Cardiac late effects after modern 3D-conformal radiotherapy in breast cancer patients: a retrospective cohort study in Germany (ESCaRa).

PURPOSE: Radiotherapy (RT) was identified as a risk factor for long-term cardiac effects in breast cancer patients treated until the 1990s. However, modern techniques reduce radiation exposure of the heart, but some exposure remains unavoidable. In a retrospective cohort study, we investigated cardiac mortality and morbidity of breast cancer survivors treated with recent RT in Germany. METHODS: A total of 11,982 breast cancer patients treated between 1998 and 2008 were included. A mortality follow-up was conducted until 06/2018. In order to assess cardiac morbidity occurring after breast cancer treatment, a questionnaire was sent out in 2014 and 2019. The effect of breast cancer laterality on cardiac mortality and morbidity was investigated as a proxy for radiation exposure. We used Cox Proportional Hazards regression analysis, taking potential confounders into account. RESULTS: After a median follow-up time of 11.1 years, there was no significant association of tumor laterality with cardiac mortality in irradiated patients (hazard ratio (HR) for left-sided versus right-sided tumor 1.09; 95% confidence interval (CI) 0.85-1.41). Furthermore, tumor laterality was not identified as a significant risk factor for cardiac morbidity (HR = 1.05; 95%CI 0.88-1.25). CONCLUSIONS: Even though RT for left-sided breast cancer on average incurs higher radiation dose to the heart than RT for right-sided tumors, we found no evidence that laterality is a strong risk factor for cardiac disease after contemporary RT. However, larger sample sizes, longer follow-up, detailed information on individual risk factors and heart dose are needed to assess clinically manifest late effects of current cancer therapy.

Bridging the Radiotherapy Education Gap in Africa: Lessons Learnt from the Cape Town Access to Care Training Programme Over the Past 5 Years (2015-2019).

The role of radiotherapy (RT) in cancer care is well described, with a clear correlation between access to radiotherapy and overall survival. Cancer mortality rates in Africa are substantially higher than those of the rest of the world, which may be partly attributed to lack of RT access and insufficient human resources. The Access to Care (A2C) Cape Town RT training programme was created in 2014 with the aim of supplementing practical RT training in the region, focusing on clinics moving from 2 to 3D conformal radiotherapy (3DCRT). The programme makes use of hybrid teaching methods, including pre-course e-learning followed by 17 on-site days of free-thinking design exercises, didactic learning, hands-on treatment planning computer sessions (39% of total teaching time), virtual simulation training and departmental demonstration sessions. Email support is offered to all teams for 3 months after each course to develop clinical protocols. Thirteen teams (radiation oncologist, medical physicist and radiation therapy technologist) from Africa attended the course between 2015 and 2019, with additional participants from seven South African and four international centres. E-learning done on the LäraNära training platform was only successful once formal progress tracking was introduced in 2019 (34% vs. 76% test completion rate). Delays between course attendance and initial clinical use of equipment proved to be detrimental to knowledge retention, with some centres having to send a second team for training. The course will be modified for remote teaching in 2021, to make provision for the global changes in travel due to Covid-19.

IMRT versus 2D/3D conformal RT in oropharyngeal cancer: A review of the literature and meta-analysis.

Based on literature, intensity-modulated radiation therapy (IMRT) provides less related toxicity compared with conventional 2D/3D-RT with no impact on oncological outcomes for oropharyngeal cancer. The aim of this systematic review and meta-analysis is to assess whether IMRT might provide similar clinical outcomes with reduced related toxicity in comparison with conventional 2D/3D RT in patients treated for clinically advanced oropharyngeal cancer (OPC). Inclusion criteria for paper selection included: squamous OPC patients, treatment performed by concomitant CRT or RT alone, four treatment performed for curative intent, and presence of clinical outcome of interest, namely, overall survival (OS) and disease-free survival (DFS) and full paper available in English. Acute and late toxicities were retrieved together with OS and DFS. Crude relative risk estimates of relapse and death comparing 2D/3D-RT versus IMRT were calculated from tabular data, extracting events at 2-3 years of follow-up. Eight studies were selected. Six of them were included in the meta-analysis considering summary relative risk. Considering both acute and late toxicities, the considered studies evidenced advantages for IMRT populations, with the 2D/3D-RT population showing higher frequencies than the IMRT one. No statistical difference between IMRT and 2D/3D-RT in terms of death (SRR = 0.93, 95% CI: 0.83-1.04 with no heterogeneity I2  = 0%) and relapse (SRR = 0.92, 95% CI: 0.83-1.03, with no heterogeneity I2  = 0%) was found. Results of our study suggest the improvement in the therapeutic index with IMRT with evidenced reduced toxicity without any worsening in clinical outcome when compared to 2D/3DCRT.

