Breast Irradiation Techniques Research Articles

Abstract ED05-02: When less is more: Patient-friendly radiation courses with WBI and PBI

Abstract Over the past few decades, remarkable progress has been made in understanding the biology and pathology of breast cancer. A personalized conservative approach has been currently adopted addressing the patient's individual risk of relapse. After postoperative whole breast irradiation for early-stage breast cancer, a rate of recurrences outside the initial tumour bed lower than 4% at 5 years was observed. Thus, the highest benefits of breast irradiation seem to result from the dose delivered to the tissue neighbouring the tumour bed. Nonetheless, reducing treatment morbidity while maintaining radiation therapy's ability to decrease local recurrences is an important challenge in treating patients with radiation therapy. In this regard, strategies such as partial-breast irradiation and whole breast hypofractionation have been developed to reduce toxicity without compromising oncologic outcomes. According to the national and international published guidelines, clinical oncologists can refer to specific dose/fractionation schedules and eligible criteria. However, there are still some areas of open questions. Breast cancer represents a multidisciplinary paradigm; it should be considered a heterogeneous disease where a "one-treatment-fits-all" approach cannot be considered an appropriate option. A wide overview on the main partial and whole breast irradiation advantages, risks, timings, techniques, and available recommendations is presented, providing practical findings to support clinical decision-making, exploring future perspectives, towards a balance for optimisation of breast cancer. Citation Format: I. Meattini. When less is more: Patient-friendly radiation courses with WBI and PBI [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr ED05-02.

Intra-fractional dose rate effect in continuous and interrupted irradiation of the MCF-7 cell line: Possible radiobiological implications for breath-hold techniques in breast radiotherapy?

To investigate the effects of different dose rates (DRs) in continuous and interrupted irradiation on in-vitro survival of the MCF-7 cell line, towards finding possible radiobiological effects of breath-hold techniques in breast radiotherapy (RT), in which intra-fractional beam interruptions and delivery prolongation can occur. MCF-7 cells were irradiated continuously or with regular interruptions using 6 MV x-rays at different accelerator DRs (50-400 cGy/min) to deliver a 2 Gy dose. The interrupted irradiation was delivered in a 10 s on, 10 s off manner. Then, cell survival and viability were studied using colony and MTT assays, respectively. Survival and viability with continuous and interrupted irradiation were similar (P > 0.5). A significant increase in survival at 50, 100, and 400 cGy/min compared to 200 and 300 cGy/min was observed, also a significant decreasing and then increasing trend from 50 to 200 cGy/min and 200 to 400 cGy/min, respectively (P < 0.04). Relative to 200 cGy/min, the survival fractions at 50, 100, 300, and 400 cGy/min were 1.24, 1.23, 1.05, and 1.20 times greater, respectively. Cell viability did not show significant differences between the DRs, despite following the same trend as cell survival. Our results suggest that for continuous irradiation of in-vitro MCF-7 cells, with increasing DR within the 50-400 cGy/min range, sensitivity increases and then decreases (inverse effect), also that up to doubling of treatment time in breath-hold techniques does not affect in-vitro radiobiological efficacy with 200-400 cGy/min accelerator DRs. Further confirmatory studies are required.

Brachytherapy in Breast Cancer Treatment: Physical and Biological Aspects

This scientific paper focuses on the treatment of breast cancer, one of the most common cancers among women. Despite increased awareness and the popularity of screening tests, statistics indicate a significant rise in incidence. The paper presents breast-conserving treatment methods, including brachytherapy, as a modern technique with promising outcomes. It describes the physical properties of ionizing radiation used in brachytherapy, discussing the photoelectric effect, Compton effect, and the phenomenon of pair production.&#x0D; The paper then delves into the biological effects of ionizing radiation, emphasizing the dependence on the cell cycle phase. It highlights lethal, sublethal, and potentially lethal cellular damage, categorizing the effects of radiation interaction into early and late responses.&#x0D; The discussion transitions to the application of brachytherapy in breast cancer treatment, focusing on various techniques such as LDR, PDR, and HDR. The paper provides a detailed description of brachytherapy's use in breast-conserving treatment, considering contraindications, treatment planning, and Accelerated Partial Breast Irradiation (APBI) techniques.&#x0D; The radioisotopes used in brachytherapy are also presented, with special attention to Iridium-192. The physical and practical aspects related to this isotope are discussed, along with other commonly used radioisotopes such as Cesium-137, Cobalt-60, and Strontium-90.&#x0D; The paper concludes with a summary, emphasizing the significance of brachytherapy in breast cancer treatment and outlining its prospects for development. The authors highlight precision and shortened therapy duration.

