Conventional Radiotherapy Techniques Research Articles

Stereotactic Body Radiotherapy in Recurrent and Oligometastatic Head and Neck Tumours

The treatment of head and neck cancers (HNCs) encompasses a complex paradigm involving a combination of surgery, radiotherapy, and systemic treatment. Locoregional recurrence is a common cause of treatment failure, and few patients are suitable for salvage surgery. Reirradiation with conventional radiation techniques is challenging due to normal tissue tolerance limits and the risk of significant toxicities. Stereotactic body radiotherapy (SBRT) has emerged as a highly conformal modality that offers the potential for cure while limiting the dose to surrounding tissue. There is also growing research that shows that those with oligometastatic disease can benefit from curative intent local ablative therapies such as SBRT. This review will look at published evidence regarding the use of SBRT in locoregional recurrent and oligometastatic HNCs.

Spectrum of Imaging Patterns of Lung Cancer following Radiation Therapy.

Radiation therapy using conventional or newer high-precision dose techniques, including three-dimensional conformal radiotherapy, intensity-modulated radiation therapy, stereotactic body radiation therapy, four-dimensional conformational radiotherapy, and proton therapy, is an important component of treating patients with lung cancer. Knowledge of the radiation technique used and the expected temporal evolution of radiation-induced lung injury, as well as patient-specific parameters such as previous radiotherapy, concurrent chemoradiotherapy, or immunotherapy, is important in image interpretation. This review discusses factors that affect the development and severity of radiation-induced lung injury and its radiological manifestations, as well as the differences between conventional and high-precision dose radiotherapy techniques.

Patient-Reported Outcomes of Rectal Cancer Patients Treated on a 1.5T MR-Linac within the MOMENTUM Study.

With the 1.5 MR-Linac, planning target volume (PTV) margins for the treatment of rectal cancer can be reduced by 1/3 compared to conventional radiotherapy techniques. This allows better sparing of surrounding tissues, potentially resulting in less toxicity and greater patient comfort. Patient-reported outcomes (PROs) after rectal cancer treatment on a 1.5T MR-Linac have not yet been reported. Through international collaboration, the 'Multi-OutcoMe EvaluatioN of radiation Therapy Using the MR-Linac (MOMENTUM)' registry provides the unique opportunity to study these outcomes in a relatively large patient cohort. The aim of this study is to assess PROs of rectal cancer patients treated on a 1.5T MR-Linac within MOMENTUM. An international, prospective, observational cohort study was performed, including all patients with rectal cancer who were treated with 25 Gy in five fractions on an MR-Linac in three institutions located in the Netherlands (2019-2022). Patient-reported outcomes were measured using the general EORTC QLQ-C30 and colorectal cancer-specific EORTC QLQ-CR29 questionnaires. Scores were calculated according to the EORTC QLQ-C30 scoring manual. A high score for a functional scale represents a high functioning level, while a high score for a symptom scale represents a high symptomatology level. Outcomes were measured at regular time points (i.e., at baseline and after three, 6 and 12 months follow-up). Patients who underwent tumor resection were censored at the date of surgery. In total, 152patients were included, with a median follow-up of 17 (interquartile range [IQR] 11-27) months. Of these, six patients (4%) had American Joint Committee on Cancer (AJCC) stage I disease, 11 patients (7%) stage II, 85 patients (56%) stage III, and 12 patients (8%) stage IV. A total of 87 patients (57%) reached three months follow-up without surgery, 60 patients (39%) six months, and 40 patients (26%) twelve months. At six months follow-up, 25/132 patients (19%) had received additional chemotherapy. The median global health score was 83 (interquartile range [IQR] 67-83) at baseline, 75 (IQR 58-83) at three months, 75 (IQR 58-83) at six months and 83 (IQR 83-100) at twelve months. In most QLQ-C30 domains, functional and symptom scores deteriorated during the first six months after treatment, but returned to or exceeded baseline scores at 12 months. Overall, treatment resulted in improved QLQ-CR29 scores after 12 months follow-up. Most frequently reported symptoms were blood and mucus in stool, urinary frequency, stool frequency and anxiety. This study presents patient-reported outcomes in the currently largest cohort of patients with rectal cancer who received treatment on a 1.5T MR-Linac. Overall, treatment resulted in improved symptom management, and stabilized or improved quality of life outcomes after twelve months of follow-up.

