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Accuracy and reproducibility of the patient’s position is crucial for successful delivery of radiotherapy (RT). Data on palliative patients’ set-up uncertainties are sparse. The aim of this study was to calculate set-up errors observed for palliative patients positioned using one skin mark (Group 1) versus three skin marks (Group 2) and to assess the accuracy of both approaches.
Methods:
Displacements in the left–right (L–R) and superior–inferior (S–I) directions were retrospectively analysed for 175 sites treated with a course of fractionated palliative RT. Population mean, systematic and random errors were calculated in both directions for patients positioned with one and three skin marks. Frequency of deviations was also examined for both groups.
Results:
The population mean, systematic and random errors for Group 1 and 2 for the L–R direction were 0·0, 4·4, 4·8 and 0·4, 3·1 and 3·3 mm, respectively, and in the S–I direction: 0·1, 3·4, 4·2 and 1·2, 2·7 and 3·3 mm, respectively. Frequency of images within the clinical tolerance of 5 mm was 47·1% for Group 1 and 65·9% for Group 2.
Conclusion:
Three skin marks are recommended for patients receiving a fractionated course of palliative RT, as it reduces set-up error, reduces the number of gross displacements (>10 mm) and increases the number of displacements within the clinically acceptable tolerance of 5 mm.
The virtual environment for radiotherapy training (VERT) helps students to gain technical skills and understanding of 3D anatomy and dosimetry. It has potential as a tool for treatment plan evaluation, although little formal evidence currently supports this.
Aim:
This paper reports findings from a plan evaluation workshop that facilitated comparison of VERT plan evaluation tools with those provided by conventional treatment planning software (TPS).
Method:
Students on a pre-registration Post-Graduate Diploma in Radiotherapy worked in small groups evaluating lung plans using both VERT and Eclipse TPS tools. All students were invited to provide ratings concerning how helpful each modality was for a range of evaluation parameters and preferences for use.
Results:
Most students (11 out of 14) found the session useful and expressed a desire to use VERT in future plan evaluation. The TPS was perceived to be more helpful with constraint-based evaluation while VERT was more helpful with evaluating plans for clinical set-up and delivery (p < 0·001).
Conclusion:
Student therapeutic radiographers found VERT to be helpful as a plan evaluation tool alongside standard TPS tools, in particular for clinical set-up and delivery aspects of planning. Future work is ongoing to identify the specific impact of VERT as a plan evaluation tool for both students and qualified planners.
Treatment of metachronous second primary non-small cell lung cancer (NSCLC) in patients already treated with definitive radiotherapy is a matter of debate, since most patients are excluded from surgical treatment, which remains a therapeutic standard for patients with isolated lung masses. Salvage chemotherapy or immunotherapy alone offers a low probability of disease control. The option of re-irradiation often remains the only viable, but the risks of severe acute or late toxicities affecting the surrounding normal tissues make this a real clinical challenge.
Materials and methods:
From January 2015 to April 2018, five patients (male/female: 4/1; age 54–81 years, median 68) with previously irradiated NSCLC presented with a second primary lung tumour.
Results:
A partial response was seen in four patients, one complete responses in the fifth. The toxicity was low: two patients experienced a grade 2 asymptomatic radiation pneumonitis after 6 and 12 months from the end of stereotactic body radiation therapy, resolved with cortisone therapy. No acute or late oesophageal or cardiac toxicity was found.
Findings:
In this work, we present our initial experience about the use of stereotactic radiotherapy technique in already irradiated patients. We reported a local disease control in all cases with an acceptable toxicity.
The purpose of this study is to investigate quantitatively the correlation of displacement vector fields (DVFs) from different deformable image registration (DIR) algorithms to register images from helical computed tomography (HCT), axial computed tomography (ACT) and cone beam computed tomography (CBCT) with motion parameters.
Materials and methods:
CT images obtained from scanning of the mobile phantom were registered with the stationary CT images using four DIR algorithms from the DIRART software: Demons, Fast-Demons, Horn–Schunck and Lucas–Kanade. HCT, ACT and CBCT imaging techniques were used to image a mobile phantom, which included three targets with different sizes (small, medium and large) that were manufactured from a water-equivalent material and embedded in low-density foam to simulate lung lesions. The phantom was moved with controlled cyclic motion patterns where a range of motion amplitudes (0–20 mm) and frequencies (0·125–0·5 Hz) were used.