Cardiac protective techniques in left breast radiotherapy: rapid selection criteria for routine clinical decision making

ObjectiveIn left breast radiotherapy (RT) desired heart doses may be achieved without heart-sparing RT techniques in some patients. We aimed to examine the existence of predictive factors and cutoff points to determine which patients are the main candidates for heart-sparing RT techniques.Material and methodDosimetric data for left breast cancer was examined. RT plans were made at conventional doses to the breast and peripheral lymph nodes. Statistical analyses were performed using SPSS 22.0 (SPSS Inc., IBM Corp., Armonk, NY).Result114 cases were evaluated by ROC (Receiver operating characteristic) analysis in the breast-conserving surgery (BCS) and mastectomy groups. While only left lung volume (AUC: 0.74, 95% CI 0.61–0.87, p = 0.002) was significant in BCS cases, in cases with mastectomy, left lung volume (AUC: 0.81, 95% CI 0.69–0.94, p = 0.002) and lung/heart volume ratio (AUC: 0.83, 95% CI 0.70–0.96, p = 0.001) had a significant relationship with the relevance of heart doses. The cutoff point of 1.92 was selected for the lung/heart volume ratio for the mastectomized patients. Moreover, the cutoff point 1154 cc and 1208 cc was determined for the left lung volume for the BCS and mastectomized patients, respectively.ConclusionVarious cutoff points in left breast RT can be used to predict whether RT plans will meet QUANTEC (Quantitative Analysis of Normal Tissue Effects in the Clinic) heart dose limits. Evaluating only these few cutoff points before planning makes it possible to eliminate 70% of patients with BCS and 40% of patients with mastectomy from respiratory-controlled methods, which require time and effort. Patients with lung volume and lung/heart volume ratio smaller than the cutoff values can be considered primary candidates for heart-sparing techniques.

Experience with intraoperative radiation therapy in an urban cancer center

Background/objectiveIntra-operative radiation therapy (IORT) is a newer partial breast irradiation technique that has been well studied in 2 large randomized trials, the TARGIT-A and ELIOT trials. We initiated our IORT program in 2018 in the context of a registry trial, and aim to report our early results thus far.MethodsWe instituted an IORT practice using Intrabeam® low energy 50kVp x-rays for selected breast cancer cases in 2018. Patients were enrolled on our institutional registry protocol which allowed for IORT in ER + patients with grade 1–2 DCIS ≤ 2.5 cm or invasive disease ≤ 3.5 cm in patients of at least 45 years of age.ResultsBetween January 2018 and December 2021, 181 patients with clinical stage 0-IIA ER + breast cancer were evaluated. One hundred sixty-seven patients ultimately received IORT to 172 sites. The majority of patients received IORT at the time of initial diagnosis and surgery (160/167; 95.8%). Re-excision post IORT occurred in 16/167 patients (9.6%) due to positive margins. Adjuvant RT to the whole breast +/- LN was ultimately given to 23/167 (13.8%) patients mainly due to positive sentinel LN found on final pathology (12/23; 52%); other reasons were close margins for DCIS (3/23; 13%), tumor size (3/23; 4.3%), and multifactorial (5/23; 17.4%). Five patients (3%) had post-operative complications of wound dehiscence. There were 3 local recurrences (1.6%) at a median follow-up of 27.9 months (range: 0.7– 54.8 months).ConclusionsIORT has been proven to be a safe and patient-centered form of local adjuvant RT for our population, in whom compliance with a longer course of external beam radiation can be an issue. Long term efficacy remains to be evaluated through continued follow up. In the era of COVID-19 and beyond, IORT has been an increasingly attractive option, as it greatly minimizes toxicities and patient visits to the clinic.Trial registrationAll patients were prospectively enrolled on an institutional review board-approved registry trial (IRB number: 2018–9409).