Boron neutron capture therapy in the new age of accelerator-based neutron production and preliminary progress in Canada

Each year more than 3000 Canadians are diagnosed with brain cancers like glioblastoma multiforme or recurrent head and neck cancers, which are difficult to treat with conventional radiotherapy techniques. One of the most clinically promising treatments for these cancers is boron neutron capture therapy (BNCT). This procedure involves selectively introducing a boron delivery agent into tumor cells and irradiating them with a neutron beam, which kills the cancer cells due to the high-linear energy transfer radiation produced by the 10B(n,α)7Li capture reaction. The theory of BNCT has been around for a long time since 1936, but has historically been limited by poor boron delivery agents and non-optimal neutron source facilities. Although significant improvements have been made in both of these domains, it is mainly the advancements of accelerator-based neutron sources that have led to the expansion of over 20 new BNCT facilities worldwide in the past decade. Additionally in this work, particle and heavy ion transport code system simulations, in collaboration with the University of Tsukuba, were performed to examine the effectiveness of the Ibaraki BNCT beam shaping assembly to moderate a neutron beam suitable for BNCT at the proposed prototype Canadian compact accelerator-based neutron source (CANS) site, which uses a similar but slightly higher energy 10 MeV proton accelerator with a 1 mA average current. The advancements of CANSs in recent decades have enabled significant improvements in BNCT technologies, allowing it to become a more viable clinical treatment option.

Multi-institutional dose audit in radiotherapy facilities using in-house developed optically stimulated luminescence disc dosimeters.

The aim of this study was to carried out the audit of radiotherapy centers practicing conformal radiotherapy techniques and demonstrate the suitability of this indigenous optically stimulated luminescence (OSL) disc dosimeters in beam quality audit and verification of patient-specific dosimetry in conventional and conformal treatments in radiotherapy. Dose audit in conventional and conformal (intensity-modulated radiotherapy and volumetric-modulated arc therapy) radiotherapy techniques was conducted using in-house developed Al2O3:C-based OSL disc dosimeter and commercially available Gafchromic EBT3 film in 6 MV (flat and unflat) photon and 6 and 15 MeV electron beams. OSL disc dosimeter and Gafchromic EBT3 film measured dose values were verified using the ionization chamber measurements. Percentage variations of doses measured by OSL disc dosimeters and EBT3 Gafchromic film for conventional radiotherapy technique were in the range of 0.15%-4.6% and 0.40%-5.45%, respectively, with respect to the treatment planning system calculated dose values. For conformal radiotherapy techniques, the percentage variations of OSL disc and EBT3 film measured doses were in the range of 0.1%-4.9% and 0.3%-5.0%, respectively. The results of this study supported by statistical evidence provided the confidence that indigenously developed Al2O3:C-based OSL disc dosimeters are suitable for dose audit in conventional and advanced radiotherapy techniques.

Profile of Radiotherapy Side Effects in Patients Treated for Cervical Cancer in Cameroon: Case of the Douala General Hospital

Background: Radiotherapy is one of the main therapeutic strategies used in cervical cancer. The first radiotherapy services in Cameroon have existed since 1987 and still treat by conventional radiation techniques. With the evolution of radiation techniques, acute, subacute, and late complications are minimized. Our study aimed to describe the profile of side effects in patients with uterine cervix cancer treated by conventional radiotherapy, still used in our services. Methods: This was a retrospective and descriptive study of the records of patients treated in the radiotherapy department of the Douala General Hospital from January 2015 to December 2019. Data concerning radiation-induced toxicities were collected using the CTCAE Version 4.0 classification. Data analysis was performed using SPSS version 20.0. Results: A total of 270 records were selected. The median age was 54 years. The mean total radiation dose was 55.9 ± 11.8 Gy and 71.1% of patients were treated for less than 8 weeks. We found a frequency of 66.7% of radio-induced lesions with 99% being acute. The main acute lesions encountered were radio dermatitis (40%), radiation cystitis (17.7%), and radiation proctitis (17.1%). As late lesions, we found one case of vaginal fibrosis (0.4%). Exclusive radiotherapy, classical fractionation, and total doses lower than 45 Gy seemed to decrease the toxicity linked to conventional radiotherapy. Conclusion: The frequency of side effects of radiotherapy for cervical cancer at the Douala General Hospital remains high. Early lesions are the most encountered but strategies should be put in place to better evaluate late lesions.

