Analysis of risk factors for disease progression after salvage radiation therapy with androgen deprivation therapy in prostate cancer patients who have prostate-specific antigen persistence after radical prostatectomy.

PURPOSE: To assess risk factors of disease progression after salvage radiation therapy (SRT) with androgen deprivation therapy (ADT) in case of prostate-specific antigen (PSA) persistence after radical prostatectomy (RP). MATERIALS AND METHODS: We analyzed 57 patients who received SRT with ADT between 2013 and 2019 due to PSA persistence after RP. The endpoint was disease progression defined by biochemical recurrence or clinical recurrence. Age, Pre-RP PSA level, Gleason score, pathologic stage, presence of pelvic lymph node dissection, surgical margins, and PSA at 6-8 weeks after RP were analyzed as predictive factors for disease progression. Kaplan-Meier method and Cox regression models were used for data analysis. RESULTS: At a median follow-up of 38 months (interquartile range, 26-61), 17 patients had disease progression. Pathologic T stage (pT3b vs. pT3a or lower; hazard ratio [HR] = 9.20; p = 0.035) and PSA level at 6-8 weeks after RP (≥2.04 vs. <2.04 ng/mL; HR = 5.85; p = 0.002) were predictors of disease progression. The 5-year disease progression-free survival rate was 46.7% in pT3b group as compared to 92.9 % in pT3a or lower group, and 18.4% for PSA ≥2.04 ng/mL after RP as compared to 79.2% for PSA <2.04 ng/mL. CONCLUSION: Pathological T stage (pT3b) and post RP PSA ≥2.04 ng/mL are independent risk factors of disease progression after SRT with ADT in patients with PSA persistence after RP.

Use of a pressure sensor array for multifunctional patient monitoring in radiotherapy: A feasibility study.

BACKGROUND: Modern radiotherapeutic techniques, such as intensity-modulated radiation therapy or stereotactic body radiotherapy, require high-dose delivery precision. However, the precise localization of tumors during patient respiration remains a challenge. Therefore, it is essential to investigate effective methods for monitoring respiration to minimize potential complications. Despite several systems currently in clinical use, there are drawbacks, including the complexity of the setup, the discomfort to the patient, and the high cost. PURPOSE: This study investigated the feasibility of using a novel pressure sensor array (PSA) as a tool to monitor respiration during radiotherapy treatments. The PSA was positioned between the treatment couch and the back of the patient lying on it and was intended to overcome some limitations of current methods. The main objectives included assessing the PSA's capability in monitoring respiratory behavior and to investigate prospective applications that extend beyond respiratory monitoring. METHODS: A PSA with 31 pressure-sensing elements was used in 12 volunteers. The participants were instructed to breathe naturally while lying on a couch without any audio or visual guidance. The performance of the PSA was compared to that of a camera-based respiratory monitoring system (RPM, Varian, USA), which served as a reference. Several metrics, including pressure distribution, weight sensitivity, and correlations between PSA and RPM signals, were analyzed. The PSA's capacity to provide information on potential applications related to patient stability was also investigated. RESULTS: The linear relationship between the weight applied to the PSA and its output was demonstrated in this study, confirming its sensitivity to pressure changes. A comparison of PSA and RPM curves revealed a high correlation coefficient of 0.9391 on average, indicating consistent respiratory cycles. The PSA also effectively measured the weight distribution at the volunteer's back in real-time, which allows for monitoring the patient's movements during the radiotherapy. CONCLUSION: PSA is a promising candidate for effective respiratory monitoring during radiotherapy treatments. Its performance is comparable to the established RPM system, and its additional capabilities suggest its multifaceted utility. This paper shows the potential use of PSA for patient monitoring in radiotherapy and suggests possibilities for further research, including performance comparisons with other existing systems and real-patient applications with respiratory training.

Low albumin-to-alkaline phosphatase ratio is associated with inferior prognosis in patients with head and neck cancer underwent concurrent chemoradiation: A propensity score-matched analysis.

