Efficacy of breast shielding during CT of the head

The effect of contact radiation shielding on breast dose during CT abdomen-pelvis: a phantom study

This study aims to investigate if contact shielding reduces breast radiation dose during computed tomography (CT) abdomen-pelvis examinations using automatic tube current modulation to protect one of the four most radiosensitive organs during CT examinations. Dose measurements were taken with and without contact shielding across the anterior and lateral aspects of the breasts and with and without organ dose modulation (ODM) to quantify achievable dose reductions. Although there are no statistically significant findings, when comparing with and without shielding, the mean breast surface dose was reduced by 0.01 μSv without ODM (1.92-1.91 μSv, p = 0.49) and increased by 0.03 μSv with ODM (1.53-1.56 μSv, p = 0.44). Comparing with and without ODM, the mean breast surface dose was reduced by 0.35 μSv with shielding (1.91-1.56 μSv, p = 0.24) and by 0.39 μSv without shielding (1.92-1.53 μSv, p = 0.17). The addition of contact shielding does not provide significant breast surface radiation dose reduction during CT abdomen-pelvis.

THE EFFECT OF OUT-OF-PLANE PATIENT SHIELDING ON CT RADIATION EXPOSURE AND TUBE CURRENT MODULATIONS: A PHANTOM STUDY ACROSS THREE VENDORS

The aim of this study was to evaluate how out-of-plane patient shielding affects radiation exposure parameters and tube current modulation on different vendors' computed tomography (CT) scanners. Helical CT scans were performed using two homogenous phantoms to mimic patient attenuation. Four CT scanners from three vendors were investigated by varying the distance of the patient shield from the border of the imaging volume. Scans were performed with a shield placed before and after the localizer. Changes in volume computed tomography dose index (CTDIvol), dose-length product (DLP) and tube current-time products were studied. Out-of-field lead shield increased the CTDIvol and DLP values for each scanner at least for one scan setting when the shield was present in the localizer. The most notable changes were recorded with >1.3 pitch values when the shield was closest to the scanned volume (2.5 cm), and the scan direction was towards the shield. The usage of patient shields in the localizer CT scans can disturb TCM even when placed 7.5 cm away from the edge of the scan.

A dual-modality quantification of scattered radiation from head to female breasts during radiological investigations in a tertiary hospital in Nigeria

Background

To quantify the amount of scattered radiation reaching the breasts during x-ray and CT investigations of the head in order to find appropriate justification for an intended change in practice involving torso shielding.

Results

Scattered radiation from the head reached the breasts in both procedures. The range and mean dose were (CR 1.02–3.61/1.94 ± 0.63 mGy) and (CT 2.20–8.50/3.74 ± 2.28 mGy). Both breasts had enormous dose difference in CR (72.3%) and CT (51.4%) which were statistically significant (p < 0.05). Correlation of dose with anthropometric parameters gave weak results.

Conclusion

Despite dose mitigation strategies such as software and hardware modifications in radiological modalities, use of anti-scatter grid, appropriate collimation and dose optimization by radiographers, scattered radiation still traveled from the head to the breasts. These were, however, significantly reduced when shielding was applied. For a dose-safe practice, radiographers are urged, in addition to current strategies at mitigating scatters, to adopt torso shielding during examinations involving contiguous anatomies to the breast.

The efficiency of lead and non-lead shielding on breast dose in head CT

The aim of the study was to assess the effect of the shielding material and its thickness on the measured skin dose to the breasts during the CT examination of the head. The helical and axial head CT was performed on an anthropomorphic phantom (PBU 60). Two types of shielding were tested-lead and non-lead (antimony-bismuth) shielding. Measurements with different thicknesses were performed and the shielding efficiency of the materials was compared. Skin dose to the breasts was measured with an educational direct dosimeter (EDD-30). The shielding efficiency during both scanning protocols indicated an increased dose reduction with the thicker equivalent thickness in both shielding materials. Dose reduction was the highest at 0.5 mm equivalent thickness for both materials; lead shielding reduced the dose by 91% and 83%, the antimony-bismuth shielding by 90% and 86%, during the axial and helical head CT protocols, respectively. Statistically significant differences were found between the materials of the same equivalent thickness (0.175, 0.25 and 0.5 mm) during the helical protocol in favor of the antimony-bismuth shielding. During the axial protocol there were no statistically significant differences. Shielding of radiosensitive organs can prevent unnecessary exposure of radiosensitive organs outside the primary beam. Due to the significant decrease in radiation dose to the breasts, and many other positive attributes, use of the antimony-bismuth shielding instead of the lead shielding should be considered, especially during the helical CT scan of the head.