Post-operative small pelvic field radiation therapy in patients with intermediate risk early stage cervix cancer: a safe and efficient treatment modality.

BACKGROUND: The treatment of early stage cervical cancer has different therapeutic options. Adjuvant external beam radiotherapy for surgically treated intermediate risk cervical cancer patients has shown acceptable oncological outcomes with a low incidence of toxicity. The aim of this study was to analyze the oncological outcomes and safety of adjuvant small pelvic field radiotherapy in surgically treated stage IB1-2 cervical cancer patients who met the Sedlis intermediate-risk criteria. MATERIALS AND METHODS: A retrospective cohort study was carried out with 28 patients treated from 2007 to November 2019 with biopsy proven intermediate risk stage IB1-2 cervical cancer previously treated with radical hysterectomy and bilateral lymphadenectomy who received adjuvant small pelvic field radiotherapy. The primary endpoints were local and distant control and overall survival. Secondary endpoints were acute and late gastrointestinal and genitourinary toxicity. Survival curves were analyzed using the Kaplan-Meier method. RESULTS: After a median follow up period of 41.5 (27.5-80.5) months, adjuvant small pelvic field radiotherapy showed a 100% overall survival rate, 81.82% disease free survival and 86.36% local recurrence-free survival with no incidence of grade 3 or 4 acute or late toxicity. Three patients suffered from relapse, 1 in the vaginal cuff, 1 in the retrovesical area and 1 patient in the retroperitoneal area. CONCLUSIONS: Adjuvant small pelvic field radiotherapy is an efficient and safe treatment option that offers excellent oncological outcomes to surgically treated intermediate-risk stage IB1-2 cervical cancer patients with an excellent toxicity profile.

Radiotherapy of prostate cancer: impact of treatment characteristics on the incidence of second tumors.

BACKGROUND: It has been hypothesized that radiotherapy (RT) techniques delivering radiations to larger volumes (IMRT, VMAT) are potentially associated with a higher risk of second primary tumors. The aim of this study was to analyse the impact of RT technique (3D-CRT vs IMRT/VMAT) on the incidence of second tumors in prostate cancer (PCa) patients. METHODS: A retrospective study on 2526 previously irradiated PCa patients was performed. Patients were treated with 3D-CRT (21.3%), IMRT (68.1%), or VMAT (10.6%). Second tumors incidence was analysed in 3 categories: pelvic, pelvic and abdominal, and "any site". The correlation with RT technique was analysed using log-rank test and Cox's proportional hazard method. RESULTS: With a median follow-up of 72 months (range: 9-185), 92 (3.6%) cases of second tumors were recorded with 48 months (range: 9-152) median interval from RT. Actuarial 10-year second tumor free survival (STFS) was 87.3%. Ten-year STFS in patients treated with 3D-CRT and IMRT/VMAT was 85.8 and 84.5%, respectively (p: .627). A significantly higher 10-year cumulative incidence of second tumors in the pelvis was registered in patients treated with IMRT/VMAT compared to 3D-CRT (10.7% vs 6.0%; p: .033). The lower incidence of second pelvic cancers in patients treated with 3D-CRT was confirmed at multivariable analysis (HR: 2.42, 95%CI: 1.07-5.47, p: .034). CONCLUSIONS: The incidence of second pelvic tumors after RT of PCa showed a significant correlation with treatment technique. Further analyses in larger series with prolonged follow-up are needed to confirm these results.

Efficacy of a hydrogel spacer in three-dimensional conformal radiation therapy for prostate cancer.

