• The Journal of Korean Society for Radiation Therapy
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• v.27 no.1
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• pp.45-52
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• 2015

Purpose : The dose distribution of organ at risk (OAR) and normal tissue is affected by treatment technique in postoperative radiation therapy for prostate cancer. The aim of this study was to compare dose distribution characteristic and to evaluate treatment efficiency by devising VMAT plans according to applying differed number of arc and IMRT plan for postoperative patient of prostate cancer radiation therapy using a rectal balloon. Materials and Methods : Ten patients who received postoperative prostate radiation therapy in our hospital were compared. CT images of patients who inserted rectal balloon were acquired with 3 mm thickness and 10 MV energy of HD120MLC equipped Truebeam STx (Varian, Palo Alto, USA) was applied by using Eclipse (Version 11.0, Varian, Palo Alto, USA). 1 Arc, 2 Arc VMAT plans and 7-field IMRT plan were devised for each patient and same values were applied for dose volume constraint and plan normalization. To evaluate these plans, PTV coverage, conformity index (CI) and homogeneity index (HI) were compared and $R_{50%}$ was calculated to assess low dose spillage as per treatment plan. $D_{25%}$ of rectum and bladder Dmean were compared on OAR. And to evaluate the treatment efficiency, total monitor units(MU) and delivery time were considered. Each assessed result was analyzed by average value of 10 patients. Additionally, portal dosimetry was carried out for accuracy verification of beam delivery. Results : There was no significant difference on PTV coverage and HI among 3 plans. Especially CI and $R_{50%}$ on 7F-IMRT were the highest as 1.230, 3.991 respectively(p=0.00). Rectum $D_{25%}$ was similar between 1A-VMAT and 2A-VMAT. But approximately 7% higher value was observed on 7F-IMRT compare to the others(p=0.02) and bladder Dmean were similar among the all plan(P>0.05). Total MU were 494.7, 479.7, 757.9 respectively(P=0.00) for 1A-VMAT, 2A-VMAT, 7F-IMRT and at the most on 7F-IMRT. The delivery time were 65.2sec, 133.1sec, 145.5sec respectively(p=0.00). The obvious shortest time was observed on 1A-VMAT. All plans indicated over 99.5%(p=0.00) of gamma pass rate (2 mm, 2%) in portal dosimetry quality assurance. Conclusion : As a result of study, postoperative prostate cancer radiation therapy for patient using a rectal balloon, there was no significant difference of PTV coverage but 1A-VMAT and 2A-VMAT were more efficient for dose reduction of normal tissue and OARs. Between VMAT plans. $R_{50%}$ and MU were little lower in 2A-VMAT but 1A-VMAT has the shortest delivery time. So it is regarded to be an effective plan and it can reduce intra-fractional motion of patient also.

• Progress in Medical Physics
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• v.8 no.2
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• pp.27-34
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• 1997

In radiation therapy, the goal of three dimensional conformal radiation therapy(3DCRT) is to conform the apatial distribution of the prescribed radiation dose to the precise 3D configuration of the tomor, and at the same time, to minimize the dose to the surrounding normal tissues. To optimize treatment volume of tomor, treatment volume will be same tomor volume. Biological considerations need to be incorporated in the intensity modulation optimization process. Planning of intensity modulated treatment can irradiate more 20％ in tomor compare to conventional 3DCRT. In lung cancer and rectal cancer, planning of intensity modulated treatment showed optimizing dose distribution.

• Radiation Oncology Journal
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• v.6 no.1
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• pp.93-99
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• 1988

Some modern accerelators provide a dual energy for photon beam treatment. The main advantages of dual energy in the treatment of rectosigmoid or rectal cancer are as fellows. 1. Dose in the critical organ such as small intestine, bladder and genital organ are reduced. 2. Presacral and perineal area is fully covered. Dose distribution analysis such as calculation of dose in a target volume, isocenter, $D_{nax}$ and dose spectrum in any region of interest are possible. Examples of plan are given and results are discussed.

• Journal of radiological science and technology
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• v.40 no.3
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• pp.415-421
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• 2017

In the case of radiation therapy for prostate cancer, a balloon infused with a certain amount of air through the anus is used to reduce rectal dose. Because of the reason, radiation therapy for prostate cancer has acquired CBCT for daily image induction. In order to maintain the anatomical structure most similar to the first CT taken before treatment, it is pretreated, but it can not be said to be perfectly consistent. In two actual treatment regimens, the volume of the bladder was measured as 45.82 cc and 63.43 cc, and the equivalent diameter was 4.4 cm and 4.9 cm. As a result of this study, the mean volume of the bladder was estimated to be 56.2 cc, 105.6 cc by 20 CBCT. The mean dose of CBCT was 1.74% and the mean Bladder mean dose was 96.67%. In case B, PTV mean dose was 4.31%, Bladder mean Dose was estimated to be 97.35%. The changes in the volume of the bladder resulted in changes in the dose of PTV and bladder. The correlation coefficient of bladder dose according to the change of bladder volume showed linearity of mean dose $R^2=-0.94$. The correlation coefficient of the PTV dose according to the volume change of the bladder showed linearity of mean dose $R^2=0.04$. It was found that the dose change of PTV was larger than that of bladder according to the change of bladder volume.

