To introduce a method to generate a ‘dose–volume histogram (DVH) band’ for plan evaluation of photon therapy and explore its various potentials.

Intensity-modulated radiotherapy (IMRT) plans for head and neck cancer patients were analysed, retrospectively, for setup errors noted during treatment. From the maximum observed random errors, absolute displacement was calculated using Euclidian formula. The original plan with same beam parameters and leaf sequence were used to generate six plans with shifts applied in three axes in six directions. The DVH curves from these six plans were superimposed to form the DVH band. Plans were reviewed with set tolerance criteria.

Method to generate and visualise DVH band was developed. DVH bands were created for 20 patients with head and neck cancer who underwent treatment with IMRT. It was found that seven out these 20 plans were rejected as they crossed the set tolerance criteria using DVH band as an evaluation tool.

DVH band in photon therapy can help the clinician visualise the impact of setup errors at planning and may help select the plan with lesser influence of setup errors over another.

Intraoperative radiotherapy (IORT) has gained popularity over recent years due to its impact on shortening the radiotherapy treatment time for early breast cancer. It has certainly proven effective as an exclusive treatment or when combined with whole breast irradiation (WBIR). Seroma is a common non-life-threatening complication that may delay treatment and impose challenges on radiological diagnostic follow-up.

To review and compare the occurrence of seroma in patients who received exclusive IORT or when combined with WBIR and to outline the diagnostic challenges encountered during radiological follow-up.

Based on strict selection criteria, all eligible patients who received IORT ± WBIR treatment between 2012 and 2019 in a university hospital setting were included. Demographic data, histological diagnosis, tumour size, tumour grade, lymphovascular invasion, nodal status, receptor status, treatment with neoadjuvant hormonal chemotherapy, applicator size, dose used, duration of radiotherapy treatment, timing of seroma development and duration of seroma were documented. Both clinical and radiological follow-up were exercised in all patients.

The total number of patients treated with breast conserving surgery (BCS) and IORT was 86. Age ranged between 31 and 75 years with the median age of 51 years. Patients treated exclusively with IORT were 39 (45%) while those who received the IORT as a boost were 47 (55%). Seroma was observed in 39(45%) of both IORT and IORT\WBIR patients. Those included 15(38%) of the exclusive IORT treated patients and 24 (62%) of those treated as a boost. Duration of asymptomatic seroma ranged from 6 months to 6 years. Repeated aspiration was performed in 2 (5%) patients. Postoperative seroma occurred independent of age histological diagnosis, tumour size, tumour grade, lymphovascular invasion, nodal status, receptor status, treatment with neoadjuvant hormonal\chemotherapy, applicator size, dose used or duration of radiotherapy treatment. All reviewed patients have shown increased risk of developing seroma; however, an increased incidence of seroma in the IORT + WBIR treated patients was higher than those who received exclusive IORT treatment.

Postoperative seroma is a common non-life-threatening entity that occasionally may lead to delay in the subsequent treatment plan. IORT is a safe modality with many benefits; however, it may increase the risk of seroma formation independent of the clinical parameters. Promoting the expertise in post IORT breast imaging aids in overcoming diagnostic challenges.

This study aimed to determine the potential role and guidelines for implementation of skill-based peer mentoring for radiotherapy planning education.

After four weekly mentoring sessions, both Year 3 mentors (n=9) and Year 2 mentees (n=9) were invited to complete a short online questionnaire relating to the impact of the initiative. The tool contained a mixture of Likert-style questions concerning student enjoyment and perceived usefulness of the initiative as well as more qualitative open questions that gathered perceptions of the peer mentoring process, implementation methods and potential future scope.

Several key discussion themes related to benefits to each stakeholder group, challenges arising, improvements and potential future directions. There were high levels of enjoyment and perceived value of the mentoring from both sides with 100% of the 18 respondents enjoying the experience. The informal format encouraged further learning, while mentors reported acquisition of valuable skills and gains in knowledge.

Peer mentoring has a valuable and enjoyable role to play in radiotherapy planning training and helps consolidate theoretical understanding for experienced students. An informal approach allows for students to adopt the most appropriate mentoring model for their needs while providing them with a free space to engender additional discussion.

Primary non-Hodgkin’s lymphoma (NHL) of the orbit is rare. Orbital NHLs show good response to both radiotherapy (RT) and chemotherapy, and hence, the emphasis should be to ensure maximum cure rate with minimum morbidity. In this study, we present the clinical profile and treatment outcomes of patients with NHL who had initial presentation in the orbit.