OBJECTIVES: We aimed to compare the dose constraints fulfillment rate of the three-dimensional conformal radiotherapy treatment plan before and after a hydrogel spacer insertion. METHODS: The planning computed tomography scans of 39 patients who received stereotactic body radiotherapy for prostate cancer were used. All patients inserted a hydrogel spacer and underwent computed tomography scans before and after spacer insertion. The three-dimensional conformal radiotherapy plans according to NCCN classification, low-, intermediate- and high-risk, were made for each patient. Clinical target volume included prostate and seminal vesicle 2 cm for high risk, prostate and seminal vesicle 1 cm for intermediate risk and prostate only for low risk. Three-dimensional conformal radiotherapy including a seven-field conformal technique with 76 Gy in 38 fractions. Dose constraints for rectum and bladder were V70 Gy ≤ 15%, V65 Gy ≤ 30% and V40 Gy ≤ 60%. RESULTS: Among 39 patients, 35 (90%), 19 (49%) and 13 (33%) and 38 (97%), 38 (97%) and 34 (87%) patients before and after the spacer insertion fulfilled rectum dose constraints for low-, intermediate- and high-risk plans, respectively. A hydrogel spacer significantly reduced rectum dose and improved the rectum dose constraints fulfillment rate in intermediate (P < 0.01) and high (P < 0.01), but no difference was found in low-risk plan (P = 0.25). On multivariate analysis, spacer use was associated with the higher rectum dose constraints fulfillment rate. CONCLUSIONS: A hydrogel spacer reduced rectum dose and improved the dose constraints fulfillment rate in three-dimensional conformal radiotherapy plan. Although IMRT is the standard treatment, 3D-CRT using a hydrogel spacer may be a treatment option.

Definitive-intent uniform megavoltage fractioned radiotherapy protocol for presumed canine intracranial gliomas: retrospective analysis of survival and prognostic factors in 38 cases (2013-2019).

BACKGROUND: Radiotherapy (RT) is currently considered the treatment of choice for presumed canine intracranial gliomas. However, variable therapeutic responses are described, due to heterogeneous populations and different radiation methods or protocols. Only one study dedicated to intracranial suspected glioma highlighted prognostic criteria. Determination or confirmation of specific clinical and imaging prognostic factors may guide the therapeutic management of these tumours. The objectives were to provide data on long-term clinical outcome (including quality of life, QoL) and to determine specific prognostic factors associated with survival time. We report a single-institution retrospective study, including all dogs with suspected symptomatic primary solitary intracranial glioma, treated with a complete uniform fractionated megavoltage radiation protocol of 15x3Gy over 5 weeks, between January 2013 and February 2019. Thirty-eight client-owned dogs were included. Medical records were retrospectively evaluated for median overall survival time (MST), clinical and imaging responses. Prognostic factors on survival were researched in terms of signalment, clinical presentation, tumour imaging characteristics and response following RT. Finally, the RT's impact on the dogs' clinical signs and Qol were evaluated by the owners. RESULTS: The disease-specific MST was 698 days (95% CI: 598-1135). Survival at 1 and 2 years were respectively 74.2 ± 7.4% and 49.0 ± 9.8%. Initial clinical signs were related to survival, as well as tumour characteristics such as cystic-pattern, mass effect and Tumour/Brain volume ratio. No significant adverse effect or radiotoxicity was observed. CONCLUSIONS: RT appears as a safe and effective treatment for canine intracranial gliomas, allowing long-term tumour control, improvement of life's quality and management of associated clinical signs. The initial clinical signs and MRI characteristics (Tumour/Brain volume ratio, cyst-like lesion and mass effect) may help predict the prognosis.

Dosimetric verification of lung phantom calculated by collapsed cone convolution: A Monte Carlo and experimental evaluation.

OBJECTIVE: To evaluate the dose calculation accuracy in the Prowess Panther treatment planning system (TPS) using the collapsed cone convolution (CCC) algorithm. METHODS: The BEAMnrc Monte Carlo (MC) package was used to predict the dose distribution of photon beams produced by the Oncor® linear accelerator (linac). The MC model of an 18 MV photon beam was verified by measurement using a p-type diode dosimeter. Percent depth dose (PDD) and dose profiles were used for comparison based on three field sizes: 5×5, 10×10, and 20×20cm2. The accuracy of the CCC dosimetry was also evaluated using a plan composed of a simple parallel-opposed field (11×16cm2) in a lung phantom comprised of four tissue simulating media namely, lung, soft tissue, bone and spinal cord. The CCC dose calculation accuracy was evaluated by MC simulation and measurements according to the dose difference and 3D gamma analysis. Gamma analysis was carried out through comparison of the Monte Carlo simulation and the TPS calculated dose. RESULTS: Compared to the dosimetric results measured by the Farmer chamber, the CCC algorithm underestimated dose in the planning target volume (PTV), right lung and lung-tissue interface regions by about -0.11%, -1.6 %, and -2.9%, respectively. Moreover, the CCC algorithm underestimated the dose at the PTV, right lung and lung-tissue interface regions in the order of -0.34%, -0.4% and -3.5%, respectively, when compared to the MC simulation. Gamma analysis results showed that the passing rates within the PTV and heterogeneous region were above 59% and 76%. For the right lung and spinal cord, the passing rates were above 80% for all gamma criteria. CONCLUSIONS: This study demonstrates that the CCC algorithm has potential to calculate dose with sufficient accuracy for 3D conformal radiotherapy within the thorax where a significant amount of tissue heterogeneity exists.