• Radiation Oncology Journal
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• v.16 no.1
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• pp.51-61
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• 1998

Purpose : Treatment of choice for uterine cervix cancer stage IIB is radiotherapy. We analyzed survivals, Prognostic factors, patterns of failure and complications. Materials and Methods : This is a retrospective analysis of 167 patients with stage IIB carcinoma of uterine cervix treated with curative external pelvic and high dose rate intracavitary radiotherapy at the Department of Therapeutic Radiology, Soonchunhyang University Hospital from August 1985 to August 1994. All the patients followed up from 3 to 141 months(mean 60 months) and age of patients ranged from 31 to 78 years at presentation(mean : 55 years). Results : Overall complete response rate was $84\%$. The response rate for squamous cell carcimoma and adenocarcinoma were $86\%$ and $60\%$, respectively. Overall 5-years survival rate and disease free survival rate was 62 and $59\%$, respectively Mass size and treatment response were significant Prognostic factors for survival Pathologic type and parametrial involvement were marginally significants Prognostic factors. Local failure was 43 cases, distant metastasis was 14 cases and local failure plus distant metastasis was 3 cases, and most of local failures occurred within 24 months, distant metastasis within 12 months after treatment Twenty eight($16.8\%$) patients developed late rectal and urinary complications There were tendency to increasing severity and frequency according to increased fractional dose and total(rectal and bladder) dose. Conclusions : Survival rate was significantly related to tumor size and radiotherapy response. Tumor size should be considered in the clinical s1aging. To increased survival and local control, clinical trials such as decreasing duration of radiotherapy or addition of chemotherapy is needed. To detect early recurrence, regular follow up after RT is important. Because total rectal and bladder dose affected late complications. meticulous vaginal packing is needed to optimize dose of normal tissues and to decrease late complications.

• The Journal of Korean Society for Radiation Therapy
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• v.19 no.2
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• pp.99-106
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• 2007

Purpose: The patient's position and anatomy during the treatment course little bit varies to some extend due to setup uncertainties and organ motions. These factors could affected to not only the dose coverage of the gross tumor but over dosage of normal tissue. Setup uncertainties and organ motions can be minimized by precise patient positioning and rigid immobilization device but some anatomical site such as prostate, the internal organ motion due to physiological processes are challenge. In planning procedure, the clinical target volume is a little bit enlarged to create a planning target volume that accounts for setup uncertainties and organ motion as well. These uncertainties lead to differences between the calculated dose by treatment planning system and the actually delivered dose. The purpose of this study was to evaluate the differences of interfractional displacement of organ and GTV based on the tomoimages. Materials and Methods: Over the course of 3 months, 3 patients, those who has applied rectal balloon, treated for prostatic cancer patient's tomoimage were studied. During the treatment sessions 26 tomoimages per patient, Total 76 tomoimages were collected. Tomoimage had been taken everyday after initial setup with lead marker attached on the patient's skin center to comparing with C-T simulation images. Tomoimage was taken after rectal balloon inflated with 60 cc of air for prostate gland immobilization for daily treatment just before treatment and it was used routinely in each case. The intrarectal balloon was inserted to a depth of 6 cm from the anal verge. MVCT image was taken with 5 mm slice thickness after the intrarectal balloon in place and inflated. For this study, lead balls are used to guide the registration between the MVCT and CT simulation images. There are three image fusion methods in the tomotherapy, bone technique, bone/tissue technique, and full image technique. We used all this 3 methods to analysis the setup errors. Initially, image fusions were based on the visual alignment of lead ball, CT anatomy and CT simulation contours and then the radiation therapist registered the MVCT images with the CT simulation images based on the bone based, rectal balloon based and GTV based respectively and registered image was compared with each others. The average and standard deviation of each X, Y, Z and rotation from the initial planning center was calculated for each patient. The image fusions were based on the visual alignment of lead ball, CT anatomy and CT simulation contours. Results: There was a significant difference in the mean variations of the rectal balloon among the methods. Statistical results based on the bone fusion shows that maximum x-direction shift was 8 mm and 4.2 mm to the y-direction. It was statistically significant (P=<0.0001) in balloon based fusion, maximum X and Y shift was 6 mm, 16mm respectively. One patient's result was more than 16 mm shift and that was derived from the rectal expansions due to the bowl gas and stool. GTV based fusion results ranging from 2.7 to 6.6 mm to the x-direction and 4.3$\sim$7.8 mm to the y-direction respectively. We have checked rotational error in this study but there are no significant differences among fusion methods and the result was 0.37$\pm$0.36 in bone based fusion and 0.34$\pm$0.38 in GTV based fusion.