Background: Low albumin-to-alkaline phosphatase ratio (AAPR) is associated with tumor progression and poor survival outcome in some malignancies. Purpose: We aimed to determine the prognostic value of AAPR in head and neck cancer (HNC) patients underwent concurrent chemoradiotherapy (CCRT). Materials and Methods: We retrospectively reviewed medical records of 342 patients with HNC treated with definitive or adjuvant CCRT from 2007 to 2017. Receiver-operator characteristic curve assessed the cut-off value and predictive accuracy of AAPR for disease progression. Propensity score-matched (PSM) method was performed to balance baseline characteristics. Multivariate Cox regression analyses screened the independent prognostic factors for progression-free survival (PFS) and overall survival (OS). Results: The median follow-up duration was 40 months. The optimal cut-off level of AAPR was 0.523. In the PSM cohort, an AAPR < 0.523 was related to worse PFS and OS (PFS: Hazard ratio [HR], 1.936; 95% confidence interval [CI], 1.212 to 3.249; P = 0.001 and OS: HR, 1.832; 95% CI, 1.117 to 3.478; P = 0.02) compared with those with an AAPR ≥ 0.523. AJCC stage IVA-B also showed poor survival outcome compared with patients with AJCC stage II--III (PFS: HR, 1.855; 95% CI, 1.173 to 2.933; P = 0.008 and OS: HR, 1.905; 95% CI, 1.131 to 3.211; P = 0.015). Conclusions: HNC patients with low AAPR independently have worse survival outcomes than do high AAPR patients. These findings might help physicians predict treatment outcome and guide treatment strategy in patients with HNC underwent CCRT.

Predictive Power of the Albumin-Bilirubin Score for Hepatotoxicity in Stereotactic Ablative Radiation Therapy for Hepatocellular Carcinoma.

Assessment of liver function is crucial in predicting treatment outcomes for hepatocellular carcinoma (HCC). This study aimed to evaluate the prognostic performance of the albumin-bilirubin (ALBI) score for predicting hepatotoxicity following stereotactic body radiation therapy (SBRT) in HCC patients. A retrospective analysis was conducted on 123 HCC cases treated between 2018 and 2020. ALBI and Child-Turcotte-Pugh (CTP) scores were calculated, and hepatotoxicity was defined as a post-SBRT CTP score increase ≥2. Receiver operating characteristic (ROC) curves were used for comparison. The optimal cutoff value of the ALBI score was determined. Among the 121 patients analyzed, hepatotoxicity occurred in 5%. The ALBI score showed better predictive accuracy (area under the ROC curve: 0.77) than the CTP score. The optimal cutoff value of the ALBI score was -2.47, with a sensitivity of 85.7% and a specificity of 71.1%. Multivariable analysis revealed that ALBI score and PTV were significant factors for hepatotoxicity. In conclusion, the ALBI score demonstrated prognostic value for hepatotoxicity prediction after SBRT in HCC patients. Considering the ALBI score and PTV provides valuable insights for assessing hepatotoxicity risk during SBRT treatment for HCC.

Risk factors for primary site necrosis after definitive concurrent chemoradiotherapy in head and neck cancer.

