurrence had FIGO grade 2 tumors and one had a grade 3 tumor. Two patients (3.2%) died without evidence of recurrent disease. Relapse free survival at 5 years was 94.4% and overall survival was 93.1%. Conclusions: Patients with stage IB disease in our study demonstrated relatively low recurrence rates although the majority of them received no adjuvant treatment. Surgery alone may be sufficient for most patients with this stage of endometrial cancer.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.14
• /
• pp.5957-5961
• /
• 2015

Background: We designed this randomized controlled trial (RCT) to assess whether lobaplatin-based concurrent chemotherapy might be superior to cisplatin-based concurrent chemotherapy for FIGO stage II and III cervical cancer in terms of efficacy and safety. Materials and Methods: This prospective, open-label RCT aims to enroll 180 patients with FIGO stage II and III cervical cancer, randomly allocated to one of the three treatment groups (cisplatin $15mg/m^2$, cisplatin $20mg/m^2$ and lobaplatin $35mg/m^2$), with 60 patients in each group. All patients will receive external beam irradiation (EBRT) and high-dose-rate intracavitary brachytherapy (HDR-ICBT). Patients in cisplatin $15mg/m^2$ and $20mg/m^2$ groups will be administered four cycles of $15mg/m^2$ or $20mg/m^2$ cisplatin intravenously once weekly from the second week to the fifth week during EBRT, while patients inthe lobaplatin $35mg/m^2$ group will be administered two cycles of $35mg/m^2$ lobaplatin intravenously in the second and fifth week respectively during pelvic EBRT. All participants will be followed up for at least 12 months. Complete remission rate and progression-free survival (PFS) will be the primary endpoints. Overall survival (OS), incidence of adverse events (AEs), and quality of life will be the secondary endpoints. Results: Between March 2013 and March 2014, a total of 61 patients with FIGO stage II and III cervical cancer were randomly assigned to cisplatin $15mg/m^2$ group (n=21), cisplatin $20mg/m^2$ group (n=21) and lobaplatin $35mg/m^2$ group (n=19). We conducted a preliminary analysis of the results. Similar rates of complete remission and grades 3-4 gastrointestinal reactions were observed for the three treatment groups (P=0.801 and 0.793, respectively). Grade 3-4 hematologic toxicity was more frequent in the lobaplatin group than the cisplatin group. Conclusions: This proposed study will be the first RCT to evaluate whether lobaplatin-based chemoraiotherapy will have beneficial effects, compared with cisplatin-based chemoradiotherapy, on complete remission rate, PFS, OS, AEs and quality of life for FIGO stage II and III cervical cancer.

• Journal of the Korean Society of Radiology
• /
• v.15 no.5
• /
• pp.715-721
• /
• 2021

In radiation brachytherapy, the wrong source location may cause excessive dose to normal tissue. Therefore, research on digital dosimeters is being made to replace the analog detection method. Therefore, in this study, a lead (II) oxide (PbO) dosimeter applied with a passive layer (PL) was fabricated as a basic study to improve the dosimeter performance. Afterwards, reproducibility, linearity, and distance dependence were evaluated to analyze the performance of the Ir-192 source under irradiation conditions. The reproducibility of the PL-PbO dosimeter was 0.40%, which satisfies the evaluation criteria of 1.5%, and showed improved results compared to the PbO dosimeter. Linear function R2 showed excellent results as 0.9995, and slope analysis through regression analysis of the linear function was excellent in PL-PbO. The distance dependence of the PL-PbO dosimeter was +0.599 higher than that of PbO when the slope obtained through regression analysis of the power function was compared with the inverse square value. This study presents the effects and measurement variables according to the measurement configuration of the solid-state dosimeter, and can be used in various radiation detection fields.

• Journal of the Korean Society of Radiology
• /
• v.15 no.4
• /
• pp.429-435
• /
• 2021

In intracavitary radiotherapy, incorrect location of the source can cause excessive dose to normal tissue, so it is essential to evaluate the location accuracy of the source. In this study, basic research was performed on digital line dosimeter based on lead (II) oxide (PbO) to improve analog verification method. Therefore, a polycrystalline PbO unit cell dosimeter was manufactured and the measurement performance for Ir-192 sources was evaluated. As a result, the reproducibility satisfies the evaluation criteria of 1.5% with a relative standard deviation of 0.85%. Linearity showed excellent results with a linear coefficient of R² of 0.9998. In the case of distance dependence evaluation, the power function R² showed 0.9855 for PbO and 0.9974 for diode, and the overall average difference was 1.66% for PbO and 2.18% for diode. This study presents the basic detection performance of the polycrystalline PbO dosimeter for the Ir-192 source and can provide basic data in the field of radiation measurement.

• Journal of the Korean Society of Radiology
• /
• v.16 no.1
• /
• pp.61-66
• /
• 2022

The purpose of this study is to derive photon energy fluence and mass energy absorption coefficient for 1 Gy of absorbed dose of water in brachytherapy using an Ir¹⁹² source. From the radiotherapy physics written by Khan, the half-value of lead for the gamma ray beam of the Ir¹⁹² source was obtained. The linear attenuation coefficient and the mass attenuation coefficient were calculated from the obtained half-value layer of lead. By matching the calculated lead mass attenuation coefficient with the NIST mass attenuation coefficient data, the photon energy of the matching mass attenuation coefficient was determined as the effective energy. By matching the determined effective energy with the photon energy of the NIST data on the mass energy absorption coefficient of water, the mass energy absorption coefficient of water was obtained as 0.03273 cm²/g(32.73 cm²/kg). The photon energy fluence was calculated as 0.03055 J/cm² by dividing the obtained mass energy absorption coefficient (32.73 cm²/kg) by the absorbed dose of water 1 Gy.

• Progress in Medical Physics
• /
• v.5 no.1
• /
• pp.67-74
• /
• 1994

Dose distribution of point source represents an inverse square law as the distance, Difference of measurement value and calculation value according to moving distance of radiation source show very large error in dose calculation of Brachytherapy. Therefore, in RALS of high dose rate, dose calculation have an important effect in treatment of uterine cervix cancer and recurrent rate. In this paper, authors measured moving distance of radiation source carrying out RALS. And we measured Rectum dose compared with calculationdose.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.12
• /
• pp.6251-6255
• /
• 2012

Radiation proctitis and radiation cystitis are major complications for patients with cervical carcinoma following radiotherapy. In the present study, we aimed to determine the potential risk factors for the development of radiation proctitis and radiation cystitis after irradiation. A total of 1,518 patients with cervical carcinoma received external beam radiotherapy (EBRT) followed by high-dose-rate intracavitary brachytherapy (HDRICB) in our hospital. The incidences of radiation proctitis and radiation cystitis were recorded and associations with different factors (age, time period, tumor stage) were analyzed with ${\chi}^2$ (chi-squared) and Fisher exact tests. We found that 161 and 94 patients with cervical carcinoma were diagnosed with radiation proctitis and radiation cystitis, respectively, following radiotherapy. The prevalence of Grade I-II radiation proctitis or radiation cystitis was significantly lower than that of Grade III (radiation proctitis: 3.82% vs. 6.76%, P < 0.05; radiation cystitis: 2.31% vs. 3.87%, P < 0.05) and was significantly enhanced in patients with late stage (IIIb) tumor progression compared to those in early stage (Ib, IIa) (P < 0.05). Moreover, the incidence of radiation proctitis and cystitis was not correlated with age or, time period following radiation, for each patient (P > 0.05). These observations indicate that a late stage of tumor progression is a potential risk factor for the incidence of radiation proctitis and cystitis in cervical carcinoma patients receiving radiotherapy.