Current Cardioprotective Strategies for the Prevention of Radiation-Induced Cardiotoxicity in Left-Sided Breast Cancer Patients.

Breast cancer (BC) is the most common malignancy in females, accounting for the majority of cancer-related deaths worldwide. There is well-established understanding about the effective role of radiotherapy (RT) in BC therapeutic strategies, offering a better local-regional control, prolonged survival, and improved quality of life for patients. However, it has been proven that conventional RT modalities, especially in left-sided BC cases, are unable to avoid the administration of high RT doses to the heart, thus resulting in cardiotoxicity and promoting long-term cardiovascular diseases (CVD). Recent radiotherapeutic techniques, characterized by dosimetric dose restrictions, target volume revision/modifications, an increased awareness of risk factors, and consistent follow-ups, have created an advantageous context for a significant decrease inpost-RT CVD incidence. This review presents the fundamental role of current cardioprotective strategies in the prevention of cardiotoxic effects in left-BCRT. A literature search was conducted up to January 2023 using the Cochrane Central Register of Controlled Trials and PubMed Central databases. Our review refers to new radiotherapeutic techniques carried out on patients after BC surgery. Specifically, a dose evaluation of the heart and left anterior descending coronary artery (LADCA) was pointed out for all the included studies, depending on the implemented RT modality, bed positioning, and internal mammary lymph nodes radiation. Several studies reporting improved heart sparing with new RT techniques in BC patients were searched. In addition to the RT modality, which definitely determines the feasibility of achieving lower doses for the organs at risk (OARs), better target coverage, dose conformity and homogeneity, and the patient's position, characteristics, and anatomy may also affect the evaluated RT dose to the whole heart and its substructures. Modern BC RT techniques seem to enable the administration of lower doses to the OARs without compromising on the target coverage. The analysis of several anatomical parameters and the assessment of cardiac biomarkers potentiate the protective effect of these new irradiation modalities, providing a holistic approach to the radiation-associated risks of cardiac disease for BC patients. Despite technological advances, an inevitable cardiac radiation risk still exists, while adverse cardiac events may be observed even many years after RT. Studies with longer follow-ups are required in order to determine the effectiveness of modern breast RT techniques.

Special issue. De-escalation of loco-regional treatment in breast cancer: Time to find the balance? Partial breast irradiation.

Breast cancer is the most common cancer in women worldwide. Over the past few decades, remarkable progress has been made in understanding the biology and pathology of breast cancer. A personalized conservative approach has been currently adopted addressing the patient's individual risk of relapse. After postoperative whole breast irradiation for early-stage breast cancer, a rate of recurrences outside the initial tumour bed lower than 4% was observed. Thus, the highest benefits of breast irradiation seem to result from the dose delivered to the tissue neighbouring the tumour bed. Nonetheless, reducing treatment morbidity while maintaining radiation therapy's ability to decrease local recurrences is an important challenge in treating patients with radiation therapy. In this regard, strategies such as partial-breast irradiation have been developed to reduce toxicity without compromising oncologic outcomes. According to the national and international published guidelines, clinical oncologists can refer to specific dose/fractionation schedules and eligible criteria. However, there are still some areas of open questions. Breast cancer represents a multidisciplinary paradigm; it should be considered a heterogeneous disease where a "one-treatment-fits-all" approach cannot be considered an appropriate option. This is a wide overview on the main partial breast irradiation advantages, risks, timings, techniques, and available recommendations. We aim to provide practical findings to support clinical decision-making, exploring future perspectives, towards a balance for optimisation of breast cancer.