OBJECTIVE: To identify risk factors of primary site necrosis (PSN) after definitive concurrent chemoradiation therapy (CCRT) in patients with nonoral cavity head and neck cancer (HNC). METHODS: We retrospectively reviewed the records of 256 patients treated with CCRT for HNC during 2010-2018. Patient-related (age, sex, history of smoking, hypertension, diabetes mellitus, serum hemoglobin and albumin), tumor-related (tumor site, American Joint Committee on Cancer stage), and treatment-related (induction chemotherapy, maximum point dose and mean dose of planning target volume [PTV] of primary site, absolute volumes of the PTV receiving >50-75 Gy [V50-V75]) variables were analyzed. Critical dosimetric parameters of PSN were identified using receiver operating characteristic (ROC) curve analysis. Univariate and multivariate Cox regression analyses were used to select the significant variables for PSN development. RESULTS: After median follow-up of 44 months (range, 5-127), 7 patients (2.7%) developed PSN with a median time to event of 10 months (range, 3-12). V70 ⩾79.8 mL was the most critical dosimetric parameter for PSN (area under the ROC curve 0.873, sensitivity 0.857, specificity 0.747). In univariate analyses, pretreatment serum hemoglobin <11.0 g/dL and V70 ⩾79.8 mL were significantly associated with higher risk of PSN occurrence. V70 ⩾79.8 mL (hazard ratio 5.960, 95% confidence interval 1.289-27.548; p = 0.022) remained significant predictors of PSN in multivariate analyses. CONCLUSIONS: V70 ⩾79.8 mL is significantly related to the risk of developing PSN. These findings offer valuable clues for clinicians to minimize PSN incidence in HNC treated with curative CCRT.

Influence of respiratory movement during post mastectomy radiotherapy on targets and heart for breast cancer.

BACKGROUND/AIM: This study aimed to compare the dosimetric consequences of respiratory movement in volumetric-modulated arc therapy (VMAT) and three-dimensional conformal radiation therapy (3D-CRT) during postmastectomy radiation therapy, including internal mammary nodes (IMNs). MATERIALS AND METHODS: Respiratory motion was implemented to a phantom using a dynamic device. The plans were delivered during cranial-caudal and ventral-dorsal movement in 5-mm (R05) and 10-mm (R10) amplitudes. RESULTS: At the IMN, the dose errors were -2.8% (R05) and -6.2% (R10) for 3D-CRT and -4.9% (R05) and -8.5% (R10) for VMAT. The dose errors in chest wall were -.5% (R05) and -6.0% (R10) for 3D-CRT and -1.9% (R05) and -5.3% (R10) for VMAT. The left anterior descending doses showed significantly small absolute values. The gamma pass rates of VMAT were higher than those of 3D-CRT. CONCLUSIONS: The benefit of VMAT technique in dose distribution was maintained, except in occasional instances of large breathing motion.

Incidence of hypothyroidism after treatment for breast cancer: A Korean population-based study.

This Korean population-based study aimed to describe the patterns of hypothyroidism after adjuvant radiation therapy (RT) in patients with breast cancer. The Korean Health Insurance Review and Assessment Service database was searched for patients with invasive breast carcinomas. We calculated the cumulative incidence and incidence rates per 1,000 person-years of subsequent hypothyroidism and compared them using the log-rank test and the Cox proportional hazards model. Between 2007 and 2018, 117,135 women diagnosed with breast cancer with a median follow-up time of 4.6 years were identified. The 8-year incidence of hypothyroidism was 9.3% in patients treated with radiation and 8.6% in those treated without radiation (p = 0.002). The incidence rates per 1,000 person-years in the corresponding treatment groups were 6.2 and 5.7 cases, respectively. The hazard ratio (HR) in patients receiving RT was 1.081 (95% confidence interval [CI], 1.013-1.134; p = 0.002). After mastectomy, RT showed a trend toward a higher risk of hypothyroidism (HR = 1.248; 95% CI, 0.977-1.595; p = 0.076). Our study provides one of the largest population-based data analyses regarding the risk of hypothyroidism among Korean patients with breast cancer. The adjusted risk for patients treated with RT exceeded that for patients with breast cancer treated without RT. The effect was evident immediately after treatment and lasted up to approximately 9 years.

Radiotherapy dose-volume parameters predict facial lymphedema after concurrent chemoradiation for nasopharyngeal carcinoma.

