In this issue
In this issue
- Angela Duxbury
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- Published online by Cambridge University Press:
- 01 February 2019, pp. 1-4
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Professional implications of introducing artificial intelligence in healthcare: an evaluation using radiation medicine as a testing ground
- Caitlin Gillan, Emily Milne, Nicole Harnett, Thomas G. Purdie, David A. Jaffray, Brian Hodges
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- Published online by Cambridge University Press:
- 03 October 2018, pp. 5-9
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This study will evaluate radiation medicine professionals’ perceptions of clinical and professional risks and benefits, and the evolving roles and responsibilities with artificial intelligence (AI).
MethodsRadiation oncologists (ROs), medical physicists (MPs), treatment planners (TP-RTTs) and treatment delivery radiation therapists (TD-RTTs) at a cancer centre in preliminary stages of implementing an AI-enabled treatment planning system were invited to participate in uniprofessional focus groups. Semi-structured scripts addressed the perceptions of AI, including thoughts regarding changing roles and competencies. Sessions were audiorecorded, transcribed and coded thematically through consensus-building.
ResultsA total of 24 participants (four ROs, five MPs, seven TP-RTTs and eight TD-RTTs) were engaged in four focus groups of 58 minutes average duration (range 54–61 minutes). Emergent themes addressed AI’s impact on quality of care, changing professional tasks and changing competency requirements. Time-consuming repetitive tasks such as delineating targets, generating treatment plans and quality assurance were thought conducive to offloading to AI. Outcomes data and adaptive planning would be incorporated into clinical decision-making. Changing workload would necessitate changing skills, prioritising plan evaluation over generation and increasing interprofessional communication. All groups discussed AI reducing the need for TP-RTTs, though displacement was thought more likely than replacement.
ConclusionsIt is important to consider how professionals perceive AI to be proactive in informing change, as gains in quality and efficiency will require new workflows, skills and education.
A novel perimeter-based index for evaluating the similarity of structure contours
- King Hang Wicger Wong, Lucullus HT Leung, Dora LW Kwong
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- Published online by Cambridge University Press:
- 28 September 2018, pp. 10-15
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Introduction
The authors proposed a novel perimeter-based index (PBI) that was capable of evaluating the accuracy in the appraisal of auto-segmentation software. A quantitative value, that is time saved in editing the auto-segmented contours, was used to compare the effectiveness of two other commonly used indices in this study.
MethodsThe relationship between the proposed index and the amount of the contouring time that could be saved was studied. The performances of two other commonly used similarity indices, namely Dice similarity coefficient (DSC) and the modified normalised average Hausdorff distance (MNAHD), were also evaluated. Ten nasopharyngeal cases and ten prostate cases that were previously treated with intensity-modulated radiation therapy technique were recruited as the validation cases in this study. Three observers were invited to contour four structures (bladder, rectum, brain stem and parotid gland) on computed tomography images of the validation cases without any aids. The time taken for contouring was recorded as the manual contouring time. By using an atlas-based auto-segmentation software, three sets of contours were generated for each validation case with different library sizes to produce different degrees of similarity level. The values of the three similarity indices of the auto-segmented contours were calculated. The observers were asked to edit the auto-segmented contours and the editing time was recorded.
The correlation between the editing time and the similarity indices was studied. The amount of time saved was calculated by subtracting the editing time from the manual contouring time. The performances of PBI, DSC and MNAHD were evaluated using Pearson correlation coefficient and receiver operating curve (ROC) analysis.
ResultsThe PBI showed a positive linear relationship with the amount of contouring time saved. Pearson correlation coefficient ranged from 0·73 to 0·86 for the four structures. The PBI had a stronger correlation than the DSC in bladder and parotid gland, while there was no significant difference between the two indices in rectum and brain stem. The MNAHD had an inferior correlation than the proposed index. For the ROC analysis, the cut-off values for the PBI were 0·549, 0·401 and 0·301 for the three levels of contouring time saved, namely 50, 25 and 0%, respectively. The accuracy of PBI was over 77% and the Youden index was >0·6 for all three levels.
