Stereotactic radiosurgery in India: A nationwide survey of technology and quality assurance practices.

PURPOSE: India is rapidly adopting advanced treatments like Stereotactic Radiosurgery (SRS). However, there is a paucity of data on SRS practice. The aim of study is to assess the current status of technology and practices of machine quality assurance (QA) and patient specific quality assurance for SRS in India. MATERIALS AND METHODS: A survey questionnaire was designed using Google Forms and sent to chief/senior medical physicists across 220 radiotherapy centers in India on July 15, 2022. It contained questions on infrastructure availability, treatment planning, and QA. RESULTS: SRS was found to be extensively used for the treatment of brain metastases (99.3%), followed by meningioma (50.3%), acoustic neuroma (45.5%), and pituitary tumours (33.1%). The most commonly used photon energy and treatment technique were 6MV FFF and VMAT, respectively. A prescription isodose line ranging from 70% to 100% was selected by linac users. Most linac institutes verify pretreatment doses. There was a lack of uniformity in the analysis metrics such as Low Dose Threshold, Dose Difference, and Distance to Agreement. A survey revealed that the variety of SRS QA programs being followed at Indian radiotherapy centers. CONCLUSION: This is the first study to report the physics practice of SRS in India. The survey shows a need to carry out a postal dose audit for small static photon fields in India.

Application of LiMgPO4 crystal for proton beam quality control in radiotherapy.

The radioluminescence (RL) emitted by LiMgPO4 detector under proton beam irradiation was investigated in real time at the radiotherapy facility in the Institute of Nuclear Physics Polish Academy of Sciences in Krakow. The facility uses protons accelerated by the AIC-144 isochronous cyclotron up to the energy of 60 MeV. The measurements of RL were carried out using a remote optical fiber device with a luminophore detector and photomultiplier located at opposite ends of the optical fiber. A thin slice of LiMgPO4 doped with Tm (1.2 mol%) crystal was exposed to the proton beam. The tested detector allowed for the measurement of proton beam current, flux fluence and determination of proton beam time structure parameters. The investigation of LiMgPO4 crystal showed its high sensitivity, fast reaction time to irradiation and possibility of application as the detector for control of proton beam parameters.

Reirradiation Using 198Au Grain Brachytherapy for Recurrent Oral Cancer Cases Previously Treated by Definitive Radiotherapy.

BACKGROUND/AIM: We investigated treatment outcomes and complications during reirradiation of patients with oral cancers. PATIENTS AND METHODS: Six patients who received definitive radiotherapy for oral cancer as the initial treatment and brachytherapy for recurrence were included. Local control and overall survival rates, soft tissue and mandibular complications, and tooth extraction were investigated. RESULTS: The five-year local control and overall survival rates were 83.3% and 100%, respectively. The occurrence rate of grade 2 soft tissue and mandible complications was 33.3%, and the primary sites were the buccal mucosa and the floor of mouth. The positions of the extracted tooth in the two cases were adjacent to the tumor, and one case developed grade 2 complication of the mandible. CONCLUSION: During recurrence of the buccal mucosa and the floor of mouth cancers, reirradiation should be avoided considering mandibular complications. To avoid reirradiation-related complications, tooth extraction near the radiation field should be avoided.

DEVIATION BETWEEN THE PLANNED DOSE AND THE IN VIVO DOSIMETRY RESULTS DURING POSTOPERATIVE IRRADIATION IN PATIENTS WITH UTERINE CANCER DEPENDING ON ANTHROPOMETRIC DATA. / VIDKhYLENNIa MIZh ZAPLANOVANOIu DOZOIu I REZUL'TATAMY DOZYMETRIÏ IN VIVO PRY PISLIaOPERATsIINOMU OPROMINENNI U PATsIIeNTOK, KhVORYKh NA RAK TILA MATKY, ZALEZhNO VID ANTROPOMETRYChNYKh DANYKh.

