Prognostic value of the maximum standardized uptake value for the locoregional control in early glottic cancer

Purpose@#To evaluate the prognostic value of the pretreatment maximum standardized uptake value (SUVmax) for locoregional control (LRC) of early glottic cancer treated with primary radiotherapy. @*Materials and Methods@#We retrospectively reviewed the medical records of 101 patients with T1-T2N0 glottic cancer treated with helical tomotherapy between 2013 and 2016. The clinical T-stages were T1 in 87 (86.1%) and T2 in 14 (13.9%) patients. The median total dose was 63 Gy (63–67.5 Gy) in 2.25 Gy per fraction. The survival outcomes were plotted using Kaplan-Meier curves. Receiver operating characteristic curves were used to assess the optimal SUVmax cut-off value for predicting locoregional recurrence. @*Results@#The median follow-up period was 58 months (range, 11 to 90 months). The 5-year overall survival (OS) and locoregional recurrence-free survival rates were 96.8% and 85.4%, respectively. The median pretreatment SUVmax of the primary tumor for all 101 patients was 2.3 (range, 1.1 to 9.1). The best cut-off value for SUVmax for predicting LRC was 3.3, with a sensitivity of 78.6% and specificity of 73.6%. Univariate analysis showed that T-stage, overall treatment time (≥43 days), and high SUVmax (≥3.3) were significant predictors of LRC. Multivariate analysis showed that LRC was independently affected by a high SUVmax (≥3.3) (hazard ratio = 5.505, p = 0.020). @*Conclusion@#High pretreatment SUVmax (≥3.3) is a negative prognostic factor for LRC in early glottic cancer patients treated with primary radiotherapy.

Adaptive Image Rescaling for Weakly Contrast-Enhanced Lesions in Dedicated Breast CT:A Phantom Study

Purpose@#Dedicated breast CT is an emerging volumetric X-ray imaging modality for diagnosis that does not require any painful breast compression. To improve the detection rate of weakly enhanced lesions, an adaptive image rescaling (AIR) technique was proposed. @*Materials and Methods@#Two disks containing five identical holes and five holes of different diameters were scanned using 60/100 kVp to obtain single-energy CT (SECT), dual-energy CT (DECT), and AIR images. A piece of pork was also scanned as a subclinical trial. The image quality was evaluated using image contrast and contrast-to-noise ratio (CNR). The difference of imaging performances was confirmed using student’s t test. @*Results@#Total mean image contrast of AIR (0.70) reached 74.5% of that of DECT (0.94) and was higher than that of SECT (0.22) by 318.2%. Total mean CNR of AIR (5.08) was 35.5% of that of SECT (14.30) and was higher than that of DECT (2.28) by 222.8%. A similar trend was observed in the subclinical study. @*Conclusion@#The results demonstrated superior image contrast of AIR over SECT, and its higher overall image quality compared to DECT with half the exposure. Therefore, AIR seems to have the potential to improve the detectability of lesions with dedicated breast CT.

Adjuvant external beam radiation and brachytherapy for vaginal resection margin positive cervical cancer

PURPOSE: To evaluate the treatment outcomes of adjuvant external beam radiation therapy (EBRT) and vaginal brachytherapy (VB) following radical hysterectomy in cervical cancer patients with involved vaginal resection margin (VRM). MATERIALS AND METHODS: We retrospectively reviewed the medical records of 21 patients treated with postoperative EBRT and VB for positive VRM FIGO stage IB–IIA cervical cancer between 2003 and 2015. Concurrent platinum-based chemotherapy was administered to all patients. RESULTS: The median whole pelvis EBRT dose was 50.4 Gy (range, 45 to 50.4 Gy). In the VB, the median dose per fraction, number of fractions, and total dose delivered were: 4 Gy (range, 3.0 to 4.0 Gy), 4 fractions (range, 3 to 5 fractions), and 16 Gy (range, 12 to 20 Gy), respectively. At a median follow-up of 46 months (range, 9 to 122 months), local recurrence was observed in 2 patients, and distant metastasis was present in 7 patients. All patients with local recurrence subsequently developed distant metastases. The 5-year local control, disease-free survival, and overall survival rates were 89.1%, 65.9%, and 62.9%, respectively. Of the 21 patients, 7 patients (33.3%) reported grade 2 acute toxicity; however, there were no grade 3 or higher acute adverse events. Grade 1–2 late toxicities were observed in 8 patients. Late grade 3 urinary toxicity was reported in 1 patient. CONCLUSIONS: Adjuvant EBRT and VB showed excellent local control and low toxicity in cervical cancer patients with positive VRM. Although limited by its retrospective nature, the findings from our study provide evidence supporting the use of additional VB in pathologically involved VRM.

