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ICRP PUBLICATION 117, 2011

RADIOLOGICAL PROTECTION IN

FLUOROSCOPICALLY GUIDED PROCEDURES

PERFORMED OUTSIDE THE IMAGING

DEPARTMENT

陳建全

醫學物理師 醫事放射師

台灣醫學物理公司 www.tmpinc.com.tw

陳建全 • 學歷

• 陽明大學醫放系 學士

• 成功大學醫工所 碩士

• 專業證書

• 教育部部定講師

• 放射診斷醫學物理師證書

• 醫事放射師證書

• 研究成果

• SCI 第一作者1篇

• SCI 共同作者11篇

• 研究計畫主持人1件

• 研究計畫共同主持人6件

• 經歷 • 台灣醫學物理公司

• 總經理

• 長庚大學 • 兼任講師

• 林口長庚紀念醫院 • 磁振造影中心醫學物理師 • 影像診療部醫學物理師

• 中華民國醫學物理學會 • 常務監事

• 桃園縣醫事放射師公會 • 理事 • 總幹事

• 考試院醫事放射師檢覈考試 • 命題/審題委員

• 國健署乳篩計畫 • 醫學物理組委員

• 原能會醫療曝露品質保證計畫 • 講師 • 命題及口試委員

CHAPTERS IN THIS REPORT

1. WHAT IS THE MOTIVATION FOR THIS REPORT?

2. HEALTH EFFECTS OF IONISING RADIATION

3. PATIENT AND OCCUPATIONAL PROTECTION

4. SPECIFIC CONDITIONS IN CLINICAL PRACTICE

5. PREGNANCY AND CHILDREN

6. TRAINING

7. RECOMMENDATIONS

PREFACE

• International Commission on Radiation Protection, ICRP

• Report 84: Pregnancy and Medical Radiation

• Report 85: Avoidance of Radiation Injuries from Medical Interventional Procedures

• Report 86: Prevention of Accidents to Patients Undergoing Radiation Therapy

• Report 87: Managing Patient Dose in Computed Tomography

• Report 93: Managing Patient Dose in Digital Radiology

• Report 94: Release of Patients after Therapy with Unsealed Radionuclides

• Report 97: Prevention of High-dose-rate Brachytherapy Accidents

• Report 98: Radiation Safety Aspects of Brachytherapy for Prostate Cancer using

Permanently Implanted Sources

• Report 102: Managing Patient Dose in Multi-Detector Computed Tomography (MDCT)

• Report 105: Radiological Protection in Medicine

• Report 112: Preventing Accidental Exposures from New External Beam Radiation Therapy

Technologies

• Report 113: Education and Training in Radiological Protection for Diagnostic and

Interventional Procedures

• Report 120: Radiological Protection in Cardiology

RADIATION DOSE UNITS

• Bq (Becquerel) : activity of radioactive nuclides (1/s)

• Gy (Gray) : energy absorbed from radiation per kilogram of

material (Joules/kg)

• Sv (Sievert) : radiation hazard to human (Joules/kg)

Radiation weighting factors (ICRP 2007)

MAIN POINTS (4 OF 19) • Procedures such as endovascular aneurysm repair, renal angioplasty, iliac

angioplasty, ureteric stent placement, therapeutic endoscopic retrograde cholangio-pancreatography, and bile duct stenting and drainage have the potential to impart skin doses exceeding 1 Gy.

• Termination of pregnancy at fetal doses of

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1. WHAT IS THE MOTIVATION FOR THIS REPORT

1.1. Which procedures are of concern and who is involved?

1.2. Who has the potential to receive high radiation doses?

1.3. Lack of training, knowledge, awareness, and skills in

radiological protection

1.4. Patient vs occupational radiation doses

1.5. Fear and overconfidence

1.6. Training

1.7. Why this report?

• An increasing number of medical specialists are using fluoroscopy outside imaging departments, and

expansion of its use is much greater today than at any time in the past.

• There has been general neglect of radiological protection coverage of fluoroscopy machines used outside

imaging departments.

• Lack of radiological protection training of workers using fluoroscopy outside imaging departments can increase

the radiation risk to workers and patients.