Topometry is an integral part of irradiation whose task is to repeat the position of the patient set by the simulator to repeat the PTV and the spatial relationship between the radiation field and the risk organs that were identified during planning. The dose distribution formulated in the plan is only an ideal model. There is some gap between the actual and planned dose distribution, especially in overweight patients. OBJECTIVE: evaluate the effect of anthropometric data on the deviation between the planned dose and the results of dosimetry in vivo in patients with uterine cancer during postoperative irradiation. MATERIALS AND METHODS: The authors analyzed the results of treatment of 110 patients with stage IB-II uterine can- cer who were treated at the Department of Radiation Therapy of the Institute of Medical Radiology and Oncology of the National Academy of Medical Sciences of Ukraine from 2016 to 2019. The technique of classical fractionation was used with a single focal dose of 2.0 Gy 5 times a week, the total focal dose was 42.0-50.0 Gy. To assess the effect of the patient's anthropometric data on the difference between the actual and calculated dose, the authors per- formed in vivo dosimetry after the first session and in the middle of the postoperative course of external beam radi- ation therapy. RESULTS: Рatients with BSA < 1.92 m2, had the median relative deviation at the first session -4.12 %, after 20.0 Gy - 3.61 %, patients with BSA > 1.92 m2: -2.06 % and -1.55 % respectively. After 20 Gy 34.8 % of patients with BSA < 1.92 m2 there was an increase in deviation from the planned dose, 65.2 % a decrease, while in 56.1 % of patients with BSA > 1.92 m2 there was an increase, and in 43.9 % - its reduction. With increasing BMI, the actual dose received on the rectal mucosa in the tenth session of irradiation is approaching the calculated one. CONCLUSIONS: When irradiated on the ROKUS-AM device, we did not find a probable dependence of the influence of the constitutional features of patients between the received and planned radiation dose. When treated with a Clinac 600 C, only body weight and body mass index at the tenth irradiation session have a likely effect on the dose differ- ence. Therefore, issues related to the individual approach to the treatment of uterine cancer, depending on anthro- pometric data is an urgent problem of modern radiotherapy.

A Mathematical Method to Adjust MLC Leaf End Position for Accurate Dose Calculation in Carbon Ion Beam Radiation Therapy Treatment Planning System.

INTRODUCTION: We present a mathematical method to adjust the leaf end position for dose calculation correction in the carbon ion radiation therapy treatment planning system. METHODS AND MATERIALS: A straggling range algorism of 400 MeV/n carbon ion beam in nine different multileaf collimator (MLC) materials was conducted to calculate the dose 50% point to derive the offset corrections in the carbon ion treatment planning system (ciPlan). The visualized light field edge position in the treatment planning system is denoted as X tang.p, and MLC position (X mlc.p) is defined as the source to leaf end midpoint projection on axis for monitor unit calculation. The virtual source position of energy at 400 MeV/n and straggling range in MLC at different field sizes were used to calculate the dose 50% position on axis. On-axis MLC offset (correction) could then be obtained from the position corresponding to 50% of the central axis dose minus the X mlc.p. RESULTS: The exact MLC position in the carbon ion treatment planning system can be used as an offset to do the correction. The offset correction of pure tungsten is the smallest among the others due to its shortest straggling range of carbon ion beam in MLC. The positions of 50% dose of all MLC materials are always located in between X tang.p and X mlc.p under the largest field of 12 cm by 12 cm. CONCLUSIONS: MLC offset should be adjusted carefully at different field sizes in the treatment planning systems especially of its small penumbra characteristic in the carbon ion beam. It is necessary to find out the dose 50% position for adjusting MLC leaf edge on-axis location in the treatment planning system to reduce dose calculation error.

Analysis of the Dose Drop at the Edge of the Target Area in Heavy Ion Radiotherapy.

BACKGROUND: The dose distribution of heavy ions at the edge of the target region will have a steep decay during radiotherapy, which can better protect the surrounding organs at risk. OBJECTIVE: To analyze the dose decay gradient at the back edge of the target region during heavy ion radiotherapy. METHODS: Treatment planning system (TPS) was employed to analyze the dose decay at the edge of the beam under different incident modes and multiple dose segmentation conditions during fixed beam irradiation. The dose decay data of each plan was collected based on the position where the rear edge of the beam began to fall rapidly. Uniform scanning mode was selected in heavy ion TPS. Dose decay curves under different beam setup modes were drawn and compared. RESULTS: The dose decay data analysis showed that in the case of single beam irradiation, the posterior edge of the beam was 5 mm away, and the posterior dose could drop to about 20%. While irradiation in opposite direction, the posterior edge of the beam was 5 mm away, and the dose could drop to about 50%. In orthogonal irradiation of two beams, the posterior edge of the beam could drop to about 30-38% in a distance of 5 mm. Through the data analysis in the TPS, the sharpness of the dose at the back edge of the heavy ion beam is better than that at the lateral edge, but the generated X-ray contamination cannot be ignored. CONCLUSIONS: The effect of uneven CT value on the dose decay of heavy ion beam should also be considered in clinical treatment.

