To compare the dosimetry and reproducibility of set-up with monoisocentric technique (MIT) and dual isocentric technique (DIT) in adjuvant breast radiotherapy (RT).

Breast cancer patients treated with MIT or DIT were retrospectively studied. The organ-at-risk dose was compared between two groups. All patients underwent set-up verification with an electronic portal imaging device, and set-up time was recorded for each fraction. Treatment reproducibility was assessed in terms of systematic and random error.

Twenty patients were included (11 right and 9 left-sided tumours) and ten received whole breast RT, while the rest received chest wall RT. Overall, the mean heart dose was less with MIT (0.40 versus 0.79, p = <0.001) as well as in left-sided tumours (0.37 versus 0.98, p = 0.003). The maximum dose at the field junction was significantly higher with DIT (43 Gy, 107%, p = 0.003). The maximum total error was 1 cm in lateral for supraclavicular field and 8 mm in superior–inferior in tangents for both techniques. There was no difference in set-up errors between the two techniques.

MIT resulted in better dose homogeneity at the field junctions and reduced mean heart dose as compared to DIT. MIT is safe for implementation in clinical practice for breast cancer treatment.

This study is one of the few studies comparing MIT with DIT in terms of the dosimetry and the first one to compare set-up errors between the two techniques. The ease of set-up and better dosimetry with MIT was achieved.

To study the effect of deep inspiration breath hold (DIBH) on Fast-Forward trial for left-sided breast radiotherapy dosimetrically using tangential field-in-field (FiF), flattening filtered volumetric-modulated arc therapy (FF-VMAT) and flattening filter free volumetric-modulated arc therapy (FFF-VMAT) in comparison with free breathing (FB).

Computed tomography images were acquired on 15 patients with carcinoma of left breast in FB and DIBH. Planning target volume (PTV) and organs at risk were contoured on both image sets. Dose of 26 Gy in five daily fractions was prescribed to PTV. FiF, FF-VMAT and FFF-VMAT plans were created in treatment planning system on both FB and DIBH. PTV V95%, V107%, D0·1 cc, CI and HI, heart V1·5 Gy, V7 Gy, lung left V8 Gy, monitor units (MU) and beam ON time were used for evaluation. Different technique analysis in same breathing condition and FB versus DIBH for same planning technique were performed.

Mean of all 15 patients was reported as mean ± 1 standard deviation. PTV V95% was 97·55 ± 0·10 (FiF), 95·75 ± 0·66 (FF-VMAT) and 96·15 ± 0·46 (FFF-VMAT) in FB while 97·34 ± 0·50 (FiF), 96·03 ± 0·71 (FF-VMAT) and 95·86 ± 0·63 (FFF-VMAT) in DIBH. Heart V7 Gy was 8·53 ± 4·26 (FiF), 8·86 ± 2·20 (FF-VMAT) and 9·27 ± 2·46 (FFF-VMAT) in FB while 6·30 ± 2·98 (FiF), 5·23 ± 2·20 (FF-VMAT) and 4·68 ± 2·01 (FFF-VMAT) in DIBH. p-value of heart V7 Gy between FB and DIBH was 0·278 (FiF), 0·009 (FF-VMAT) and 0·003 (FFF-VMAT). Beam ON time for FFF-VMAT was reduced by 65% (FF-VMAT) and 11% (FiF).

Conformal dose to PTV was achieved better with VMAT plans. FFF-VMAT was delivered in less time compared to FF-VMAT and FiF for 26 Gy in five fractions. Heart dose can be significantly minimised with DIBH for VMAT plans.

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.

To evaluate the prevalence and risk factors of arm lymphedema in patients with breast cancer.

Between 2006 and 2017, we investigated patients with breast cancer after breast surgery who received adjuvant radiotherapy at the breast or chest wall, and/or adjuvant radiotherapy at regional lymph nodes, and standard systemic chemotherapy depending on disease stage and risk factors. We assessed arm lymphedema using arm circumference measurement differences on the treated side compared with the opposite arm (≥2 cm measurements at any one position). Associations between arm lymphedema and potential risk factors were identified using statistical analysis.