• Radiation Oncology Journal
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• v.23 no.1
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• pp.22-31
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• 2005

Purpose : To conduct a nationwide survey on the principals in radiotherapy for rectal cancer, and produce a database of Korean Patterns of Care Study. Materials and Methods : We developed web-based Patterns of Care Study system and a national survey was conducted using random sampling based on power allocation methods. Eligible patients were who had postoperative radiotherapy for rectal cancer without gross residual tumor after surgical resection and without previous history of other cancer and radiotherapy to pelvis. Data of patients were Inputted to the web based PCS system by each investigators in 19 institutions. Results : Informations on 309 patients with rectal cancer who received radiotherapy between 1998 and 1999 were collected. Male to female ratio was 59 : 41, and the most common location of tumor was lower rectum ($46\%$). Preoperative CEA was checked in $79\%$ of cases and its value was higher than 6 ng/ml in $32\%$. Pathologic stage were I in $1.5\%$, II in $32\%$, III in $53\%$, and IV in $1.6\%$. Low anterior resection was the most common type of surgery and complete resection was peformed in $95\%$ of cases. Distal resection margin was less than 2 cm in $30\%$, and number of lymph node dissected was less than 12 in $31\%$. Chemotherapy was peformed in $91\%$ and most common regimen was 5-FU and leucovorine ($59\%$). The most common type of field arrangement used for the initial pelvic field was the four field box (Posterior-Right-Left) technique ($65.0\%$), and there was no AP-PA parallel opposing field used. Patient position was prone in $81.2\%$, and the boost field was used in $61.8\%$. To displace bowel outward, pressure modulating devices or bladder filling was used in $40.1\%$. Radiation dose was prescribed to isocenter in $45.3\%$ and to isodose line in 123 cases ($39.8\%$). Percent delivered dose over $90\%$ was achieved in $92.9\%$. Conclusion : We could find the Patterns of Care for the radiotherapy in Korean rectal cancer patients was similar to that of US national survey. The type of surgery and the regimen of chemotherapy were variable according to institutions and the variations of radiation dose and field arrangement were within acceptable range.

• Progress in Medical Physics
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• v.25 no.2
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• pp.89-94
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• 2014

We investigated whether regional hyperthermia (HT) increased post-surgical complications in patients with locally advanced rectal cancer treated with preoperative concurrent chemoradiotherapy (CCRT). Between 1996 and 2007, 205 patients treated with preoperative CCRT and curative surgery were evaluable for the analysis of acute and late toxicities. A total dose of 39.6 Gy or 45 Gy was delivered concurrently with one or two cycles of chemotherapy (5-fluorouracil, leucovorin). Eighty-eight patients received regional HT twice a week using an 8-MHz radiofrequency capacitive heating device. Surgery was performed 4~6 weeks after the completion of preoperative CCRT. The median age was 59 years (range, 18~83) and the median follow-up period was 61months (range, 2~191). The 5-year overall survival and complication-free survival rate of all patients was 77.4% and 73.7%, respectively. Early leakage, delayed leakage, anastomotic stricture, fistula, and small bowel obstruction occurred in 1.0%, 2.9%, 1.5%, 5.9%, and 17.1%, respectively. HT did not increase all kinds of complications. The 5-year complication-free survival rate was 71.8% in the non-HT group and 76.3% in the HT group (p=0.293). Regional HT did not increase postoperative complications in patients with locally advanced rectal cancer treated with preoperative CCRT followed by curative surgery.

• Radiation Oncology Journal
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• v.16 no.1
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• pp.63-69
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• 1998

Purpose : This study is to evaluate the efficacy of small bowel displacement system(SBDS) in post-operative pelvic radiation therapy(RT) of rectal cancer patients by measurement of small bowel volume included in the radiation fields receiving therapeutic dose. Materials and Method : Ten consecutive new rectal cancer patients referred to the department of Radiation Oncology of Samsung Medical Center in May of 1997 were included in this study. All patients were asked to drink $Castrographin^(R)$ before simulation and were laid prone for conventional simulation and CT scans with and without SBDS. The volume of opacified small bowel on CT scans, which was to be included in the radiation fields receiving therapeutic dose, was measured using Picture archiving and communication system (PACS). Results : The average small bowel volumes with and without SBDS were 176.0ml(5.2-415.6ml) and 185.1ml(54.5-434.2ml), respectively The changes of small bowel volume with SBDS compared to those without SBDS were more than $10\%$ decrease in three, less than 10% decrease in two, less than $10\%$ increase in three, and more than $10\%$ increase in two patients. Conclusion : No significant advantage of using SBDS in post-operative pelvic RT for rectal cancer patients has been shown by small bowel volume measurement using CT scan considering additional effort and time needed for simulation and treatment setup.

• 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.