Association of radiation dose intensity with overall survival in patients with distant metastases.

BACKGROUND: Patients with metastatic cancer referred to radiation oncology have diverse prognoses and there is significant interest in personalizing treatment. We hypothesized that patients selected for higher biologically equivalent doses have improved overall survival. METHODS: The study population consists of 355 consecutive adult patients with distant metastases treated by a single radiation oncologist from 2014 to 2018. The validated NEAT model was used to prospectively stratify patients into four distinct cohorts. Radiation dose intensity was standardized using the equivalent dose in 2 Gy fractions (EQD2) model with an α/ß of 10. Radiation dose intensity on survival was assessed via Cox regression models and propensity score match pairing with Kaplan-Meier analysis. RESULTS: The median survival was 9.3 months and the median follow-up for surviving patients was 18.3 months. The NEAT model cohorts indicated median survivals of 29.5, 11.8, 4.9, and 1.8 months. Patients receiving an EQD2 of ≥40 Gy had a median survival of 16.0 months versus 3.8 months for patients receiving an EQD2 of <40 Gy (p < 0.001). On multivariable analysis, performance status, primary tumor site, radiation dose intensity, albumin, liver metastases, and number of active tumors were all independent predictors of survival (p < 0.05 for all). Propensity score matching was performed for performance status, albumin, number of active tumors, primary tumor site, and liver metastasis, finding higher EQD2 to remain significantly associated with improved survival within the matched cohort (p = 0.004). CONCLUSION: Higher radiation dose intensity was used in patients with better prognosis and was associated with improved survival for patients with metastatic disease.

Quality Assurance for Small-Field VMAT SRS and Conventional-Field IMRT Using the Exradin W1 Scintillator.

BACKGROUND: Plastic scintillator detector (PSD) Exradin W1 has shown promising performance in small field dosimetry due to its water equivalence and small sensitive volume. However, few studies reported its capability in measuring fields of conventional sizes. Therefore, the purpose of this study is to assess the performance of W1 in measuring point dose of both conventional IMRT plans and VMAT SRS plans. METHODS: Forty-seven clinical plans (including 29 IMRT plans and 18 VMAT SRS plans with PTV volume less than 8 cm3) from our hospital were included in this study. W1 and Farmer-Type ionization chamber Exradin A19 were used in measuring IMRT plans, and W1 and microchamber Exradin A16 were used in measuring SRS plans. The agreement between the results of different types of detectors and TPS was evaluated. RESULTS: For IMRT plans, the average differences between measurements and TPS in high-dose regions were 0.27% ± 1.66% and 0.90% ± 1.78% (P = 0.056), and were -0.76% ± 1.47% and 0.37% ± 1.34% in low-dose regions (P = 0.000), for W1 and A19, respectively. For VMAT SRS plans, the average differences between measurements and TPS were -0.19% ± 0.96% and -0.59% ± 1.49% for W1 and A16 with no statistical difference (P = 0.231). CONCLUSION: W1 showed comparable performance with application-dedicated detectors in point dose measurements for both conventional IMRT and VMAT SRS techniques. It is a potential one-stop solution for general radiotherapy platforms that deliver both IMRT and SRS plans.

FIELDRT: an open-source platform for the assessment of target volume delineation in radiation therapy.