ConclusionsThe proposed index showed a stronger relationship to the amount of contouring time saved. It was a simple tool that could be used to evaluate the performance of different segmentation algorithms.
Postoperative endometrial cancer treatments with electronic brachytherapy source
- Sergio Lozares-Cordero, Jose Antonio Font-Gómez, Almudena Gandía-Martínez, Agustina Méndez-Villamón, David Villa-Gazulla, Anabela Miranda-Burgos, Verónica Alba-Escorihuela, Sara Jiménez-Puertas
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- Published online by Cambridge University Press:
- 20 September 2018, pp. 16-20
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Purpose
This study is a dosimetric and acute toxicity comparison of endometrial cancer patients treated with either Axxent (Xoft, Inc., San José, CA, USA) electronic and interstitial brachytherapy versus interstitial high dose rate brachytherapy (HDRBT).
Materials and MethodsBetween 2015 and 2017, 94 patients with postoperative endometrial cancer were treated in our centre with the Axxent electronic brachytherapy (eBT) system. The V150 and V200 are evaluated prospectively for each plan. The mean age of patients was 65.9 years (age range 33–84 years), with different tumour staging. Of the 94 patients, 37 received exclusive adjuvant brachytherapy (25 Gy in five sessions); the remaining patients received external beam radiotherapy (EBRT) with a regimen of 23 sessions of 2 Gy each to the entire pelvis, followed by eBT (15 Gy in three sessions). Additionally, the absorbed doses received by the organs at risk (OAR), urinary bladder, rectum and sigmoid colon were compared with HDRBT plans, evaluating D2cc, V50% and V35%. Median follow-up was done for each of the 94 patients to assess the toxicity of the treatment: vaginal mucosa toxicity, rectal and urinary toxicity; and results are presented for acute toxicity, toxicity at 1 month after the end of treatment and follow-up after 12 months for a portion of patients according to the Radiation Therapy Oncology Group (RTOG) toxicity criteria.
ResultsThe doses in OAR for eBT plans were lower than that for HDRBT plans, both Ir-192 and Co-60 plans, whose doses were similar. The dose in bladder with eBT was 63.8% of the prescribed dose for D2cc versus 70.1% for HDRBT Ir-192, for V50% was 7.2% versus 12.7% and for V35% was 15.2% versus 28.2%. In rectum the D2cc was 61.2% versus 68.4%, for V50% was 7.9% versus 14.3% and for V35% was 16.7% versus 32%. Results demonstrated lower doses to OAR in all eBT plans. Acute toxicity in eBT was very low in cases of mucositis, with only one case of toxicity greater than grade 1, rectal toxicity and urinary toxicity; results at 1 month are equally good, toxicity symptoms disappeared and no relapses have occurred to date.
ConclusionsThe results of treatment with the Axxent eBT unit for 94 patients are very good, as no recurrence has been observed and the toxicity of the treatment is very low. The increase in V150 and V200 has not produced an increase in vaginal mucosa toxicity, and the doses in the OAR are lower than in the plans implemented for HDRBT with Ir-192 or Co-60. eBT is a good alternative to treat endometrial cancer in centres without conventional HDR availability. To date, there are limited published studies reporting on outcomes from patients treated with eBT.
Compliance, toxicity and efficacy in weekly versus 3-weekly cisplatin concurrent chemoradiation in locally advanced head and neck cancer
- Sandeep Muzumder, Nirmala Srikantia, Ganesha Dev Vashishta, Avinash H. Udayashankar, John Michael Raj, M. G. John Sebastian, Prashanth Bhat Kainthaje
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- 04 September 2018, pp. 21-25
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Weekly low-dose cisplatin is routinely used in concurrent chemoradiation (CCRT) in locally advanced head and neck cancer (LAHNC), despite 3-weekly cisplatin being the standard of care. We compared compliance, toxicity and efficacy in weekly versus 3-weekly cisplatin CCRT in LAHNC.