In 308 patients, arm lymphedema prevalence was 6·2%. Patients having ≥20 lymph nodes removed (hazard ratio (HR) = 3·29; 95% confidence interval (CI): 1·12–8·87), undergoing regional lymph node irradiation (HR = 1·81; 95% CI: 1·09–13·28), and no arm and shoulder exercises after treatment (HR = 3·16; 95% CI: 1·89–5·26) had a higher risk of arm lymphedema.

Arm lymphedema is a serious breast cancer complication and is a preventable morbidity. Planning arm and shoulder exercises in line with adjuvant treatments and increasing clinical awareness of early indications could help lower the risk of occurrence.

The aim of this study was to develop a method for accurately measuring the intra-fraction motion in cine electronic portal imaging device (EPID) images of tangential breast irradiation.

The cine EPID images were acquired for 18 breast cancer patients during medial tangential breast radiotherapy. The skin surface and the chest wall were segmented separately in each EPID image using an automated MATLAB algorithm to obtain the magnitude of intra-fraction motion.

The patients had an average age of 55 years (range 43–69 years), with the highest observed displacement at 3·50 mm. The mean intra-fraction motion due to respiration for the skin surface and chest wall was 1·04 ± 0·24 mm and 1·10 ± 0·27 mm, respectively. The amount of intra-fraction motion showed no significant association with either the patient’s age or the side of the breast receiving the treatment.

In this study, by utilising cine EPID technology and the automated MATLAB algorithm, the intra-fraction motion during breast radiotherapy treatment was accurately measured and analysed. Results indicate minimal skin surface and chest wall motion (approximately 1 mm), confirming negligible intra-fraction motions during conformal radiotherapy in breast cancer patients.

There are only limited studies available in literature that discuss methods to reduce the oesophageal dose and acute oesophagitis during breast cancer radiotherapy. The aim of this study is to compare dose volumetric parameters of oesophagus in radiation treatment of breast with and without oesophagus delineation.

Treatment plans of 44 patients, who underwent chest wall and supraclavicular fossa irradiation, were selected for the study. Oesophagus was later delineated and treatment replanned using three-dimensional conformal radiotherapy (3DCRT) considering oesophagus as an organ at risk (OAR). The dose prescribed was 40 Gy/15 fractions to the planning target volume (PTV). Dose volumetric parameters of oesophagus such as maximum dose (Dmax), mean dose (Dmean), the percentage of oesophagus volume receiving ≥15Gy (V15), ≥25Gy(V25), ≥33Gy(V33) and ipsilateral lung volume parameters V4, V8 and V16 were compared with already executed plans in which oesophagus was not delineated.

Contouring the oesophagus as an OAR as a part of the radiotherapy treatment for Carcinoma Breast resulted in statistically significant reduction in dose to the oesophagus. No statistically significant change was found in the ipsilateral lung volume parameters. No compromise in plan quality was required as evident from the statistically non-significant differences in Homogeneity index and Conformity index.

3DCRT planning with oesophagus delineation can be considered as a method to reduce oesophageal dose and the acute oesophageal toxicity during radiotherapy for carcinoma breast.

Accurate and reproducible patient positioning is a critical step in radiotherapy for breast cancer. This has seen the use of permanent skin markings becoming standard practice in many centres. Permanent skin markings may have a negative impact on long-term cosmetic outcome, which may in turn, have psychological implications in terms of body image. The aim of this study was to investigate the feasibility of using a semi-permanent tattooing device for the administration of skin marks for breast radiotherapy set-up.

This was designed as a phase II double-blinded randomised-controlled study comparing our standard permanent tattoos with the Precision Plus Micropigmentation (PPMS) device method. Patients referred for radical breast radiotherapy were eligible for the study. Each study participant had three marks applied using a randomised combination of the standard permanent and PPMS methods and was blinded to the type of each mark. Follow up was at routine appointments until 24 months post radiotherapy. Participants and a blind assessor were invited to score the visibility of each tattoo at each follow-up using a Visual Analogue Scale. Tattoo scores at each time point and change in tattoo scores at 24 months were analysed by a general linear model using the patient as a fixed effect and the type of tattoo (standard or research) as covariate. A simple questionnaire was used to assess radiographer feedback on using the PPMS.