Efficacy of breast shielding during head computed tomography examination

BACKGROUND

Female breasts are exposed to scattered radiation regardless of not being included in the primary field during head CT. This study aimed to investigate whether the use of lead shielding is beneficial in dose reduction to the breasts during head CT.

PATIENTS AND METHODS

The study was performed in two different hospitals on two different CT units and included 120 patients. Half of the measurements (n = 60) was conducted without the use of lead shielding and the other half (n = 60) with the use of lead shielding of 0.5 mm equivalent thickness.

RESULTS

Significant skin dose reduction to the breasts during head CT in both hospitals with the use of lead shielding was discovered; 81% (338.2 ± 43.7 μGy to 64.3 ± 18.8 μGy) in Hospital A and 74% (from 253.1 ± 35.1 μGy to 65.3 ± 16.9 μGy) in Hospital B.

CONCLUSIONS

Considering the assumed carcinogenic effect of low doses of radiation, high frequency of the head CT scans and the significant reduction of radiation doses to the highly radiosensitive breasts, the use of lead shielding is highly recommendable.

A PHANTOM STUDY SHOWING THE IMPORTANCE OF BREAST SHIELDING DURING HEAD CT

This study aimed to investigate the dose to the breasts during head computed tomography (CT) if lead shielding is used. The study was performed in two major hospitals using helical and axial protocols on an anthropomorphic phantom. Measurements were performed with and without the use of a lead shield of 0.5 mm equivalent density. The results showed a significant decrease in dose with the lead shielding in both hospitals. During the helical protocol, the use of shielding significantly reduced the dose by 96% in Hospital A and 82% in Hospital B. The dose reduction during axial protocol was also significant: 95% in Hospital A and 86% in Hospital B with lead shielding. Considering the significant dose reduction of 82% up to 96% during this study, we highly recommend the shielding of breasts regardless of the protocol used during head CT examinations.

Effectiveness of Breast and Eye Shielding During Cervical Spine Radiography: An Experimental Study

Purpose

This study assessed the effectiveness of breast and eye shielding and measured the radiation dose to radiosensitive tissues (eyes and breasts) due to scatter radiation during cervical spine X-ray radiography examinations.

Methods

Using an anthropomorphic phantom, the scattered radiation dose was measured before and after the placement of the lead shield over the eyes and breasts in the anteroposterior (AP) and left lateral projection. A regression formula was utilized to determine the exposure. Mean values and standard deviation of breasts and eyes doses were calculated. The paired two sample t-test was used to compare the recorded dose before and after shielding placement.

Results

Radiation shielding of eyes and breasts during AP cervical spine X-ray decreased radiation dose to the breasts by 99.9% and to the left and right eye by 91% and 89%, respectively. For the left lateral cervical spine X-ray, the radiation dose decreased by 26% and 31% for the left and right eye, respectively, and by 23% and 99% for the left and right breast, respectively. A significant difference was noted comparing the dose before and after the implementing shielding on the eye and breast.

Conclusion

According to the results presented, the dose is significantly reduced, especially considering that they are not in the area of interest but are exposed to scatter radiation.

Effects of shielding the radiosensitive superficial organs of ORNL pediatric phantoms on dose reduction in computed tomography

In computed tomography (CT), some superficial organs which have increased sensitivity to radiation, receive doses that are significant enough to be matter of concern. Therefore, in this study, the effects of using shields on the amount of dose reduction and image quality was investigated for pediatric imaging. Absorbed doses of breasts, eyes, thyroid and testes of a series of pediatric phantoms without and with different thickness of bismuth and lead were calculated by Monte Carlo simulation. Appropriate thicknesses of shields were chosen based on their weights, X-ray spectrum, and the amount of dose reduction. In addition, the effect of lead shield on image quality of a simple phantom was assessed quantitatively using region of interest (ROI) measurements. Considering the maximum reduction in absorbed doses and X-ray spectrum, using a lead shield with a maximum thickness of 0.4 mm would be appropriate for testes and thyroid and two other organs (which are exposed directly) should be protected with thinner shields. Moreover, the image quality assessment showed that lead was associated with significant increases in both noise and CT attenuation values, especially in the anterior of the phantom. Overall, the results suggested that shielding is a useful optimization tool in CT.

Usefulness of a lead shielding device for reducing the radiation dose to tissues outside the primary beams during CT

PURPOSE

This study was done to investigate the efficacy of a lead shield in protecting the tissues outside the primary beams, such as the breast and thyroid, by measurement of the entrance skin dose during CT of the brain, neck, abdomen, and lumbar spine.