Reirradiation of metastases of the central nervous system: part 2-metastatic epidural spinal cord compression.

An increasing number of patients irradiated for metastatic epidural spinal cord compression (MESCC) experience an in-field recurrence and require a second course of radiotherapy. Reirradiation can be performed with conventional radiotherapy or highly-conformal techniques such as intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), and stereotactic body radiation therapy (SBRT). When using conventional radiotherapy, a cumulative biologically effective dose (BED) ≤120 calculated with an α/β value of 2 Gy (Gy2) was not associated with radiation myelopathy in a retrospective study of 124 patients and is considered safe. In that study, conventional reirradiation led to improvements of motor deficits in 36% of patients and stopped further symptomatic progression in another 50% (overall response 86%). In four other studies, overall response rates were 82-89%. In addition to the cumulative BED or equivalent dose in 2 Gy fractions (EQD2), the interval between both radiotherapy courses <6 months and a BED per course ≥102 Gy2 (corresponding to an EQD2 ≥51 Gy2) were identified as risk factors for radiation myelopathy. Without these risk factors, a BED >120 Gy2 may be possible. Scoring tools have been developed that can assist physicians in estimating the risk of radiation myelopathy and selecting the appropriate dose-fractionation regimen of re-treatment. Reirradiation of MESCC may also be performed with highly-conformal radiotherapy. With IMRT or VMAT, rates of pain relief and improvement of neurologic symptoms of 60-93.5% and 42-73%, respectively, were achieved. One-year local control rates ranged between 55% and 88%. Rates of myelopathy or radiculopathy and vertebral compression fractures were 0% and 0-9.3%, respectively. With SBRT, rates of pain relief were 65-86%. Two studies reported improvements in neurologic symptoms of 0% and 82%, respectively. One-year local control rates were 74-83%. Rates of myelopathy or radiculopathy and vertebral compression fractures were 0-4.5% and 4.5-13.8%, respectively. For SBRT, a cumulative maximum EQD2 to thecal sac ≤70 Gy2, a maximum EQD2 of SBRT ≤25 Gy2, a ratio ≤0.5 of thecal sac maximum EQD2 of SBRT to maximum cumulative EQD2, and an interval between both courses ≥5 months were associated with a lower risk of myelopathy. Additional prospective trials are required to better define the options of reirradiation of MESCC.

Quality of Life in Locally Advanced Head and Neck Cancer Patients with Different Radiotherapy Techniques after Definitive Chemo Radiotherapy - A Real-World Data Study with Indian Patients

BACKGROUND&#x0D; The standard of care in non-resectable locally advanced head and neck cancer with squamous cell histology is radical radiotherapy (RT) along with concurrent chemotherapy. Previously, these patients were treated with conventional radiotherapy techniques. Such conventional techniques can lead to morbidity with an impact on quality-of-life (QOL) in long-term survivors. Conformal radiotherapy experiences significant improvements in QOL domains versus conventional techniques. Radiotherapy planning and treatment with conformal techniques require advanced and relatively expensive equipment. Our study is aimed at evaluating the feasibility of conventional radiotherapy techniques in terms of quality of life in locally advanced head and neck cancer patients in comparison to the conformal technique in the Indian setting.&#x0D; METHODS&#x0D; Sixty patients with locally advanced head and neck cancer who received chemo-radiation therapy and came for follow-up after a minimum of two years were scheduled to complete the QOL questionnaire (QLQ-C30 and QLQ-H&amp;N35 scores). These scores were compared between the patients who were treated with conventional and conformal techniques.&#x0D; RESULTS&#x0D; Results showed that when comparing EORTC QLQ–C30 scoring, patients who were treated with conventional RT had a significantly higher median score for emotional QOL and lower median scores for fatigue, pain, appetite loss, and financial difficulties as compared to the conformal RT group. But only the financial difficulties scale showed a significant p-value. When comparing EORTC QLQ–H&amp;N35 scores, all QLQ-HN35 scores did not show any significant difference, except for speech problems. Patients treated with the conventional technique had a significantly lower median score for speech problems compared to the conformal RT group.&#x0D; CONCLUSIONS&#x0D; Based on these results, it is concluded that conventional radiotherapy techniques can be advised to locally advanced head and neck cancer patients when conformal radiotherapy techniques are not available, especially in developing or underdeveloped countries.