Materials and methodsIn this retrospective study, weekly cisplatin 50 mg flat dose was compared with 3-weekly cisplatin 100 mg/m2, when given in CCRT in LAHNC with curative intent. The study outcome was compliance, toxicity, loco-regional control (LRC), disease-free survival (DFS) and overall survival (OS).
ResultsEighty-four patients received CCRT from January 2013 to June 2017, 40 in weekly and 44 in 3-weekly arm. There was no difference between the arms not completing scheduled radiation therapy or chemotherapy. Patient receiving 200 mg/m2 cisplatin is higher in 3-weekly arm compared with weekly arm (75 versus 40·9%; p<0·0015). Compared with 3-weekly arm, more patient in weekly arm developed grade ≥3 mucositis (52·5 versus 15·9%, p=0·0004), day care intravenous hydration (82·5 versus 38·6% <0·0001) and in-patient admission (55·0 versus 18·2%; p=0·0004). The 2-year LRC, DFS and OS in weekly versus 3-weekly arm were: 70 versus 61·4% (p=0·406); 67·5 versus 56·8% (p=0·314); 67·5 versus 61·4% (p=0·558), respectively. The median time to LRR, DFs and OS was not reached.
ConclusionsWeekly cisplatin is comparable with 3-weekly cisplatin in terms of compliance, disease control and survival, but with increased grade 3 mucositis and higher admissions for supportive care.
Patient-specific quality control for intensity-modulated radiation therapy and volumetric-modulated arc therapy using electronic portal imaging device and two-dimensional ion chamber array
- Abu Kausar, Karthick R. Mani, Hasin A. Azhari, Golam A. Zakaria
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- 05 September 2018, pp. 26-31
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The purpose of this study was to develop the patient-specific quality control (QC) process by most commonly used dosimeters in Bangladesh and recommend a suitable passing rate for QC, irrespective of the dosimetric tools used.
Materials and methodsIntensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans of five head-and-neck (HN) and five prostate patients were selected for the patient-specific QC. These plans were generated using the Eclipse TPS v11·0 (Varian Medical Systems, Inc., Palo Alto, CA, USA) 6 MV X-ray from a Varian TrueBeam linear accelerator (Varian Medical Systems, Inc.) for each case. Each IMRT and VMAT plans were measured by two-dimensional (2D) ion chamber arrays (I’matriXX) and electronic portal imaging devices (EPID), respectively. The passing rates of the dosimetric tools were calculated using criteria of 3%/3 mm.
ResultsThe average passing rates (±SD) of I’matriXX for prostate and HN were 97·9±0·76 and 98·88±0·24, respectively. For VMAT verification, the average passing rates of EPID for prostate for arc1 and arc2 were 96·15±0·49 and 97·8±0·70, respectively; similarly, for HN the rates were 97·85±0·63 and 97·2±0·56, respectively.
ConclusionThe results showed that both the dosimeters can be used in patient-specific QC, although the EPID-based IMRT and VMAT QC is more advantageous in terms of time-saving and ease of use. Hence, for patient-specific QC, one can use the ion chamber arrays (I’matriXX) or EPID in hospital, but the systems need to be cross-checked.
Evaluation of various dose homogeneity indices for treatment of patients with cervix cancer using intensity-modulated radiation therapy technique
- Atia Atiq, Maria Atiq, Khalid Iqbal, Quratul Ain Shamsi, Saeed Ahmad Buzdar
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- 09 August 2018, pp. 32-37
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This study is primarily aimed at the analysis of various dose homogeneity indices (HIs) essential for the evaluation of therapeutic plans by employing intensity-modulated radiation therapy (IMRT) on patients with cervix cancer. Also integral dose (ID) to healthy surrounding organs is computed.
Materials and methodsEffectiveness of different HIs (A, B, C, D) was explored for IMRT plans using 15 MV photon beam. In total, 18 patients were selected at random for treatment of cervix cancer, and dose of 5,040 cGy was delivered in 28 equal fractions.