• Recent reports of opacities in the eyes of workers who use fluoroscopy have drawn attention to the need to

strengthen radiological protection measures for the eyes.

1.1. Which procedures are of concern and who is involved?

Radiation Dose Management for

Fluoroscopically Guided Interventional

Medical Procedures,

NCRP report 168, 2011

NCRP REPORT 168, 2011

• Opacification of the lens of the eye may occur following exposure to significantly lower doses of ionizing radiation (perhaps without a threshold, previous threshold: 2-5 Gy)

• ICRP 2011, Occupational dose limits to lens: 150 mGy/year • Absorbed dose 0.5 Gy • Equivalent dose limit: 20 mSv in a year averaged over 5

year period, no single year exceeding than 50 mSv • Potential risks at varying dose level :

• 100 mSv = acceptable in context of the expected benefit

1.2. Who has the potential to receive high radiation doses?

• Workers in radiotherapy facilities either work away from the radiation source or only work near heavily shielded sources. As a result, in normal circumstances, occupational radiation exposure is typically minimal.

• Even if radiation is always present in nuclear medicine facilities, overall exposure of workers can still be less than the exposure for those who work near an x-ray tube.

• The situation in imaging [radiography and computed tomography (CT)] is similar, in the sense that workers normally work away from the radiation sources, and are based at consoles that are shielded from the x-ray radiation source.

• The actual dose depends upon the time spent in the fluoroscopy room (when the fluoroscope is being used), the shielding garments used (lead apron, thyroid and eye protection), the mobile ceiling-suspended screen and other hanging lead flaps that are employed, as well as equipment parameters.

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• Occupational radiological protection is much more important than

patient protection :

• workers are likely to work with radiation for their entire career

• patients undergo radiation exposure for their own benefit

• patients are only exposed to radiation for medical purposes a few

times in their life

• An increase in the frequency of use of higher dose procedures per

patient has been reported (NCRP 2009)

• UNSCEAR Report 2010:

• Occupational exposure: 0.5 mSv/year (22.5 mSv in 45 years)

1.4 Patient vs occupational radiation doses

Ionizing Radiation Exposure of the Population of the United States, NCRP report 160, 2009

UNSCEAR, 2010. Sources and Effects of Ionizing Radiation, UNSCEAR 2008 Report

NCRP REPORT 160, 2009 1.6 Training

https://rpop.iaea.org/RPOP/RPoP/Content/AdditionalResources/Training/2_TrainingEvents/Doctorstraining.htm

HEALTH EFFECTS OF IONISING RADIATION

• Introduction

• Intensity of x-ray tube > radioactive substances in medicine

• Electromagnetic radiations cause heat and ionizing effects

• Radiation exposure in context

• Health effects of ionizing radiation

• Although tissue reactions among patients and workers from fluoroscopy

procedures have, to date, only been reported in interventional radiology and

cardiology, the level of fluoroscopy use outside imaging departments creates

potential for such injuries.

• Patient dose monitoring is essential whenever fluoroscopy is used.

• Global averaged natural background radiation: 2.4 mSv/year

• India, Brazil, Iran have higher: 5-15 mSv/year

• Whole-body effective dose limits for workers:

• 20 mSv/year (averaged over 5-year period; 100 mSv in 5 years, no single year exceeding 50 mSv)

• Use protective tools less than 1 mSv/year

2.2 Radiation exposure in context

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• Deterministic:

• visible, documented, confirmed within a relative short time

• Skin erythema, hair loss, cataract, infertility, circulatory disease

• Stochastic:

• estimated, years or decades to manifest

• Cancer, genetic effects

2.3 Health effects of ionizing radiation

• Have thresholds that are typically quite high

• Skin erythema

• Hair loss

• Cataracts (even in low doses of radiation)

• 5 Sv for protracted exposures

• 2 Sv for acute exposures

• Epidemiological evidence suggesting thresholds

(equivalent dose):

• Lens of eye: 0.5 Gy

• Circulatory system: 0.5 Gy

2.3.1 Tissue reactions

• Detriment-adjusted nominal risk coefficient at low dose rate:

• Cancer – 5.5 %/Sv

• Genetic effects – 0.2 %/Sv (non-human species)