Outcomes of Patients With Breast Cancer Treated With or Without Internal Mammary Irradiation: A Single-Center, Retrospective Propensity Score–Matched Study

PurposeInternal mammary lymph node radiation therapy (IMN-RT) has unclear benefits. Historical data were based on only conventional (2-dimensional) radiation techniques. In this 3-dimensional radiation therapy era, we compared the distant metastasis–free survival (DMFS) rates of patients receiving IMN-RT with those who did not include coverage of the IMN (non–IMN-RT). This study aimed to determine the relationship between IMN-RT and distant metastasis control in patients with lymph node–positive breast cancer. Methods and MaterialsThis was a single-center retrospective cohort study. Patients were divided into 2 groups: IMN-RT and non–IMN-RT. The criterion of the IMN-RT group was that 80% of the prescribed dose covered ≥98% of the Clinical Target Volume of IMN. The primary outcome was 4-year DMFS, and the secondary outcomes were 4-year overall survival, 4-year disease-free survival, and cardiac toxicity. ResultsFrom January 2012 to December 2018, 570 patients were evaluated (IMN-RT, 143 patients; non–IMN-RT, 427 patients). Propensity score matching decreased the number of patients in each group to 139. The median follow-up was 4.3 years. The 4-year DMFS rates were as follows: IMN-RT, 79.1% (95% confidence interval [CI], 70.1%-85.6%), and non–IMN-RT, 82.8% (95% CI, 74.2%-88.7%; P = .43). The groups’ 4-year overall survival and disease-free survival rates did not differ. The 4-year overall survival rates were 84.3% (95% CI, 76.4%-89.8%) for IMN-RT and 88.1% (95% CI, 81.0%-92.7%; P = .39) for non–IMN-RT. The 4-year disease-free survival rates were 77.1% (95% CI, 68.1%-83.8%) for IMN-RT and 82.1% (95% CI, 73.6%-88.1%; P = .29) for non–IMN-RT. There was no significant difference in cardiac toxicity (IMN-RT, 1.4%; non–IMN-RT, 1.4%; P = 1.0). ConclusionsIn the modern radiation technique era with real-world data, we could not find a benefit of internal mammary irradiation.

Impact of chemotherapy cycles on oncological outcomes in elders with locally advanced cervical cancer treated with concurrent chemoradiotherapy.

To investigate the association between chemotherapy (CMT) cycles and oncological outcomes in elders with locally advanced cervical cancer (LACC) who treated with concurrent chemoradiotherapy (CCRT). We retrospective studied 498 elders with LACC who treated with radiotherapy (RT) or CCRT between 2002 and 2018. Patients were divided into three groups: RT, CCRT with 1-4 and CCRT with 5-6 cycles of CMT. We compared progression-free survival (PFS) and overall survival (OS) among the three groups and explored survival prognostic factors via multivariate analysis and time-varying analysis effect. There were 453 eligible patients; 222, 119 and 112 patients who received RT, CCRT with 1-4 and CCRT with 5-6 cycles of CMT, respectively. Patients in the RT group had older age, poorer performance status, more treatment with conventional RT technique and earlier treatment year comparing with both CCRT groups. Patients who received 5-6 cycles of CMT were less to have underweight, comorbidities and anaemia compared with the RT group. There were patients with lower FIGO stage in 5-6 cycles than in 1-4 cycles of CMT and RT groups. The 5-year PFS and OS between RT, CCRT with 1-4 and CCRT with 5-6 cycles of the CMT group were significantly different. Performance status, comorbidity, histology, FIGO stage and total received 5-6 CMT cycles were significant prognostic factors of PFS and OS. However, the benefits of receiving 5-6 CMT cycles were evidenced only within the first 2.5 years. Elders with LACC who received 5-6 cycles of CMT concurrently with RT can improve PFS and OS, but the benefit persisted only within the first 2.5 years.