ResultsThe study was undertaken to compare four HI formulas and coefficient of determination between each set of HI was known by calculating R2 value. Mean±SD of HI A, HI B, HI C and HI D were 1·12±0·02, 0·13±0·04, 0·10±0·02 and 0·99±0·03, respectively. Mean value of ID for rectum is 3·16 and for bladder is 10·3.
FindingsOur data suggested that HI calculated using four formulas provided good plan quality. The results advocate that all the studied HIs can be effectively used for assessment of uniformity inside the target volume. However, values of HI C were closest to ideal value as compared with other three formulas; hence, it is considered a better measure to compute homogeneity of dose within target volume. The ID gives satisfactory results for surrounding normal tissues such as rectum and bladder and significant critical tissue sparing was achieved by using IMRT technique.
Validation of GATE Monte Carlo code for simulation of proton therapy using National Institute of Standards and Technology library data
- Shiva Zarifi, Hadi Taleshi Ahangari, Sayyed Bijan Jia, Mohammad Ali Tajik-Mansoury
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- 05 November 2018, pp. 38-45
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To validate the Geant4 Application for Tomographic Emission (GATE) Monte Carlo simulation code by calculating the proton beam range in the therapeutic energy range.
Materials and methodsIn this study, the GATE code which is based on Geant4 was used for simulation. The proton beams in the therapeutic energy range (5–250 MeV) were simulated in a water medium, and then compared with the data from National Institute of Standards and Technology (NIST) in order to investigate the accuracy of different physics list available in the GATE code. In addition, the optimal value of SetCut was assessed.
ResultsIn all energy ranges, the QBBC physics had a greater deviation in the ranges relative to the NIST data. With respect to the range calculation accuracy, the QGSP_BIC_EMY and QGSP_BERT_HP_EMY physics were in the range of statistical uncertainty; however, QGSP_BIC_EMY produced better results using the least squares. Based on an investigation into the range calculation precision and simulation efficiency, the optimal SetCut was set at 0·1 mm.
FindingsBased on an investigation into the range calculation precision and simulation yield, the QGSP_BIC_EMY physics and the optimal SetCut was recommended to be 0·1 mm.
Dosimetric comparison between three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) in the treatment of different stages of nasopharyngeal carcinoma
- Mohamed S. Ibrahim, Ehab M. Attalla, Mostafa El Naggar, Wael M. Elshemey
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- 10 September 2018, pp. 46-51
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Background
This work aims to compare the dosimetric performance of three-dimensional conformal radiotherapy (3D-CRT), a relatively available technique in developing countries, to intensity-modulated radiotherapy (IMRT) in the treatment of different stages of nasopharyngeal carcinoma (NPC).
Materials and MethodsAccording to the diagnostic stages, 40 NPC patients were divided into two equal groups. Three planning techniques such as 3D-CRT, seven-field IMRT (7F-IMRT) and nine-field IMRT (9F-IMRT) were compared. Dose prescriptions of 70 and 66 Gy were delivered in 35 fractions to gross planning target volume (PTV1) and bilateral retropharyngeal carcinoma (PTV2), respectively.
ResultsStage I dose data for almost all of the three investigated planning techniques obey the international recommendations. The dose delivered to PTV1 and PTV2 for 3D-CRT and 7F-IMRT are statistically similar, whereas 9F-IMRT is significantly better than 3D-CRT. For organs at risk (OARs), the delivered dose is significantly better for 9F-IMRT compared with the other two techniques, whereas 7F-IMRT is significantly better than 3D-CRT.
Conclusions3D-CRT is an acceptable alternative treatment technique for stage I NPC patients in developing countries suffering from the lack of advanced radiotherapy treatment techniques. 3D-CRT and 7F-IMRT have comparable performance in PTVs, while 9F-IMRT is superior in PTVs and OARs.
Quantification of DNA double-strand break induced by radiation in cervix cancer cells: in vitro study
- Sothing Vashum, Rabi Raja Singh I, Saikat Das, Mohammed Azharuddin KO, Prabhakaran Vasudevan
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- 10 October 2018, pp. 52-54
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DNA double-strand break (DSB) results in the phosphorylation of the protein, H.2AX histone. In this study, the effect of radiotherapy and chemotherapy on DNA DSB in cervical cancer cells is analysed by the phosphorylation of the protein.