In total, 60 patients were recruited to the study, of which 55 were available for follow-up at 24 months. Semi-permanent tattoos were more visible at 24 months than the permanent tattoos. Semi-permanent tattoos demonstrated a greater degree of fade than the permanent tattoos at 24 months (final time point) post completion of radiotherapy. This was not statistically significant, although it was more apparent for the patient scores (p=0·071) than the blind assessor scores (p=0·27). No semi-permanent tattoos required re-marking before the end of radiotherapy and no adverse skin reactions were observed.

The PPMS presents a safe and feasible alternative to our permanent tattooing method. An extended period of follow-up is required to fully assess the extent of semi-permanent tattoo fade.

Few studies claimed that dynamic jaw (DJ) mode in Helical TomoTherapy® (HT) could improve the cranio-caudal dose distribution without prolonging the treatment time in treating different types of cancer. Also, studies suggested that DJ with a wider 5 cm field width (FW) could replace fixed jaws (FJ) with 2.5 cm FW to reduce the delivery time with the sustainable plan quality. Yet, the study on breast cancer with supraclavicular fossa (SCF) nodal involvement using DJ mode in HT is limited. This study aims to evaluate the DJ mode retrospectively by comparing their dosimetric quality with normal tissue complication probability (NTCP) of organs at risk and treatment delivery time with FJ mode on treating left-side breast with SCF nodal involvement.

All post-mastectomy patients, who had been irradiated for left-side breast with SCF nodal involvement were selected retrospectively in this study. With the same dose constraint and prescription as the treated DJ2.5 plan, two extra plans using DJ mode with 5 cm FW(DJ5.0) and FJ mode with 2.5 cm FW (FJ2.5) were computed for plan comparison.

No statistical significance was found in all the parameters of PTV and OARs, except for V20 of whole lung. DJ5.0 received V20 in ipsilateral left lung than FJ2.5 and DJ2.5. However, the average delivery time of DJ5.0 was significantly lower than that of DJ2.5 and FJ2.5 by almost 40%.

No statistical significance was found in those dosimetric and radiobiological parameters among three modes while the delivery time has greatly reduced by using DJ5.0. A shorter treatment time can minimise intra-fractional error and better the patient’s experience during treatment.

This study compares three different hybrid plans, for left-sided chest wall (CW) and nodal stations irradiation using a hypofractionated dose regimen.

Planning target volumes (PTVs) of 25 breast cancer patients that included CW, supraclavicular (SCL) and internal mammary node (IMN) were planned with 3 different hybrid techniques: 3DCRT+IMRT, 3DCRT+VMAT and IMRT+VMAT. All hybrid plans were generated with a hypofractionated dose prescription of 40·5 Gy in 15 fractions. Seventy per cent of the dose was planned with the base-dose component and remaining 30% of the dose was planned with the hybrid component. All plans were evaluated based on the PTVs and organs at risk (OARs) dosimetric parameters.

The results for PTVs parameters have shown that the 3DCRT+IMRT and 3DCRT+VMAT plans were superior in uniformity index to the IMRT+VMAT plan. The OARs dose parameters were comparable between hybrid plans. The IMRT+VMAT plan provided a larger low dose volume spread to the heart and ipsilateral lung (p < 0·001). The 3DCRT+VMAT plan required less monitor units and treatment time (p = 0·005) than other plans.

The 3DCRT+VMAT hybrid plan showed superior results with efficient treatment delivery and provide clinical benefit by reducing both low and high dose levels.

The purpose of this study is to evaluate the effectiveness and sensitivity of the Varian portal dosimetry (PD) system as a quality assurance (QA) tool for breast intensity-modulated radiation therapy (IMRT) treatment plans.