On the use of AAA and AcurosXB algorithms for three different stereotactic ablative body radiotherapy (SABR) techniques: Volumetric modulated arc therapy (VMAT), intensity modulated radiation therapy (IMRT) and 3D conformal radiotherapy (3D-CRT).

AIM: The purpose of this study was to investigate the dosimetric characteristics of three stereotactic ablative body radiotherapy (SABR) techniques using the anisotropic analytical algorithm (AAA) and Acuros XB algorithm. The SABR techniques include coplanar volumetric modulated arc therapy (C-VMAT), non-coplanar intensity modulated radiation therapy (NC-IMRT) and non-coplanar three-dimensional conformal radiotherapy (NC-3D CRT). BACKGROUND: SABR is a special type of radiotherapy where a high dose of radiation is delivered over a short time. The treatment outcome and accuracy of the dose delivered to cancer patients highly depend on the dose calculation algorithm and treatment technique. MATERIALS AND METHODS: Twelve lung cancer patients underwent 4D CT scanning, and three different treatment plans were generated: C-VMAT, NC-IMRT, NC-3D CRT. Dose calculation was performed using the AAA and Acuros XB algorithm. The dosimetric indices, such as conformity index (CI), homogeneity index, dose fall-off index, doses received by organs at risk and planning target volume, were used to compare the plans. The accuracy of AAA and Acuros XB (AXB) algorithms for the lung was validated against measured dose on a CIRS thorax phantom. RESULTS: The CIs for C-VMAT, NC-IMRT and NC-3D CRT were 1.21, 1.28 and 1.38 for the AAA, respectively, and 1.17, 1.26 and 1.36 for the Acuros XB algorithm, respectively. The overall dose computed by AcurosXB algorithm was close to the measured dose when compared to the AAA algorithm. The overall dose computed by the AcurosXB algorithm was close to the measured dose when compared to the AAA algorithm. CONCLUSION: This study showed that the treatment planning results obtained using the Acuros XB algorithm was better than those using the AAA algorithm in SABR lung radiotherapy.

3D conformal radiotherapy is not associated with the long-term cardiac mortality in breast cancer patients: a retrospective cohort study in Germany (PASSOS-Heart Study).

PURPOSE: In breast cancer patients treated in the 1970s and 1980s, radiation therapy (RT) for left-sided tumors has been associated with an elevated risk of cardiac mortality. In recent years, improved RT techniques have reduced radiation exposure of the heart and major coronary vessels, but some exposure remains unavoidable. In a retrospective cohort study, we investigated the long-term cardiac mortality risk of breast cancer survivors treated with modern RT in Germany. METHODS: A total of 11,982 women were included who were treated for breast cancer between 1998 and 2008. A systematic mortality follow-up was conducted until December 2012. The effect of breast cancer laterality on cardiac mortality and on overall mortality was investigated as a surrogate measure of exposure. Using Cox regression, we analyzed survival time as the primary outcome measure, taking potential confounding factors into account. RESULTS: We found no evidence for an effect of tumor laterality on mortality in irradiated patients (N = 9058). For cardiac mortality, the hazard ratio was 0.94 (95% CI 0.64-1.38) for left-sided versus right-sided tumors. For all causes of death, the hazard ratio was 0.95 (95% CI 0.85-1.05). A diagnosis of cardiac illness prior to breast cancer treatment increased both cardiac mortality risk and overall mortality risk. CONCLUSIONS: Contemporary RT seems not to be associated with an increased risk of cardiac mortality or overall mortality for left-sided breast cancer relative to right-sided RT. However, an extended follow-up period and exact dosimetry might be necessary to confirm this observation.

Evolving Clinical Cancer Radiotherapy: Concerns Regarding Normal Tissue Protection and Quality Assurance.