MethodsThe cervical cancer cells (HeLa cells) were cultured and exposed to ionising radiation. Radiation sensitivity was measured by clonogenic survival fraction after exposing to ionising radiation. Since the phosphorylation of H.2AX declines with time, the DNA damage was quantified at different time points: 1 hour, 3 hours and 1 week after exposed to the radiation. The analysis of γ-H.2AX was done by Western-blot technique. The protein expression was observed at different dose of radiation and combination of both radiation and paclitaxel.
ResultsLow-dose hypersensitivity was observed. By 1 week after radiation at 0·5, 0·8 and 2 Gy, there was no expression of phosphorylated H.2AX. Previous experiments on the expression of phosphorylated H.2AX (γ-H.2AX) in terms of foci analysis was found to peak at 1 hour and subsequently decline with time. In cells treated with the DNA damaging agents, the expression of phosphorylated H.2AX decreases in a dose-dependent manner when treated with radiation alone. However, when combined with paclitaxel, at 0·5 Gy, the expression peaked and reduces at 0·8 Gy and slightly elevated at 2 Gy.
FindingsIn this study, the peak phosphorylation was observed at 3 hour post irradiation indicating that DSBs are still left unrepaired.
Commissioning and evaluation of a radiochromic EBT3 film dosimetry system
- Muhammad Isa Khan, Muhammad Bilal Tahir, Muhammad Rafique, Tahir Iqbal, Sabiha Zulfiqar, Aliza Zahoor, Jalil ur Rehman, Khalid Iqbal, James Chow
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- 30 October 2018, pp. 55-62
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Purpose
This work reports our study to commission a radiochromic film dosimetry system using the timely EBT3 film. We carried out dosimetric evaluations on different characteristics of photon beams (e.g., flatness, symmetry and penumbra) in radiation dose delivery.
Materials and MethodsA Varian linear accelerator producing 6 and 15 MV photon beams with 120 multi-leaf collimator was used in this study. PTW ionisation chamber was used to measure the beam characteristics such as symmetry, flatness and penumbra and these measurements were used to commission the radiochormic EBT3 film dosimetry system. The results of irradiated films were analysed using the radiochromic film QA Pro software 2016.
ResultsThe measured film doses were analysed at two different colour channels (green and red) using two scanning geometries (i.e., upper or lower side of film facing the scanner light source) at two dose levels (10 and 40 Gy). The difference between the ionisation chamber and film results was found insignificant and within the acceptable range as per the World Health Organisation standard.
ConclusionResults of the comparison between the ionisation chamber and film measurements show that our radiochormic EBT3 film dosimetry system is reliable and cost-effective in the output measurement of a linear accelerator. Our measurements confirm that our EBT3 film dosimetry agreed well with the ionisation chamber, and can be used as a re-validation tool for linear accelerator quality control.
Tumour bed localisation after oncoplastic breast conservative surgery: a comparative contouring study
- Radwa Fawzy, Shaimaa Lasheen, Maha Kamaleldin, Rasha Wessam, Emad Khallaf, Mohamed Moussa
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- 13 September 2018, pp. 63-69
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Purpose
To investigate the modalities of tumour bed (TB) localisation of target volume delineation [clinically computed tomography (CT), ultrasound (US) compared with surgical clips-guided] and the impact of their differences in delineated TB volumes.
Material and methodsIn total, 27 patients who underwent oncoplastic breast conservative surgery with surgical clips insertion (at least three) were included. CT and US imaging for TB localisation were done 3–4 weeks post-operatively in the same treatment position. TB was delineated four times, guided by surgical clips, clinical data, CT (seroma) and US. A plan was done for each TB delineated. The four delineated volumes were compared regarding the volumetric differences, the geographical miss index (GMI) and the overlap index.
