Doses to critical organs following radiotherapy and concomitant imaging of the larynx and breast

Harrison, R. M.; Wilkinson, Michael; Rawlings, David J.; Moore, Mary

doi:10.1259/bjr/32814323

Cited by 28 publications

(19 citation statements)

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“…The use of CBCT to improve the setup accuracy in breast RT can increase dose to organs at risk significantly, 15,[33][34][35] and potentially increasing the patients' likelihood of developing a secondary cancer. 36 The associated imaging dose and risks should be carefully considered before use of CBCT for breast especially now that we have identified no statistically significant benefit with CBCT-B use.…”

Section: Discussionmentioning

confidence: 99%

Comparison of setup accuracy of three different image assessment methods for tangential breast radiotherapy

et al. 2016

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IntroductionTo compare the differences in setup errors measured with electronic portal image (EPI) and cone‐beam computed tomography (CBCT) in patients undergoing tangential breast radiotherapy (RT). Relationship between setup errors, body mass index (BMI) and breast size was assessed.MethodsTwenty‐five patients undergoing postoperative RT to the breast were consented for this study. Weekly CBCT scans were acquired and retrospectively registered to the planning CT in three dimensions, first using bony anatomy for bony registration (CBCT‐B) and again using breast tissue outline for soft tissue registration (CBCT‐S). Digitally reconstructed radiographs (DRR) generated from CBCT to simulate EPI were compared to the planning DRR using bony anatomy in the V (parallel to the cranio‐caudal axis) and U (perpendicular to V) planes. The systematic (Σ) and random (σ) errors were calculated and correlated with BMI and breast size.ResultsThe systematic and random errors for EPI (Σ V = 3.7 mm, Σ U = 2.8 mm and σ V = 2.9 mm, σ U = 2.5) and CBCT‐B (Σ V = 3.5 mm, Σ U = 3.4 mm and σ V = 2.8 mm, σ U = 2.8) were of similar magnitude in the V and U planes. Similarly, the differences in setup errors for CBCT‐B and CBCT‐S in three dimensions were less than 1 mm. Only CBCT‐S setup error correlated with BMI and breast size.Conclusions CBCT and EPI show insignificant variation in their ability to detect setup error. These findings suggest no significant differences that would make one modality considered superior over the other and EPI should remain the standard of care for most patients. However, there is a correlation with breast size, BMI and setup error as detected by CBCT‐S, justifying the use of CBCT‐S for larger patients.

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Section: Discussionmentioning

confidence: 99%

Comparison of setup accuracy of three different image assessment methods for tangential breast radiotherapy

et al. 2016

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“…Daily volumetric imaging has been shown to be effective in reducing systematic and random uncertainties in patient positioning for various tumour sites [1][2][3] and improved dose delivery. 4,5 Volumetric imaging may offer additional information to improve the setup accuracy in breast radiotherapy; [6][7][8] however, daily imaging with ionising radiation can increase the dose to organs at risk (OAR) significantly, [9][10][11] potentially increasing the patients' likelihood of developing a secondary cancer. 12 Numerous studies have reported the dose to OAR from various image guidance procedures.…”

Section: Introductionmentioning

confidence: 99%

Imaging dose in breast radiotherapy: does breast size affect the dose to the organs at risk and the risk of secondary cancer to the contralateral breast?

Batumalai

Quinn

Jameson

et al. 2015

J of Medical Radiation Sci

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IntroductionCorrect target positioning is crucial for accurate dose delivery in breast radiotherapy resulting in utilisation of daily imaging. However, the radiation dose from daily imaging is associated with increased probability of secondary induced cancer. The aim of this study was to quantify doses associated with three imaging modalities and investigate the correlation of dose and varying breast size in breast radiotherapy.MethodsPlanning computed tomography (CT) data sets of 30 breast cancer patients were utilised to simulate the dose received by various organs from a megavoltage computed tomography (MV-CT), megavoltage electronic portal image (MV-EPI) and megavoltage cone-beam computed tomography (MV-CBCT). The mean dose to organs adjacent to the target volume (contralateral breast, lungs, spinal cord and heart) were analysed. Pearson correlation analysis was performed to determine the relationship between imaging dose and primary breast volume and the lifetime attributable risk (LAR) of induced secondary cancer was calculated for the contralateral breast.ResultsThe highest contralateral breast mean dose was from the MV-CBCT (1.79 Gy), followed by MV-EPI (0.22 Gy) and MV-CT (0.11 Gy). A similar trend was found for all organs at risk (OAR) analysed. The primary breast volume inversely correlated with the contralateral breast dose for all three imaging modalities. As the primary breast volume increases, the likelihood of a patient developing a radiation-induced secondary cancer to the contralateral breast decreases. MV-CBCT showed a stronger relationship between breast size and LAR of developing a radiation-induced contralateral breast cancer in comparison with the MV-CT and MV-EPI.ConclusionsFor breast patients, imaging dose to OAR depends on imaging modality and treated breast size. When considering the use of imaging during breast radiotherapy, the patient's breast size and contralateral breast dose should be taken into account.

