In this issue there are six original articles covering a range of themes and topics including a paper exploring the use of the process of reflection, in order to increase skills levels in practitioners. Three papers have a focus on radiotherapy treatment for prostate cancer and two papers review treatment accuracy and immobilisation, one paper reviews outcomes of patients with endometrial cancer treated with intracavitary vaginal brachytherapy and the final paper is concerned with the dosimetry of kilovoltage X-ray beams.
For those interested in the use of PET imaging in oncology, there is a case report on endometrial recurrence in the proximal vagina and brachytherapy volume delineation with 18FDG PET-CT. To complete this issue there is a technical note on the quality factors of X-rays and Gamma rays and a book review: CT Anatomy for Radiotherapy by Pete Bridge and David Tipper, published in 2011 by M & K update Ltd.
The aim of the first paper is to highlight the importance of reflection in practice and of encouraging and valuing the process of reflection in order to increase skill levels in practitioners. The authors, Tan, Cashell and Bolderston review the value of workshops to develop reflective skills in practitioners. The authors believe that reflection is a way of evaluating best practice and challenging existing norms, while at the same time, considering one's personal values and assumptions in our personal and professional lives. They suggest that many health practitioners may lack the skills to do this effectively and through participation in a series of three workshops, they found that practitioners learned and acquired new skills to encourage reflection and reflective practice in themselves and their colleagues, as well as with their students. Results of the evaluation indicate that the participants' knowledge of reflective practice has improved their understanding of reflection in practice.
In the second paper, Kong et al. evaluate the toxicity of hypofractionated helical intensity-modulated radiotherapy (IMRT) for men with intermediate- and high-risk prostate cancer.
This is a retrospective toxicity analysis performed for 22 patients treated definitively with hypofractionated helical IMRT. The helical IMRT plans were designed to deliver 75 Gy in 2.5 Gy/fraction to the prostate gland, 63 Gy in 2.1 Gy/fraction to seminal vesicle, and 54 Gy in 1.8 Gy/fraction to pelvic lymph nodes. Toxicity was graded by the Radiation Therapy Oncology Group scales. This study demonstrates that hypofractionated helical IMRT with high biologic effective dose is well tolerated with favourable toxicity rate. If longer followup periods and larger cohorts confirm the favourable biochemical control rate and the favourable toxicity assessment results, the hypofractionated IMRT (total 75 Gy, 2.5 Gy/fraction) might be implemented in the clinical field for the treatment of prostate cancer.
The treatment of prostate cancer is also a theme in the next paper, in which the authors D'Aquino et al., evaluate the set-up accuracy of an external immobilisation system for patients receiving radical radiotherapy for prostate cancer. The portal imaging data were audited in 20 patients treated using an in-house immobilisation system and 20 patients treated using an indexed commercial immobilisation system (Combifix™). Individual and group random and systematic errors were calculated to determine the accuracy of setup using skin marks alone and with a no action level protocol. The initial results showed a larger systematic error in the Combifix™ in the anterior-posterior direction (2.7 mm) compared to the in-house system (1.5 mm). The possible source of this was identified as the difficulty in accurately aligning the laser to a curved couch top prior to setting the isocentre height. A change in the process of setting the isocentre was introduced and comparable baseline set-up accuracy was achieved. This was with a systematic error of ≤2.0 mm and a random error ≤1.5 mm of patient position set-up error with skin marks alone, using the Combifix™. The systematic errors were further reduced to <1 mm with an off line no action level protocol. They conclude that using the Combifix™ system a high level of set-up accuracy was reproduced in routine daily practice.
The theme of prostate cancer and immobilisation continues in the fourth article in which McIlwraith and Blyth present their study of the impact on accuracy of the introduction of a bellyboard as an immobilisation device for the radical radiotherapy treatment of prostate cancer patients. The purpose of the study was to investigate the effect on accuracy of the introduction of a bellyboard to the existing prone technique used for radical radiotherapy treatment of prostate cancer. Thirty patients were treated using the bellyboard in the standard method and portal images were compared with those of a control group of patients who had treatment with no rigid immobilisation. Patients in both groups were male with prostate cancer that underwent radical radiotherapy treatment. Images were analysed using anatomy matching and deviations from the isocentre were noted. Conclusions drawn were the introduction of the bellyboard was seen to be equivalent to the use of the control technique.
In the next paper, Alzouebi, Pledge and Martin present their research to investigate current adjuvant practices by reviewing outcomes of patients with endometrial cancer treated with intracavitary vaginal brachytherapy (VB). A retrospective analysis was carried out of all women at their Centre, with stage II endometrial adenocarcinoma treated at with adjuvant VB from 2003-2006. The data collected and analysed included histology, stage and grade of disease, radiotherapy treatment-related parameters, morbidity, recurrence rates and survival rates. Kaplan-Meier was used to analyse recurrence-free and overall survival rates. Wilson's score was used to determine statistical significance of outcomes. Attention was focused on the method of treatment delivery and this was compared with available literature. They concluded that when rates of vaginal relapses were comparable to the available literature suggesting current VB practice is an effective adjuvant local treatment and mode of treatment delivery did not play a crucial role. The study highlights the importance of surveillance and patient education regarding toxicity and its prevention with particular attention drawn to vaginal stenosis.
In the final article, Akber and Kehwar assess the partial volume (spatial) response of four ionization chambers (Keithley) in kilovoltage x-ray beams, generated by the Philips Super 80CP x-ray unit. The volume of the ionization chambers were of 10 cm3, 15 cm3, 150 cm3, and 600 cm3 used with Keithley electrometer Model 35040. The beam output was measured using a monitor chamber (Radcal 6.0 cm3) placed close to the collimator. The source to chamber distance was kept constant at 1 m. For the measurement of the response of ionization chambers of 15 cm3, 150 cm3, and 600 cm3, a slit of 2.0 mm wide was made in a lead sheet of 3.2 mm thick and size of 30 × 30 cm2 and was placed on the ionization chamber. The measurements were made for 81 kVp, 400 mA, and 0.25 s and the slit was moved in an increment of 2.0 mm over the entire length of the chamber. For the measurements of the ionization chamber of 10 cm3 (CT chamber), the beams of 120 kVp, 200 mA and 0.2 s were generated, and a slit of 5 mm wide was made in a similar lead sheet that was moved in an increment of 5.0 mm. From the results it appears that the sensitive volumes of the ionization chambers affect the response of the ionization chamber to incident radiation.
Included in this issue is a case study presented by Wickers et al., in which the authors share their experience of using 18FDG and PET-CT, to image brachytherapy volume delineation in the treatment of endometrial recurrence in the proximal vagina.
Professor Angela Duxbury
