IMRT commissioning: multiple institution planning and dosimetry comparisons, a report from AAPM Task Group 119.

AAPM Task Group 119 has produced quantitative confidence limits as baseline expectation values for IMRT commissioning. A set of test cases was developed to assess the overall accuracy of planning and delivery of IMRT treatments. Each test uses contours of targets and avoidance structures drawn within rectangular phantoms. These tests were planned, delivered, measured, and analyzed by nine facilities using a variety of IMRT planning and delivery systems. Each facility had passed the Radiological Physics Center credentialing tests for IMRT. The agreement between the planned and measured doses was determined using ion chamber dosimetry in high and low dose regions, film dosimetry on coronal planes in the phantom with all fields delivered, and planar dosimetry for each field measured perpendicular to the central axis. The planar dose distributions were assessed using gamma criteria of 3%/3 mm. The mean values and standard deviations were used to develop confidence limits for the test results using the concept confidence limit = /mean/ + 1.96sigma. Other facilities can use the test protocol and results as a basis for comparison to this group. Locally derived confidence limits that substantially exceed these baseline values may indicate the need for improved IMRT commissioning

Long-term results and recurrence patterns from SCOPE-1: a phase II/III randomised trial of definitive chemoradiotherapy +/? cetuximab in oesophageal cancer

Background: The SCOPE-1 study tested the role of adding cetuximab to conventional definitive chemoradiotherapy (dCRT), and demonstrated greater toxicity and worse survival outcomes. We present the long-term outcomes and patterns of recurrence. Methods: SCOPE-1 was a phase II/III trial in which patients were randomised to cisplatin 60mgm�2 (day 1) and capecitabine 625mgm�2 bd (days 1–21) for four cycles þ/� cetuximab 400mgm�2 day 1 then by 250mgm�2 weekly. Radiotherapy consisted of 50 Gy/25# given concurrently with cycles 3 and 4. Recruitment was between February 2008 and February 2012, when the IDMC recommended closure on the basis of futility. Results: About 258 patients (dCRT¼129; dCRTþcetuximab (dCRTþC)¼129) were recruited from 36 centres. About 72.9% (n¼188) had squamous cell histology. The median follow-up (IQR) was 46.2 (35.9–48.3) months for surviving patients. The median overall survival (OS; months; 95% CI) was 34.5 (24.7–42.3) in dCRT and 24.7 (18.6–31.3) in dCRTþC (hazard ratio (HR)¼1.25, 95% CIs: 0.93–1.69, P¼0.137). Median progression-free survival (PFS; months; 95% CI) was 24.1 (15.3–29.9) and 15.9 (10.7–20.8) months, respectively (HR¼1.28, 95% CIs: 0.94–1.75; P¼0.114). On multivariable analysis only earlier stage, full-dose RT, and higher cisplatin dose intensity were associated with improved OS. Conclusions: The mature analysis demonstrates that the dCRT regimen used in the study provided useful survival outcomes despite its use in patients who were largely unfit for surgery or who had inoperable disease. Given the competing risk of systemic and local failure, future studies should continue to focus on enhancing local control as well as optimising systemic therapy

Quantitative 3D determination of radiosensitization by Bismuth-based nanoparticles

The nanoparticle-induced dose enhancement effect has been shown to improve the therapeutic efficacy of ionizing radiation in external beam radiotherapy. Whereas previous studies have focused on gold nanoparticles (AuNPs), no quantitative studies have been conducted to investigate the potential superiority of other high atomic number (Z) nanomaterials such as bismuth-based nanoparticles. The aims of this study were to experimentally validate and quantify the dose enhancement properties of commercially available bismuth-based nanoparticles (bismuth oxide (Bi2O3-NPs) and bismuth sulfide (Bi2S3-NPs)), and investigate their potential superiority over AuNPs in terms of radiation dose enhancement. Phantom cuvettes doped with and without nanoparticles where employed for measuring radiation dose enhancement produced from the interaction of radiation with metal nanoparticles. Novel 3D phantoms were employed to investigate the 3D spatial distribution of ionising radiation dose deposition. The phantoms were irradiated with kilovoltage and megavoltage X-ray beams and optical absorption changes were measured using a spectrophotometer and optical CT scanner. The radiation dose enhancement factors (DEFs) obtained for 50 nm diameter Bi2O3-NPs and AuNPs were 1.90 and 1.77, respectively, for 100 kV energy and a nanoparticle concentration of 0.5 mM. In addition, the DEFs of 5 nm diameter Bi2S3-NPs and AuNPs were determined to be 1.38 and 1.51, respectively, for 150 kV energy and a nanoparticle concentration of 0.25 mM. The results demonstrate that both bismuth-based nanoparticles can enhance the effects of radiation. For 6 MV energy the DEFs for all the investigated nanoparticles were lower (<15%) than with kilovoltage energy

Characterization of novel water-equivalent PRESAGE® dosimeters for megavoltage and kilovoltage x-ray beam dosimetry

In this paper we introduce three novel PRESAGE<sup>®</sup> dosimeters referred to as metal optimized dosimeters (MODs) 1, 2 and 3, and determine their sensitivity, as well as their water equivalency. All three formulations contained very small concentrations (0.01 wt%) of metal compounds. The radiological properties were key factors that were considered when designing and formulating the new dosimeters. The dosimeters were prepared in spectrophotometric cuvettes, irradiated with a 6 MV X-ray beam, and the change in optical density of each dosimeter was measured using a spectrophotometer. Results show that all three MOD formulations exhibit radiological properties closer to water than the recently introduced PRESAGE<sup>®</sup> dosimeter formulation referred to as formulation A, with mass densities of the novel formulations varying by only 3.9% from that of water, as compared to 5.3% for the commercial formulation. Whereas the novel formulations have almost identical Z<inf>eff</inf> values to that of water (Z<inf>eff</inf> = 7.42), the Z<inf>eff</inf> for the commercial formulation was 3.7% higher than that of water. Comparison of mass energy coefficients for all MOD formulations showed a maximum variation of approximately 0.6 times closer to water especially MOD 3 whereas commercial formulation was 1.23 times larger than water at approximately 40 keV. The same effect was observed for mass attenuation coefficients comparison. MOD 3 was also more sensitive to radiation than MOD 1 and 2 as a result of the inclusion of bromine-based halocarbons in the formulation. All novel MOD formulations were comparable to commercial formulation in terms of probability of Compton scatter and pair production compared to water. However, the probability of photoelectric absorption in the three novel MOD formulations varied significantly less (1.3 times greater) from that of water as compared to the commercial formu