Radiotherapy, which is one of three major cancer treatment methods in modern medicine, has continued to develop for a long period, more than a century. The development of radiotherapy means allowing the administration of higher doses to tumors to improve tumor control rates while minimizing the radiation doses absorbed by surrounding normal tissues through which radiation passes for administration to tumors, thereby reducing or removing the incidence of side effects. Such development of radiotherapy was accomplished by the development of clinical radiation oncology, the development of computers and machine engineering, the introduction of cutting-edge imaging technology, a deepened understanding of biological studies on the effects of radiation on human bodies, and the development of quality assurance (QA) programs in medical physics. The development of radiotherapy over the last two decades has been quite dazzling. Due to continuous improvements in cancer treatment, the average five-year survival rate of cancer patients has been close to 70%. The increases in cancer patients' complete cure rates and survival periods are making patients' quality of life during or after treatment a vitally important issue. Radiotherapy is implemented in approximately 1/3 to 2/3s of all cancer patients; and has improved the quality of life of cancer patients in the present age. Over the last century, as a noninvasive treatment, radiotherapy has unceasingly enhanced complete tumor cure rates and the side effects of radiotherapy have been gradually decreasing, resulting in a tremendous improvement in the quality of life of cancer patients.

Radiation-induced Esophagitis in Breast Cancer Patients Treated With Supraclavicular Field Irradiation.

BACKGROUND/AIM: The objective of this research was to assess the frequency and intensity of radiation-induced esophagitis in breast cancer patients treated with supraclavicular radiotherapy field irradiation. PATIENTS AND METHODS: This study involved 100 patients with positive lymph nodes receiving radiotherapy to the breast or chest wall along with supraclavicular field irradiation, with toxicity levels assessed weekly. Treatment utilized the 3D conformal technique, and variables, such as mean and maximum dose to the cervical esophagus, mean dose to the entire esophagus, and length of the esophagus within the treated area were recorded. RESULTS: The occurrence of grade 2 or higher esophagitis was 48%, with patients facing the risk of developing such esophagitis at an average dose of 13 Gy. The probability of grade 2 esophagitis occurring at doses exceeding 13 Gy was statistically significantly higher (p<0.001) with an odds ratio of 24.4. CONCLUSION: Limiting the mean cervical esophagus dose to <13 Gy could help reduce the frequency and severity of grade 2 or higher toxicity.

Superficial Dosimetry Study of the Frequency of Bolus Using in Volumetric Modulated Arc Therapy after Modified Radical Mastectomy.

OBJECTIVE: To investigate the effect of various frequencies of bolus use on the superficial dose of volumetric modulated arc therapy after modified radical mastectomy for breast cancer. METHODS: Based on the computed tomography images of a female anthropomorphic breast phantom, a 0.5 cm silicone-based 3D-printed bolus was created. Nine points evenly distributed on the breast skin were selected for assessing the skin dose, and a volume of subcutaneous lymphatic drainage of the breast (noted as ROI2-3) was delineated for assessing the chest wall dose. The treatment plans with and without bolus (plan_wb and plan_nb) were separately designed using the prescription of 50 Gy in 25 fractions following the standard dose constraints of the adjacent organ at risk. To characterize the accuracy of treatment planning system (TPS) dose calculations, the doses of the nine points were measured five times by thermoluminescence dosimeters (TLDs) and then were compared with the TPS calculated dose. RESULTS: Compared with Plan_nb (144.46 ± 10.32 cGy), the breast skin dose for plan_wb (208.75 ± 4.55 cGy) was significantly increased (t = -18.56, P < 0.001). The deviation of skin dose was smaller for Plan_wb, and the uniformity was significantly improved. The calculated value of TPS was in good agreement with the measured value of TLD, and the maximum deviation was within 5%. Skin and ROI2-3 doses were significantly increased with increasing frequencies of bolus applications. The mean dose of the breast skin and ROI2-3 for 15 and 23 times bolus applications were 45.33 Gy, 50.88 Gy and 50.36 Gy, 52.39 Gy, respectively. CONCLUSION: 3D printing bolus can improve the radiation dose and the accuracy of the planned dose. Setting Plan_wb to 15 times for T1-3N+ breast cancer patients and 23 times for T4N+ breast cancer patients can meet the clinical need. Quantitative analysis of the bolus application frequency for different tumor stages can provide a reference for clinical practice.

Daily fraction dose-adjusted radiotherapy policy to avoid prolonging the overall treatment time for early glottic squamous cell carcinoma: a single-institutional retrospective study.