PO-2003 Comparison of Hybrid and VMAT planning technique for breast and lymph nodes irradiation

PO-2003 Comparison of Hybrid and VMAT planning technique for breast and lymph nodes irradiation

Lateral wedge with medial only cardiac shielding (LEMONADE) technique in left breast radiotherapy

This dosimetric study analyzed the lateral wedge with medial only cardiac shielding (LEMONADE) technique for left breast radiotherapy (LBRT) against three other commonly used techniques which is a follow-up from our earlier publication of LEMONADE technique in left chest wall (LCW) radiotherapy.&#x0D; Dosimetric parameters of 30 consecutive patients who underwent LBRT with LEMONADE technique (P1) after breast conserving surgery (BCS) were compared with 3 other virtually reconstructed plans: no cardiac shielding with paired wedges; P2 (paired wedges and medial only Y-direction shielding) and P3 (paired wedges and bilateral Y-direction shielding).&#x0D; P1 had target volume (TV) coverage [mean 90% isodose coverage of 89.00% ± 3.96 vs 86.28% ± 4.80 and 84.43% ± 5.70 for P2 and P3, respectively]. While there is 3.07% drop in TV coverage compared to no cardiac shielding, the V26Gy of heart dropped from 5.26% to a negligible 0.56% for P1. Low dose region (TV receiving &lt; 30Gy) is also significantly lesser for P1 compared to P2 and P3 (1.50% vs 3.61% and 5.65%).&#x0D; The earlier positive LEMONADE dosimetric study of LCW radiotherapy has been replicated in this study with much better dose volume parametres likely due to the physical properties of intact breast. LEMONADE is an easily re-producible and simple radiotherapy technique that can be implemented in most radiotherapy centres. Further study is needed on the use of LEMONADE technique in extreme hypofractionation.

Abstract ED8-1: Overview of the current state of the art – what patients and oncologists need to know

Abstract While radiation therapy plays a significant role in the treatment of breast cancer for many patients, the nuances of modern day radiation therapy are often poorly understood by both patients and referring providers. Radiation therapy techniques to reduce toxicity and improve treatment accuracy have rapidly evolved in the past decade. This session will introduce non-radiation oncologists to recent innovations that allow increased personalization of treatment based on anatomical variations. Methods to improve patient positioning will be discussed. Frequently utilized dosimetric techniques for breast radiotherapy will be described and compared, including Volumetric Modulated Arc Therapy (VMAT), Intensity Modulated Radiation Therapy (IMRT), and 3D conformal planning. New methods for patient monitoring during treatment and the purpose of respiratory gating will be reviewed. Finally, the impact of surgical therapies on radiation planning and delivery will also be examined. Attendees should leave the session having a greater understanding of the current available options for radiotherapy and rationale for the choice of treatment technique. Citation Format: Rachel Jimenez. Overview of the current state of the art – what patients and oncologists need to know [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr ED8-1.

Planning system-dependent recommendations of intensity-modulated technique for breast radiotherapy: A literature review-based adaptation and institutional dosimetric experience from a large-volume tertiary cancer care hospital

Planning system-dependent recommendations of intensity-modulated technique for breast radiotherapy: A literature review-based adaptation and institutional dosimetric experience from a large-volume tertiary cancer care hospital

Experimental determination of breast skin dose using volumetric modulated arc therapy and field-in-field treatment techniques