ResultsComparing the four modalities, median TB volume was for clinical (60.7), CT (60.8) and US (49.3) cm3, in comparison with 59.7 cm3 for clips, p=0.05. Median of GMI (represented the tissue at risk of recurrence and not had been treated) was for clinical (61.8), CT (45) and US (62.4)%, with significant difference of p=0.02. Median of normal tissue index (normal tissue has been included unnecessarily) was for clinical (59.5), CT (49.6) and US (62.3)%, p=0.17. Overlap index with clips-guided was for clinical (0.36), CT (0.42) and US (0.35) with significance of p=0.04. Median superior/inferior direction was 0.72, −0.03 and −0.2 cm for clinical, CT and US, respectively, with significant value of p=0.02, whereas the anterior–posterior was −0.07, −0.15 and −0.09 cm, p-value=0.45 and the medio–lateral was 0.4, −0.13 and 0.09 cm, p=0.60.
ConclusionSignificant differences in shifts and indices were detected between each of modalities compared with surgical clips. Thus, in the setting of oncoplastic breast surgery, surgical clips should be routinely used for TB localisation. In view of the larger volumes of breast tissue excised and the extensive remodelling that are inherent to oncoplastic procedures, the concept of TB boost irradiation should be re-challenged.
Preliminary dosimetric evaluation of 90Y-BPAMD as a potential agent for bone marrow ablative therapy
- Ali Rabiei, Hassan Yousefnia, Samaneh Zolghadri, Mojtaba Shamsaei
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- 23 October 2018, pp. 70-74
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Aim
Bone-seeking radiopharmaceuticals are potential therapeutic tools for bone marrow ablation in patients with multiple myeloma. In this procedure, estimation of radiation absorbed dose received by the target and non-target organs is one of the most important parameters that should be undertaken. This research revolves around the absorbed dose to human organs after 90Y-BPAMD injection.
Materials and methods90Y-(4-{[(bis(phosphonomethyl))carbamoyl]methyl}-7,10-bis(carboxymethyl)-1,4,7,10-tetraazacyclododec-1-yl) acetic acid (90Y-BPAMD) complex was successfully prepared under optimised conditions. The human absorbed dose of the complex was estimated based on the biodistribution data on rats using the radiation-absorbed dose-assessment resource method. The target to non-target absorbed dose ratios for the complex was compared with the ratios for 166Ho-DOTMP, as the main radiopharmaceutical for bone marrow ablation.
ResultsAs expected, the highest amounts of absorbed dose were observed in the bone surface and the bone marrow with 2·52 and 2·29 mGy/MBq, respectively. The red marrow to the most organ absorbed dose ratios for 90Y-BPAMD are much higher than the ratios for 166Ho-DOTMP.
Findings90Y-BPAMD has interesting characteristics compared with 166Ho-DOTMP and can be considered as a high potential agent for bone marrow ablative therapy of the patient with multiple myeloma.
A comparison of Monte Carlo, anisotropic analytical algorithm (AAA) and Acuros XB algorithms in assessing dosimetric perturbations during enhanced dynamic wedged radiotherapy deliveries in heterogeneous media
- Ashfaq Zaman, Muhammad Basim Kakakhel, Amjad Hussain
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- 06 August 2018, pp. 75-81
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Background
A comparison of anisotropic analytical algorithm (AAA) and Acuros XB (AXB) dose calculation algorithms with Electron Gamma Shower (EGSnrc) Monte Carlo (MC) for modelling lung and bone heterogeneities encountered during enhanced dynamic wedged (EDWs) radiotherapy dose deliveries was carried out.
Materials and methodsIn three heterogenous slab phantoms: water–bone, lung–bone and bone–lung, wedged percentage depth doses with EGSnrc, AAA and AXB algorithms for 6 MV photons for various field sizes (5×5, 10×10 and 20×20 cm2) and EDW angles (15°, 30°, 45° and 60°) have been scored.