BACKGROUND: To investigate risk factors for developing radiation-associated facial lymphedema (FL) in nasopharyngeal carcinoma (NPC) patients after concurrent chemoradiation (CCRT). METHODS: Clinical data from 87 patients who underwent definitive CCRT for NPC in 2010-2018 was retrospectively evaluated. FL severity was graded using MD Anderson Cancer Center head and neck lymphedema rating scale. Logistic regression analysis was used to examine the factors associated with the presence of moderate/severe FL (grade ≥ 2). RESULTS: At a median follow-up of 34 months (range, 18-96), 26/87 (29.9%) patients experienced grade ≥ 2 FL. A majority (84.6%) was experienced grade ≥ 2 FL 3-6 months after CCRT. Mean dose to the level IV, level I-VII neck node and N stage were significantly correlated with grade ≥ 2 FL at univariate analysis. At multivariate analysis, mean dose of level IV neck node (hazard ratio [HR], 1.238; 95% confidence interval [CI] = 1.084-1.414; p = 0.002) and level I-VII neck node (HR, 1.384; 95% CI = 1.121-1.708; p = 0.003) were independent predictors. Receiver Operating Characteristics (ROC) curve analysis showed that cut-off value of mean level IV neck node dose was 58.7 Gy (area under the curve [AUC] = 0.726; 95% CI = 0.614-0.839, p = 0.001) and mean level I-VII neck node dose was 58.6 Gy (AUC = 0.720; 95% CI = 0.614-0.826, p = 0.001) for grade ≥ 2 FL. CONCLUSIONS: Keeping mean dose to the level IV and level I-VII below 58.7 Gy and 58.6 Gy may reduce the likelihood of moderate/severe FL after CCRT for NPC.

MONTE CARLO DOSE ASSESSMENT IN DENTAL CONE-BEAM COMPUTED TOMOGRAPHY.

Most dental cone-beam computed tomography (CBCT) uses an x-ray beam field covering the maxillomandibular region and the width-truncated detector geometry. The spatial dose distribution in dental CBCT is analyzed in terms of local primary and remote secondary doses by using a list-mode analysis of x-ray interactions obtained from the Monte Carlo simulations. The patient-dose benefit due to the width-truncated detector geometry is also investigated for a wide range of detector offsets. The developed dose estimation agrees with the measurement in a relative error of 7.7%. The secondary dose outside of the irradiation field becomes larger with increasing tube voltage. The dose benefit with the width-truncated geometry linearly increases as the detector-offset width is decreased. Leaving the CT image quality out of the account, the MC results reveal that the operation of dental CBCT with a lower tube voltage and a smaller detector-offset width is beneficial to the patient dose.

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.

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.

Who are the optimal candidates for partial breast irradiation?

At the 2017 St. Gallen International Expert Consensus Conference on the Primary Therapy for Early Breast Cancer, the consensus panel recognized "partial breast irradiation as an option for women meeting the low-risk criteria put forward by the American Society for Radiation Oncology/European Society for Radiotherapy and Oncology (ASTRO/ESTRO) guideline," although acknowledging that there was less evidence for this approach. Partial breast irradiation is defined as irradiation localized to the surgical resection cavity only as opposed to the entire breast. Accelerated partial breast irradiation (APBI) involves intensive treatment in a short time period. The methods vary, and three available APBI options are brachytherapy, external beam and intra-operative irradiation. The long-term follow-up results from two large-scale, well-designed phase III randomized clinical trials have been released. However, further discussion of the optimal treatment candidates and delivery method is needed before the clinical application of APBI as a mainstream breast conservation treatment.

Comparison of local recurrence after mastectomy for pure ductal carcinoma in situ with close or positive margins: A meta-analysis.