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“…[26][27][28][29][30] . The contributions of IGRT to non-target organ doses have been put into context by Harrison et al [28][29][30] who showed that intense IGRT imaging procedures contributed 5 -30% of the total dose to non-target organs with the remainder dose from the radiotherapy scattered and leakage radiation. Harrison et al expressed reluctance to assign risk estimates to their measured organ doses although, other groups have found the risk models useful to compare different treatment methods whilst accepting the large uncertainties in an absolute risk value.…”

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confidence: 99%

Second cancer incidence risk estimates using BEIR VII models for standard and complex external beam radiotherapy for early breast cancer

et al. 2012

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Purpose-To compare organ specific cancer incidence risks for standard and complex external beam radiotherapy including cone beam CT verification following breast conservation surgery for early breast cancer.Method-Doses from breast radiotherapy and kilovoltage cone beam CT (CBCT) exposures were obtained from thermoluminescent dosimeter (TLD) measurements in an anthropomorphic phantom in which the positions of radiosensitive organs were delineated. Five treatment deliveries were investigated : (i) conventional tangential field whole breast radiotherapy (WBRT), (ii) noncoplanar conformal delivery applicable to accelerated partial beast irradiation (APBI), (iii) twovolume simultaneous integrated boost (SIB) treatment, (iv) forward planned three-volume SIB, (v) inverse-planned three volume SIB. Conformal and intensity modulated radiotherapy (IMRT) methods were used to plan the complex treatments. Techniques spanned the range from simple methods appropriate for patient cohorts with a low local cancer recurrence risk to complex plans relevant to cohorts with high recurrence risk. Delineated organs at risk included brain, salivary glands, thyroid, contra-lateral breast, left and right lung, oesophagus, stomach, liver, colon and bladder. Biological Effects of Ionising Radiation (BEIR) VII cancer incidence models were applied to the measured mean organ doses to determine Lifetime Attributable Risk (LAR) for ages at exposure from 35 to 80 years according to radiotherapy techniques, and included dose from the CBCT imaging.Results-All LAR decreased with age at exposure and were lowest for brain, thyroid, liver and bladder (< 0.1%). There was little dependence of LAR on radiotherapy technique for these organs and for colon and stomach. LAR values for the lungs for the three SIB techniques were two to three times those from WBRT and APBI. Uncertainties in the LAR models outweigh any differences in lung LAR between the SIB methods. Constraints in the planning of the SIB methods ensured that contra-lateral breast doses and LAR were comparable to WBRT, despite their added complexity. The smaller irradiated volume of the ABPI plan contributed to a halving of LAR for contralateral breast compared with the other plan types. Daily image guided radiotherapy (IGRT) Europe PMC Funders Author ManuscriptsEurope PMC Funders Author Manuscripts for a left breast protocol using kilovoltage CBCT contributed <10% to LAR for the majority of organs, and did not exceed 22% of total organ dose.Conclusion-Phantom measurements and calculations of LAR from the BEIR VII models predict that complex breast radiotherapy techniques do not increase the theoretical risk of second cancer incidence for organs distant from the treated breast, or the contralateral breast where appropriate plan constraints are applied. Complex SIB treatments are predicted to increase the risk of second cancer incidence in the lungs compared to standard whole breast radiotherapy ; this is outweighed by the threefold reduction in 5 year local recurrence risk for patie...

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Doses to critical organs following radiotherapy and concomitant imaging of the larynx and breast

Cited by 28 publications

References 10 publications

Comparison of setup accuracy of three different image assessment methods for tangential breast radiotherapy

Comparison of setup accuracy of three different image assessment methods for tangential breast radiotherapy

Imaging dose in breast radiotherapy: does breast size affect the dose to the organs at risk and the risk of secondary cancer to the contralateral breast?

Second cancer incidence risk estimates using BEIR VII models for standard and complex external beam radiotherapy for early breast cancer

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