This study examined the response characteristics of three commercially available radiochromic films when exposed to low energy (50 kVp) X‐rays. The aim was to evaluate the films for potential use in 2D dosimetry for a low‐kV intraoperative radiotherapy (IORT) device known as the ‘Intrabeam’. Dose‐response relationships were obtained for Gafchromic EBT, XR‐RV2, and XR‐QA film in water at several distances from the Intrabeam device. It was found that the dose rates from the source were excessive for use of the XR‐QA film, and that all three film types showed significant energy dependence within the limits of measurement uncertainty. Basic modeling of primary X‐ray spectra indicated large changes in the lower energy components with distance from the source, and it is hypothesized that the changes in film response are a result of changes in film energy response. This is in contrast to previous studies indicating less or negligible energy response. All films showed non‐linearity in response over the ranges examined. These results imply significant limitations for the use of these films for low‐kV dosimetry.PACS number: 87.53.Bn

Suction rectal biopsy (SRB) may not include sufficient submucosa for histological diagnosis of Hirschsprung's disease (HD) and a repeat biopsy is required. Substitution of the conventional syringe for sustained suction from a machine or wall suction unit could provide a more consistently adequate tissue biopsy. This study was conducted to compare the adequacy of SRB specimens using a conventional method of syringe suction (SSRB) with those taken by wall or machine suction (WSRB). Hospital records of patients who had a SRB between 2002 and 2004 were studied retrospectively. The biopsy was considered inadequate if there was insufficient submucosa and a repeat specimen was requested. SSRB were taken using the conventional SSRB technique. WSRB were taken with the same Noblett forceps but with suction from wall suction or from a portable suction machine. Ninety-five infants had 103 SRB, 24 had WSRB and all (100%) were adequate for histopathological diagnosis or exclusion of HD. Seventy nine conventional SSRB were undertaken in 71 infants of which 64 (81.02%) were adequate. The difference in adequacy between WSRB and SSRB was statistically significant (P = 0.02). There were no instances of haemorrhage or bowel perforation in either subgroup. WSRB with the Noblett biopsy forceps is more likely to produce an adequate specimen and to reduce the incidence of repeat biopsies.

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A novel hexa aza cage, N(1)-(4-isothiocyanatobenzyl)-3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane-1,8-diamine (SarAr-NCS) was synthesized in good yield and characterized by (1)H NMR and electrospray mass spectrometry. A new method for the synthesis of the related N(1)-(4-carboxybenzyl)-3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane-1,8-diamine (AmBaSar) using the p-carboxybenzaldehyde is reported. The complexation of Cu(2+), Co(2+) and Zn(2+) by the two ligands over a range of pHs was found to be similar to the parent derivative SarAr. SarAr-NCS was conjugated to both silica particles (≈90 nm diam.) and the model B72.3 murine antibody. The SarAr-NCSN-silica particles were radiolabeled with Cu(2+) doped (64)Cu and the number of ligands conjugated was calculated to be an average of 7020 ligands per particle. Conjugation of SarAr-NCS to the B72.3 antibody was optimized over a range of conditions. The SarAr-NCSN-B72.3 conjugate was stored in buffer and as a lyophilized powder at 4 °C over 38 days. Its radiolabeling efficiency, stability and immunoreactivity were maintained. The development of a high yielding synthesis of SarAr-NCS should provide an entry point for a wide range of Cu and Zn radiometal PET imaging agents and potentially radiotherapeutic agents with (67)Cu.

We measured the excitation functions of (nat)Zn (p,x) reactions up to 17.6MeV, using the stacked-foils activation technique. High-purity natural zinc (and copper) foils were irradiated with proton beams generated by an 18MeV isochronous cyclotron. Activated foils were measured using high-purity Ge gamma spectroscopy to quantify the radionuclides (61)Cu, (66)Ga, (67)Ga, and (65)Zn produced from the reactions. Thick-target integral yields were also deduced from the measured excitation functions of the produced radioisotopes. These results were compared with the published literature and were found to be in good agreement with most reports, particularly those most recently compiled.

Abstract. Copper-61 ( 61 Cu) shares with 64 Cu certain advantages for PET diagnostic imaging, but has a shorter half-life (3.4hr vs. 12.7hr) and a greater probability of positron production per disintegration (61% vs. 17.9%). One important application is for in vivo imaging of hypoxic tissue. In this study 61 Cu was produced using the 64 Zn(p,D) 61 Cu reaction on natural Zn or enriched 64 Zn targets. The enriched 64 Zn (99.82%) was electroplated onto high purity gold or silver foils or onto thin Al discs. A typical target bombardment used 30PA; at 11.7, 14.5 or 17.6MeV over 30-60min. The 61 Cu (radiochemical purity of >95%) was separated using a combination of cation and anion exchange columns. The 64 Zn target material was recovered after each run, for re-use. In a direct comparison with enriched 64 Zn-target results, 61 Cu production using the cheaper nat Zn target proved to be an effective alternative.

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