IL CENTRO NAZIONALE DI ADROTERAPIA ONCOLOGICA: INNOVAZIONI TECNICO-SCIENTIFICHE E NUOVE PROSPETTIVE DELLA BNCT PER LA LOTTA AI TUMORI

Protons and carbon ions (hadrons) have useful properties for the treatments of patients affected by oncological pathologies. They are more precise than conventional X-rays and possess radiobiological characteristics suited for treating radio-resistant or inoperable tumors. This paper gives an overview of the status of hadron therapy around the world. It focusses on the Italian National Centre for Oncological Hadron therapy (CNAO), describing the centre and the expansion projects. There is growing evidence that supports safety and effectiveness of hadron therapy for a variety of clinical situations. However, there is still a lack of high-level evidence directly comparing hadron therapy with modern conventional radiotherapy techniques. The results give an overview of pre-clinical and clinical research studies and of the treatments of 3700 patients performed at CNAO. The success and development of hadron therapy is strongly associated with the creation of networks among hadron therapy facilities, clinics, universities and research institutions.

Technical Radiotherapy Advances – The Role of Magnetic Resonance Imaging-Guided Radiation in the Delivery of Hypofractionation

Safe delivery of hypofractionated radiotherapy requires high levels of accuracy due to the high doses of radiation delivered per fraction. Magnetic resonance guided radiotherapy (MRgRT) represents a new treatment paradigm which allows improved visualisation of targets and organs at risk, alongside the capability to adapt the treatment plan in real time prior to treatment delivery. There are challenges to delivering hypofractionated radiotherapy with conventional image-guided radiotherapy (IGRT) techniques and MRgRT may help to improve accuracy in radiation delivery in a number of clinical and anatomical scenarios.Specifically, there is an emerging role of MRgRT in delivering stereotactic body radiotherapy (SBRT) for locally advanced pancreatic cancer (LAPC) due to the superior soft tissue contrast provided by Magnetic Resonance Imaging combined with the ability to accommodate variation in anatomical appearances during treatment delivery. Reported data on the use of MRgRT in LAPC and it's role in enabling dose escalation are discussed in this article.There are further potential benefits to the use of MRgRT, for example the use of functional imaging during treatment delivery and generation of synthetic computed tomography, which have previously been impractical or unachievable. The overall aim of this article is to demonstrate the utility of MRgRT in facilitating safe delivery of hypofractionated radiotherapy and to highlight ways in which it may help to overcome challenges posed by current IGRT techniques.

Hadron Therapy Achievements and Challenges: The CNAO Experience

Protons and carbon ions (hadrons) have useful properties for the treatments of patients affected by oncological pathologies. They are more precise than conventional X-rays and possess radiobiological characteristics suited for treating radio-resistant or inoperable tumours. This paper gives an overview of the status of hadron therapy around the world. It focusses on the Italian National Centre for Oncological Hadron therapy (CNAO), introducing operation procedures, system performance, expansion projects, methodologies and modelling to build individualized treatments. There is growing evidence that supports safety and effectiveness of hadron therapy for a variety of clinical situations. However, there is still a lack of high-level evidence directly comparing hadron therapy with modern conventional radiotherapy techniques. The results give an overview of pre-clinical and clinical research studies and of the treatments of 3700 patients performed at CNAO. The success and development of hadron therapy is strongly associated with the creation of networks among hadron therapy facilities, clinics, universities and research institutions. These networks guarantee the growth of cultural knowledge on hadron therapy, favour the efficient recruitment of patients and present available competences for R&amp;D (Research and Development) programmes.

Stereotactic radiotherapy and the potential role of magnetic resonance-guided adaptive techniques for pancreatic cancer.

BACKGROUNDPancreatic cancer is a malignancy with one of the poorest prognoses amongst all cancers. Patients with unresectable tumours either receive palliative care or undergo various chemoradiotherapy regimens. Conventional techniques are often associated with acute gastrointestinal toxicities, as adjacent critical structures such as the duodenum ultimately limits delivered doses. Stereotactic body radiotherapy (SBRT) is an advanced radiation technique that delivers highly ablative radiation split into several fractions, with a steep dose fall-off outside target volumes. AIMTo discuss the latest data on SBRT and whether there is a role for magnetic resonance-guided techniques in multimodal management of locally advanced, unresectable pancreatic cancer.METHODSWe conducted a search on multiple large databases to collate the latest records on radiotherapy techniques used to treat pancreatic cancer. Out of 1229 total records retrieved from our search, 36 studies were included in this review.RESULTSStudies indicate that SBRT is associated with improved clinical efficacy and toxicity profiles compared to conventional radiotherapy techniques. Further dose escalation to the tumour with SBRT is limited by the poor soft-tissue visualisation of computed tomography imaging during radiation planning and treatment delivery. Magnetic resonance-guided techniques have been introduced to improve imaging quality, enabling treatment plan adaptation and re-optimisation before delivering each fraction.CONCLUSIONTherefore, SBRT may lead to improved survival outcomes and safer toxicity profiles compared to conventional techniques, and the addition of magnetic resonance-guided techniques potentially allows dose escalation and conversion of unresectable tumours to operable cases.