BACKGROUND: There is controversy regarding the relationship between margin status and risk of local recurrence (LR) in patients with Ductal carcinoma in situ(DCIS) treated by mastectomy. PURPOSE: We sought to assess the LR rates for patients with DCIS breast cancer treated by mastectomy with respect to the resection margin (RM) status. MATERIALS AND METHODS: Systematic search of MEDLINE, EMBASE, and Cochrane library published was performed. Studies of pure DCIS breast cancer with treatment of mastectomy and studies that reported surgical RM and LR were included. RESULTS: A total of 12 retrospective studies were included, encompassing 2902 patients with a mean follow-up of 86.4 months. Overall LR rates were 5.3% (27/508) for positive or close margins and 1.6% (37/2367) for negative margin, and most of the recurrences (93.7%) are invasive cancers. Patients with positive or close margins showed a 3.72-fold (95% confidence interval [CI] = 2.30-6.01,P < 0.01, I[2] = 11%) higher risk of LR than patients with negative margin. Patients with positive margin showed a 2.91-fold (95% CI = 1.14-7.41,P = 0.03, I[2] = 0%) higher risk of LR than patients with close margin. Postmastectomy radiation therapy (RT) was not associated with a decreased risk of LR (Risk ratio 0.50; 95% CI = 0.06-4.08,P= 0.52, I[2] = 0%) in patients with positive or close margins. CONCLUSIONS: The RM status after mastectomy has a great impact on LR. However, the recurrence rate was insufficient to warrant a recommendation for postmastectomy RT in patients with close or positive margins.

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.

Generation of polychromatic projection for dedicated breast computed tomography simulation using anthropomorphic numerical phantom.

Numerical simulations are fundamental to the development of medical imaging systems because they can save time and effort in research and development. In this study, we developed a method of creating the virtual projection images that are necessary to study dedicated breast computed tomography (BCT) systems. Anthropomorphic software breast phantoms of the conventional compression type were synthesized and redesigned to meet the requirements of dedicated BCT systems. The internal structure of the breast was randomly constructed to develop the proposed phantom, enabling the internal structure of a naturally distributed real breast to be simulated. When using the existing monochromatic photon incidence assumption for projection-image generation, it is not possible to simulate various artifacts caused by the X-ray spectrum, such as the beam hardening effect. Consequently, the system performance could be overestimated. Therefore, we considered the polychromatic spectrum in the projection image generation process and verified the results. The proposed method is expected to be useful for the development and optimization of BCT systems.

Extraordinary radiation super-sensitivity accompanying with sorafenib combination therapy: what lies beneath?

Primary liver tumor, especially hepatocellular carcinoma (HCC), is a common cause of cancer death worldwide. The incidence is generally higher in Asian countries than in western countries. Carcinogenesis of HCC is often associated with hepatitis viral infections. Current standard treatment of HCC is surgical resection or transplantation in patients with early stage disease. However, the patient with advanced stage disease, surgical resection is often limited. Sorafenib or other treatment modalities are not so effective as well. We report a case of unusual radiation super-sensitivity in advanced stage HCC, and review the literature.

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.

Generation of hybrid sinograms for the recovery of kV-CT images with metal artifacts for helical tomotherapy.