Results:
The DVF obtained from different algorithms correlated well with motion amplitudes applied on the mobile phantom for CBCT and HCT, where the maximal DVF increased linearly with the motion amplitudes of the mobile phantom. In ACT, the DVF correlated less with motion amplitudes where motion-induced strong image artefacts and the DIR algorithms were not able to deform the ACT image of the mobile targets to the stationary targets. Three DIR algorithms produce comparable values and patterns of the DVF for certain CT imaging modality. However, DVF from Fast-Demons deviated strongly from other algorithms at large motion amplitudes.
Conclusions:
The local DVFs provide direct quantitative values for the actual internal tumour shifts that can be used to determine margins for the internal target volume that consider tumour motion during treatment planning. Furthermore, the DVF distributions can be used to extract motion parameters such as motion amplitude that can be extracted from the maximal or minimal DVF calculated by the different DIR algorithms and used in the management of the patient motion.
During the radiation therapy of tumoral breast, the contralateral breast (CB) will receive scattered doses. In the present study, the photon and thermal neutron dose values received by CB surface during breast cancer radiation therapy were measured.
Materials and methods:
The right breast region of RANDO phantom was considered as CB, and the measurements of photon and thermal neutron dose values were carried out on this region surface. The phantom was irradiated with 18 MV photon beams, and the dose values were measured with thermoluminescent dosimeter (TLD-600 and TLD-700) chips for 11 × 13, 11 × 17 and 11 × 21 cm2 field sizes in the presence of physical and dynamic wedges.
Results:
The total dose values (photon + thermal neutron) received by the CB surface in the presence of physical wedge were 12·06%, 15·75% and 33·40% of the prescribed dose, respectively, for 11 × 13, 11 × 17 and 11 × 21 cm2 field sizes. The corresponding dose values for dynamic wedge were 9·18%, 12·92% and 29·26% of the prescribed dose, respectively. Moreover, the results showed that treatment field size and wedge type affect the received photon and thermal neutron doses at CB surface.
Conclusion:
According to our results, the total dose values received at CB surface during breast cancer radiotherapy with high-energy photon beams are remarkable. In addition, the dose values received at CB surface when using a physical wedge were greater than when using a dynamic wedge, especially for medial tangential fields.
Radiotherapy is one of the treatments used to treat prostate cancer, and dose escalation to 74–78 Gy in conventional fractionation is the standard regimen. Currently, according to the hypothesis of low alpha/beta ratio in prostate cancer cells, using hypo-fractionation has been reported in many publications with promising results. This retrospective study was designed to evaluate the implementation of a moderate hypo-fractionation regimen in high-risk prostate cancer in our division.
Materials and Methods:
Between 2012 and 2017, 40 patients with high-risk, localised prostate cancer were treated by a moderate hypo-fractionation regimen (70 Gy at 2·5 Gy per fraction) with intensity-modulated radiation therapy. The data related to treatment outcomes and toxicities were evaluated.
Results:
The mean PSA at diagnosis was 86·2 ng/mL (95% CI 49·9–122·4). Thirty-eight patients received long-term hormonal therapy. Fifty-two percent had a Gleason score of 8–10, and 65% had an initial PSA >20 ng/mL. The mean doses (in EQD2) to the D50% of PTV, D2% of organs at risk (bladder, rectum and bowels) were 80, 78·3, 76·4, and 50·2 Gy, respectively. Two patients had biochemical recurrence during the follow-up period.
Conclusion:
A moderate hypo-fractionation regimen (70 Gy at 2·5 Gy per fraction) is feasible. Our experience found that this regimen yields tolerable, acceptable toxicity profiles in high-risk, localised prostate cancer patients.
To compare the dosimetric results regarding the sparing effect on normal tissue between RapidArc (RA) and helical tomotherapy (HT) plans for nasopharyngeal carcinoma (NPC) patients in cases of the equal target dose controls utilising two techniques.
Materials and Methods:
Thirteen NPC patients treated with HT were replanned using the Varian Eclipse treatment planning system (TPS) for the RA plan. The target dose of the RA plan was optimised equally to the HT plan in terms of target coverage, dose conformity (CI) and dose homogeneity (HI) for assessing the normal tissue sparing between two techniques. All dose–volume parameters monitor units (MUs) and delivery time were also investigated.
