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Purpose [18F]Fluoromethylcholine ([18F]FMCH) is a radiopharmaceutical used in positron emission tomography (PET) imaging for the study of prostate, breast, and brain tumors. It is usually synthesized in cyclotron facilities where 18F is produced by proton irradiation of [18O]H2O through 18O(p,n)18F reaction. Due to the activation of target materials, the bombardment causes unwanted radionuclidic impurities in [18O]H2O, that need to be removed during the radiopharmaceutical synthesis. Thus, the aim of this study is to quantify the radionuclide impurities in the 18F production process and in the synthesized [18F]FMCH, demonstrating the radionuclidic purity of this radiopharmaceutical. Methods Long-lived radionuclide impurities were experimentally assessed using high-resolution gamma and liquid scintillation spectrometries, while short-lived impurities were monitored analyzing the decay curve of the irradiated [18O]H2O with an activity calibrator. As spectrometric radionuclide library, a Geant4 Monte Carlo simulation of the 18F-target assembly was previously performed. Results 3H, 52,54Mn, 56,57,58Co, 95m,96Tc, 109Cd, and 184Re were found in the irradiated [18O]H2O, but no radionuclide was found in the non-irradiated [18O]H2O neither in the final [18F]FMCH solution with an activity concentration greater than the minimum detectable activity concentration. A total impurity activity 99.9999998% was estimated. Finally, the decay curve of the irradiated [18O]H2O revealed a very low maximum of 13N activity ( Conclusions This study demonstrated the radionuclidic purity of [18F]FMCH according to the EU Pharmacopeia.

To evaluate the incidence of toxicity in breast cancer with helical tomotherapy (HT).51 patients with breast cancer were assigned to postoperative radiotherapy by means of HT to the chest wall/breast plus draining nodes. During HT treatment, toxicity was monitored and were assessed using the Common Terminology Criteria for Adverse Events 4.0 scale.Acute skin G3 toxicity observed in 1.9% cases. No acute or late G4 toxicity was observed. At a median follow-up of 21 months 2 patients have late G1 toxicity.HT was associated with a low incidence of low-grade skin toxicity.

Patient: Female, 60 Final Diagnosis: Complete remission Symptoms: None Medication: — Clinical Procedure: Radiotherapy Specialty: Oncology Objective: Rare disease Background: Synchronous bilateral breast cancer is rare. A case is presented where whole breast irradiation (WBI) was planned after breast conserving surgery in a patient with synchronous bilateral breast cancer. A comparison was made between the feasibility of helical tomotherapy and direct tomotherapy. Case Report: A 60-year-old woman was found to have bilateral breast nodules on routine mammographic screening, resulting in bilateral lumpectomy and sentinel lymph node biopsy. Histopathology showed a 6 mm diameter invasive ductal carcinoma in the right breast (Grade 1, hormone receptor positive, HER2 negative) and an 8mm diameter tubular carcinoma in the left breast (Grade 1, hormone receptor positive, HER2 negative). Lymph node biopsy and histology, chest X-ray, abdominal ultrasound scan, and bone scintigraphy were negative for metastases (both tumors were Stage 1). Adjuvant therapy with commenced with anastrozole, but no chemotherapy was given. Clinical target volumes (CTVs) were contoured on computed tomography (CT) images. For planning target volumes (PTVs), CTVs were expanded by 1 cm in all directions, except for the medial 5 mm. Since dose constraints to organs at risk (OARs) were beyond established limits, CTVs were expanded by 5 mm. For PTVs, OAR doses and homogeneity indices for helical tomotherapy and direct tomotherapy were compared. Helical tomotherapy provided better target volume coverage and OAR sparing than direct tomotherapy. Conclusions: In a case of bilateral synchronous Stage 1 and Grade 1 breast cancer, helical tomotherapy appeared more suitable than direct tomotherapy.

