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Background: Recently, several clinical studies have reported that combination treatments of radiation therapy (RT) and immunotherapy in patients with multiple lesions can improve tumor regression a...

BackgroundAlthough there are some controversies regarding whole pelvic radiation therapy (WPRT) due to its gastrointestinal and hematologic toxicities, it is considered for patients with gynecological, rectal, and prostate cancer. To effectively spare organs-at-risk (OAR) doses using multi-leaf collimator (MLC)’s optimal segments, potential dosimetric benefits in volumetric modulated arc therapy (VMAT) using a half-beam technique (HF) were investigated for WPRT.MethodsWhile the size of a fully opened field (FF) was decided to entirely include a planning target volume in all beam’s eye view across arc angles, the HF was designed to use half the FF from the isocenter for dose optimization. The left or the right half of the FF was alternatively opened in VMAT-HF using a pair of arcs rotating clockwise and counterclockwise. Dosimetric benefits of VMAT-HF, presented with dose conformity, homogeneity, and dose–volume parameters in terms of modulation complex score, were compared to VMAT optimized using the FF (VMAT-FF). Consequent normal tissue complication probability (NTCP) by reducing the irradiated volumes was evaluated as well as dose–volume parameters with statistical analysis for OAR. Moreover, beam-on time and MLC position precision were analyzed with log files to assess plan deliverability and clinical applicability of VMAT-HF as compared to VMAT-FF.ResultsWhile VMAT-HF used 60%–70% less intensity modulation complexity than VMAT-FF, it showed superior dose conformity. The small intestine and colon in VMAT-HF showed a noticeable reduction in the irradiated volumes of up to 35% and 15%, respectively, at an intermediate dose of 20–45 Gy. The small intestine showed statistically significant dose sparing at the volumes that received a dose from 15 to 45 Gy. Such a dose reduction for the small intestine and colon in VMAT-HF presented a significant NTCP reduction from that in VMAT-FF. Without sacrificing the beam delivery efficiency, VMAT-HF achieved effective OAR dose reduction in dose–volume histograms.ConclusionsVMAT-HF led to deliver conformal doses with effective gastrointestinal-OAR dose sparing despite using less modulation complexity. The dose of VMAT-HF was delivered with the same beam-on time with VMAT-FF but precise MLC leaf motions. The VMAT-HF potentially can play a valuable role in reducing OAR toxicities associated with WPRT.

Background/Aim: Anal canal toxicity tends to be ignored in pelvic radiotherapy (RT). However, patients with hemorrhoids can be troubled by lower radiation dose. We tried to determine whether a correlation exists between hemorrhoids and anal symptoms in patients with cervical cancer undergoing RT. Patients and Methods: The insurance claim data of patients who underwent definitive treatment for cervical cancer from 2015 to 2019 were analyzed. Adverse events including bleeding, proctitis, and hemorrhoids, were documented for 1 year after treatment completion. Odds ratios (ORs) were estimated by unconditional Poisson regression and adjusted for age, treatments, chemotherapy, and comorbidities. Results: Details of 67,114 insured cervical cancer patients treated between 2015 and 2019 were obtained. Among them, 5,919 patients with follow-up data for at least one year, treated with curative intent, were analyzed. The OR of the definitive radiotherapy group (DRT group) for anal bleeding was 10.57 higher than that of the operation alone group (surgical group) (p

Background In this study, an external 8 mm thick aluminum target was installed on the upper accessory tray mount of a medical linear accelerator head. The purpose of this study was to determine the effects of the external aluminum target beam (Al-target beam) on the portal image quality by analyzing the spatial and contrast resolutions. In addition, the image resolutions with the Al-target beams were compared with those of conventional 6 megavoltage (MV) images. Methods The optimized Al-target beam was calculated using Monte Carlo simulations. To validate the simulations, the percentage depth dose and lateral profiles were measured and compared with the modeled dose distributions. A PTW resolution phantom was used for imaging to assess the image resolution. The spatial resolution was quantified by determining the modulation transfer function. The contrast resolution was determined by a fine contrast difference between the 27 measurement areas. The spatial and contrast resolutions were compared with the those of conventional portal images. Results The measured and calculated percentage depth dose of the Al-target beam were consistent within 1.6%. The correspondence of measured and modelled profiles was evaluated by gamma analysis (3%, 3 mm) and all gamma values inside the field were less than one. The critical spatial frequencies (f 50) of the images obtained with the Al-target beam and conventional imaging beam were 0.745 lp/mm and 0.451 lp/mm, respectively. The limiting spatial frequencies (f 10) for the Al-target beam image and the conventional portal image were 2.39 lp/mm and 1.82 lp/mm, respectively. The Al-target beam resolved the smaller and lower contrast objects better than that of the MV photon beam. Conclusion The Al-target beams generated by the simple target installation method provided better spatial and contrast resolutions than those of the conventional 6 MV imaging beam.