The role of surgical clips in the evaluation of interfractional uncertainty for treatment of hepatobiliary and pancreatic cancer with postoperative radiotherapy

PURPOSE: To evaluate the utility of implanted surgical clips for detecting interfractional errors in the treatment of hepatobiliary and pancreatic cancer with postoperative radiotherapy (PORT). METHODS AND MATERIALS: Twenty patients had been treated with PORT for locally advanced hepatobiliary or pancreatic cancer, from November 2014 to April 2016. Patients underwent computed tomography simulation and were treated in expiratory breathing phase. During treatment, orthogonal kilovoltage (kV) imaging was taken twice a week, and isocenter shifts were made to match bony anatomy. The difference in position of clips between kV images and digitally reconstructed radiographs was determined. Clips were consist of 3 proximal clips (clip_p, ≤2 cm) and 3 distal clips (clip_d, >2 cm), which were classified according to distance from treatment center. The interfractional displacements of clips were measured in the superior-inferior (SI), anterior-posterior (AP), and right-left (RL) directions. RESULTS: The translocation of clip was well correlated with diaphragm movement in 90.4% (190/210) of all images. The clip position errors greater than 5 mm were observed in 26.0% in SI, 1.8% in AP, and 5.4% in RL directions, respectively. Moreover, the clip position errors greater than 10 mm were observed in 1.9% in SI, 0.2% in AP, and 0.2% in RL directions, despite respiratory control. CONCLUSION: Quantitative analysis of surgical clip displacement reflect respiratory motion, setup errors and postoperative change of intraabdominal organ position. Furthermore, position of clips is distinguished easily in verification images. The identification of the surgical clip position may lead to a significant improvement in the accuracy of upper abdominal radiation therapy.

Effect of Coenzyme Q10 on Radiation Nephropathy in Rats

The kidney is one of the most radiosensitive organs in the abdominal cavity and is the dose-limiting structure in cancer patients receiving abdominal or total body irradiation. In the present study, the effect of coenzyme Q10 (CoQ10) on radiation nephropathy was evaluated in rats. A total of 72 rats were equally randomized into 4 groups: Control, CoQ10, irradiation with 10 Gy (RT) + placebo, or RT + CoQ10. The 2 RT groups received single 10 Gy of abdominal irradiation. The 2 CoQ10 groups were supplemented daily with 1 mL of soybean oil containing 10 mg/kg of CoQ10. The RT + placebo and control groups received same dose of soybean oil. After 24 weeks, laboratory and histopathologic findings were compared. The 2 RT groups showed significant increases in blood urea nitrogen (BUN) and creatinine levels and significant pathologic changes such as glomerulosclerosis and tubulointerstitial fibrosis. CoQ10 supplementation resulted in significant reductions of BUN and creatinine levels compared with the RT + placebo group (P < 0.001 and P = 0.038, respectively). CoQ10 treatment significantly attenuated glomerular and tubular changes of irradiated kidney in semiquantitative analysis (P < 0.001 for both). Administration of CoQ10 can alleviate the radiation-induced nephropathy.