• Cancer risks are estimated on the basis of probability

• Organ dose > 100 mGy carcinogenic effects

• Stochastic risks have no threshold

2.3.2 Stochastic effects

Tissue weighting factor of gonads: 0.2 0.08 (ICRP, 2007)

1 chest CT scan ~ 8 mSv 20 mGy to breast

5 ~ 15 CT scans carcinogenic effects

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http://www.rerf.jp/radefx/late_e/cancrisk.html

For the average radiation exposure of survivors within 2,500 meters (about 0.2 Gy), the increase is

about 10% above normal age-specific rates. For a dose of 1.0 Gy, the corresponding cancer excess

is about 50% (relative risk = 1.5)

The excess number of solid cancers is estimated as 848 (10.7%)

The dose-response relationship appears to be linear, without any apparent threshold below which

effects may not occur

The probability that an A-bomb survivor will have a cancer caused by A-bomb radiation (excess

lifetime risk) depends on the dose received, age at exposure, and sex.

Other analyses (not shown) indicate that females have somewhat higher risks of cancer from

radiation exposure than males do. • different tissues and organs have different radiosensitivities

• females are generally more radiosensitive than males to

cancer induction

• young patients are more radiosensitive than older patients

• individual genetic differences in susceptibility to radiation-

induced cancer

• These general aspects of radiosensitivity should be taken

into account in the process of justification and optimization

of radiological protection in fluoroscopically guided

procedures

2.3.3 Individual differences in radiosensitivity

• Pre-existing auto-immune and connective tissue disorders predispose patients to the development of severe skin injuries in an unpredictable fashion.

• These disorders include scleroderma, systemic lupus erythematosus, and possibly rheumatoid arthritis, although there is controversy regarding whether systemic lupus erythematosus predisposes patients to these effects.

• Genetic disorders that affect DNA repair, such as the defect in the ATM gene responsible for ataxia telangiectasia, also predispose individuals to increased radiation sensitivity.

• Diabetes mellitus, a common medical condition, does not increase sensitivity to radiation, but does impair healing of radiation injuries

PATIENT AND OCCUPATIONAL PROTECTION

• General methods and principles of radiological protection

• Requirements for the facility

• Common aspects of patient and occupational protection

• Specific aspects of occupational protection

• Manufacturers should develop systems to indicate patient dose indices with the possibility

to produce patient dose reports that can be transferred to the hospital network.

• Manufacturers should develop shielding screens that can be used for the protection of

workers using fluoroscopy machines in operating theatres without hindering the clinical task.

• Every action to reduce patient dose will have a corresponding impact on occupational dose,

but the reverse is not true.

• Periodic quality control testing of fluoroscopy equipment can provide confidence in

equipment safety.

• The use of radiation shielding screens for protection of workers using x-ray machines in

operating theatres is recommended, wherever feasible.

Contents

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• Time:

• Minimize duration of radiation, number of frames or images

• Distance

• Keep distance from x-ray sources as much as possible

• Shielding

• Protect breasts, female gonads, eyes, thyroid

• Justification

• Any decision that alters the radiation exposure situation should

do more good than harm

• Optimization

• Protection, procedure, equipment, patient

3.1 General methods and principles of radiological protection

• 3.3.1 Patient-specific factors

• Thickness of the body part in the beam

• Complexity of the procedure

• Complexity represents the mental and physical effort

required to perform a procedure.

3.3 Common aspects of patient and occupational protection

• 3.3.2 Technique factors

• Rotating the x-ray beam to avoid irradiation of the same

area

• Fingers with overcouch geometry receive 100 times

radiation dose than undercouch geometry

• Machine functionality should be known

Overcouch geometry Undercouch geometry

• 3.3.2 Technique factors

• Position of the x-ray tube and image receptor

• Avoid steep gantry angulations when possible

• Keep unnecessary body parts out of the x-ray beam

• Use pulsed fluoroscopy at a low pulse rate

• Use low fluoroscopy dose rate settings

• Collimation

• Only use magnification when it is essential

• Fluoroscopy vs image acquisition and minimization of

the number of images

• Minimize fluoroscopy time

• Monitoring of patient dose

skin dose rate varies with the ratio (SID/SSD)2

Position of the x-ray tube and image receptor Avoid steep gantry angulations when possible