OBJECTIVES: Target volume delineation (TVD) has been identified as a weakness in the accuracy of radiotherapy, both within and outside of clinical trials due to the intra/interobserver variations affecting the TVD quality. Sources of variations such as poor compliance or protocol violation may have adverse effect on treatment outcomes. In this paper, we present and describe the FIELDRT software developed for the ARENA project to improve the quality of TVD through qualitative and quantitative feedbacks and individual and personalized summary of trainee"s performance. METHODS: For each site-specific clinical case included in the FIELDRT software, reference volumes, minimum and maximum "acceptable" volumes and organ at risk were derived by outlines of consultants and senior trainees. The software components currently developed include: (a) user-friendly importing interface (b) analysis toolbox to compute quantitative and qualitative (c) visualiser and (d) structured report generator for personalised feedback. The FIELDRT software was validated by comparing the performance of 63 trainees and by measuring performance over time. In addition, a trainee evaluation day was held in 2019 to collect feedback on FIELDRT. RESULTS: Results show the trainees' improvement when reoutlining a case after reviewing the feedback generated from the FIELDRT software. Comments and feedback received after evaluation day were positive and confirmed that FIELDRT can be a useful application for training purposes. CONCLUSION: We presented a new open-source software to support education in TVD and ongoing continuous professional development for clinical oncology trainees and consultants. ARENA in combination with FIELDRT implements site-specific modules with reference target and organs at risk volumes and automatically evaluates individual performance using several quantitative and qualitative feedbacks. Pilot results suggests this software could be used as an education tool to reduce variation in TVD so to guarantee high quality in radiotherapy. ADVANCES IN KNOWLEDGE: FIELDRT is a new easy and free to use software aiming at supporting education in TVD and ongoing continuous professional development. The software provides quantitative/qualitative feedback and an exportable report with an individual and personalised summary of trainee's performance.

Analysis of using high-precision radiotherapy in the treatment of liver metastases regarding toxicity and survival.

BACKGROUND: Hepatic metastases occur frequently in the context of many tumor entities. Patients with colorectal carcinoma have already developed liver metastases in 20% at the time of diagnosis, and 25-50% develop metastases in the further course of the disease and therapy. The frequent manifestation and the variable appearance of liver metastases result in an interdisciplinary challenge, regarding treatment management. The aim of this study was to evaluate high-precision stereotactic body radiotherapy (SBRT) for liver metastases. METHODS: A cohort of 115 patients with 150 irradiated liver metastases was analyzed. All metastases were treated between May 2004 and January 2020 using SBRT. A contrast-enhanced computed tomography (CT) was performed in all patients for treatment planning, followed by image-guided high-precision radiotherapy using cone-beam CT. A median cumulative dose of 35 Gy and a median single dose of 7 Gy was applied. RESULTS: Median OS was 20.4 months and median LC was 35.1 months with a 1-year probability of local failure of 18% (95%-CI: 12.0-24.3%). In this cohort, 18 patients were still alive at the time of evaluation. The median FU-time in total was 11.4 months and for living patients 26.6 months. 70.4% of patients suffered from acute toxicities. There were several cases of grade 1 and 2 toxicities, such as constipation (13.9%), nausea (24.4%), loss of appetite (7.8%), vomiting (10.4%), diarrhea (7.8%), and abdominal pain (16.5%). 10 patients (8.7%) suffered from grade 3 toxicities. Late toxicities affected 42.6% of patients, the majority of these affected the gastrointestinal system. CONCLUSION: SBRT is becoming increasingly important in the field of radiation oncology. It has evolved to be a highly effective treatment for primary and metastasized tumors, and offers a semi-curative treatment option also in the case of oligometastatic patients. Overall, it represents a very effective and well-tolerated therapy option to treat hepatic metastases. Based on the results of this work and the studies already available, high-precision radiotherapy should be considered as a valid and promising treatment alternative in the interdisciplinary discussion.

Method of Measuring High-LET Particles Dose.

In boron neutron capture therapy, the total absorbed dose is the sum of four dose components with different relative biological effectiveness (RBE): boron dose, "nitrogen" dose, fast neutron dose and γ-ray dose. We present a new approach for measuring the first three doses. In this work, we provide the details of this method of dose measurement and results when this proposed method is employed.

SEOR SBRT-SG survey on SRS/SBRT dose prescription criteria in Spain.