Neoadjuvant intra-arterial chemotherapy combined with radiotherapy and surgery in patients with advanced maxillary sinus cancer

PURPOSE: The optimal treatment of advanced maxillary sinus cancer has been challenging for several decades. Intra-arterial chemotherapy (IAC) for head and neck cancer has been controversial. We have analyzed the long-term outcome of neoadjuvant IAC followed by radiation therapy (RT) and surgery. MATERIALS AND METHODS: Twenty-seven patients with advanced maxillary sinus cancer were treated between 1989 and 2002. Five-fluorouracil (5-FU, 500 mg/m2) was infused intra-arterially, and followed by RT (total 50.4 Gy/28 fractions). A planned surgery was performed 3 to 4 weeks after completion of IAC and RT. RESULTS: At a median follow-up of 77 months (range, 12 to 169 months), the 5-year rates of overall survival in all patients were 63%. The 5-year rates of overall survival of stage T3/T4 patients were 70.0% and 58.8%, respectively. Seven of fourteen patients with disease recurrence had a local recurrence alone. The 5-year actuarial local control rates in patients with stage T3/T4, and in all patients were 20.0%, 32.3%, and 27.4%, respectively. Overall response rate after the completion of IAC and RT was 70.3%. During the follow-up, seven patients (25.9%) showed mild to moderate late complications. The tumor extent (i.e., the involvement of either orbit and/or base of skull) appeared to be related with local recurrence. CONCLUSION: Neoadjuvant IAC with 5-FU followed by RT and surgery may be effective to improve local tumor control in the patients with advanced maxillary sinus cancer. However, local failure was still the major cause of death. Further investigations are required to determine the optimal treatment schedule, radiotherapy techniques and chemotherapy regimens.

Short-course palliative radiotherapy for uterine cervical cancer

PURPOSE: The purpose of this retrospective study was to evaluate the efficacy and feasibility of short-course hypofractionated radiotherapy (RT) for the palliation of uterine cervical cancer. MATERIALS AND METHODS: Seventeen patients with cancer of the uterine cervix, who underwent palliative hypofractionated 3-dimensional conformal radiotherapy between January 2002 and June 2012, were retrospectively analyzed. RT was delivered to symptomatic lesions (both the primary mass and/or metastatic regional lymph nodes). The total dose was 20 to 25 Gy (median, 25 Gy) in 5 Gy daily fractions. RESULTS: The median follow-up duration was 12.2 months (range, 4 to 24 months). The median survival time was 7.8 months (range, 4 to 24 months). Vaginal bleeding was the most common presenting symptom followed by pelvic pain (9 patients). The overall response rates were 93.8% and 66.7% for vaginal bleeding control and pelvic pain, respectively. Nine patients did not have any acute side effects and 7 patients showed minor gastrointestinal toxicity. Only 1 patient had grade 3 diarrhea 1 week after completion of treatment, which was successfully treated conservatively. Late complications occurred in 4 patients; however, none of these were of grade 3 or higher severity. CONCLUSION: Short-course hypofractionated RT was effective and well tolerated as palliative treatment for uterine cervical cancer.

Helical Tomotherapy in Elderly Prostate Cancer Patients

BACKGROUND: Helical tomotherapy is a new form of image-guided intensity modulated radiation therapy that may improve local control and decrease radiation toxicity. The aim of this study was to evaluate if high-dose helical tomotherapy is tolerated by patients aged 75 years or older and if the side effects are comparable with those experienced by younger patients. METHODS: Between January 2011 and August 2012, patients with prostate cancer who underwent helical tomotherapy without elective pelvic irradiation as definitive aim were reviewed and divided into two age groups: > or =75 years and <75 years. Acute genitourinary (GU) and lower gastrointestinal (GI) toxicities between the two groups were compared. RESULTS: Twenty patients aged 75 years or older and 23 patients younger than 75 years were evaluated. Radiotherapy was administered to a total dose of 76-78Gy in 38-39 fractions or 70Gy in 28 fractions. There was no grade 3 or 4 acute toxicity and no grade 2 acute lower GI symptom, but the patients complained of grade 2 acute GU toxicity, 25.0% for the older group and 13.0% for the younger group. There was no significant difference in the rate of acute toxicity between the age groups. Hypofractionation showed a significant association with higher grade 2 acute GU toxicity (p=0.024) with the grade 2 acute GU toxicity having no significant correlation with T-stage, Gleason score, prostate specific antigen level, androgen deprivation therapy, and comorbidities. CONCLUSION: High-dose helical tomotherapy to the prostate without pelvic irradiation was well tolerated by elderly prostate cancer patients 75 years and older.