Four hundred portal dose images from 200 breast cancer patient IMRT treatment plans were analysed. The images were obtained using Varian PortalVision electronic portal imaging devices (EPIDs) on Varian TrueBeam Linacs. Three patient plans were selected, and the multi-leaf collimator (MLC) positions were randomly altered by a mean of 0·5, 1, 1·5 and 2 mm with a standard deviation of 0·1 mm on 50, 75 and 100% of control points. Using the improved/global gamma calculation algorithm with a low-dose threshold of 10% in the EPID, the change in gamma passing rates for 3%/3 mm, 2%/2 mm and 1%/1 mm criterion was analysed as a function of the introduced error. The changes in the dose distributions of clinical target volume and organ at risk due to MLC positioning errors were also analysed.

Symmetric and asymmetric breast or chest wall plan fields are different in delivery as well as in the QA. An average gamma passing rate of 99·8 ± 0·5 is presented for 3%/3 mm symmetric plans and 96·9 ± 4·5 is presented for 3%/3 mm asymmetric plans. An average gamma passing rate of 98·4 ± 4·3 is presented for 2%/2 mm symmetric plans and 89·7 ± 9·5 is presented for 2%/2 mm asymmetric plans. A large-induced error in MLC positioning (2·0 mm, 100% of control points) results in an insignificant change in dose that would be delivered to the patient. However, EPID portal dosimetry is sensitive enough to detect even the slightest change in MLC positioning error (0·5 mm, 50% of control points).

Stricter pre-treatment QA action levels can be established for breast IMRT plans utilising EPID. For improved sensitivity, a multigamma criteria approach is recommended. The PD tool is sensitive enough to detect MLC positioning errors that contribute to even insignificant dose changes.

This study compares tumor control probability (TCP) and normal tissue complication probability (NTCP) across different hypo-fractionated (HypoRT) and conventional breast radiotherapy regimens using radiobiological models.

Computed tomography data from 30 patients with left breast-conserving surgery were used to evaluate three HypoRT regimens (39 Gy and 41·6 Gy in 13 fractions, and 40 Gy in 15 fractions) and a conventional regimen (50 Gy in 25 fractions). Dose-volume histograms (DVHs) were extracted for radiobiological calculations using Equivalent Uniform Dose (EUD) and Poisson models for TCP, and EUD and LKB (Lyman-Kutcher-Burman) models for NTCP.

Conventional treatment achieved significantly higher TCP (95%) than all HypoRT regimens (p < 0·001), with no significant differences between HypoRT regimens (p > 0·05. The 39 Gy/13 fraction regimen showed the lowest lung NTCP (p < 0·05). HypoRT regimens had significantly lower NTCP for the lungs and heart compared to the conventional regimen (p < 0·01). TCP and NTCP values from Poisson and LKB models were higher than those from the EUD model (p < 0·01).

HypoRT regimens reduced NTCP, with the lowest values in the regime of 39 Gy/13 fractions regimen, though the conventional regimen had higher TCP.

To evaluate efficacy of helical tomotherapy (HT) for treatment of breast cancer with internal mammary lymph node involvement.

This is a retrospective clinical audit of planning, dosimetry, toxicity and short-term survival of a cohort of 65 patients. Patients were treated between November 2014 and May 2019. The primary and nodal region was prescribed a dose of 50 Gray (Gy) in 25 fractions, while all cases of breast conserving surgery received a simultaneous integrated boost to a dose of 61 Gy in 25 fractions.

The 95% coverage for the primary, supraclavicular, internal mammary node and tumour bed was 93·4%, 96·8%, 90·7% and 98·3%, respectively. Mean dose to total lung, heart and contra-lateral breast was 10·6 Gy, 6·92 Gy and 4·32 Gy, respectively. None developed grade III skin or oesophageal toxicity. Twenty-one patients had progression; of which eighteen developed only distant failure while three also had loco-regional recurrence. At a median follow-up of 36 months, the 3-year loco-regional control, disease-free survival and overall survival were 93·5, 73·9 and 85·9%, respectively.