Background: Different modern radiation therapy treatment solutions for breast cancer (BC) and regional nodal irradiation (RNI) have been proposed. In this study, we evaluate the potential reduction in radiation-induced skin morbidity obtained by intensity modulated proton therapy (IMPT) compared with intensity modulated photon therapy (IMXT) for left-side BC and RNI. Material and Methods: Using CT scans from 10 left-side BC patients, treatment plans were generated using IMXT and IMPT techniques. A dose of 50 Gy (or Gy [RBE] for IMPT) was prescribed to the target volume (involved breast, the internal mammary, supraclavicular, and infraclavicular nodes). Two single filed optimization IMPT (IMPT1 and IMPT2) plans were calculated without and with skin optimization. For each technique, skin dose-metrics were extracted and normal tissue complication probability (NTCP) models from the literature were employed to estimate the risk of radiation-induced skin morbidity. NTCPs for relevant organs-at-risk (OARs) were also considered for reference. The non-parametric Anova (Friedman matched-pairs signed-rank test) was used for comparative analyses. Results: IMPT improved target coverage and dose homogeneity even if the skin was included into optimization strategy (HIIMPT2 = 0.11 vs. HIIMXT = 0.22 and CIIMPT2 = 0.96 vs. CIIMXT = 0.82, p < .05). A significant relative skin risk reduction (RR = NTCPIMPT/NTCPIMXT) was obtained with IMPT2 including the skin in the optimization with a RR reduction ranging from 0.3 to 0.9 depending on the analyzed skin toxicity endpoint/model. Both IMPT plans attained significant OARs dose sparing compared with IMXT. As expected, the heart and lung doses were significantly reduced using IMPT. Accordingly, IMPT always provided lower NTCP values. Conclusions: IMPT guarantees optimal target coverage, OARs sparing, and simultaneously minimizes the risk of skin morbidity. The applied model-based approach supports the potential clinical relevance of IMPT for left-side BC and RNI and might be relevant for the setup of cost-effectiveness evaluation strategies based on NTCP predictions, as well as for establishing patient selection criteria.

Purpose Individual dosimetry allows to quantify doses from ionizing radiation of exposed workers. Scientific and epidemiological evidences highlight the need for adequate measures for a greater protection of the eye and a reduction in annual doses. ICRP Publication 103, illustrating the operational dose quantity Hp(d) for the individual monitoring, proposes a depth d = 3 mm for eye lens monitoring, indicating that even the Hp(0.07) can be used. In this study, it was investigated if there are differences in the evaluation of the equivalent dose to eye lens (Hlens) using Hp(3) or Hp(0.07). Materials and methods A slab phantom calibration was performed by an Accredited Calibration Laboratory in terms of Hp(3) and Hp(0.07) using ext-rad TLD-100 (LiF:Mg,Ti) dosimeters. Hp(0.07) and Hp(3) were measured for 26 exposed workers to assess Hlens. The measuring took place monthly in 2017 to obtain both semestral and annual doses. Results Hlens(0.07) was always smaller than Hlens(3). However, the differences were not statistically significant (Mann-Whitney test, p > 0.05) for both semestral and annual doses. The percentage differences were 7 ± 3%, 6 ± 3% and 7 ± 2% for I semester, II semester and whole year, respectively. The mean underestimation index 0.99, coefficient of variation Conclusions No statistical evidence was found that the use of Hp(0.07) underestimates the equivalent dose to eye lens obtained through Hp(3).

BACKGROUND: Intensity-modulated radiotherapy (IMRT) improves dose distribution in head and neck (HN) radiation therapy. Volumetric-modulated arc therapy (VMAT), a new form of IMRT, delivers radiation in single or multiple arcs, varying dose rates (VDR-VMAT) and gantry speeds, has gained considerable attention. Constant dose rate VMAT (CDR-VMAT) associated with a fixed gantry speed does not require a dedicated linear accelerator like VDR-VMAT. The present study explored the feasibility, efficiency and delivery accuracy of CDR-VMAT, by comparing it with IMRT and VDR-VMAT in treatment planning for HN cancer. METHODS AND MATERIALS: Step and shoot IMRT (SS-IMRT), CDR-VMAT and VDR-VMAT plans were created for 15 HN cancer patients and were generated by Pinnacle(3) TPS (v 9.8) using 6 MV photon energy. Three PTVs were defined to receive respectively prescribed doses of 66 Gy, 60 Gy and 54 Gy, in 30 fractions. Organs at risk (OARs) included the mandible, spinal cord, brain stem, parotids, salivary glands, esophagus, larynx and thyroid. SS-IMRT plans were based on 7 co-planar beams at fixed gantry angles. CDR-VMAT and VDR-VMAT plans, generated by the SmartArc module, used a 2-arc technique: one clockwise from 182° to 178° and the other one anti-clockwise from 178° to 182°. Comparison parameters included dose distribution to PTVs (D(mean), D(2%), D(50%), D(95%), D(98%) and Homogeneity Index), maximum or mean doses to OARs, specific dose-volume data, the monitor units and treatment delivery times. RESULTS: Compared with SS-IMRT, CDR-VMAT significantly reduced the maximum doses to PTV1 and PTV2 and significantly improved all PTV3 parameters, except D(98%) and D(95%). It significantly spared parotid and submandibular glands and was associated with a lower D(mean) to the larynx. Compared with VDR-VMAT, CDR-VMAT was linked to a significantly better D(mean), to the PTV3 but results were worse for the parotids, left submandibular gland, esophagus and mandible. Furthermore, the D(mean) to the larynx was also worse. Compared with SS-IMRT and VDR-VMAT, CDR-VMAT was associated with higher average monitor unit values and significantly shorter average delivery times. CONCLUSIONS: CDR-VMAT appeared to be a valid option in Radiation Therapy Centers that lack a dedicated linear accelerator for volumetric arc therapy with variable dose-rates and gantry velocities, and are unwilling or unable to sanction major expenditure at present but want to adopt volumetric techniques.