OBJECTIVE: To install a low-Z target on the wedge tray mount of a medical linear accelerator to create a new image beam and to confirm image contrast enhancement. METHODS: Experimental low-energy photon beams were produced with the linac running in the 6 MeV electron mode and with a low-Z target installed on the wedge tray mount [denoted 6 MeV (low-Z target)]. Geant4 Monte Carlo simulation was performed to analyse the energy spectrum and image contrast of a 6 MeV (low-Z target) beam. This study modelled the 6 MeV (low-Z target) beam and the 6 MV (megavoltage) radiotherapy photon beam and verified model validity by measurement. In addition, a contrast phantom was modelled to quantitatively compare the image contrasts of the 6 MeV (low-Z target) beam and the 6 MV radiotherapy photon beam. A low-Z target was fabricated to generate low-energy photons (25–150 keV) from incident electrons, and a portal image of the Alderson RANDO phantom was acquired using a clinical linear accelerator for qualitative analysis. RESULTS: The measured and calculated percentage depth dose of the 6 MV photon and 6 MeV (Al) beams were consistent within 1.5 and 1.6%, respectively, and calculated lateral profiles of the 6 MV photon beam and the 6 MeV (Al) beam were consistent with the measured results within 1.5 and 1.9%, respectively. Although low-energy photons (25–150 keV) of the 6 MV photon beam were only 0.3%, the Be, C, and Al low-Z targets, but not the Ti target, generated 34.4 to 38.5% low-energy photons. In 5 to 20 cm water phantoms, contrast of the 6 MeV (Al) beam was approximately 1.16 times greater than that of the 6 MV beam. The contrasts of 6 MeV (Al) and 6 MV photon beams in the 20 cm water phantom were ~34% lower than those in the 5 cm water phantom. 6 MeV (Al)/CR (computed radiography) images of the human body phantom were more vivid and detailed than 6 MV/EPID (electronic portal imaging device) and 6 MeV (Al)/EPID images. CONCLUSION: The experimental beam with a low-Z target, which was simply installed on the wedge tray mount of the radiotherapy linear accelerator, generated significantly more low-energy photons than the 6 MV radiotherapy photon beam, and provided better quality portal images. ADVANCES IN KNOWLEDGE: This study shows that, unlike the existing low-Z beam studies, a low-Z target can be installed outside the head of a linear accelerator to improve portal image quality.

OBJECTIVE The purpose of the present study was to evaluate treatment outcomes and prognostic factors in cervical cancer patients with isolated para-aortic lymph node (PALN) metastases. We especially tried to evaluate PALN factors such as size, site and number. METHODS From August 1994 to December 2009, 40 cervical cancer patients with isolated PALN node metastases at initial diagnosis were selected for analysis. Patients underwent both extended field external beam and intracavitary brachytherapy. Fourteen patients received 5-fluorouracil and cisplatin (FP) and 16 patients received weekly concurrent cisplatin. Information of PALN, such as size, site, and number, was founded before PALN radiotherapy. RESULTS The median follow-up time after primary treatment was 28.5 months (range, 2 to 213 months). The 3-year overall and progression-free survival rate after primary treatment was 44.3% and 31.3%, respectively. In multivariate analysis including tumor stage, performance status, and chemotherapy, FP regimen concurrent chemoradiotherapy was more effective than radiotherapy alone (p=0.030). The 3-year progression-free survival rate was 41.9% and 11.1% in patients with PALN numbers of ≤1 and ≥2, respectively (p=0.008). The 3-year progression-free survival rate was 42.1% and 19.2% in patients with PALN size of

Purpose The role of postmastectomy radiotherapy in the treatment of T1–2 primary tumor with 1–3 positive lymph nodes is controversial. We compared treatment outcomes between breast conserving surgery followed by radiotherapy (BCS+RT) and total mastectomy alone (TM) in the setting of modern adjuvant systemic treatments. Methods Patients with T1–2 primary breast cancer and 1–3 positive lymph nodes who were treated between 2001 and 2011 were divided into 2 groups based on the treatment approach: BCS+RT (n = 169) and TM (n = 117). All patients received adjuvant chemotherapy including taxanes. Adjuvant endocrine therapy was administered to patients with positive hormone receptors according to their menstrual status. Results During a median follow-up of 76.5 months, 21 patients (7.3%) experienced locoregional recurrence as the first event, including 7 patients (4.1%) in the BCS+RT group and 14 patients (12.0%) in the TM group. The 5-year cumulative incidence rate of locoregional recurrence was 2.5% for BCS+RT versus 9.5% for TM (p = 0.016). Competing risk regression analysis revealed that TM was associated with a relative risk for locoregional recurrence of 5.347 (p = 0.003). TM was also associated with a significantly lower 5-year disease-free survival rate compared with BCS+RT (hazard ratio, 2.024; 95% confidence interval, 1.090–3.759; p = 0.026). Conclusion To improve treatment outcomes for TM even after modern systemic treatments, postmastectomy radiotherapy might be required for patients with T1–2 primary breast cancer and 1–3 positive lymph nodes.