Development of a Method to Measure the Radiation Isocenter Size of Linear Accelerators and Quantitative Analysis of the Radiation Isocenter Size for Clinac 21EX Linear Accelerator / 의학물리

A method to get a size of the radiation isocenter of linear accelerators using star-shot images was presented and a computer program was developed to automate the method. Accuracy of the method was verified. The developed program was used to measure sizes of the radiation isocenters for a Clinac 21EX (Varian, USA) using data of quality assurance (QA) performed from June 2008 to December 2010. To calculated the size of radiation isocenter, positions of two points on each central ray of the star-shot image were found and the equation of the central ray was determined using the positions of two points. Using the equations of central rays the radius of the minimum circle intersecting all the central rays, which is one half of the size of radiation isocenter, was calculated. The program measured X-intercepts and y-intercepts of the central rays within errors of 0.084 mm and sizes of radiation isocenters within 0.053 mm. All the errors were less than the spatial resolution of star-shot images 0.085 mm. The radiation isocenter sizes of Clinac 21EX were 0.33+/-0.27 mm, 0.71+/-0.36 mm, 0.50+/-0.16 mm for collimator, gantry and couch respectively. During the measurement period all the measured sizes were less than 2.0 mm and within tolerance. The developed program could calculate the size of radiation isocenters and it would be helpful to routine QA.

A Method to Calculate a Pass Rate of the gamma-index Analysis in Tomotherapy Delivery Quality Assurance (DQA) / 의학물리

DQA, a patient specific quality assurance in tomotherapy, is usually performed using an ion chamber and a film. The result of DQA is analysed with the treatment planning system called Tomo Planning Station (TomoPS). The two-dimensional dose distribution of film measurement is compared with the dose distribution calculated by TomoPS using the gamma-index analysis. In gamma-index analysis, the criteria such as 3%/3 mm is used and we verify that whether the rate of number of points which pass the criteria (pass rate) is within tolerance. TomoPS does not provide any quantitative information regarding the pass rate. In this work, a method to get the pass rate of the gamma-index analysis was suggested and a software PassRT which calculates the pass rate was developed. The results of patient specific QA of the intensity modulated radiation therapy measured with I'mRT MatriXX (IBA Dosimetry, Germany) and DQA of tomotherapy measured with film were used to verify the proposed method. The pass rate was calculated using PassRT and compared with the pass rate calculated by OmniPro I'mRT (IBA Dosimetry, Germany). The average difference between the two pass rates was 0.00% for the MatriXX measurement. The standard deviation and the maximum difference were 0.02% and 0.02%, respectively. For the film measurement, average difference, standard deviation and maximum difference were 0.00%, 0.02% and 0.02%, respectively. For regions of interest smaller than 24.3x16.6 cm2 the proposed method can be used to calculate the pass rate of the gamma index analysis to one decimal place and will be helpful for the more accurate DQA in tomotherapy.