MATERIALS AND METHODS

Institutional Review Board approval was obtained. This study included 150 patients (male:female 25:125, age range 15-45 years). In females, brain, lumbar spine, and abdominal CT scans, pre-/post-contrast neck CT scans, and post-contrast liver dynamic CT scans were performed. In males, brain CT scans only were performed. Breast shielding was performed in all females, and thyroid shielding was conducted in patients with brain CT. During all CT studies, the left breast or left thyroid was shielded using a lead shield, and the contralateral side was left unshielded. Thus, each breast or thyroid measurement had its own control for the same demographic data. The efficacy of the shielding of both breasts and thyroids during CT was assessed.

RESULTS

During brain, abdominal, lumbar, pre-/post-contrast neck, and post-contrast liver dynamic CT, 33.5, 26.0, 17.4, 26.5, and 16.2 % of the breast skin dose were reduced, respectively. During brain CT, the thyroid skin dose was reduced by 17.9 % (females) and 20.6 % (males). There were statistically significant differences in the skin doses of shielded organs (p < 0.05). Breast shielding during neck and liver dynamic CT was the most effective compared with breast or thyroid shielding during other CT scans.

CONCLUSIONS

We recommend breast shielding during neck and liver dynamic CT in young female patients to avoid unnecessary radiation exposure.

The effect of breast shielding during lumbar spine radiography

BACKGROUND

The aim of the study was to determine the influence of lead shielding on the dose to female breasts in conventional x-ray lumbar spine imaging. The correlation between the body mass index and the dose received by the breast was also investigated.

MATERIALS AND METHODS

Breast surface dose was measured by thermoluminescent dosimeters (TLD). In the first phase measurements of breast dose with and without shielding from lumbar spine imaging in two projections were conducted on an anthropomorphic phantom. In the second stage measurements were performed on 100 female patients, randomly divided into two groups of 50, with breast shielding only used in one group.

RESULTS

On average, breast exposure dose in lumbar spine imaging in both projections (anteroposterior (AP) and lateral) was found reduced by approximately 80% (p < 0,001) when shielding with 0.5 mm lead equivalent was used (from 0.45±0.25 mGy to 0.09±0.07 mGy on the right and from 0.26±0.14 mGy to 0.06±0.04 mGy on the left breast). No correlation between the body mass index (BMI) and the breast surface radiation dose was observed.

CONCLUSIONS

Although during the lumbar spine imaging breasts receive low-dose exposure even when shielding is not used, the dose can be reduced up to 80% by breast shielding with no influence on the image quality.

Efficacy of colour Doppler ultrasound in diagnosis of cervical lymphadenopathy

OBJECTIVES

The purpose of the study was to evaluate the efficacy of colour doppler ultrasound (CDUS) in diagnosis of cervical lymphadenopathy.

MATERIALS AND METHODS

The study group consisted of 30 patients with clinical evidence of cervical lymphadenopathy (19 patients with clinically suspected reactive/benign cervical lymphadenopathy and 11 patients with clinically suspected malignant/metastatic cervical lymphadenopathy). CDUS examinations were carried out for one lymph node (LN) in each patient and fine needle aspiration cytology of the same LN was obtained. To evaluate the efficacy of CDUS, comparison between clinical features, CDUS features and cytological features of enlarged cervical LNs were then done.

RESULTS

Clinical examination evaluated 54 cervical LNs. CDUS evaluation discovered an additional 55 LNs (54 + 55 = 109). Accuracy of the CDUS examination was higher than clinical evaluation. Patterns of colour doppler flow signals when correlated with cytological diagnosis showed central flow for benign nodes and peripheral flow for malignant nodes. The mean pulsatility index (PI) was 1.977 ± 0.669 in LNs involved with metastases and 0.839 ± 0.135in LNs affected by benign processes. LNs involved with metastases showed a characteristic high resistive index (RI) and a high pulsatility index than the lymph nodes affected by benign processes. The RI and PI were significantly different between LNs affected by benign versus malignant disease.

CONCLUSION

Nodal vascularity of the LNs can be used to differentiate benign from malignant lymphadenopathy. CDUS can be trusted upon as a reliable marker for the diagnosis of cervical lymphadenopathy.

Organ and effective dose reduction in adult chest CT using abdominal lead shielding

OBJECTIVES

The purpose of this study was to evaluate and compare organ and effective dose savings that could be achieved using conventional lead aprons and a new, custom-designed shield as out-of-plane shielding devices during chest CT scans.