Abstract Introduction: The use of volumetric modulated arc therapy (VMAT) on the breast has several dosimetric advantages but its impact on skin dose should be evaluated and compared to well-established treatment techniques using tangential fields. The aim of this work is to contrast the skin dose for VMAT and field-in-field (FIF) and to estimate the magnitude of the skin dose involved. Method: The skin dose was measured, without build-up, using thermoluminescent dosimeter (TLD) and optically stimulated luminescence dosimeter (OSLD) in breast radiotherapy by an in-house anthropomorphic phantom. Two different treatment techniques were used: FIF and VMAT, based on the planning strategy proposed by Nicolini et al. The dose levels were 4300 cGy, 4600 cGy and 5600 cGy in 20 fractions. In vivo dosimetry with TLD for VMAT was performed for different breast sizes in the same locations as phantom measurements. Results: The ipsilateral phantom breast skin dose using both treatment techniques was equivalent. TLD measured doses by the VMAT technique were up to 5% higher than OSLD, although they agree if we consider the geometry uncertainty of the TLD. In accordance with in vivo dosimetry, the mean dose of the ipsilateral breast skin was 62 ± 6% (51%, 75%) relative to the prescribed dose, regardless of the breast size for the volumes considered with this small population (n = 9) as shown by Mann–Whitney U-test (Z = 1·9, 95% confidence). The uncertainty expected in this region due to geometry (volume) changes is up to 9% higher for volumes from 225·9 cc to 968·8 cc. According to the treatment techniques and in vivo dosimetry, the contralateral breast skin dose was 1·0% in FIF and 2·5% in VMAT concerning the prescribed dose. Conclusion: There is no difference in skin dosimetry between VMAT and FIF techniques on the ipsilateral breast. It provides useful support for the use of VMAT as a planning technique for breast irradiation. The work describes the importance of quantifying potential differences in skin dosimetry.

Three-dimensional conformal radiotherapy breast cancer planning: An evaluation study comparing two techniques using homemade phantom

Anthropomorphic phantoms, which can provide equivalent human tissue densities, are one of the best solutions for verifying the quality of radiotherapy treatment plans produced by treatment planning systems. The goal of this work was to develop and fabricate a breast phantom to estimate radiation doses to the breast, lung, and surface using radiochromic films (EBT3) for basically two techniques of three-dimensional conformal radiotherapy (3D-CRT) treatment planning. Thirty-two acrylic slices were used to construct the phantom. Cork and Teflon were used to mimic the lung and bone, respectively. Four slots were drilled for dosimetry purposes to allow access to the areas of ionization chamber installation. Both wedged and open of two tangential beams techniques were applied. With a mean deviation of 1.02 ± 1.1, the variation between estimated point doses and measurements using the three ionization chambers ranged from 2.9 to 1.4%. Using 0, 5 and 10 mm boluses, the mean percentage doses on the target surface were 54.7, 88.6 and 91.7% of the prescribed dose (PD), respectively. The homemade phantom was appropriate for conducting quality control (QC) tests for 3D-CRT planning techniques for breast radiotherapy.

Fetal dose estimation for Virtual Tangential-fields Arc Therapy whole breast irradiation by optically stimulated luminescence dosimeters

Breast cancer is the most frequently diagnosed tumor in pregnant women and radiation therapy should carefully be weighted up because of the dose to the fetus. The aim of this study was to investigate fetal dose in a patient treated with Virtual Tangential-fields Arc Therapy (ViTAT), an innovative technique for whole breast irradiation. Optically stimulated luminescence detectors (OSLDs) were calibrated on a Varian TrueBeam linac, with both a 6X and 6XFFF beam quality, and used for out-of-field measurements. Fetal dose related with ViTAT technique was compared to the standard 3D conformal radiation therapy technique (3DCRT). The fetal dose delivered with a ViTAT technique planned with 6XFFF beam was also investigated. Measurements were taken on a phantom composed of Rando Alderson Phantom slices and solid water slabs. OSLDs were placed in a region identified by the height of the fundus from conception to the twentieth week using a custom made PMMA grid. Due to the higher number of monitor units, the peripheral dose of ViTAT delivered with 6X beams is higher than that of 3DCRT. However, nanoDots measurements prove that ViTAT can be used in place of 3DCRT while maintaining similar fetal dose levels if 6XFFF beams are used.