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3.4 Specific aspects of occupational protection

• 3.4.1 Shielding

• Lead apron

• Ceiling-suspended shielding

• Mounted shielding

0.5-mm lead equivalence, reduce over 90% x-ray

• 3.4.2 Individual monitoring

• Individual monitoring of workers exposed to ionising

radiation using film, thermoluminescent dosimeters,

optically stimulated luminescence badges, or other

appropriate devices is used to verify the effectiveness of

radiation control practices in the workplace.

Whole body dose limit for workers of 20 mSv/year

(averaged over a defined 5-year period; 100 mSv in 5 years)

1

2

3

1 necessary, inside the apron

2 optional, outside the apron at the collar level closest to x-ray tube

3 optional, on the skin surface

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HT = DT x WR

E = HT x WT

DT = absorbed dose (gray, Gy)

HT = equivalent dose (sievert, Sv)

E = effective dose (sievert, Sv)

Absorbed dose

DT 轉換因子

Equivalent dose

HT 轉換因子

Effective dose

E

類型 定義 \ 單位 Gy (gray) Sv (sievert) Sv (sievert)

外部曝露

任何物質

吸收劑量

人體組織或器官 (全身曝露)

WR

等效劑量

WT

有效劑量

強穿輻射 (10 mm深處軟組織)

個人等效劑量 弱穿輻射 (0.07 mm深處軟組織)

眼球水晶體 (3 mm深處)

組織或器官 器官劑量 等價劑量

人群 集體有效劑量

攝入曝露 組織或器官 約定等價劑量 約定有效劑量

SPECIFIC CONDITIONS IN CLINICAL PRACTICE

• Vascular surgery

• Urology

• Orthopaedic surgery

• Obstetrics and gynaecology

• Gastroenterology and hepatobiliary system

• Anaesthetics and pain management

• Sentinel lymph node biopsy

• Procedures such as endovascular aneurysm repair (EVAR), renal

angioplasty, iliac angioplasty, ureteric stent placement, therapeutic

endoscopic retrograde cholangio-pancreatography (ERCP), and bile duct

stenting and drainage have potential to impart skin doses exceeding 1 Gy.

• Radiation dose management for patients and workers is a challenge that

can only be met through an effective radiological protection program.

Contents

4.1 Vascular surgery 血管外科

EVAR (Endovascular aneurysm repair) using fluoroscopy increased

(5.9% in 2001 to 18.9% in 2006)

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• 4.1.1 Levels of radiation dose

• Dose to patient • EVAR (Endovascular aneurysm repair)

• Greater screening time greater radiation exposure

• Entrance skin dose typically 0.85 Gy (0.51-3.74 Gy)

• Dose-area product (DAP) 1516 Gycm2 (520-2453 Gycm2)

• Mean effective dose:

• Routine EVAR for infrarenal aneurysm: 8.7-27 mSv

• Follow-up by CT: 79 mSv

• Skin dose: 1/3 patients received over 2 Gy in EVAR

• 4.1.1 Levels of radiation dose

• Dose to patient • Abdominal aortic aneurysm repair

• Fluoroscopy time ~ 21 min (12-24 min), 92% in standard fluoroscopy,

8% in cine-fluoroscopy; 49% in normal FOV, 51% in magnified view.

• Peak skin dose DAP and body mass index, not fluoroscopy time.

1.1 Gy for obese patients, 0.5 for non-obese

• Venous access procedures

• Skin dose ~ 1 Gy, often require multiple repeated procedures within a

relative short time span

• 4.1.1 Levels of radiation dose

• Occupational dose levels

• EVAR

• Hand: 34.3 μSv/procedure (0.2-19 mSv/year)

• Body: 7.7 μSv/procedure (0.2 mSv/year ~150 procedures)

• Eye: 9.7 μSv/procedure (1 mSv/year ~150 procedures)