The objective of this study was to determine the outcomes of radical radiotherapy for early glottic squamous cell carcinoma (EGSCC) with the policy of increasing the fraction size during radiotherapy when the overall treatment time (OTT) was expected to be prolonged. Patients diagnosed with clinical T1-2N0M0 EGSCC, who were treated with radical radiotherapy between 2008 and 2019 at Hokkaido University Hospital, were included. Patients received 66 Gy in 33 fractions for T1 disease and 70 Gy in 35 fractions for T2 disease as our standard regimen (usual group [UG]). If the OTT was expected to extend for >1 week, the dose fraction size was increased from 2.0 to 2.5 Gy from the beginning or during radiotherapy (adjusted group [AG]). At this time, we performed a statistical analysis between UG and AG. In total, 116 patients were identified, and the treatment schedules of 29 patients were adjusted. The median follow-up was 60.9 months. In the T1 group, the cumulative 5-year local failure rate was 12.0% in the AG and 15.4% in the UG, and in the T2 group, the rate was 40.7% in the AG and 25.3% in the UG. There were no significant differences between the AG and UG. Similarly, no significant differences were observed for overall survival and progression-free survival rates. Our single-institutional retrospective analysis of EGSCC patients suggested that a method of adjusting the radiotherapy schedule to increase fraction size from the beginning or during the course may be effective in maintaining treatment outcomes.

Post-operative intensity-modulated vs 3D conformal radiotherapy after conservative surgery for laryngeal tumours of the supraglottic region: a dosimetric analysis on 20 patients.

Objective: To perform a dosimetric comparison between intensity modulated radiotherapy (IMRT) and 3D conformal radiotherapy in patients with locally advanced (stage III and IV) tumours of the supraglottic region treated with conservative surgery and post-operative radiotherapy. Methods: An in-silico plan using a 3D conformal shrinking field technique was retrospectively produced for 20 patients and compared with actually delivered IMRT plans. Eighteen structures (arytenoids, constrictor muscles, base of tongue, floor of mouth, pharyngeal axis, oral cavity, submandibular glands and muscles of the swallowing functional units [SFU]) were considered. Results: IMRT allowed a reduction of maximum and mean doses to 9 and 14 structures, respectively (p < .05). Conclusions: IMRT achieved a reduction of unnecessary dose to the remnant larynx and the majority of surrounding SFUs. Further prospective analyses and correlations with functional clinical outcomes are required to confirm these dosimetric findings.

A dosimetric evaluation of intensity modulated radiotherapy and three-dimensional conformal radiotherapy for prostate cancer in Ghana.

External beam radiotherapy incorporates treatment techniques such as three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT), image-guided radiotherapy and volumetric modulated arc therapy to deliver high-energy radiation to cancer. The use of IMRT for cancer treatment is also associated with significant costs for patients in low-middle-income countries. The purpose of this study was to compare the dosimetric properties of 3DCRT and IMRT treatment plans for the external beam irradiation of patients with prostate cancer (Pca) to ascertain the superiority of IMRT in terms of dose homogeneity, conformity and dose limitation to organs at risk (OAR) in a resource-limited setting. One hundred and sixty treatment plans for 80 patients were created using 3DCRT and IMRT on the Eclipse treatment planning system (version 13.6). Data were collected and assessed from the dose-volume histogram of each plan. The conformity and homogeneity index (HI) for each of the plans were calculated. The doses to the OAR were also recorded and evaluated. The mean HIs for the IMRT and 3DCRT treatment techniques were 0.04 ± 0.02 (range: 0.01-0.011) and 0.09 ± 0.02 (range: 0.04-0.016), respectively. The mean conformity index (CI) for IMRT and 3DCRT techniques were 1.257 ± 0.112 (range: 0.99-1.58) and 1.302 ± 0.196 (range: 1.10-2.26). IMRT had a better significant mean HI and CI compared to 3DCRT. Generally, for this study, IMRT had better organ sparing compared to 3DCRT. The mean doses for the OARs ranged from 4.3-74.6 Gy for IMRT and 3.1-75.9 Gy for the 3DCRT technique. Overall, this study demonstrates that IMRT may offer an enhanced therapeutic profile, potentially reducing toxicity to the patient and ensuring more precise dose delivery to the target volume compared to 3DCRT in PCa external beam irradiation.

Retrospective comparison of side effects and outcomes of three-dimensional conformal vs. intensity-modulated radiation therapy in the palliative-intent treatment (4 Gy × 5 daily fractions) of canine intranasal tumors (2010-2017).