A semi-automatic planning technique for whole breast irradiation with tangential IMRT fields

PurposeTo implement a semi-automatic planning technique for whole breast irradiation with two tangential IMRT fields and to test the produced dose distribution against clinical 3DCRT plans, for introducing the technique in clinical practice. MethodsThe Auto-Planning module of the Pinnacle3 (Philips) treatment planning system was used for generating a Treatment Technique on left-sided breast cancer patients treated in free breathing or in deep inspiration breath hold (DIBH) and to right-sided breast cancer patients. The technique was evaluated against 3DCRT clinical plans in terms of dosimetric plan parameters. Plan robustness toward patient displacements was assessed on a subset of patients by inducing shifts to the isocenter. ResultsA statistically significant improvement in target coverage and dose homogeneity was observed for autoIMRT. No statistically significant differences were observed for ipsilateral organs, except for the ipsilateral lung in left DIBH, where slightly lower Dmean and V18% are registered for autoIMRT. Slightly higher Dmean doses (although far below the constraints) to contralateral organs were observed for autoIMRT plans.AutoIMRT plans were shown to be as robust as 3DCRT plans toward isocenter shifts, with a maximum decrease in CTV coverage of −2.2% and −2.1% for autoIMRT and 3DCRT, respectively. Average planning times were 40 min for 3DCRT and 6 min for IMRT plans. ConclusionsThe developed autoIMRT technique was proven to be advantageous for target coverage and homogeneity and sufficiently robust towards isocenter displacements. The use of automated planning consistently reduces the planning workload with improvements in plan quality.

Accelerated Partial Breast Irradiation Using External Beam or Intraoperative Electron Radiation Therapy: 5-Year Oncological Outcomes of a Prospective Cohort Study

To evaluate the ipsilateral breast tumor recurrence (IBTR) after 2 accelerated partial breast irradiation (APBI) techniques (intraoperative electron radiation therapy [IOERT] and external beam APBI [EB-APBI]) in patients with early-stage breast cancer. Between 2011 and 2016, women ≥60 years of age with breast carcinoma or Ductal Carcinoma In Situ (DCIS) of ≤30 mm and cN0 undergoing breast-conserving therapy were included in a 2-armed prospective multicenter cohort study. IOERT (1×23.3 Gy prescribed at the 100% isodose line) was applied in 1 hospital and EB-APBI (10×3.85 Gy daily) in 2 other hospitals. The primary endpoint was IBTR (all recurrences in the ipsilateral breast irrespective of localization) at 5 years after lumpectomy. A competing risk model was used to estimate the cumulative incidences of IBTR, which were compared using Fine and Gray's test. Secondary endpoints were locoregional recurrence rate, distant recurrence, disease-specific survival and overall survival. Univariate Cox regression models wereestimated to identify risk factors for IBTR. Analyses were performed of the intention to treat (ITT) population (IOERT n=305; EB-APBI n=295), and sensitivity analyses were done of the per-protocol population (IOERT n=270; EB-APBI n=207). The median follow-up was 5.2 years (IOERT) and 5 years (EB-APBI). Cumulative incidence of IBTR in the ITT population at 5 years after lumpectomy was 10.6% (95% confidence interval, 7.0%-14.2%) after IOERT and 3.7% (95% confidence interval, 1.2%-5.9%) after EB-APBI (P=.002). The locoregional recurrence rate was significantly higher after IOERT than EB-APBI (12.1% vs 4.5%, P=.001). There were no differences between groups in other endpoints. Sensitivity analysis showed similar results. For both groups, no significant risk factors for IBTR were identified in the ITT population. In the per-protocol population, surgical margin status of the DCIS was the only significant risk factor for developing IBTR in both treatment groups. Ipsilateral breast tumor recurrences and locoregional recurrence rates were unexpectedly high in patients treated with IOERT, and acceptable in patients treated with EB-APBI.