METHODS

Thermoluminescent dosimeters were used to measure doses throughout the abdomen and pelvis during CT scans of the chest of a RANDO phantom. Dose measurements were made with no shielding, with lead aprons and with the new shield around the abdomen and pelvis in order to quantify the achievable organ and effective dose reductions.

RESULTS

Average dose savings in the 10 phantom sections ranged from 5% to 78% with the highest point dose saving of 93% being found in the mid-pelvis. When shielding was used, the maximum measured organ dose reduction was a 72% dose saving to the testes. Significant dose savings were found throughout the abdomen and pelvis, which contributed to an effective dose saving of 4% that was achieved over and above the dose savings obtained through conventional optimisation strategies. This could yield significant population dose savings and reductions in collective radiation risk.

CONCLUSION

In this study significant organ and effective dose reductions have been achieved through the use of abdominal shielding during chest CT examinations and it is therefore recommended that out-of-plane patient shielding devices should be used for all chest CT scans and potentially for every CT scan, irrespective of body part.

Adaptive planning using megavoltage fan-beam CT for radiation therapy with testicular shielding

This study highlights the use of adaptive planning to accommodate testicular shielding in helical tomotherapy for malignancies of the proximal thigh. Two cases of young men with large soft tissue sarcomas of the proximal thigh are presented. After multidisciplinary evaluation, preoperative radiation therapy was recommended. Both patients were referred for sperm banking and lead shields were used to minimize testicular dose during radiation therapy. To minimize imaging artifacts, kilovoltage CT (kVCT) treatment planning was conducted without shielding. Generous hypothetical contours were generated on each "planning scan" to estimate the location of the lead shield and generate a directionally blocked helical tomotherapy plan. To ensure the accuracy of each plan, megavoltage fan-beam CT (MVCT) scans were obtained at the first treatment and adaptive planning was performed to account for lead shield placement. Two important regions of interest in these cases were femurs and femoral heads. During adaptive planning for the first patient, it was observed that the virtual lead shield contour on kVCT planning images was significantly larger than the actual lead shield used for treatment. However, for the second patient, it was noted that the size of the virtual lead shield contoured on the kVCT image was significantly smaller than the actual shield size. Thus, new adaptive plans based on MVCT images were generated and used for treatment. The planning target volume was underdosed up to 2% and had higher maximum doses without adaptive planning. In conclusion, the treatment of the upper thigh, particularly in young men, presents several clinical challenges, including preservation of gonadal function. In such circumstances, adaptive planning using MVCT can ensure accurate dose delivery even in the presence of high-density testicular shields.

Utilização de vestimentas de proteção radiológica para redução de dose absorvida: uma revisão integrativa da literatura

OBJETIVO: Avaliar a relação entre o uso de vestimenta de proteção radiológica e a diminuição da dose absorvida de radiação ionizante, reforçando a eficácia do seu uso tanto para pacientes quanto para indivíduos ocupacionalmente expostos. MATERIAIS E MÉTODOS: O estudo foi desenvolvido utilizando-se o método de revisão integrativa de literatura, e teve como materiais: 21 artigos, 2 livros, 1 tese, 1 trabalho de conclusão de curso, 1 programa de computador, 4 pesquisas em base de dados (Instituto Brasileiro de Geografia e Estatística e Departamento de Informática do Sistema Único de Saúde) e 2 diretrizes de proteção radiológica. RESULTADOS: A utilização da vestimenta de proteção radiológica, teoricamente, reduz 86% a 99% a dose absorvida. Na prática, a redução nos pacientes pode ser de 88% na radiologia convencional e chegar a 95% no exame tomográfico. Nos indivíduos ocupacionalmente expostos, a redução durante um cateterismo cardíaco é em torno de 90% e durante uma cirurgia ortopédica é de 75%. CONCLUSÃO: Conforme demonstrado em várias pesquisas, o uso de vestimenta de proteção radiológica é eficaz e de baixo custo e reduz a dose desnecessária nos pacientes e nos indivíduos ocupacionalmente expostos. Logo, sua utilização é necessária para a implementação de um efetivo programa de proteção radiológica em um serviço de radiodiagnóstico.