• 4.1.2 Radiation dose management

• Patient dose management

• EVAR

• Risk of tissue reactions or stochastic effects is minimal

• Fenestrated or branched stent-graft placement has greater

risk of tissue reactions or stochastic effects

• Need of repeat procedures for treatment of endoleaks and

the CT scans life-long surveillance

• Venous access procedures

• Single venous access case is relative low

• Well-trained operator have lower radiation dose to patients

• 4.1.2 Radiation dose management

• Occupational dose management

• Technique- and operator-related factors in EVAR

• Single cinematography run, multiple initial runs to assess

anatomy and plan stent-graft positioning are rarely

necessary and should be avoided

• Keep hands out of primary beam

• lead gloves not useful

• AEC might increase x-ray technique factors

• Minimal beam collimation, SID and field-of-view size,

proper x-ray filter, regular servicing of equipment

• Use radiation-attenuating surgical drape

• Use tableside lead shield and portable lead shielding

• Urinary and renal studies account for 16% and 1.6% of all

fluoroscopically guided interventional procedures, mean

effective dose of 2 mSv and 5 mSv (NCRP 2009)

• Workers receive 0.1 % of patient radiation dose

4.2 Urology 泌尿科 • 4.2.1 Levels of radiation dose • Dose to patient

• Acute kidney stone:

• Plain KUB, abdomino-pelvic CT, IVP 20 ~ >50 mSv

• Lithotripsy (ESWL, extracorporeal shock wave lithotripsy)

• < 1 ~ 2 mSv (50~78% through fluoroscopy)

• Nephrostomy

• Effective dose ~ 7.7 mSv (3.4-15 mSv)

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• 4.2.1 Levels of radiation dose

• Occupational dose levels

• Mean effective dose to urologist for PCN is 12.7 μSv/procedure,

3 mSv/year (5 procedures per week) *1

• Finger dose: 8-25 mGy/year (30-100 μGy/procdure) *2, 0.27

mSv/procedure (0.1-2 mSv/procedure) *3,4

• Head and neck dose: 5-10 mGy/year (20-40 μGy/procedure) *2

• Collar level above lead apron to radiologist: 0.1 mSv/procedure

(0.02-0.32 mSv) *3

• Nurse/radiological technologist, anesthetist: 0.04, 0.04, 0.03

mSv/procedure *3

• Lower extremities dose: 126-167 μSv/procedure *1,2, 40

mSv/year *5 (250 procedures/year), annual limit is 500 mSv/year

• Head and neck dose to urologist: 0.1 mSv/procedure *3 lens

of eyes ~ 25 mSv/year *6; with protection ~ 26 μSv/procedure

1: Safak 2009, 2: Hellawell 2005, 3: Bush 1985, 4: Kumari 2006, 5: ICRP 2007, 6: Ciraj-Bjelac 2010

• 4.2.2 Radiation dose management

• Patient dose management

• Digital image receptors decrease patient dose

• ESWL:

• Effective dose: 1.6 mSv/patient

• Ultrasound/x-ray localization: 0.25/1.2 mSv

• Experienced/inexperience operator: 26.4/33.8 mGy

• Reduction in number of images: dose reduction 20-62 %

(a) shock wave unit,

(b) patient positioning system,

(c) X-ray localization system with C-arm,

(d) Flat Panel Detector (FPD)

(e) X-ray tube,

(f) isocentric ultrasonic localization arm

• 4.2.2 Radiation dose management

• Occupational dose management

• common procedures in urology can be performed with little

radiation exposure of workers

• endourological procedures:

• Dose rate to urologist up to 11 mSv/h, drapes can reduce

70-96%

• Overcouch x-ray tube systems: more radiation to lens

The actual exposure depends upon the

time, workload, and shielding (e.g. lead

apron and additional lead glass

protective screens)

• Arthrography, orthopaedics, and joint imaging procedures:

• 8.4 % of all fluoroscopy guided procedures

• Average effective dose to patient: 0.2 mSv/procedure, 0.2 % to total collective dose

4.3 Orthopaedic surgery 骨科

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• 4.3.1 Levels of radiation dose

• Dose to patient

• Mean entrance skin dose for: • intramedullary nailing of pertrochanteric fractures: 183 mGy