In this retrospective analysis, case records of patients with a diagnosis of NHL of the orbit were analysed from January 2005 to January 2015. Patients were worked up and staged according to the Ann Arbor system. Patients with large tumours were initially given chemotherapy with CHOP regimen (cyclophosphamide, vincristine, adriamycin and prednisolone) three weekly for 4–6 cycles. Patients with residual disease were given RT 20–30 Gy at 2 Gy per fraction. RT when given as a primary treatment consisted of 36–45 Gy at 1·8–2 Gy per fraction on either Cobalt 60 machine or linear accelerator.

A total of 52 patients with diagnosis of orbital NHL were included in this study. Median age at presentation was 57 years (range 13–71). Left, right and bilateral orbit was involved in 21 (40%), 28(54%) and 3(6%) patients, respectively. Low- and high-grade pathology was seen in 39(75%) and 13(25%) patients, respectively. On immunohistochemistry, 23(44%) tumors were CD 20 positive. After staging, 33 (63%) patients had stage I disease. Median tumour size was 4·0 × 3·2 × 1·5 cm (1·7 × 1·7 × 1·4 cm to 5·8 × 4·0 × 4·7 cm). Primary RT was given to 7(13%) patients. Upfront chemotherapy was given in 45(86·5%) patients, out of which 24 had stage I disease. RT consolidation was done in 26 (50%) patients for residual disease after chemotherapy. Median follow-up was 88 months (range 29–183 months). Relapse occurred in 6(9·6%) patients; 2 local; 2 local + distant and in 2 distant alone. These patients were successfully salvaged with systemic chemotherapy and local RT. One patient died due to neutropenia. Overall survival in this series was 96%.

Excellent local control was achieved with initial chemotherapy followed by RT for primary orbital NHL with minimal toxicity. We recommend a dose of 36–40 Gy for definitive RT and 30 Gy for lymphoma following chemotherapy using 2 Gy/fraction for Indian patients who present with bulky tumours. RT should be incorporated in treatment of orbital NHL whenever possible as it is safe, effective and is associated with minimal complications.

During radiation therapy, unwanted scatter to healthy tissues outside the target field may occur. Children and adolescents are more sensitive to radiation injury, and the thyroid gland is particularly susceptible to these effects.

To assess acute changes in thyroid function and volume in children and adolescents undergoing radiotherapy for a variety of non-thyroid cancers.

Thirty-one children and adolescents underwent radiation therapy of various body areas in which the thyroid was not included. Thyroid-stimulating hormone (TSH), thyroxine (T4), free thyroxine (fT4), triiodothyronine (T3), anti-thyroperoxidase antibodies and thyroglobulin were measured before, on the last day and at 1 and 3 months after the end of radiotherapy. Ultrasound scans were taken and 6- and 24-hour 131I uptake was measured before and after treatment. The scattered dose to the thyroid region was estimated with a treatment planning system or measured with thermoluminescent dosimeters.

The median radiation dose scattered to the thyroid was 296·6 cGy (IQR 16·7–1,709·0). Levels of TSH (p = 0·575), T4 (p = 0·950), fT4 (p = 0·510), T3 (p = 0·842), thyroglobulin (p = 0·620) and anti-thyroid peroxidase antibodies (p = 0·546) were statistically similar at all four time points. There were no differences between pre- and post-radiotherapy thyroid volume and 131I uptake (p = 0·692 and 0·92, respectively).

More sensitive methods may be required to ascertain whether acute injury to the follicular epithelium occurs with lower radiation doses scattered to the thyroid.

The use of bowel preparation strategies to reduce the degree of rectal distension during prostate radiotherapy is well documented. This retrospective pilot study analysed and compared a probiotic agent against a psyllium-supplemented diet to establish the feasibility of probiotics as a bowel preparation for patients receiving radical radiotherapy for prostate cancer.

A retrospective chart review of five patients taking probiotics and five taking psyllium husk (psyllium) during their course of radiotherapy treatment was conducted. On treatment, cone beam computed tomography (CBCT) scans were compared with planning CTs to quantify inter-fractional variation in rectal volume and distension.

Forty-five CBCT scans were available in both the psyllium and probiotics groups for analysis. Variation in mean difference in rectal volume from planning (ΔRV), mean rectal cross-section area (CSA) and mean relative cross-section area (CSArel) was significantly increased for the probiotics group compared with the psyllium group (p=0·001, 0·008 and 0·007, respectively). No statistically significant differences in mean ΔRV, CSA and CSArel were detected between the two groups.

This retrospective analysis suggests that a probiotics-based bowel preparation that utilises Lactobacillus acidophilus and Bifidobacterium lactis may result in increased rectal volume and CSA variation throughout treatment in comparison with a psyllium-supplemented diet.