Evaluation of the Effect of Axillary Radiotherapy Dose and the Development of Lymphedema in Breast Cancer Patients

Purpose: The present study is aiming to correlate different radiotherapy techniques, fractionations, and doses received by each axillary LN level and axillary vessels with the development of breast cancer-related lymphedema (BCRL). Methods and Materials: We retrospectively studied 181 female breast cancer patients who were diagnosed and treated by radiation therapy during the period from January 2012 to December 2017. The radiotherapy treatment plans were recalled from the archives. The axillary LN levels I, II, III, supraclavicular LN were contoured as well as axillary vessels. New dose volume histograms were generated to correlate between the radiotherapy dose t and the development of BCRL. Results: The study included 162 patients treated with a 3D radiotherapy technique and 19 treated with a 2D radiotherapy technique; 124 patients underwent MRM, while 57 patients underwent BCS; 117 patients were treated with a hypofractionated technique, while 64 patients were treated with a conventional radiotherapy technique. The cumulative incidence of BCRL after radiotherapy was 20.4%. There was a statistically significant relationship between the 2D radiotherapy technique compared with 3DCRT and development of lymphedema (55 vs. 16.6, respectively; p < 0.001). Patients who were treated with conventional radiotherapy had significantly higher rates of lymphedema (42.2%) compared with hypofractionated radiotherapy (8.5%) (p < 0.001). There was a non-significant relationship between mean radiotherapy dose to axillary levels or axillary vessels and development of lymphedema. Conclusion: Breast cancer radiotherapy with the 2D technique and conventional fractionation protocol might increase the risk of BCRL. No correlation was observed between radiotherapy dose to each axillary LN level, axillary vessels and BCRL.

Dosimetric comparison between carbon, proton and photon radiation for renal retroperitoneal soft tissue sarcoma recurrence or metastasis after radical nephrectomy

Objective To compare the dosimetric difference between various modalities in the radiation treatment for renal retroperitoneal soft tissue sarcoma recurrence or metastasis (RRSTSRM) after radical nephrectomy, and assess the dosimetric advantage on protecting the organs at risk (OARs) in the carbon and proton radiotherapy for the patients with a single kidney. Methods A total of 12 patients with RRSTSRM who underwent radical nephrectomy were enrolled in this study. Carbon, proton, and photon radiotherapy were implemented for treatment planning. The prescription dose was fulfilled by simultaneously integrated boosting technique, with giving the planning target volume-1 (PTV-1) 51Gy (RBE) and planning target volume-2 (PTV-2) 60 Gy (RBE). Doses in the patient’s spinal cord, stomach, duodenum, bowel, colon, and contralateral kidney were evaluated. The normal tissue complication probability (NTCP) of the duodenum, bowel, colon, and contralateral kidney was derived under Lyman-Kutcher-Burman (LKB) estimation. Results In the carbon plans, the percentage volume of 95% prescription dose (V95%) covering PTV-1 (PTV-2) was 95.93% ± 3.42% (95.61% ± 4.26%). No significant dosimetric difference on the target was obtained between the four radiation modalities (P > .05). The percentage volume of receiving 40 Gy (RBE) [V40Gy (RBE)] in the duodenum could be reduced from 12.94% ± 15.99% in the IMRT plans to 6.36% ± 8.79% (8.44% ± 12.35%) in the carbon (proton) plans (P < .05). The V40Gy (RBE) in the bowel could be reduced from 13.48% ± 13.12% in the IMRT plans to 7.04% ± 9.32% (7.34% ± 9.89%) in the carbon (proton) plans (P < .05). The mean value of NTCP for the duodenum was 0.43 ± 0.47 (0.45 ± 0.48) by using carbon (proton) radiation. The value was 0.05 (0.03) lower than the IMRT plans on average, with a reduction of 0.20 (0.13) for the patients with lesions <5 mm away from the duodenum. The mean doses of the contralateral kidney were 0.28 ± 0.37 Gy (RBE) [0.28 ± 0.40 Gy (RBE)] in the IMCT (IMPT) plans, which was 92.43% (92.43%) lower than the value in the IMRT plans respectively (P < .05). Conclusion Compared to the conventional radiation techniques, particle radiotherapy of carbon and proton could significantly spare more OARs in the treatment for RRSTSRM after radical nephrectomy. Patients, especially those whose residuals are close to the duodenum would potentially benefit from the particle radiation therapy for RRSTSRM on the decrease in radiation-related side-effect.