ResultsFor all the scenarios, AAA and AXB results were within ±1% of the MC in the pre-inhomogeneity region. For water–bone AAA and AXB deviated by 6 and 1%, respectively. For lung–bone an underestimation in lung (AAA: 5%, AXB: 2%) and overestimation in bone was observed (AAA: 13%, AXB: 4%). For bone–lung phantom overestimation in bone (AAA: 7%, AXB: 1%), a lung underdosage (AAA: 8%, AXB: 5%) was found. Post bone up to 12% difference in the AAA and MC results was observed as opposed to 6% in case of AXB.
ConclusionThis study demonstrated the limitation of the AAA (in certain scenarios) and accuracy of AXB for dose estimation inside and around lung and bone inhomogeneities. The dose perturbation effects were found to be slightly dependent on the field size with no obvious EDW dependence.
Penumbra width determination of single beam and 201 beams of Gamma Knife machine model 4C using Monte Carlo simulation
- Atefeh Mahmoudi, Alireza Shirazi, Ghazale Geraily, Tahereh Hadisi nia, Masoume Bakhshi, Maryam Maleki
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- 11 September 2018, pp. 82-87
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Background
One of the stereotactic radiosurgery techniques is Gamma Knife radiosurgery, in which intracranial lesions that are inaccessible or inappropriate for surgery are treated using 201 cobalt-60 sources in one treatment session. In this conformal technique, the penumbra width, which results in out-of-field dose in tumour-adjacent normal tissues should be determined accurately. The aim of this study is to calculate the penumbra widths of single and 201 beams for different collimator sizes of Gamma Knife machine model 4C using EGSnrc/BEAMnrc Monte Carlo simulation code and comparison the results with EBT3 film dosimetry data.
Methods and materialsIn this study, simulation of Gamma Knife machine model 4C was performed based on the Monte Carlo codes of EGSnrc/BEAMnrc. To investigate the physical penumbra width (80−20%), the single beam and 201 beams profiles were obtained using EGSnrc/DOSXYZnrc code and EBT3 films located at isocentre point in a spherical Plexiglas head phantom.
ResultsBased on the results, the single beam penumbra widths obtained from simulation data for 4, 8, 14 and 18 mm collimator sizes along X axis were 0·75, 0·77, 0·90 and 0·92 mm, respectively. The data for 201 beams obtained from simulation were 2·61, 4·80, 7·92 and 9·81 mm along X axis and 1·31, 1·60, 1·91 and 2·14 mm along Z axis and from film dosimetry were 3·21, 4·90, 8·00 and 10·61 mm along X axis and 1·22, 1·69, 2·01 and 2·25 mm along Z axis, respectively.
ConclusionThe differences between measured and simulated penumbra widths are in an acceptable range. However, for more precise measurement in the penumbra region in which dose gradient is high, Monte Carlo simulation is recommended.
Dosimetric evaluation of cobalt-60 teletherapy in advanced radiation oncology
- Manny Mathuthu, Nhlakanipho Wisdom Mdziniso, Yihunie Hibstie Asres
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- Published online by Cambridge University Press:
- 26 October 2018, pp. 88-92
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Background
Recent investigations demonstrate a strong potential for cobalt-60 (Co-60)-based teletherapy. The influence of the lower energy and penetration of a cobalt-60 beam compared with linear accelerator beams is negligible for intensity-modulated radiotherapy.
PurposeThe aim of this research is to investigate source head fluence modulation in cobalt-60 teletherapy by using a three-dimensional (3D) physical compensator and secondary collimator jaw motion.
Materials and methodsThe Oncentra treatment planning system was used to develop three hypothetical plans by secondary collimator jaw motion. A clinical MDS Nordion Equinox 80 cobalt-60 teletherapy unit was used to acquire conventional water phantom beam characteristics. Fluence modulation experiments were executed at 5·0 cm depth in a PTW universal intensity-modulated radiation therapy (IMRT) verification phantom using calibrated Gafchromic external beam therapy 2 (EBT2) and RTQA2-1010 film batches. Gafchromic EBT2 film was used to sample intensity maps generated by secondary collimator jaw motion, yet Gafchromic RTQA2-1010 film sampled maps from the 3D physical compensator. The solid-state drives used were 75·0 and 74·3 cm for the Gafchromic EBT2 and Gafchromic RTQA2-1010 film measurements.