Purpose Hippocampal avoidance during irradiation is hypothesized to reduce the risk of memory function decline. This study is designed to evaluate the dosimetric and clinical results of Helical Tomotherapy (HT) whole brain radiotherapy with hippocampal avoidance (WBHA) and Simultaneous Integrated Boost (SIB). Methods A total of 19 patients with 1 to 4 brain metastases (BM), diameter ⩽3 cm, absent or controlled extracranial disease were planned for WBHA with SIB using HT, from September 2014 to November 2017. The hippocampus was contoured on diagnostic T1-weighted magnetic resonance imaging (MRI) which had been registered with the planning CT image set. The hippocampal Planning Risk Volume was generated using a 5 mm uniform margin around the hippocampi. The BM were contoured on T1-weighted MRI registered with the planning computed tomography (CT), and the BM-PTV was the BM expanded 3 mm in all directions. The whole-brain planning target volume (WB-PTV) was defined as the whole-brain tissue volume, expanded 3 mm in all directions, minus hippocampal PRV and BM-PTVs. HT plans were generated with the following parameters: field width set at 1.05 cm, pitch 0.287, modulation factor (MF) set in the range 2–3 leading to a final value of 2 on average (range 1.3–2.8). Prescription dose was 30 Gy for WB-PTV and 40 Gy for each BM-PTVs in 10 fractions. Results Dosimetric result were reported in Table 1: all the parameter analysed were very promising and in accord to the RTOG 0933 trial [1] . The mean treatment time was 8.7 min (range 6.5–12.6 min). Conclusions HT plans achieved three objectives: quite homogeneous whole brain dose distribution; conformal hippocampal avoidance; and high coverage to the BM. Download : Download high-res image (323KB) Download : Download full-size image

Purpose Classical Kaposi’s sarcoma (KS) was usually treated with large parallel and opposed photon beam. To spare muscles and bones, a patient with an extended KS (from limbs to fits on both legs) was treated with Helical Tomotherapy (HT). Because of the skin involvement two polyurethane foam cushions (PFC) were applied as immobilization device and as bolus material, in a “shell” configuration. Methods The patient was positioned inside a PFC shell: the inner surface of the shell fitted the skin, in order to act as a bolus material. The CTV extended at least 5 mm inside legs; the PTV was the CTV expanded of 5 mm in all directions. A core structure distant 2 mm from the PTV was created for each leg and completely blocked in order to force HT to deliver only tangential beams to the PTV. The prescription was 60 Gy in 30 fraction; because of the length of target (1 m) the larger field width (5.02 cm), a pitch of 0.430, and a modulation factor of 2.0 were used. The irradiation time resulted in 15 min and the time required for the positioning and the MVCT was about 20 min. The surface doses was measured on the first session by means of EBT3 films: 24 films (2 cm × 2.5 cm) were placed all over the skin of the legs and feet. Results The dosimetric results were reported in Table 1. The density of PFC was measured from the CT and resulted in 0.0066 g/cm3. The measured doses ranged from 83% to 94% with a mean value of 88% (1.75 Gy). Conclusions In KS irradiation, the combination of a core blocked HT and the PSC shell offered an adequate dose coverage on the whole target, including the skin, spearing at the same time the muscles and skeleton. Download : Download high-res image (169KB) Download : Download full-size image

To evaluate the efficacy and feasibility of external beam radiotherapy (EBRT) for duodenal adenocarcinoma in an 84-year-old female who underwent EBRT (2.2 Gy/d for a total dose of 46.2 Gy) using helical tomotherapy (HT). Toxicity was evaluated on the National Cancer Institute's common toxicity criteria (CTCAE 3.0). The patient completed the treatment without G3-G4 toxicity. After 22-mo follow-up, she is alive and well, in complete remission with no late side effects. HT seems to be feasible and effective for duodenal adenocarcinoma in old to very old patients.