• open reduction and internal fixation of malleolar fractures: 21 mGy

• intramedullary nailing of diaphyseal fractures of the femur: 331 mGy

• Trauma surgery (guiding bony reduction and implant placement in pelvic

region): 40 mGy/min

• femoral or tibial fracture nailing: 183 mGy

• pedicle screw placement in lumbar/cervical spine: 46/173 mGy

• visualization to facilitate implant placement of spine(PA/Lat): 60/79 mGy

• Effective dose for: • nailing osteosynthesis of proximal pertrochanteric fractures: 14 mSv

• Lower extremity fractures: 0.1 mSv

• pedicle screw internal fixation (male/femal): 1.52/0.14 mSv, 0.67/0.12

mSv for gonadal dose

• 4.3.1 Levels of radiation dose • Occupation dose levels

• Dose to orthopaedic surgeons use C-arm fluoroscopy is much lower than the dose limits

• Dose in common procedures (intramedullary nailing of pertrochanteric fracture) :

• Direct exposure from the beam in: extremity positioning, implant placement, and confirmation of acceptable bony alignment should be noted

• Dose rate using Mini C-arm/standard C-arm: • Away beam: 4-20/230 μGy/h • In beam: 37/65 mGy/h

Body part Radiation dose (mGy/min) 204 procedures (mGy)

Hands 0.103 72

Chest 0.023 16

Thyroid 0.013 9.4

Eyes 0.012 8.3

Gonads 0.066 46

Legs 0.045 31

Using lead aprons and collars

will reduce to 10% or less

Workers’ dose depends on the arc of the C-arm and the distance of the surgeon from the x-ray source

Staff Distance to X-ray Dose to lens

Surgeon 30 cm 0.1 mSv/min

1st assistant 70 cm 0.06 mSv/min

Nurse 90 cm Negligible

During foot/ankle surgery, scattered dose rate at eye level :

• 4.3.2 Radiation dose management

• Patient dose management: • Depending on the imaging configuration used, patient entrance skin

dose rate with the mini C-arm device (0.6 mGy/min) can be

approximately half that of the standard C-arm device (1.1 mGy/min).

• Increase SSD (source-to-surface distance) is important.

• Occupational dose management • Staff position to region of exposure:

• 10 cm – 0.20 mSv/case,

• 90 cm – 0.03 mSv/case

• Lead garment should be tested (73% outside tolerance level 5%)

• Under-lead exposures are 30-60% than over-lead exposures

• Thyroid shield reduce 90% or more radiation

• Lateral projection, staff position:

• x-ray tube side: 2.5 cm77 mGy/h, 45 cm1.5 mGy

• image receptor side: 2.5 cm1.9 mGy/h, 45 cm0.2 mGy/h

• Procedures: • Hysterosalpingography (HSG), pelvimetry, uterine artery

embolization

4.4 Obstetric and gynaecology 婦產科 • 4.4.1 Levels of radiation dose • Dose to patient

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• 4.4.1 Levels of radiation dose

• Occupational dose levels

• HSG:

• entrance surface dose ~ 0.18 mGy/procedure (film/digital:

0.21/0.14 mGy)

• lens / thyroid / hands – 0.22 / 0.15 / 0.19 mGy/procedure

• 0.35~0.5 mm lead equivalence apron absorbs radiations

• 4.4.2 Radiation dose management

• Patient dose management

• HSG

• Total effective dose ~ 2 mSv (AP/oblique ~ 1.3/0.7 mSv)

• Increase kV reduce 50% radiation dose (70120 kV)

• Use PA (posterior-anterior) projection and increased

filtration reduce >80% radiation dose

• Screen-film/digital imaging: 15 and 2.5 mGy (ovarian dose

3.5/0.5 mGy)

• Radiography / fluoroscopy ~ 75% / 25% in total dose

• 4.4.2 Radiation dose management

• Occupational dose management

• Skills dependent

• Over-couch x-ray unit increases scatter radiation more dose

to face, neck, and upper parts of operator’s body

• X-ray studies (upper and lower GI series), small bowel

biopsy, esophageal dilatation, colonscopy, ERCP, …

• ERCP

• 8.5% of all fluoroscopically guided procedures, 4 mSv

(4~5% total collective dose from fluoroscopy)