Use of lead shields for radiation protection of superficial organs in patients undergoing head CT examinations

Head computed tomography examinations are often accompanied with unnecessary irradiation of superficial organs that are rarely the main target for the investigation. The aim of this work is to demonstrate that lead shields could be effectively used to protect superficial organs without compromising image quality where superficial organ itself is not a target and that the irradiation of the superficial organ is unavoidable. The objective was achieved by first assessing the image quality using phantom measurements made with and without lead shielding in order to determine optimal shielding thickness for patient applications. The entrance surface doses (ESDs) to superficial organs of sixty patients were measured using LiF-thermoluminescent dosemeters without, with one layer, or with two layers of lead shields. Phantom studies demonstrated that the use of modified lead shields of up to 0.25 mm thickness could be used without significant effect on the image quality for central and posterior regions. In these studies, lead shields of 0.25 mm thickness reduce the ESDs to the lens of the eyes and thyroid by 44 and 51%, respectively. The image quality reduction by eye shields was significant to the anterior (i.e. orbital) region but marginal to the central and posterior regions (cerebrum). In view of the above, the use of modified lead shields could reduce the dose to the superficial organs considerably without significantly compromising image quality.

Investigation into the effects of lead shielding for fetal dose reduction in CT pulmonary angiography

This work aims to determine whether lead shielding can be used to decrease the radiation dose to the fetus during CT scans for the diagnosis of pulmonary embolism during early stage pregnancy. An anthropomorphic phantom was modified to contain a 15 cc ionization chamber at the site of the uterus to enable fetal dose to be measured. The effects of a range of scan parameters, positioning of lead and thicknesses of lead were investigated. Fetal dose was lower with lower values of kV(p) and mAs. An increasing thickness of lead decreased the radiation dose to the uterus, as did increasing the proportion of the patient covered by the lead shielding. Fetal dose increased exponentially as the edge of the scan volume moved closer to the point of measurement. In no experiment was the dose to the fetus increased by the presence of the lead. It was found that the fetal radiation dose from a CT scan following a pulmonary embolism protocol can be effectively reduced by the use of lead shielding.

Dose reduction in paediatric MDCT: general principles

The number of multi-detector array computed tomography (MDCT) examinations performed per annum continues to increase in both the adult and paediatric populations. Estimates from 2003 suggested that CT contributed 17% of a radiology department's workload, yet was responsible for up to 75% of the collective population dose from medical radiation. The effective doses for some CT examinations today overlap with those argued to have an increased risk of cancer. This is especially pertinent for paediatric CT, as children are more radiosensitive than adults (and girls more radiosensitive than boys). In addition, children have a longer life ahead of them, in which radiation induced cancers may become manifest. Radiologists must be aware of these facts and practise the ALARA (as low as is reasonably achievable) principle, when it comes to deciding CT protocols and parameters.

Quantitative assessment of selective in-plane shielding of tissues in computed tomography through evaluation of absorbed dose and image quality

This study aimed at assessment of efficacy of selective in-plane shielding in adults by quantitative evaluation of the achieved dose reduction and image quality. Commercially available accessories for in-plane shielding of the eye lens, thyroid and breast, and an anthropomorphic phantom were used for the evaluation of absorbed dose and image quality. Organ dose and total energy imparted were assessed by means of a Monte Carlo technique taking into account tube voltage, tube current, and scanner type. Image quality was quantified as noise in soft tissue. Application of the lens shield reduced dose to the lens by 27% and to the brain by 1%. The thyroid shield reduced thyroid dose by 26%; the breast shield reduced dose to the breasts by 30% and to the lungs by 15%. Total energy imparted (unshielded/shielded) was 88/86 mJ for computed tomography (CT) brain, 64/60 mJ for CT cervical spine, and 289/260 mJ for CT chest scanning. An increase in image noise could be observed in the ranges were bismuth shielding was applied. The observed reduction of organ dose and total energy imparted could be achieved more efficiently by a reduction of tube current. The application of in-plane selective shielding is therefore discouraged.

CT dose reduction in children

World wide, the number of CT studies in children and the radiation exposure by CT increases. The same energy dose has a greater biological impact in children than in adults, and scan parameters have to be adapted to the smaller diameter of the juvenile body. Based on seven rules, a practical approach to paediatric CT is shown: Justification and patient preparation are important steps before scanning, and they differ from the preparation of adult patients. The subsequent choice of scan parameters aims at obtaining the minimal signal-to-noise ratio and volume coverage needed in a specific medical situation; exposure can be divided in two aspects: the CT dose index determining energy deposition per rotation and the dose-length product (DLP) determining the volume dose. DLP closely parallels the effective dose, the best parameter of the biological impact. Modern scanners offer dose modulation to locally minimise exposure while maintaining image quality. Beyond the selection of the physical parameters, the dose can be kept low by scanning the minimal length of the body and by avoiding any non-qualified repeated scanning of parts of the body. Following these rules, paediatric CT examinations of good quality can be obtained at a reasonable cost of radiation exposure.