ResultsA 2D gamma index analysis was coded to compare EBT2 film measurements with Digital Imaging and Communications in Medicine data. This analysis was also used to verify film measurements versus Monte-Carlo simulations.
ConclusionLateral beam profiles generated from water phantom measurements were used to establish source head fluence modulation on the film measurements. The source head fluence of a cobalt-60 teletherapy beam could be modulated by secondary collimator jaw motion and using a 3D physical compensator.
Literature Review
The psychosocial issues of women with cancer of the vulva
- J. Boden, S. Willis
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- 17 September 2018, pp. 93-97
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Background
Cancer of the vulva is rare, it is a disease commonly diagnosed in elderly women, however, the incidence in younger women is rising. Many patients diagnosed and treated for vulval cancer face physical, social, sexual and psychological challenges. It is essential that therapy radiographers and members of the wider multidisciplinary team understand such challenges in order to provide patient centred care.
AimThis review aims to highlight the key psycho-social issues experienced by patients with cancer of the vulva, identifying implications for practice in order to improve the holistic care for this patient group.
MethodA search of English literature was performed using Medline, Pubmed, CINAHL and PsycINFO. Search terms included, vulva or vulval cancer, psychosocial, psychosexual impact and quality of life. Articles were excluded if they focussed on cancers other than gynaecological and vulval cancers.
Results and ConclusionsAlthough there are numerous reports on the psychological and psychosocial problems faced by gynaecological cancer patients; there was a paucity of literature pertaining to patients with cancer of the vulva, this is consistent with previous research. Studies show a significant negative, psychosocial impact experienced by these women. Common themes being isolation, loneliness, stigmatisation and lack of information for patients and their carers, themes spanning over three decades. Nevertheless, it is important to be aware of the findings from recent studies consistent with patient’s needs, highlighting that listening to women’s narratives on living with cancer of the vulva is essential if we are to help with the psychosocial issues experienced by these women. They underline a necessity to raise awareness among healthcare professionals and the general public, to improve holistic support for this particular group of women. This is particularly important in the radiotherapy setting as many of these women undergo lengthy courses of treatment and the appropriately trained therapeutic radiographer can play a vital role in addressing the physical and psychosocial problems.
Breast intraoperative radiotherapy: a review of available modalities, dedicated machines and treatment procedure
- Hamid Reza Baghani, Hajar Moradmand, Seyed Mahmoud Reza Aghamiri
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- 31 August 2018, pp. 98-106
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Background
Breast intraoperative radiotherapy (IORT) is a partial irradiation technique that delivers a single fraction of radiation dose to the tumour bed during surgery. The use of this technique is increasing (especially in the Middle East), and therefore, it is essential to have a comprehensive approach to this treatment modality. The aim of this study is to conduct a literature review on available IORT modalities during breast irradiation as well as dedicated IORT machines and associated treatment procedures. The main IORT trials and corresponding clinical outcomes are also studied.
Materials and MethodsA computerised search was performed through MEDLINE, PubMed, PubMed Central, ISI web of knowledge and reference list of related articles.
ResultsIORT is now feasible through using two main modalities, including low-kilovolt IORT and intraoperative electron radiotherapy (IOERT). The dedicated machines employed and treatment procedure for mentioned modalities are quite different. The outcomes of implemented clinical trials showed that IORT is not inferior to external beam radiotherapy (EBRT) in specifically selected and well-informed patients and can be considered as an alternative to EBRT.
ConclusionAlthough the clinical outcomes of introduced IORT methods are comparable, but based on the review results, it could be said that IOERT is the most effective technical method, in view of the treatment time and dose uniformity concepts. The popularity of IORT is mainly due to the distinguished obtained results during breast cancer treatment. Despite the presence of some technical challenges, it is expected that the IORT technique will become more widespread in the immediate future.