We report encouraging clinical outcome for patients treated uniformly with HT. The predominant pattern of failure was distant metastases which suggests the need for systemic control intensification.

During the SARS-CoV-2 virus pandemic, University Hospital Birmingham NHS Trust Oncology Department incorporated the ultrahypofractionated regime of 26Gy/5 fractions alongside the moderate hypofractionated regime of 40Gy/15 fractions as part of local adjuvant breast radiotherapy treatment (RT) for eligible patients. We conducted a local study to assess the real-life experience of patients undergoing ultrahypofractionated schedule to compare feasibility and toxicity to the fast-forward trial during the COVID − 19 pandemic.

A single institution, retrospective, qualitative study. Patients included had early-stage breast cancer and received adjuvant radiotherapy between 23 March 2020 and 31 May 2020, a total of 211 patients. Inclusion was irrespective of any other neoadjuvant/adjuvant treatments. Data were collected retrospectively for treatment dose, boost dose and toxicity.

Of the total 211 patients, 85 were treated with 26Gy in 5# and 19 patients received a boost as per the fast-forward protocol. Of these 85 patients, 15·9% did not report any skin toxicity post-treatment. 63·5% of patients reported RTOG Grade 1, 15·9% had RTOG Grade 2, and 1·6% reported RTOG Grade 3 skin toxicity. 3·2% of the patients could not be contacted for follow-up. Of the 19 patients who received a breast boost, 10·53% reported no skin changes. 78·9% reported Grade 1 skin toxicity. Both Grades 2a and 2b skin toxicity were reported by 5·26% each. The patient demographics and tumour characteristics in our study cohort were comparable to those within the fast-forward trial. In terms of post-RT skin toxicity, fewer patients reported any toxicity in the UHB patient cohort versus those in the trial, and the number of Grade 2/3 toxicities reported was also low. A delay in toxicity reporting from 2 weeks for 40Gy/15 to 3 weeks for 26Gy/5 was observed.

Our study concluded that offering ultrahypofractionation was convenient for patients; reducing the number of hospital visits during the SARS-CoV-2 virus pandemic appeared safe in terms of acute post-RT-related skin toxicity. The reduced hospital visits limited exposure of patients and staff to the SARS-CoV-2 virus while also ensuring efficient use of Radiotherapy Department resources. Local follow-up protocols have been amended to ensure review at 3 weeks for the 26Gy/5 schedule to acknowledge the delay in acute toxicity development. To date, there is only 5-year toxicity and relapse data available from the fast-forward trial; therefore, hypofractionation schedules should be offered to patients as long as they fulfil the criteria and understand the limitations of the study as well as accelerated peer review processes in the face of the pandemic.

Optimal radiotherapy technique selection for left-sided breast cancer remains challenging. This study compared volumetric-modulated arc therapy (VMAT), VMAT+IMRT (VMAT+IMRT) and IMRT+VMAT (IMRT+VMAT) using an innovative integrated scoring system and risk factor (RF) assessment.

Retrospectively analysed 41 patients with left-sided breast cancer. Treatment plans were evaluated using an integrated scoring system considering tumour coverage and organs at risk (OARs) sparing. RF analysis assessed potential adverse effects on the heart and lungs. Correlation analysis explored relationships between integrated scores and risk factors.

VMAT showed the best overall integrated score (1·0931 ± 0·1707), followed by IMRT+VMAT (1·2011 ± 0·2440) and VMAT+IMRT (1·2264 ± 0·2499). VMAT had the highest percentage of Excellent OAR plans (14·6%), while VMAT+IMRT and IMRT+VMAT showed better PTV coverage (53·7% and 51·2% Excellent, respectively). RF analysis revealed: VMAT (heart RF: 0·341, lung RF: 0·671), VMAT+IMRT (heart RF: 0·294, lung RF: 0·750) and IMRT+VMAT (heart RF: 0·533, lung RF: 0·546). Correlation analysis showed strong positive correlations between integrated scores and lung RF for VMAT (r = 0·671) and VMAT+IMRT (r = 0·750), with IMRT+VMAT showing moderate correlations for lung (r = 0·546) and heart (r = 0·533) RFs.