Clinical Implications of Geometric and Dosimetric Uncertainties Due to Inter- and Intra-Fractional Movement During Volumetric Modulated Arc Therapy for Breast Cancer Patients

Compared to conventional radiotherapy (RT) techniques, modern RT with fewer fractions and smaller target volumes requires higher accuracy. This study evaluated the necessity of pre-treatment and intra-fractional cone-beam computed tomography (CBCT) by analyzing inter- and intra-fractional CBCT images of breast cancer patients receiving RT.From 57 patients, 1,206 pre-treatment CBCT and 1,067 intra-fractional CBCT images were collected. After positioning the patient according to the three skin markers drawn during simulation, pre-treatment CBCT images were acquired. During partial-arc volumetric modulated arc therapy, a simultaneous intra-fractional CBCT scan was taken as the gantry rotated around the patient. The change in position between simulation and the actual position of the patient before and during RT was assessed according to the differences in x-, y-, and z-axes. After the difference in each axis was measured, the absolute distance between two CT images was measured. Changes in dosimetric parameters were evaluated in selected patients with extreme intra-fractional movement.For right-sided breast cancer patients, left-sided breast cancer patients treated using deep-inspiration breath hold, and left-sided breast cancer patients treated using continuous positive airway pressure, median inter-fractional deviations were 0.53 (range 0.06-2.98) cm, 0.66 (range 0.08-4.41) cm, and 0.69 (range 0.04-3.80) cm and median intra-fractional deviations were 0.14 (range 0.00-0.62) cm, 0.23 (range 0.02-0.96) cm, and 0.24 (0.00-1.15) cm, respectively. Modified plans reflecting large changes in intra-fractional position in 10 selected cases revealed insufficient target coverage in seven cases and more than 20-fold increase in the volume of heart receiving more than 25 Gy of radiation in two cases.Even though the intra-fractional ROM was minimal in most cases, few cases showed huge variations that could significantly affect the goal of RT; therefore, intra-fractional verification might be necessary as well as inter-fractional verification.

Stereotactic vs. Conventional Radiation Therapy in Patients With Pancreatic Cancer

<h3>Purpose/Objective(s)</h3> Patients with pancreatic cancer often receive radiation therapy before undergoing surgical resection. We compared the clinical outcomes differences between SBRT and 3D/IMRT after receiving current, modern standard-of-care chemotherapy. <h3>Materials/Methods</h3> We retrospectively identified patients with borderline resectable or locally advanced pancreatic cancer treated with neoadjuvant SBRT (median: 36.0Gy/5fx), 3D-CRT (median: 50.4Gy/28fx) or IMRT (median: 50.4Gy/28fx) at one institution 2015-2020. Overall survival (OS) and progression-free survival (PFS) were analyzed using COX regression. <h3>Results</h3> : In total, 111 patients were included. Sixty patients (54.1%) were treated with SBRT, and 51 patients (45.9%) were treated with 3D/IMRT. Patients in the SBRT group were slightly older (median age: 70.0 vs 62.7 in the 3D/IMRT group). Both groups had similar proportions of patients with locally advanced pancreatic cancer (SBRT: 32, 53.3%; 3D/IMRT: 27, 52.9%). All patients were treated with chemotherapy. Patients in the SBRT group underwent slightly more surgical resection when compared to the 3D/IMRT group (36.7% vs 21.6%, respectively, <b>P</b> = 0.08). At a median follow-up of 22 months, a total of 65 patients (58.6%) died: 28 (28/60, 46.7%) in the SBRT group, and 37 (37/51, 72.5%) in the 3D/IMRT group. Median OS was slightly higher in the SBRT group (28.7 months vs 24.2 months in the 3D/IMRT group). On multivariable COX regression, the choice of radiation therapy technique was not associated with differences in OS (aHR = 0.6, 95% CI [0.3-1.1], <b>P</b> = 0.10). Moreover, patients that underwent surgical resection had better OS (aHR = 0.3, <b>P</b> = 0.003). Furthermore, PFS was also similar between patients treated with SBRT and those treated with 3D/IMRT (aHR = 0.8, <b>P</b> = 0.31). <h3>Conclusion</h3> SBRT was associated with similar clinical outcomes when compared to conventional radiation techniques, despite being delivered over a shorter period of time which would spare patients prolonged treatment burden. Future prospective data are still needed to better assess the role of SBRT in patients with pancreatic cancer.