Purpose In our centre, an on-going pilot study is testing the feasibility of TMI-TLI delivered with Helical Tomotherapy (HT) instead of TBI. We present our protocol and dosimetric results of first 28 patients treated. Methods Head and shoulders of patient are immobilized with thermoplastic mask. Hips and legs are positioned in polyethylene foam cushion. Two supine CT scans, with feet first and head first orientation, were collected with 1 cm slice thickness. For each CT a treatment plan was optimized with the following parameters: field width 5.0 cm, pitch 0.430 and modulation factor ranging from 2 to 3 for the superior region and 5.0 cm, 0.287 and 2 for the inferior region. The overlapping region was managed with 3 sections to better control the dose accumulation. Others helps structures, like a lung contractions and RVR, were used in order to better optimise the plan. The prescribed dose was 13.5 Gy in 9 fractions to the PTV, 11.5 Gy in 8 fractions to the PTV and 13.5 Gy to the bone PTV and 11.5 Gy to lymph nodes PTV in 9 fractions respectively for 2, 5 and 21 patients. Plans were optimised to ensure 90% PTV volume received at least the 90% of the prescribed dose. Dose limits were D50% Results All plans satisfied the dose constraints. Mean dosimetric results for the 21 patients treated with two dose level were reported in table in term of D90% for PTV and mean dose for the main OARs. The mean treatment times were 17.8 and 9.8 min respectively for the superior and inferior plan. Conclusions The TMI-TLI with HT showed good dosimetric results. Even though the patient cohort is small, treatments seemed associated with low toxicity and suitable for elderly and unfit young patient.

Purpose The study focused on the accuracy of intracranial frame-less radiosurgery (RS) and intracranial hypo-fractionated treatments (HFT), delivered with helical Tomotherapy (HT), by means of two different mask-based fixation systems (FPM = Five Point Mask and DSPS = Double Shell Positioning System). Methods A Megavoltage Computed Tomography (MVCT) was acquired and automatically registered with the planning CT of a Rando phantom, to evaluate the delivery accuracy of the HT image guided positioning tool. After the application of the suggested shifts, the phantom was scanned a second time and shifts in each direction and rotations were recorded; the vector displacement ( v ) was calculated as the square sum of the shifts in each directions. Analogous procedure was applied to 14 and 16 patients underwent intracranial HFT and RS respectively: overall 59 MVCT performed at the end of the treatment were acquired and analyzed. The v were analyzed in order to evaluate the intra-fraction motions. Results The mean v , obtained in the phantom acquisitions, was 0.4 ± 0.2 mm, showing that HT-IGRT system is able to achieve positioning accuracy typical of RS ( v 1 mm ). Moreover, the mean rotational variations were negligible. Results on the patient treatments, reported in Table 1, showed that both masks minimized the intra-fraction motion to an extent of 1 mm (with no statistically difference between FPM and DSPS: p v on the treatment time was observed. Conclusions Our study demonstrates that mask-based fixation systems have a high intracranial positioning accuracy, comparable with for invasive immobilization systems (v = 0.6 ± 0.9 mm (range: 0.3–1.7 mm) [1] ), therefore, they could be used for high-precision treatments, like RS. Download : Download high-res image (118KB) Download : Download full-size image

7038Background: Elderly candidates for hematopoietic stem cell transplantation (HSCT) cannot tolerate myeloablative conditioning regimens because of regimen-related toxicity and mortality rates. To...

OBJECTIVE: To compare the dosimetric outcomes of four radiotherapy (RT) techniques for treating the chest wall plus draining nodes after mastectomy and breast reconstruction. METHODS: Three-dimensional conformal radiotherapy, linac-based intensity modulated RT, helical tomotherapy (HT) and direct tomotherapy treatments were planned for 40 breast cancer patients. Dose prescription was 50 Gy. Plans were compared in terms of doses to the planning target volume, organs at risk and the homogeneity index. The non-parametric Friedman test for paired data and the Conover post hoc analysis were used for data analysis. RESULTS: HT provided the highest D90 and D98% and the lowest HI, V107% and D2%. HT was associated with the lowest D2% and V25 Gy to the heart in left-sided treatments but the mean cardiac dose was highest. HT provided the highest V5 Gy and V20 Gy to the ipsilateral lung, but the V30 Gy was lower. The contralateral breast and lung were more exposed with HT. CONCLUSION: The present dosimetric study together with daily use of CT-MV image guided RT have led us to opt for HT after mastectomy and breast reconstruction and to draw up a suitable protocol for treating the chest wall and levels III and IV draining nodes. ADVANCES IN KNOWLEDGE: HT is a suitable for treating the chest wall and levels III and IV draining nodes.