Background and purpose Since the introduction of CT-based simulation for use in whole brain radiotherapy (WBRT), we have observed that a large volume of the parotid glands is included in the radiation fields. The purpose of this study is to analyze the dose–volume statistics of the parotid glands in patients undergoing WBRT. Materials and methods Thirty-two patients received WBRT using CT-based simulation with bilateral two-field arrangement. Daily fraction was 3 Gy with total dose of 30 Gy in 2 weeks. We analyzed the radiation dose from WBRT to the parotid glands. Results Average of the mean parotid dose was 17.5 Gy (range, 10.5–26.2) for both glands. Mean parotid doses ⩾20 and ⩾25 Gy were observed in 22 (34.4%) and 4 (6.3%) of 64 individual glands. The numbers of patients with a mean parotid dose of both glands ⩾20 Gy and ⩾25 Gy were 12 (37.5%) and 1 (3.1%), respectively. Conclusions Mean parotid dose was variable in patients with WBRT. According to the parotid dose and combined potential risk factors, parotid glands can be regarded as a risk organ in WBRT for improvement of patient quality of life.

Patients with asymptomatic haemorrhoids are known to be less tolerant of radiation doses lower than known tolerance doses. In the present study, the authors sought to identify the risk factors of acute haemorrhoid aggravation after whole pelvic radiotherapy (WPRT).The records of 33 patients with cervical, rectal or prostate cancer with asymptomatic haemorrhoids, which were confirmed by colonoscopy before the start of radiotherapy (RT), were reviewed. Acute anal symptoms, such as anal pain and bleeding, were observed up to 1 month after RT completion. Dosimetric and patient factors were analysed, and subgroup analyses were performed.The median induction dose for acute anal symptoms was 34.1 Gy (range, 28.8-50.4 Gy). Post-operative treatment intent showed more acute anal toxicity of patient factors (p = 0.04). In subgroup analysis, post-operative treatment intent and concurrent chemoradiotherapy were found to be related to acute anal symptoms (p 0.01). Of the dosimetric factors, V10 tended to be related to acute anal symptoms (p = 0.08).This study indicates that asymptomatic haemorrhoid may deteriorate after low-dose radiation and that patient factors, such as treatment intent and concurrent chemotherapy, probably influence anal toxicity. In patients with asymptomatic haemorrhoids, WPRT requires careful dosimetry and clinical attention.The tolerance of anal canal tends to be ignored in patients with pelvic cancer who are undergoing WPRT. However, patients with asymptomatic haemorrhoids may be troubled by low radiation doses, and further studies are required.

Radiation induced lung fibrosis (RILF) is a major complication after lung irradiation and is very important for long term quality of life and could result in fatal respiratory insufficiency. However, there has been little information on dosimetric parameters for radiotherapy planning in the aspect of RILF. The features of RILF related with dosimetric parameters were evaluated.Forty-eight patients with non-small cell lung carcinoma who underwent post-operative radiation therapy (PORT) without adjuvant chemotherapy were analyzed. The degree of lung fibrosis was estimated by fibrosis volume and the dosimetric parameters were calculated from the plan of 3-dimensional conformal radiotherapy.The fibrosis volume and V-dose as dosimetric parameters showed significant correlation and the correlation coefficient ranged from 0.602 to 0.683 (P0.01). The degree of the correlation line was steeper as the dose increase and threshold dose was not found. Mean lung dose (MLD) showed strong correlation with fibrosis volume (correlation coefficient = 0.726, P0.01).The fibrosis volume is continuously increased with V-dose as the reference dose increases. MLD is useful as a single parameter for comparing rival plans in the aspect of RILF.

In this study, the effect of brown algae extract on postprandial glucose control was examined in male Sprague-Dawley rats. Neonatal diabetes mellitus was induced by Stretozotocin i.p. injection to ...

Radiation-induced anal toxicity can be induced by low radiation doses in patients with haemorrhoids. The object of this study was to determine the dosimetric benefits of different whole pelvic radiotherapy (WPRT) techniques in terms of dose delivered to the anal canal in post-operative patients with cervical cancer.The planning CT images of 10 patients with cervical cancer undergoing postoperative radiotherapy were used for comparison of three different plans. All patients had been treated using the conventional box technique WPRT (CV-WPRT), and we tried low-margin-modified WPRT (LM-WPRT), three-dimensional conformal techniques WPRT (CF-WPRT) and intensity-modulated WPRT (IM-WPRT) planning for dosimetric comparison of the anal canal, retrospectively.Mean anal canal doses of the IM-WPRT were significantly lower (p 0.05) than those of CV-WPRT, LM-WPRT and CF-WPRT, and V10, V20, V30 and V40 to the anal canal were also significantly lower for IM-WPRT (p 0.05). The proportion of planning target volumes (PTVs) that received ≥98% of the prescribed dose for all plans was99%, and the proportion that received ≥108% of the prescribed dose for IM-WPRT was2%. Volumes of bladders and rectums that received ≥30 or ≥40 Gy were significantly lower for IM-WPRT than for three of the four-field WPRT plans (p = 0.000).IM-WPRT can significantly reduce radiation dose delivered to the anal canal and does not compromise PTV coverage. In patients with haemorrhoids, IM-WPRT may be of value for the prevention of anal complications.Although tolerance of the anal canal tends to be ignored in patients undergoing post-operative WPRT, patients with haemorrhoids may suffer complications at low radiation doses. The present study shows IM-WPRT can be meaningful in these patients.