VMAT demonstrated the best balance between PTV coverage and OAR sparing, hybrid techniques improved target coverage but increased risk to OAR. The RF analysis highlighted varying impacts on heart and lung across techniques. This analysis provides valuable insights for technique selection, potentially improving treatment outcomes and reducing complications in left-sided breast cancer radiotherapy.

Although hypofractionated radiotherapy has been standardised in early breast cancer, even in post-mastectomy no such consensus has been developed for locally advanced breast cancer (LABC), probably due to complex planning and field matching. This study is directed towards dosimetric evaluation and comparison of toxicity, response and disease-free survival (DFS) comparison between hypofractionation and conventional radiotherapy in post-mastectomy LABC.

In total, 222 female breast cancer patients were randomly assigned to be treated with either hypofractionated radiotherapy (n = 120) delivering 40 Gy in 15 fractions over 3 weeks or conventional radiotherapy (n = 102) with 50 Gy in 25 fractions over 5 weeks after modified radical mastectomy (MRM) along with neoadjuvant and/or adjuvant chemotherapy. All patients were planned with treatment planning software and assessed regularly during and after treatment.

Median follow-up period was 178 weeks in conventional arm (CRA) and 182 weeks in hypofractionation arm (HFA). There exists a dosimetric difference between the two arms of treatment, in spite of similar dose coverage [planning treatment volume (PTV) D90 92·04% in CRA versus 92·5% in HFA; p = 0·49], average dose in HFA is less than that of CRA (p < 0·001); so is the maximum clinical target volume (CTV) dose (p < 0·001). Similarly, average lung dose in HFA arm is significantly lower than CRA (9·9 versus 10·84; p = 0·06), but the V20Gy of lung and V30Gy of heart had no difference. The toxicity of radiation was comparable with similar mean time to produce toxicity [CRA: 7 W, HFA: 10 W; hazard ratio 0·64, 95% confidence interval (CI) = 0·28–1·45]. Three-year recurrence event was alike in two arms (CRA: 4·9%, HFA: 5·8%; p = 0·76). Mean DFS in CRA is 230 weeks and that of HFA is 235 weeks with hazard ratio 1·01 (95% CI = 0·32–3·19; p = 0·987).

Though biologically effective dose (BED) in hypofractionation is lesser than that of conventional fractionation, there are indistinguishable toxicity, locoregional recurrence, distant failure rate and DFS between the two modalities.

Second primary breast cancers are among the most common risks to female patients who have received radiotherapy for mediastinal lymphoma.

This study aims to audit breast dose in women who received mediastinal radiotherapy for lymphoma and compare the combined dose parameter values measured to those in the literature.

Twenty-three patient datasets from 2017 to 2021 were obtained. Inclusion criteria, such as female gender and 30Gy prescription dose, were applied. Target volumes were delineated using involved site radiotherapy and planned on Eclipse (Varian, Palo Alto, CA) using either fixed field or VMAT. Breast contours were retrospectively outlined according to RTOG/EORTC guidance and descriptive statistics were used to compare findings to those from the literature.

Differences were found in V4gy, V5Gy and mean dose compared to the literature with mean dose being 2Gy in the literature and 4Gy in this audit.

Breast dose parameter values between patients in this study vary due to multiple factors. These include the treatment delivery method used and the position of the treatment field in relation to the location of breast tissue. Mean dose and V4% and V5% to breast tissue found in this study differ from that found in the literature. This study highlights the importance of accurate contouring and optimising breast tissue when possible.

Dosimetric comparison between volumetric-modulated arc therapy (VMAT) and helical tomotherapy (HT) in the treatment of bilateral breast cancer (BBC).