Results:
All dosimetric parameter comparisons of organs-at-risk (OARs) between the RA and HT plans were not significantly different for brain stem, spinal cord and cochlea. However, the RA plan showed a significantly lower dose to the left parotid gland. The mean and median dose were significantly lower in the RA plan versus the HT plan by p-value 0·005 and 0·039, respectively. The MUs and delivery time were also significantly lower in the RA plan with a p-value of 0·00.
Conclusions:
With the same planning target volume coverage, homogeneity and conformity, almost all of RA and HT treatment planning met the planning goal for normal tissue sparing. There were no significant differences between the two techniques except in the left parotid gland. The RA plans were superior to HT plans by effectively reducing the MUs and treatment time.
The aim of this study was to produce a low-cost anatomical model of adult male including lower limbs to evaluate the three-dimensional dose distribution for dosimetry measurements, especially in total body irradiation (TBI) and total skin electron therapy (TSET).
Materials and methods:
Computed tomography (CT) scan images of the atomic energy organisation RANDO phantom and lower limb CT scan images of 20 healthy persons were averaged. Selections of different body tissues substitute materials and phantom validation were performed according to previous studies worked on construction of radiation therapy phantoms.
Results:
The dosimetry aspect of the selected substitute materials from all considered methods showed that they were in good agreement with real human tissue, especially bone, with a percentage error of 0·5%. The results show that the electron densities obtained from the linear attenuation coefficient (reDLAC) for the tissue equivalent material used in the phantom is a better option for validation.
Conclusions:
This validated phantom has numerous advantages over the origin type of RANDO phantom. Therefore, using it in TBI and TSET dosimetry is recommendable.
Pelvic wall control and toxicity was retrospectively assessed in patients who received individually customised parametrial boost (PMB) for locally advanced cervical cancer with 2D planned external beam radiotherapy. Outcomes of a dose-escalated combined boost were also evaluated.
Materials and methods:
Toxicity and pelvic wall recurrence was evaluated over a median period of 24 months between two groups who received different pelvic wall doses. One group was randomised to receive either intracavitary brachytherapy (ICRT) with an external beam PMB using a customised midline shield, or a dose-escalated combined boost with interstitial brachytherapy (ISBT) and PMB. The comparator group received no PMB.
Results:
At 24 months, pelvic wall recurrence occurred in 2/112 and 40/130 with and without PMB, respectively (p < 0·000001). No significant difference in toxicity was noted between boost versus no-boost groups (p = 0·56). Combined ISBT/PMB dose escalation showed no significant difference in pelvic wall recurrence compared with PMB alone (p = 0·49).
Findings:
Individually customised 2D PMBs with 3D image-based ICRT was safe and improved pelvic wall control in locally advanced cervix cancer. Dose-escalated combined boosts offered no significant benefit over standard boost doses.
To evaluate the dosimetric parameters of level II lymph nodes in chest wall three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) of mastectomy patients using dual-isocentric (DIT) and mono-isocentric techniques (MIT).
Materials and methods:
Computed tomography (CT) images of 20 mastectomy patients undergoing chest wall external radiotherapy were used as the input data for the abovementioned techniques. Selected dosimetric parameters were calculated for the axillary level I–III lymph nodes, chest wall, heart and lung. Paired t-test statistical analysis was used for comparing the results of MIT and DIT in both 3D-CRT and IMRT methods.
Results:
There were significant differences in Dmin (minimum dose), Dmax (maximum dose) and maximum–minimum dose between MIT and DIT techniques (13, −8·6, −52·2% differences for Dmin, Dmax and maximum–minimum, respectively) in IMRT. There were also significant differences for Dmean (mean dose), Dmax and maximum–minimum dose (7·8, −11·4, −44·6% differences in Dmean, Dmax and maximum–minimum, respectively) in 3D-CRT (p < 0·05). In addition, there were not any differences in the dosimetric parameters for heart, lung and level I and III lymph nodes.
Conclusion:
In both 3D-CRT and IMRT methods, level II lymph node dose distribution in MIT was closer to the prescribed dose compared with DIT due to the position of these nodes in the field junction area. To achieve a better dose homogeneity, it could be recommended to use MIT instead of DIT in 3D-CRT and IMRT for mastectomy patients.
To assess the relapse-free survival (RFS) and the factors influencing local recurrence in patients with desmoid fibromatosis (DF) treated at our centre and to determine the role of post-operative radiotherapy (RT) in improving local control.
Methods:
A retrospective analysis of 51 patients treated for DF from January 2004 to December 2013 was undertaken. The RFS was calculated using the Kaplan–Meier curve. Univariate analysis was done to assess correlation with tumour size, site, the extent of surgery, margin status and adjuvant RT with RFS.