A protective effect of morning radiotherapy on acute skin toxicity in patients with breast cancer: A prospective cohort study.

The focus of this prospective cohort study was to evaluate the risk factors of severe acute skin toxicity (grade ≥2) in 100 patients with breast cancer (BC) during radiotherapy (RT).The patients were evaluated weekly during RT and 3 months after treatment. The endpoint included the occurrence of skin toxicity grade ≥2, according to Radiation Therapy Oncology Group (RTOG). Survival analysis was conducted by univariate and multivariate Cox regression analysis.In the multivariate analysis, RT in the afternoon (0–3 pm) (hazard ratios [HR] = 1.566, P = .042) was significantly associated with the early occurrence of skin toxicity, indicating a potential effect of chronotherapy related to this adverse event. In the univariate and multivariate analysis, skin phototype moderate brown (HR = 1.586, P = .042; HR = 1.706, P = .022, respectively) and dark brown or black (HR = 4.517, P < .001; HR = 5.336, P < 0.001, respectively) was significantly associated with the skin toxicity. Tangential field separation >21 cm (HR = 2.550, P = .009, HR = 2.923, P = .003), in women that were submitted to conservative surgery indicates indirectly that large breast size was also significantly associated with skin toxicity.Women with large breasts and dark brown or black skin should be followed more carefully during RT, which should be undergone in the morning, especially when submitted to conventional RT techniques, common in developing countries.

Relevance of Combined Electron and Photon Beams in Radiotherapy of Head and Neck Cancers in the Era of Intensity-Modulated Radiotherapy

Introduction External beam radiotherapy (EBRT) for head and neck (H&amp;N) cancers continues to be delivered using varied technologies, ranging from the old two-dimensional conventional radiotherapy (2DRT) techniques to the modern three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT) in different centers in India. Due to limitations of spinal cord tolerance, electron and photon beams are combined in 2DRT and 3DCRT techniques for treating nodal volume of the H&amp;N cases. However, many centers having modern technology practice IMRT/VMAT in place of electron beams. The purpose of this study is to analyze the role of combined electron and photon beams in radiotherapy of H&amp;N cancers and its relevance in the modern era of IMRT/VMAT.Materials and Methods Data were collected through a survey conducted on cancer centers in India where radiotherapy is being given by 2DRT, 3DCRT, and IMR/VMAT for the treatment of head and neck cancers.Results The mean percentage of H&amp;N (H&amp;N) cases among all cases were 39.2% (standard deviation [SD]: 14.22), out of which 16.63% (SD: 20.83) were treated with a combination of photon and electron beams and 49.73% (SD: 37.41) were treated with IMRT/VMAT. The average percentage of H&amp;N cases of government institutes was 38.39% (SD: 14.11) and that of private institutes was 40.14% (SD: 14.11). Patients treated with photon and electron combination and IMRT/VMAT were 22.19% (SD: 11.24) and 24.05% (SD: 23.99), respectively, in government institutes, and 10.29% (SD: 11.24) and 79.09% (SD: 26.75) in private institutes.Conclusion As per this study, we conclude that despite the availability of IMRT/VMAT, a combination of electron and photon beams is still relevant in India. Since a large proportion of the patients are still treated with the electron and photon combination, it is imperative that further studies on field–junction dosimetry should be conducted to ensure accurate dose delivery.