AIM: Stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS) are essential tools in radiation oncology. In Spain, the use of these techniques continues to grow as older linear accelerators (linacs) are replaced with modern equipment. However, little is known about inter-centre variability in prescription and dose heterogeneity limits. Consequently, the SBRT-Spanish Task Group (SBRT-SG) of the Spanish Society of Radiation Oncology (SEOR) has undertaken an initiative to assess prescription and homogeneity in SRS/SBRT treatment. In the present study, we surveyed radiation oncology (RO) departments to obtain a realistic overview of prescription methods used for SBRT and SRS treatment in Spain. METHODS: A brief survey was developed and sent to 34 RO departments in Spain, mostly those who are members of the SEOR SBRT-SG. The survey contained seven questions about the specific prescription mode, dose distribution heterogeneity limits, prescription strategies according to SRS/SBRT type, and the use of IMRT-VMAT (Intensity Modulated Radiation Therapy-Volumetric Modulated Arc Therapy). RESULTS: Responses were received from 29 centres. Most centres (59%) used the prescription criteria D95% ≥ 100%. Accepted dose heterogeneity was wide, ranging from 107 to 200%. Most centres used IMRT-VMAT (93%). CONCLUSIONS: This survey about SRS/SBRT prescription and dose heterogeneity has evidenced substantial inter-centre variability in prescription criteria, particularly for intended and accepted dose heterogeneity. These differences could potentially influence the mean planning target volume dose and its correlation with treatment outcomes. The findings presented here will be used by the SEOR SBRT-SG to develop recommendations for SRS/SBRT dose prescription and heterogeneity.

Comparison of different TBI techniques in terms of dose homogeneity - review study.

Total body irradiation (TBI) is a kind of external beam radiotherapy, used in conjunction with chemotherapy with the purpose of immunosuppression. Since the target in TBI is the whole body, so achieving uniform dose distribution throughout the entire body during TBI is necessary. As recommended by AAPM dose variation must be within ±10% of the prescription dose. With the evidences from literature there is limited substantiation to consider a treatment method better than others, but with regard to the size of the treatment room, workload of the radiotherapy department and prevalent technology used within each treatment department it is recommended to make the suitable and optimum method in each department. In this work, a review study was performed on different TBI techniques with the purpose of assessment and comparison of dose distribution homogeneity in these methods.

Postmastectomy Radiation Therapy Planning After Immediate Implant-based Reconstruction Using the European Society for Radiotherapy and Oncology-Advisory Committee in Radiation Oncology Practice Consensus Guidelines for Target Volume Delineation.

AIMS: To evaluate how common radiation therapy techniques perform in the setting of the new European Society for Radiotherapy and Oncology-Advisory Committee in Radiation Oncology Practice (ESTRO-ACROP) delineation recommendations for immediate breast reconstruction (IBR). MATERIALS AND METHODS: Seven Danish radiation therapy centres and six international European centres participated in this project. Two breast cancer cases (one left-sided and one right-sided) with a retropectoral implant were chosen for radiation therapy planning using deep-inspiration breath-hold. Target volumes were delineated according to ESTRO-ACROP delineation recommendations. The centres were asked to plan the cases using any radiation therapy technique according to the Danish Breast Cancer Group plan objectives. RESULTS: In total, 35 treatment plans were collected. Half of the submitted plans, for both the left-sided and the right-sided case, used the field-in-field (FiF) technique (nine for each), a quarter used volumetric arc radiation therapy (VMAT; five for right-sided, four for left-sided) and the remaining quarter was a mix of inverse intensity-modulated radiation therapy (IMRT), helicoidal therapy and hybrid (combined open fields and VMAT) techniques. Mean clinical target volume doses were in the range 99-102% of the prescribed dose. The median FiF mean heart dose (MHD) for right-sided radiation therapy was 1 Gy (range 0.8-3.7) and 5.2 Gy for left-sided radiation therapy (range 2.2-6.5). For right-sided radiation therapy, the median VMAT MHD was 3.42 Gy, for IMRT was 2.3 Gy and for helicoidal therapy was 5.1 Gy. For left-sided radiation therapy, the median VMAT MHD was 6.3 Gy, for IMRT was 7.8 Gy and for helicoidal therapy was 7.3 Gy. CONCLUSIONS: Different radiation therapy techniques could be used to plan radiation therapy in the setting of IBR. FiF provided good coverage with acceptable organ at risk doses. The best dose distribution results as a trade-off between the objectives of target volume coverage and high-dose organ at risk inclusion. The radiation therapy technique affects the interplay between these objectives.