Ten patients treated on HT were selected retrospectively. Dose prescription was 50 Gy in 25 fractions to breast/chest wall and supraclavicular fossa (SCF) while tumour bed was simultaneously boosted to 61 Gy in 25 fractions. VMAT plans were made with four mono-isocentric partial arcs. The monitoring unit (MU) and treatment time were used to quantify the treatment efficiency. Target volumes were compared for homogeneity index (HI), conformity index (CI) while organs at risk (OARs) were compared for relevant dose volumes and integral doses (IDs).

For targets, no significant difference is observed between VMAT and HT in CI but VMAT could give better HI. The mean lung dose, V20 and V5 is 10·6 Gy versus 8·4 Gy (p-value 0·03), 12% versus 11·5% (p-value 0·5) and 78·1% versus 43·4% (p-value 0·005), respectively. The mean heart dose, V30 and V5 is 4·9 Gy versus 4·7 Gy (p-value 0·88), 0·5% versus 1·5% (p-value 0·18) and 26·2% versus 22·8% (p-value 0·4). Integral dose (ID) for the whole body and heart are comparable: 289 Gy kg versus 299 Gy kg (p-value 0·24) and 2·9 Gy kg versus 2·8 Gy kg (p-value 0·80). ID for lungs was significantly higher with VMAT: 7·9 Gy kg versus 6·3 Gy kg (p-value 0·03). There is a 53% reduction in treatment time and 78% in MU with VMAT against HT.

VMAT can generate clinically acceptable plans comparable to HT for BBC. HT shows better control over low dose spillage in lungs compared to VMAT thereby increasing ID to lungs. VMAT shows better homogeneity and efficient treatment delivery than HT.

In this study, the differences between calculated and measured dose values were then analysed to assess the performance, in terms of accuracy, of the tested treatment planning system (TPS) algorithms applied to calculate electron beam dose targeted and non-targeted the breast region.

The beryllium oxide (BeO) dosimeters placed on the female RANDO phantom were irradiated 12 MeV electron energy with medical linear accelerator and repeatedly read in the Risø thermoluminescence (TL)/optically stimulated luminescence (OSL) system via OSL method at least three times.

For electron treatment, one made quantitative comparisons of the dose distributions calculated by TPSs with those from the measurements by OSL at various points in the RANDO phantom.

The mean dose measured from the dosimeters placed on the female RANDO phantom target left breast region was 160 cGy and non-target right breast region was 1·2 cGy. Analysis of Generalised Gaussian Pencil Beam (GGPB) and Electron Monte Carlo (eMC) algorithms for determined region mean point dose values, respectively, 174 and 164 cGy. Two algorithms for non-targeted region calculated same point dose values of 0·2 cGy.

The results of this study showed that BeO dosimeters can be used with OSL method in radiotherapy applications and it is a very important tool for the determination of targeted/non-targeted absorbed dose.

The aim of this study is to compare patient geometrical uncertainties in the treatment of breast boost three-dimensional conformal radiation therapy (3D-CRT) considering both manual alignment and automatic different registration methods in cone-beam computed tomography (CBCT).

A total of 85 patients were chosen for this study. A total of 254 registrations of CBCT vs planning computed tomography (CT) were retrospectively performed using automatic registration algorithms from Elekta XVI system (Clipbox and Mask) to detect patient setup uncertainties. All CBCTs were also matched manually by three health professionals. Mean shift values obtained with manual registration performed by health professionals were used as reference. Absolute value of difference between automatic algorithm shifts and reference values shifts was collected for each enrolled patient considering the three different spatial directions (x,y,z), and the magnitude was calculated (δm for Mask and δc for Clipbox).

Data analysis showed a significant difference in δm and δc. t-Test statistics showed a high difference between Mask and Clipbox, in particular mean δm = (1.3 ± 0.1) mm and δc = (3.3 ± 1.2) mm (p-value <0.0001). Mask algorithm was performed in a very similar way with respect to the reference alignment, and the differences between these two procedures were of the order of 1 mm. Clipbox algorithm showed larger differences with manual registration.

These results suggest that the Mask algorithm may be the optimal choice for patient setup verification in clinical practice for breast boost treatment in 3D-CRT.