To report of long-term results and toxicity profiles using image-guided brachytherapy (IGBT) combined with whole pelvic radiation therapy (WPRT) for cervical carcinoma.

In total, 52 patients with locally advanced cervical carcinoma were enrolled into the study. WPRT was used to treat the clinical target volume (CTV) with a dose of 45–50·4 Gy in 23–28 fractions. IGBT using computed tomography was performed at the dose of 6·5–7 Gy×4 fractions to the minimum dose covering 90% of target volume (D90) of high-risk clinical target volume (HR-CTV).

The mean cumulative dose in equivalent doses of 2 Gy for the D90 of HR-CTV, dose at 2% at refereed volume (D2cc) of bladder, D2cc of rectum and D2cc of sigmoid colon were 92·4, 87·9, 69·6, and 72 Gy, respectively. At the median follow-up time of 61 months, the 5-year local control, disease-free survival, and overall survival rates were 96·2, 75 and 84·6% respectively. Two patients (3·8%) developed grade 3–4 gastrointestinal and two patients (3·8%) developed grade 3–4 genitourinal toxicities.

The combination of WPRT plus IGBT showed very promising long-term results with excellent local control and toxicity profiles.

The purpose of the present study is to compare hybrid [three-dimensional conformal radiation therapy-volumetric-modulated arc therapy (3DCRT-VMAT)] and helical tomotherapy (HT) techniques in terms of both planning target volume (PTV) and organs at risk (OARs) in the plans we made in locally advanced non-small cell lung cancer (NSCLC) patients

Radiotherapy was planned for 15 locally advanced NSCLC patients with 2 different techniques. Large tumours with positive mediastinal lymph nodes were preferred. The prescription dose was determined as 60 Gy at 30 fractions.

Mean PTV volume was 602·5 cc (range: 265–1461). Mean total lung volume was 4264 cc (range: 1885–6803). Homogeneity index, Dmean, Dmax, D2 and V105 were found to be lower in HT, V100, total monitor units (MU) and total beam on time were found to be lower in the hybrid plan. Total lung Dmean was found to be 17 Gy in both techniques. V10 value was 42·85 in the hybrid plan and 48·67 in HT (p = 0·037). Heart Dmean was 14·5 Gy in the hybrid plan and 18·7 in HT (p < 0·001), and V30 values were 18·1 and 22·9, respectively (p = 0·009).

Suitable dose coverage and OAR doses can be provided with both techniques. Especially the opposite lung, heart and oesophagus doses can be kept lower with the hybrid plan, and lower MU and shorter beam on time can be provided.

Merkel cell carcinoma is a rare and aggressive primary cutaneous neuroendocrine carcinoma with a high risk of loco-regional and distant metastasis. It is predominantly seen in the elderly, on the head and neck or extremities. Although treated primarily with surgery, some patients are too frail. A World Health Organization performance status of two or more with co-existing medical co-morbidities, or the site of the disease adjacent to a critical structure, can prevent surgical management. In this cohort of patients, primary palliative radiotherapy has been found to achieve excellent tumour regression and improve quality of life. A new palliative split-course hypofractionated regime has been used in North Middlesex University Hospital in this cohort of patients. The purpose of this case series was to provide supporting evidence on the efficacy of this dose and fractionation regime and review the literature for the palliative management of Merkel cell carcinoma.

In total, four patients were treated with the palliative split-course hypofractionated regime. The regime consisted of an initial 20 Gray in 5 fractions over 1 week, a 2-week gap and then a further 20 Gray in 5 fractions over 1 week. Tolerability and response to treatment were evaluated by history and clinical examination.

The split-course hypofractionated regime was well tolerated, achieved excellent tumour regression and improved quality of life in all four patients. Since then, a further three patients have been successfully treated with the above regime. This case series demonstrates the efficacy of this dose and fractionation in a select group of patients too frail for radical management and adds to the evidence base for the optimal palliative management of Merkel cell carcinoma.

To investigate the effect of different energies on dose distribution in volumetric-modulated arc therapy (VMAT) plans for head and neck cancer.

Data from nine patients undergoing VMAT plans using 6 MV, 10 MV and dual-energy X-ray beams with the Pinnacle 3 V 9.10 treatment planning system (Philips Medical System, Fitchburg, WI, USA) were analysed for quality using the conformity index (CI) and homogeneity index (HI) for planning target volume (PTV), and for mean and maximum dose to the organs at risk (OARs): parotid glands, brainstem, spinal cord and optic nerves.