Magnetic resonance-guided radiotherapy feasibility in elderly cancer patients: proposal of the MASTER scoring system.

BACKGROUND: Elderly patients are often excluded from advanced treatments owing to clinical complexity or frailty. Magnetic resonance-guided radiotherapy (MRgRT) represents a new frontier of radiotherapy delivery that can play an important role in the management of these patients. AIM: To assess MRgRT feasibility in elderly patients, describe their compliance with this treatment, and provide a scoring system for elderly patient selection. METHODS: Patients aged >75 years were enrolled. No restrictions on tumor site, staging, or treatment intent were applied. Patients underwent joint radiation oncology-geriatrics visits to assess the feasibility of MRgRT and to identify the most significant items (i.e. clinical variables) for the setup of a scoring system. The proposed scoring system was then internally validated on a prospectively enrolled cohort of elderly patients who were candidates for MRgRT. RESULTS: Thirty patients were enrolled between February and March 2018. Their mean age was 81.4 ± 3.4 years (range 75-88). Radiotherapy intent was curative in 26 patients; 14 patients were considered frail at screening tests before radiotherapy. Twelve items were identified as clinically significant for the setup of the MASTER score (MRI-Guided Radiotherapy Selection Elderly Score) score. Validation of the score showed 100% reliability, with no patient discharged after selection. CONCLUSIONS: MRgRT appears to be feasible in elderly patients and the MASTER score is proposed to support clinical decision-making in recommending elderly patients for this technology.

Radiotherapy dose escalation on pelvic lymph node control in patients with cervical cancer.

OBJECTIVE: Data supporting dose escalation for node-positive cervical cancer are currently limited to small retrospective studies. The goal of this study was to assess whether radiation dose was associated with lymph node control or gastrointestinal toxicity in patients with node-positive cervical cancer. METHODS: A total of 390 patients with carcinoma of the uterine cervix were treated between October 1997 and October 2017. Patients included in our analysis were those with squamous cell carcinoma or adenocarcinoma who were node-positive, treated definitively, and with at least one follow-up visit and post-treatment imaging scan. We excluded those without follow-up and those treated with palliative intent. All patients were treated with external beam radiation to pelvic±para-aortic fields with concurrent weekly cisplatin. All lymph nodes present at the time of treatment were stratified by size as <2 cm or ≥2 cm. Acute and late gastrointestinal toxicity were recorded for all patients. RESULTS: A total of 77 patients with 206 lymph nodes were identified. Median stage at presentation was FIGO IIB. Thirteen patients underwent definitive surgical resection followed by adjuvant radiation, of which 12 were treated to doses ≤5040 (range 2700-5940) cGy. Sixty-four patients were treated with definitive chemoradiation, of which 42 (66%) received ≤5040 (range 4500-5040) cGy and 22 (34%) received >5040 (range 5300-6640) cGy. Patients with pre-chemoradiation lymph nodes ≥2 cm had inferior lymph node control compared with patients with pre-chemoradiation lymph node <2 cm at 12 months (77% vs 100%, p=0.002). Radiation dose >5040 cGy was not significantly associated with improved lymph node control compared with ≤5040 cGy when analyzing all patients (12 months, 100% vs 89%, p=0.112). In patients with pre-chemoradiation lymph nodes ≥2 cm, radiation dose >5040 cGy was associated with improved lymph node control (12 months, 100% vs 60%, p=0.020). Acute grade ≥2 gastrointestinal toxicity was not associated with radiation dose >5040 cGy (20% vs 13%, p=0.424). Two patients developed grade ≥2 late gastrointestinal toxicity, both of whom were treated to ≤5040 cGy. CONCLUSIONS: This series supports the role of dose escalation for patients with lymph nodes ≥2 cm. Dose escalation is associated with improved control in patients with larger lymph nodes, and is not associated with greater gastrointestinal toxicity.

Exploiting the full potential of proton therapy: An update on the specifics and innovations towards spatial or temporal optimisation of dose delivery.