Objective: To compare the occurrence of radiation side effects and treatment outcomes in dogs with intranasal tumors treated with a total dose of 20 Gy delivered in 5 daily 4 Gy fractions using computer-based 3D conformal (3DCRT) or intensity-modulated (IMRT) radiation therapy plans. Design: Retrospective case series. Materials and methods: Medical records for dogs with intranasal tumors treated with 4 Gy × 5 fractions between 2010 and 2017 were reviewed. Radiation side effects, time to local progression (TTLP), progression-free survival (PFS) and survival time (OS) were evaluated. Results: Thirty-six dogs (24 carcinomas, 10 sarcomas and 2 others) met the inclusion criteria. Sixteen were treated with 3DCRT and 20 with IMRT. Clinical signs improvement or resolution were reported in 84% of dogs. The median time to clinical signs improvement was 12 days (1-88 days) after the end of treatment. Eight dogs treated with 3DCRT (8/16, 50%) and 5 with IMRT (5/20, 25%) were documented acute radiation side effects. Almost all were classified as grade 1 skin, oral or ocular acute side effects. Only one dog in 3DCRT group was demonstrated grade 2 skin acute effects. The median TTLP for dogs treated with 3DCRT or IMRT was 238 days and 179 days, respectively (p = 0.967). The median PFS for 3DCRT or IMRT was 228 days and 175 days, respectively (p = 0.940). The median OS for 3DCRT or IMRT was 295 days and 312 days, respectively (p = 0.787). No significantly differences were observed in side effects, TTLP, PFS and OS between 3DCRT and IMRT groups. Conclusions: Palliative-intent conformal radiation therapy given in five daily 4 Gy fractions relieved clinical signs with minimal radiation side effects, with no statistical difference in occurrence between 3DCRT and IMRT dogs.

A Prospective Cohort Study Analyzing Radiation-Induced Xerostomia and Quality of Life of Head and Neck Cancer Patients Treated With Intensity-Modulated Radiotherapy and 3D Conformal Radiotherapy Techniques at a Tertiary Cancer Center in Eastern India.

Introduction Cancer of the head and neck is one of the most common cancers in India. Radiotherapy (RT) plays a vital role in the management of head and neck cancer both as a curative and adjuvant modality. Xerostomia is the most common acute and late toxicity. Therefore, this study aimed to analyze radiation-induced xerostomia and the quality of life of patients treated with intensity-modulated radiotherapy (IMRT) and three-dimensional (3D) conformal radiotherapy (3DCRT). Objectives We aim to evaluate radiation-induced acute xerostomia both subjectively and objectively at three-month and one-year post-radiotherapy follow-up period in patients who received radiotherapy in conformal technique (IMRT) to the head and neck region and compare it with those who received the 3DCRT technique. We also aim to assess the recovery of salivary flow in the third month post-radiotherapy by measuring the parotid scintigraphy excretion fraction. Materials and methods Forty patients with head and neck squamous cell carcinoma (SCC) were randomly assigned to the IMRT and 3DCRT arms. Xerostomia during radiation and at three-month and one-year post-radiotherapy follow-up was assessed subjectively using the xerostomia-related quality of life (XeQOL) questionnaire and objectively by measuring the salivary flow rate and parotid scintigraphy. Results The result is analyzed using an independent t-test, Mann-Whitney U test, and Fisher's exact test. The analysis showed that patients treated with radiation by IMRT showed better XeQOL scores (43.40±2.326 in IMRT and 52.10±2.573 in 3DCRT, p<0.001) and Eating Assessment Tool-10 (EAT-10) score (27.65±2.796 in IMRT and 33.80±1.936 in 3DCRT, p<0.001) compared to those treated with 3DCRT. Analysis of the excretion fraction (EF%) of parotid scintigraphy depicted improvement in EF% for both right and left parotids in the IMRT arm with statistical significance (for right parotid, 25.22±12.98 in IMRT and 19.60±10.17 in 3DCRT, p=0.136, and for left parotid, 28.03±12.51 in IMRT and 15.35±11.49 in 3DCRT, p=0.0019). The mean rate of flow (ROF) of saliva showed a declining trend during the end of radiotherapy treatment compared to baseline, but the mean ROF of saliva was better in IMRT compared to 3DCRT, and the difference was statistically significant. The ROF of saliva starts improving during the one-year post-radiotherapy follow-up period. Pearson's chi-square test was used to analyze the correlation between mean parotid dose with EF% of parotid scintigraphy, and it showed a negative correlation, which is statistically significant for both 3DCRT and IMRT arms. Conclusion Xerostomia can be reduced by precision radiotherapies such as the parotid-sparing IMRT technique in head and neck cancer patients, hence improving the quality of life.

3D-conformal very-high energy electron therapy as candidate modality for FLASH-RT: A treatment planning study for glioblastoma and lung cancer.