PURPOSE: The overall goal of this study is to restore kilovoltage computed tomography (kV-CT) images which are disfigured by patients' metal prostheses. By generating a hybrid sinogram that is a combination of kV and megavoltage (MV) projection data, the authors suggest a novel metal artifact-reduction (MAR) method that retains the image quality to match that of kV-CT and simultaneously restores the information of metal prostheses lost due to photon starvation. METHODS: CT projection data contain information about attenuation coefficients and the total length of the attenuation. By normalizing raw kV projections with their own total lengths of attenuation, mean attenuation projections were obtained. In the same manner, mean density projections of MV-CT were obtained by the normalization of MV projections resulting from the forward projection of density-calibrated MV-CT images with the geometric parameters of the kV-CT device. To generate the hybrid sinogram, metal-affected signals of the kV sinogram were identified and replaced by the corresponding signals of the MV sinogram following a density calibration step with kV data. Filtered backprojection was implemented to reconstruct the hybrid CT image. To validate the authors' approach, they simulated four different scenarios for three heads and one pelvis using metallic rod inserts within a cylindrical phantom. Five inserts describing human body elements were also included in the phantom. The authors compared the image qualities among the kV, MV, and hybrid CT images by measuring the contrast-to-noise ratio (CNR), the signal-to-noise ratio (SNR), the densities of all inserts, and the spatial resolution. In addition, the MAR performance was compared among three existing MAR methods and the authors' hybrid method. Finally, for clinical trials, the authors produced hybrid images of three patients having dental metal prostheses to compare their MAR performances with those of the kV, MV, and three existing MAR methods. RESULTS: The authors compared the image quality and MAR performance of the hybrid method with those of other imaging modalities and the three MAR methods, respectively. The total measured mean of the CNR (SNR) values for the nonmetal inserts was determined to be 14.3 (35.3), 15.3 (37.8), and 25.5 (64.3) for the kV, MV, and hybrid images, respectively, and the spatial resolutions of the hybrid images were similar to those of the kV images. The measured densities of the metal and nonmetal inserts in the hybrid images were in good agreement with their true densities, except in cases of extremely low densities, such as air and lung. Using the hybrid method, major streak artifacts were suitably removed and no secondary artifacts were introduced in the resultant image. In clinical trials, the authors verified that kV and MV projections were successfully combined and turned into the resultant hybrid image with high image contrast, accurate metal information, and few metal artifacts. The hybrid method also outperformed the three existing MAR methods with regard to metal information restoration and secondary artifact prevention. CONCLUSIONS: The authors have shown that the hybrid method can restore the overall image quality of kV-CT disfigured by severe metal artifacts and restore the information of metal prostheses lost due to photon starvation. The hybrid images may allow for the improved delineation of structures of interest and accurate dose calculations for radiation treatment planning for patients with metal prostheses.

Probiotics for rectal volume variation during radiation therapy for prostate cancer.

PURPOSE: To investigate the effect of the probiotic Lactobacillus acidophilus on the percentage volume change of the rectum (PVCR), a crucial factor of prostate movement. METHODS AND MATERIALS: Prostate cancer patients managed with tomotherapy as a radical treatment were enrolled in the study to take a probiotic capsule containing 1.0×10(8) colony-forming units of L acidophilus or a placebo capsule twice daily. Radiation therapy was performed at a dose of 78 Gy in 39 fractions. The PVCR, defined as the difference in rectal volume between the planning computed tomographic (CT) and daily megavoltage CT images, was analyzed. RESULTS: Forty patients were randomized into 2 groups. The L acidophilus group showed significantly lower median rectal volume and median PVCR values than the placebo group. L acidophilus showed a significant reduction effect on the PVCR (P<.001). However, the radiation therapy fraction number did not significantly influence the PVCR. CONCLUSIONS: L acidophilus was useful in reducing the PVCR, which is the most important determining factor of prostate position, during radiation therapy for prostate cancer.

Fractionated wide-field radiation therapy followed by fractionated local-field irradiation for treating widespread painful bone metastasis.

PURPOSE: Wide-field radiation therapy (WFRT) is an effective treatment for widespread bone metastasis. We evaluated local-field irradiation (LFI) after fractionated WFRT (f-WFRT) for treating the patients with multiple painful bone lesions. METHODS AND MATERIALS: From 1998 to 2007, 32 patients with multiple bone metastases were treated with fractionated LFI (f-LFI) after f-WFRT. All patients initially received 15 Gy in 5 fractions to a wide field, followed by LFI (9-15 Gy in 3 Gy fractions). Response was assessed by evaluating the degree of pain relief using a visual analog scale before radiotherapy, after f-WFRT, and after f-LFI. RESULTS: Fractionated LFI following f-WFRT yielded an overall relief rate of 93.8% and a complete relief rate of 43.8%. The rate of the appearance of new disease was 6.3% for the patients with complete relief, 20.5% for the patients with a partial relief, and 50% for the patients with no relief. CONCLUSION: Fractionated LFI after f-WFRT is a well-tolerated and effective treatment for multiple metastatic bone disease.