Results:
The median age was 28 years with a male:female ratio of 1:3. The most common location of the tumour was anterior abdominal wall (47%). The median tumour size was 10 cm. Wide local excision was done in most patients. Complete resection with negative margin was achieved in eight patients. Post-operative RT was indicated for 43 patients of whom 19 received RT. At a median follow-up of 37 months, RFS in the complete resection with margin negative group was 100%. RFS for the patients with positive or close margins who received RT was 79% and for those who did not receive RT, it was 87%.
Conclusions:
Complete excision with negative margins gives the best local control in DF. The benefit of post-operative RT could not be ascertained.
In this study, the radiation contamination dose (RCD) for different combinations of electron energy/distance, applicator and radius around the light intraoperative accelerator (LIAC), a high dose per pulse dedicated intraoperative electron radiotherapy machine, has been estimated. Being aware about the amount of RCDs is highly recommended for linear medical electron accelerators.
Methods and methods:
Monte Carlo Nuclear Particles (MCNP) code was used to simulate the LIAC® head and calculate RCDs. Experimental RCDs measurements were also done by Advanced Markus chamber inside a MP3-XS water phantom. Relative differences of simulations and measurements were calculated.
Result:
RCD reduction by distance from the machine follows the inverse-square law, as expected. The RCD was decreased by increasing angle from applicator walls opposed to the electron beam direction. The maximum differences between the simulation and measurement results were lower than 3%.
Conclusions:
The RCD is strongly dependent on electron beam energy, applicator size and distance from the accelerator head. Agreement between the MCNP results and ionometric dosimetry confirms the applicability of this simulation code in modelling the intraoperative electron beam and obtaining the dosimetric parameters. The RCD is a parameter that would restrict working with LIAC in an unshielded operative room.
To study 2D and 3D dosimetric values for bladder and rectum, and the influence of bladder volume on bladder dose in high dose rate (HDR) intracavitary brachytherapy (ICBT). The large patient data incorporated in this study would better represent the inherent variations in many parameters affecting dosimetry in HDR-ICBT.
Material and Methods:
We prospectively collected data for 103 consecutive cervical cancer patients (over 310 HDR fractions) undergoing CT-based HDR-ICBT at our centre. Correlation among bladder and rectum maximum volume doses and corresponding International Commission on Radiation Units and Measurement (ICRU) point doses were estimated and analysed. Impact of bladder volume on bladder maximum dose was assessed.
Results:
The ICRU point doses to bladder and rectum varied from the volumetric doses to these organs. Further, bladder volume poorly correlated with bladder maximum dose for volume variations encountered in the clinical practice at our centre.
Findings:
ICRU point doses to bladder and rectum are less likely to correlate with long-term toxicities to these organs. Further, in clinical practice where inter-fraction bladder volume does not vary widely there is no correlation between bladder volume and bladder dose.
This review evaluates whether brachytherapy can be considered as an alternative to whole breast irradiation (WBI) using criteria such as local recurrence rates, overall survival rates and quality of life (QoL) factors. This is an important issue because of a decline in local recurrence rates, suggesting that some women at very low risk of recurrence may be incurring the negative long-term side effects of WBI without benefitting from a reduction in local recurrence and greater overall survival. As such, the purpose of this literature review is to evaluate whether brachytherapy is a credible alternative to external beam radiation with a particular focus on the impact it has on patient QoL.
Methods:
The search terms used were devised by using the Population Intervention Comparison Outcome framework, and a literature search was carried out using Boolean connectors and Medical Subject Headings in the PubMed database. The resultant articles were manually assessed for relevance and appraised using the Scottish Intercollegiate Guidelines Network tool. Additional papers were sourced from the citations of articles found using the search strategy. Government guidelines and regulations were also used following a manual search on the National Institute for Health and Care Excellence website. This process resulted in a total of 30 sources being included as part of the review.
Results:
Three types of brachytherapy were the foundation for the majority of the papers found: interstitial multi-catheter brachytherapy, intra-cavity brachytherapy and permanent seed implantation. The key themes that arose from the literature were that brachytherapy is equivalent to WBI both in terms of 5-year local recurrence rates and overall survival rates at 10–12 years. The findings showed that brachytherapy was superior to WBI for some QoL factors such as being less time-consuming and equal in terms of others such as breast cosmesis. The results did also show that brachytherapy does come with its own local toxicities that could impact upon QoL such as the poor breast cosmesis associated with some brachytherapy techniques.