BACKGROUND: Pre-clinical ultra-high dose rate (UHDR) electron irradiations on time scales of 100 ms have demonstrated a remarkable sparing of brain and lung tissues while retaining tumor efficacy when compared to conventional dose rate irradiations. While clinically-used gantries and intensity modulation techniques are too slow to match such time scales, novel very-high energy electron (VHEE, 50-250 MeV) radiotherapy (RT) devices using 3D-conformed broad VHEE beams are designed to deliver UHDR treatments that fulfill these timing requirements. PURPOSE: To assess the dosimetric plan quality obtained using VHEE-based 3D-conformal RT (3D-CRT) for treatments of glioblastoma and lung cancer patients and compare the resulting treatment plans to those delivered by standard-of-care intensity modulated photon RT (IMRT) techniques. METHODS: Seven glioblastoma patients and seven lung cancer patients were planned with VHEE-based 3D-CRT using 3 to 16 coplanar beams with equidistant angular spacing and energies of 100 and 200 MeV using a forward planning approach. Dose distributions, dose-volume histograms, coverage (V95% ) and homogeneity (HI98% ) for the planning target volume (PTV), as well as near-maximum doses (D2% ) and mean doses (Dmean ) for organs-at-risk (OAR) were evaluated and compared to clinical IMRT plans. RESULTS: Mean differences of V95% and HI98% of all VHEE plans were within 2% or better of the IMRT reference plans. Glioblastoma plan dose metrics obtained with VHEE configurations of 200 MeV and 3-16 beams were either not significantly different or were significantly improved compared to the clinical IMRT reference plans. All OAR plan dose metrics evaluated for VHEE plans created using 5 beams of 100 MeV were either not significantly different or within 3% on average, except for Dmean for the body, Dmean for the brain, D2% for the brain stem, and D2% for the chiasm, which were significantly increased by 1, 2, 6, and 8 Gy, respectively (however below clinical constraints). Similarly, the dose metrics for lung cancer patients were also either not significantly different or were significantly improved compared to the reference plans for VHEE configurations with 200 MeV and 5 to 16 beams with the exception of D2% and Dmean to the spinal canal (however below clinical constraints). For the lung cancer cases, the VHEE configurations using 100 MeV or only 3 beams resulted in significantly worse dose metrics for some OAR. Differences in dose metrics were, however, strongly patient-specific and similar for some patient cases. CONCLUSIONS: VHEE-based 3D-CRT may deliver conformal treatments to simple, mostly convex target shapes in the brain and the thorax with a limited number of critical adjacent OAR using a limited number of beams (as low as 3 to 7). Using such treatment techniques, a dosimetric plan quality comparable to that of standard-of-care IMRT can be achieved. Hence, from a treatment planning perspective, 3D-conformal UHDR VHEE treatments delivered on time scales of 100 ms represent a promising candidate technique for the clinical transfer of the FLASH effect.

Monte Carlo study of organ doses and related risk for cancer in Algeria from scattered neutrons in prostate treatment involving 3D-CRT.

The present study aimed to evaluate organ doses and related risk for cancer from scattered neutrons involving 3D Conformational Radiotherapy (3D-CRT) for patients with prostate cancer in Algeria based on Monte Carlo technique and to estimate the secondary cancer risks. To this purpose, a detailed geometric Monte Carlo (MC) modeling of the LINAC Varian 2100C combined with a computational whole-body phantom was carried out. The neutron equivalent doses were calculated in-field and out-of field of patient's organs using the phase-space method. The obtained neutron equivalent doses were used to estimate the Lifetime Attributable Risks (LARs) for cancer incidence in out of field organs. LARs was evaluated assuming Biological Effects of Ionizing Radiation VII (BEIR VII) risk model for exposure age in the range 35-70 years, according to the interval's age of treated patients in Algeria. The baselines cancer risks and survival data were associated with the statistical data for the Algerian population. The results showed that the neutrons equivalent doses per prescribed dose (Photon Dose) mostly depend on the distance of organs from the treated volume. The highest and lowest equivalent doses of 1.18 mSv/Gy and 0.25 mSv/Gy were recorded in the bladder and heart, respectively. The highest estimated lifetime attributable risk per 100,000 population was found for 35 yrs' exposure age in colon 49.94, lung 16.63 and stomach 11.17. The lowest risks were found for 70 yrs' age, in spine 0.06 and thyroid 0.14. The results showed that LARs values decrease with the increase of the exposure age and cancer incidence risk is lower than the baseline cancer risk incidence for all organs. The present study may help in providing a database on the impact of radiotherapy-induced secondary cancer incidence during 3D-CRT for prostate cancer in Algeria.