Prescription and delivery of protons are somewhat different compared to photons and may influence outcomes (tumour control and toxicity). These differences should be taken into account to fully exploit the clinical potential of proton therapy. Innovations in proton therapy treatment are also required to widen the therapeutic window and determine appropriate populations of patients that would benefit from new treatments. Therefore, strategies are now being developed to reduce side effects to critical normal tissues using alternative treatment configurations and new spatial or temporal-driven optimisation approaches. Indeed, spatiotemporal optimisation (based on flash, proton minibeam radiation therapy or hypofractionated delivery methods) has been gaining some attention in proton therapy as a mean of improving (biological and physical) dose distribution. In this short review, the main differences in planning and delivery between protons and photons, as well as some of the latest developments and methodological issues (in silico modelling) related to providing scientific evidence for these new techniques will be discussed.

Methodology of dose calculation for external beam radiation combined with high dose rate brachytherapy in the era of 3-dimensional treatment planning system.

Intracavitary application of brachytherapy (BT) sources followed by external beam radiation is essential for the local treatment of carcinoma of the cervix, postate, and nasopharynx. Dose distribution of external beam radiation plus BT can be challenging for the planning system because of their dose calculation by 2 different treatment planning system (TPS). The aims of this study were to introduce a novel iterative method of dose calculation preformed in the Pinnacle plan and evaluate a combined dose distribution for external beam radiation and BT.Because it is often the goal of the planner to produce plan with uniform dose throughout the target volume and normal tissue, we present an Iridium-192 calculation program using American Association of Physicists in Medicine Task Group 43 formula and export it to other commercialized TPS though the combined dose distribution of external beam radiation and BT can be shown. To illustrate such an improved procedure, we present the treatment plans of 2 patients treated with external beam radiation plus BT.Dose distribution of the single BT source were calculated with the Plato post loading TPS and the program model, and the results of 2 methods were similar. A nasopharyngeal case and a cervical case were shown in Pinnacle with this program. The total dose distribution of BT combined with EBRT was showed in compute tomography images. And the corresponding dose volume histogram figures could be displayed correctly in Pinnacle TPS.We demonstrated a novel iterative method of dose calculation preformed in the Pinnacle plan to produce a combined dose distribution for external beam radiation and BT. We used it to evaluate the dose of target volume and normal tissues in the treatment of external beam radiation plus BT.

Patterns of Failure in Patients With Head and Neck Squamous Cell Carcinomas of Unknown Primary Treated With Chemoradiotherapy.

BACKGROUND: To evaluate the patterns of failure in patients treated for head and neck carcinoma of unknown primary and to discuss treatment practices concerning radiotherapy target volumes definition and dose prescription. METHODS: Eleven patients presenting a locoregional recurrence after head and neck carcinoma of unknown primary treatment with curative-intent radiochemotherapy performed between 2007 and 2017 in the departments of radiation oncology of 2 French cancer institutes. Images of the computed tomography scan or the magnetic resonance imaging performed at the time of the recurrence were fused with those of the simulation computed tomography scan to delimit a volume corresponding to the recurrence and to define the area of relapse compared to the volumes treated. RESULTS: Irradiation was unilateral in 6 cases and bilateral in 5 cases. The median time to onset of recurrence was 7.24 months (extreme 3-67.7 months). Six patients had only a neck node recurrence, 3 had a neck node and subsequent primary recurrence, and 1 had only a median subsequent primary recurrence. Only 1 patient had synchronous distance progression to local recurrence. All neck node recurrences were solitary and ipsilateral. The subsequent primary recurrences were in the oropharynx in 3 cases and in the contralateral oral cavity in one case. All neck node recurrences were into the irradiated volume. The subsequent primary recurrences were either within or in border of the irradiated volumes. The median of the mean dose, received by neck node recurrences, was 69.9 Gy and that of the mean dose, minimum dose, maximum dose, and dose received by 95% of the volume of recurrence was 66.7 Gy. For the primary relapses, the median of the mean dose was 52.1 Gy and that of the mean dose, minimum dose, maximum dose, and dose received by 95% of the volume of recurrence was 39.9 Gy. CONCLUSIONS: All local nodal recurrences occurred at sites that received high radiotherapy doses and doses received by sites of eventual failure did not vary significantly from sites that remain in control.