Conclusion:
In conclusion, brachytherapy was deemed a safe or acceptable alternative to WBI, but there is a need for further research on the long-term local recurrence rates, survival rates and quality of life issues as the volume of evidence is still significantly smaller for brachytherapy than for WBI. Specifically, there needs to be further investigation as to which patients will benefit from being offered brachytherapy and the influence that factors such as co-morbidities, performance status and patient choice play in these decisions.
The unique behaviour of microbubbles under ultrasound acoustic pressure makes them useful agents for drug and gene delivery. Several studies have demonstrated the potential application of microbubbles as a non-invasive, safe and effective technique for targeted delivery of drugs and genes. The drugs can be incorporated into the microbubbles in several different approaches and then carried to the site of interest where it can be released by destruction of the microbubbles using ultrasound to achieve the required therapeutic effect.
Methods:
The objective of this article is to report on a review of the recent advances of ultrasound-mediated microbubbles as a vehicle for delivering drugs and genes and its potential application for the treatment of cancer.
Conclusion:
Ultrasound-mediated microbubble technology has the potential to significantly improve chemotherapy drug delivery to treatment sites with minimal side effects. Moreover, the technology can induce temporary and reversible changes in the permeability of cells and vessels, thereby allowing for drug delivery in a spatially localised region which can improve the efficiency of drugs with poor bioavailability due to their poor absorption, rapid metabolism and rapid systemic elimination.
Accurate localisation of target position is crucial when using techniques with sharp dose fall off such as volumetric modulated arc therapy (VMAT). Gold seed fiducial markers have been used for target localisation in image-guided radiation therapy for various tumors including intact prostate cancers. However, their role for target localisation in post-prostatectomy radiotherapy is unclear. This study was undertaken to determine the feasibility and effectiveness of gold seed fiducial markers in patients undergoing prostate bed VMAT.
Materials and methods:
The institutional radiation oncology database was used to analyse the treatment data of 18 post-prostatectomy patients with implanted gold seed fiducial markers. The shifts of the fiducial markers were reviewed, tabulated and statistically analysed.
Results:
Three hundred and eighty-six orthogonal pair images for 18 patients were reviewed. Specifically, the average gold seed fiducial shifts were 0·34 cm in the superior–inferior (S/I) axis (0·31 SD), 0·31 cm (0·29 SD) in the anterior–posterior (A/P) axis and 0·28 cm (0·25 SD) in the lateral axis (R/L). As a result, the 95% probability of fiducial marker displacement was 0·96 cm in the S/I, 0·89 cm in the A/P and 0·78 cm in the R/L axes. The most frequent shifts occurred in the inferior, left and posterior directions. The percentage of shifts more than 0·5 cm were 19·74, 21·56 and 12·47% for the S/I, A/P and R/L axes, respectively.
Conclusion:
In the absence of fiducial markers, non-uniform planning target volume (PTV) margins of 1 cm for S/I, 9 mm for A/P and 8 mm for the lateral direction are necessary for target localisation in post-prostatectomy radiotherapy. By improving prostate bed localisation, gold seed fiducial markers can decrease PTV margins, reduce normal tissue radiation exposure and allow for dose-escalated and/or hypofractionated radiotherapy to be considered in appropriate clinical scenarios.
Breast cancer is the most common cancer among females worldwide. Increasing breast cancer incidence rates, improved diagnosis and management modalities and growing life expectancy have resulted in increasing numbers of women at risk of developing contralateral primary breast cancer. Bilateral breast cancer can occur synchronously or metachronously.
Material and methods:
This study reports three cases of bilateral breast cancer patients treated at our oncology department between March 2018 and March 2019. The features of presentation, investigation, diagnosis and follow-up care are the highlights of this study.
Results:
Bilateral breast cancer was noted in three patients among the study population in the age group of 35 –55 years. Two of these patients had metachronous bilateral breast cancer, and one patient developed cancer in the second breast during the course of management. The second breast cancers differed histologically from primary breast cancer.
Conclusion:
Poor awareness on breast cancer care and the lack of national screening guidelines and programmes, and poor infrastructure, all contribute to late presentation and difficult breast cancer management. Proper history, clinical examination and imaging of opposite breast should be done to ensure adequate and timely management of bilateral breast cancer.