There were no clear differences in the HIs of the PTV dose among the different plans. The CIs for 10 MV and dual-energy VMAT plans were superior to that of the 6 MV VMAT plan (0·8 ± 0·3, 0·8 ± 0·3, and 0·7 ± 0·2, respectively; p = 0·001). There were no significant differences in mean/maximum dose to the OARs among the three VMAT plans.

Compared with the 6 MV VMAT plan, the dual-energy VMAT plan slightly increased the coverage of the PTV with the prescribed dose but did not decrease dose to the OARs.

This technical note describes a quantitative assessment of the production of radioactive materials during a year-long clinical operation of a Mevion S250i Hyperscan proton therapy system. The production of accumulated radioactive materials plays an important role in determining radiation safety in and around the proton therapy facilities.

We have conducted a weekly room survey, every week for a year, during normal clinical operation.

We estimated the accumulated activity from secondary neutron activation on aluminium structures at 3 m away from isocentre in the beamline to be less than 300 μCi.

The aim of this study is to compare three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT) and tomotherapy techniques used in the treatment of prostate cancer with target and critical organ doses to be included.

The target dose was studied with 4-and 6-field 3D-CRT, 7-field IMRT and tomotherapy techniques used to treat ten patients for prostate cancer and the dose volume histograms of critical organs were analyzed. The same target volumes, critical organs doses prescribed and treatment times for the three techniques were compared. Total dose of 76 Gy was given using 6 MV and 18 MV for 3D-CRT, 6 MV for IMRT and tomotherapy techniques.

When we compare the three techniques, for rectum V35(p:0·001), V65(p:0·001), D50(p:0·020) and D25(p:0·002), for bladder V50(p:0·027), V65(p:0·006), V100(p:0·006) and for femoral head, the V50(p:0·001) dose was found to be significantly different and more favourable in the tomotherapy technique. Significant differences were found with IMRT planning in 50% of bladder volume (p:0·002). There is no significant difference between the three techniques for doses of 100% volume of rectum and 25% of volume of bladder. The minimum dose that healthy tissue received which was outside the tumour volume was investigated.

Doses to critical organs were lower using the tomotherapy technique. However, the minimum doses that healthy tissue received were higher for the tomotherapy technique. When the beam on times were compared for all three techniques, a significant difference was found in favor of tomotherapy.

Magnetic resonance imaging (MRI) is indispensable for treatment planning in prostate radiotherapy (PR). Registration of MRI when compared to planning CT (pCT) is prone to uncertainty and this is rarely reported. In this study, we have compared three different types of registration methods to justify the direct use of MRI in PR.

Thirty patients treated for PR were retrospectively selected for this study and all underwent both CT and MRI. The MR scans were registered to the pCT using markers, focused and unfocussed methods and their registration are REGM, REGF, and REGNF, respectively. Registration comparison is done using the translational differences of three axes from the centre-of-mass values of gross tumour volume (GTV) generated using MRI.

The average difference in all three axes (x, y, z) is (1, 2·5, 2·3 mm) and (1, 3, 2·3 mm) for REGF-REFNF and REGF-REGM, respectively. MR-based GTV Volume is less in comparison to CT-based GTV and it is significantly different (p < 0·001).

Image registration uncertainty is unavoidable for a regular CT–MR workflow. Additional planning target volume margin ranging from 2 to 3mm could be avoided if MR-only workflow is employed. This reduction in the margin is beneficial for small tumours treated with hypofractionation.

Microcomputers play an increasingly important role in the delivery of radiation therapy. Exposure to neutron irradiation can produce undesirable effects in modern microcomputers. The objective of this study is to measure acute and cumulative effects of neutron exposure of Intel-based microcomputers in photon and proton therapy treatment environments.

Multiple computers were irradiated with neutrons produced from MEVION S250 passive scattering proton therapy and from Varian 21EX Linear Accelerator photon therapy systems. The energy of the proton beam was 232 MeV and the photon beam energies were 6 and 18 MV. Rates of fatal errors in computer processing unit (CPU) cores were measured.

Varying rates of fatal system errors due to upsets in the CPU cores were observed. Post-exposure routine stress testing revealed no permanent hardware defects in the random access memory (RAM) or hard disk drive (HDD) of any tested systems. Microchip manufacturers fit increasingly high numbers of transistors in the same volume and the susceptibility to radiation thus increases.

This work explores if the process size of a microchip is the dominant factor and also looked at the short- and long-term effects of neutron irradiation on modern microprocessors in a clinical environment. Additionally, methods of effective shielding are proposed.