Skin Damage Sustained During Head-and-Neck and Shoulder Radiotherapy Due to the Curvature of Skin and the Use of Immobilization Mask / 의학물리

The purpose of this study was to measure curvature contour skin dose using radiochromic film and TLD for a conventional open field. We also attempted to quantify the degradation of skin sparing associated with use of immobilization devices for high energy photon beams and to calculate the skin dose with a help of Monte Carlo (MC) simulation. To simulate head-and-neck and shoulder treatment, a cylindrical solid water phantom 11 cm in diameter was irradiated with 6 MV x-rays using 40x40 cm2 field at 100 cm source axis distance (SAD) to the center of the phantom. Aquaplastic mesh mask was placed on the surface of the cylindrical phantom that mimicked relevant clinical situations. The skin dose profile was obtained by taking measurements from 0degrees to 360degrees around the circumference of the cylindrical phantom. The skin doses obtained from radiochromic film were found to be 47% of the maximum dose of D(max) at the 0degrees beam entry position and 61% at the 90degrees oblique beam position without the mask. Using the mask (1.5 mm), the skin dose received was 59% at 0degrees incidence and 78% at 80degrees incidence. Skin dose results were also gathered using thin thermoluminescent dosimeters (TLD). With the mask, the skin dose was 66% at 0degrees incidence and 80% at 80degrees incidence. This method with the mask revealed the similar pattern as film measurement. For the treatments of the head-and-neck and shoulder regions in which immobilization mask was used, skin doses at around tangential angle were nearly the same as the prescription dose. When a sloping skin contour is encountered, skin doses may be abated using thinner and more perforated immoblization devices which should still maintain immoblization.

Patient Specific Quality Assurance of IMRT: Quantitative Approach Using Film Dosimetry and Optimization / 대한방사선종양학회지

PURPOSE: Film dosimetry as a part of patient specific intensity modulated radiation therapy quality assurance (IMRT QA) was performed to develop a new optimization method of film isocenter offset and to then suggest new quantitative criteria for film dosimetry. MATERIALS AND METHODS: Film dosimetry was performed on 14 IMRT patients with head and neck cancers. An optimization method for obtaining the local minimum was developed to adjust for the error in the film isocenter offset, which is the largest part of the systemic errors. RESULTS: The adjust value of the film isocenter offset under optimization was 1 mm in 12 patients, while only two patients showed 2 mm translation. The means of absolute average dose difference before and after optimization were 2.36 and 1.56%, respectively, and the mean ratios over a 5% tolerance were 9.67 and 2.88%. After optimization, the differences in the dose decreased dramatically. A low dose range cutoff (L-Cutoff) has been suggested for clinical application. New quantitative criteria of a ratio of over a 5%, but less than 10% tolerance, and for an absolute average dose difference less than 3% have been suggested for the verification of film dosimetry. CONCLUSION: The new optimization method was effective in adjusting for the film dosimetry error, and the newly quantitative criteria suggested in this research are believed to be sufficiently accurate and clinically useful.

Patient Specific Quality Assurance of IMRT: Quantitative Approach Using Film Dosimetry and Optimization / 대한방사선종양학회지

PURPOSE: Film dosimetry as a part of patient specific intensity modulated radiation therapy quality assurance (IMRT QA) was performed to develop a new optimization method of film isocenter offset and to then suggest new quantitative criteria for film dosimetry. MATERIALS AND METHODS: Film dosimetry was performed on 14 IMRT patients with head and neck cancers. An optimization method for obtaining the local minimum was developed to adjust for the error in the film isocenter offset, which is the largest part of the systemic errors. RESULTS: The adjust value of the film isocenter offset under optimization was 1 mm in 12 patients, while only two patients showed 2 mm translation. The means of absolute average dose difference before and after optimization were 2.36 and 1.56%, respectively, and the mean ratios over a 5% tolerance were 9.67 and 2.88%. After optimization, the differences in the dose decreased dramatically. A low dose range cutoff (L-Cutoff) has been suggested for clinical application. New quantitative criteria of a ratio of over a 5%, but less than 10% tolerance, and for an absolute average dose difference less than 3% have been suggested for the verification of film dosimetry. CONCLUSION: The new optimization method was effective in adjusting for the film dosimetry error, and the newly quantitative criteria suggested in this research are believed to be sufficiently accurate and clinically useful.