Cardiac dosage comparison among whole breast irradiation and partial breast irradiation techniques

Cardiac dosage comparison among whole breast irradiation and partial breast irradiation techniques

Evaluation of Dose Accuracy in the Near-Surface Region for Whole Breast Irradiation Techniques in a Multi-institutional Consortium

PurposeTo assess the accuracy of dose calculations in the near-surface region for different treatment planning systems (TPSs), treatment techniques, and energies to improve clinical decisions for patients receiving whole breast irradiation (WBI). Methods and MaterialsA portable custom breast phantom was designed for dose measurements in the near-surface regions. Treatment plans of varying complexities were created at 8 institutions using 4 different TPSs on an anonymized patient data set (50 Gy in 25 fractions) and peer reviewed by participants. The plans were recalculated on the phantom data set. The phantom was aligned with predetermined shifts and laser marks or cone beam computed tomography, and the irradiation was performed using a variety of linear accelerators at the participating institutions. Dose was measured with radiochromic film placed at 0.5 and 1.0 cm depth and 3 locations per depth within the phantom. The film was scanned and analyzed >24 hours postirradiation. ResultsThe percentage difference between the mean of the measured and calculated dose across the participating centers was -0.2 % ± 2.9%, with 95% of measurements within 6% agreement. No significant differences were found between the mean of the calculated and measured dose for all TPSs, treatment techniques, and energies at all depths and laterality investigated. Furthermore, no significant differences were observed between the mean of measured dose and the prescription dose of 2 Gy per fraction. ConclusionThese results demonstrate that dose calculations for clinically relevant WBI plans are accurate to within 6% of measurements in the near-surface region for various complexities, TPSs, linear accelerators, and beam energies. This work lays the necessary foundation for future studies investigating the correlation between near-surface dose and acute skin toxicities.

Dose Estimation Using Optically Stimulated Luminescence Dosimeter and EBT3 Films for Various Treatment Techniques in Alderson Rando Phantom and Estimation of Secondary Cancer Incidence for Carcinoma of Left Breast.

The aim of this study was to measure the dose to planning target and organ at risk (OAR) using Alderson Rando phantom for various treatment techniques in left breast radiotherapy and to estimate the secondary cancer incidence. Eleven different combinations of plans containing four techniques (three dimensional conformal radiotherapy, intensity-modulated radiation therapy [IMRT], volumetric modulated arc therapy [VMAT], and combination of 3DCRT and VMAT plans (HYBRID)) were created with 6 MV FF and 6 MV FFF (flattening filter and flattening filter-free) photon energies in phantom. Planned target volume and OAR doses in 23 different locations were measured using optically stimulated luminescence dosimeter (OSLD) and EBT3 films. Assuming the age of exposure as 30 years, lifetime attributable risk (LAR) was estimated based on excess absolute risk (EAR) models outlined in the Biological Effects of Ionizing Radiation VII report. Film showed maximum deviations of 6.15% with IMRT_C_FF plan when compared with treatment planning system (TPS). The maximum percentage difference of 1.7% was found with OSLD measurement when compared with TPS for VMAT_T_FFF plan. EAR estimation was done for all the OARs including target. The LARs for left lung, right lung, and right breast were evaluated. The maximum LAR values of 2.92 ± 0.14 were found for left lung with VMAT_C_FFF plans. This study shows that both OSLD and EBT3 films are suitable for dose measurements using Rando phantom. OSLD shows superior results when compared with films, especially with relatively larger distances. Maximum LAR values were found with VMAT_C_FFF plans. Considering the secondary cancer risk associated with the patients treated in the younger age group, it is suggested that in vivo dose estimation should be a part of treatment quality audit whenever possible.

“Learning From Every Patient” – Countdown for the Next Congress of the European SocieTy for Radiotherapy and Oncology (ESTRO)

Dr. Anna Kirby is the ESTRO President-Elect and a Consultant Clinical Oncologist working at the Royal Marsden and Institute of Cancer Research, UK. Dr. Kirby graduated from Cambridge University in 1995 with a first-class honors degree in Medicine and Psychology. She completed her oncology training at The Royal Marsden and Guy’s and St Thomas’ Hospitals followed by a research degree at the Institute of Cancer Research. She specializes in the treatment of patients with breast cancer and leads research into novel breast radiotherapy techniques. She is Chief Investigator of the UK HeartSpare and HeartSpare Plus studies, and breast Lead Investigator on the UK CORE trial evaluating the role of stereotactic radiotherapy in treating metastatic disease.