4.5 Gastroenterology and hepatobiliary system 肝膽腸胃系統

PTBD Percutaneous transhepatic

biliary drainage

• 4.5.1 Levels of radiation dose

• Dose to patient

• Upper / lower GI tracks: 1-3 / 7-8 mSv/procedure

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• 4.5.1 Levels of radiation dose

• Occupational dose

• ERCP (endoscopists): 2-70 uSv/procedure (w/ lead apron), 94-

340 uGy to eye and thyroid, 280-830 uGy to fingers; annual

dose to thyroid and extremities 40 and 7.92 mSv (3-4

cases/week); body dose 0-3 mSv

• PTC (percutaneous transhepatic cholangiography): 300-360

uGy/procedure to eye and thyroid, 530-1000 uGy to fingers

• Over-couch x-ray unit is not adequate for ERCP

• 4.5.2 Radiation dose management

• Patient dose management

• For diagnosis, consider alternatives (i.e MRCP)

• Use pulsed fluoroscopy, grid-controlled reduce more dose

• Occupational dose management

• Actions to reduce patient dose will also reduce dose to workers

• ERCP and TIPS potentially cause high occupational dose

• 0.5 mm lead-equivalent acrylic shield reduce 91% dose

• Training and experience reduce fluoroscopic time: 200 cases/year

• Epidural injection guided by fluoroscopy or CT

• Pulsed fluoroscopy patient dose/min: 0.08, 0.11, 0.18 mSv

for 3, 7.5, 15 pulses/sec

• CT fluoroscopic guidance patient dose: 1.5-3.5 mSv and

0.22-0.43 mSv for standard and low-dose CT protocols

4.6 Anesthetics and pain management 麻醉與疼痛控制

4.7 Sentinel lymph node biopsy

99mTc sulphur colloid or fluorescent substance as labeling agents

• 4.7.1 Levels of radiation dose

• Dose to patient

• Using Tc-99m sulphur colloid: patient dose is small, fetus dose

< 0.1 mGy (typically < 0.01 mGy), effective dose to patient is <

0.5 mSv (18.5 MBq of Tc-99m)

• Occupational dose levels

• Physicians administering the radiotracer injection in SLNB

(biopsy) receive 2.3-48 (max. 164) uSv/case to hands

• Surgeons receive 2-8 (or 22-153 or 4.9-7.9) uSv/case, annual

dose is 3 mSv (20 cases/year), limit is 500 mSv

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• 4.7.2 Radiation dose management

• Patient dose management

• Consider non-ionizing radiation materials

• Occupational dose and radioactive waste management

• SNLB is a 2-day procedure where physical half-life of Tc-99m is

6.02 hours dose decreases to 1/256

• Radioactive waste created in operation and pathology laboratory,

should < 0.3 mSv/year 60-70 hours for primary specimens,

30-40 hours for lymph nodes

PREGNANCY AND CHILDREN

• Patient exposure and pregnancy

• Guidelines for patients undergoing radiological

examinations/procedures at childbearing age

• Guidelines for patients known to be pregnant

• Occupational exposure and pregnancy

• Procedures in children

• Biological effects (in-utero radiation exposure):

• Prenatal death, intra-uterine growth restriction, small head size,

mental retardation, organ malformation, childhood cancer

• Gestational age to exposure, fetal cellular repair mechanism,

absorbed radiation dose level

• Organogenesis and early fetal period is most sensitive

• Childhood cancer risk (prenatal exposure of 10 mGy) is 1.4 (+40%),

1 cancer death per 1700 children exposed to 10 mGy

• Diagnostic procedures typically present no increased risk

5.1 Patient exposure and pregnancy

conception organogenesis 3-5 weeks 12 weeks

Fetal death

----

> 100 mGy

< 100 mGy

Decreased IQ, malformation

----

Decreased IQ

----

• Pregnancy can occur in adolescent girls

• Menstrual period is overdue, or missed ?

• Pregnancy test may be required prior to fluoroscopy

• Justification of procedures for pregnant patients

5.2 Guidelines for patients undergoing radiological

examinations/procedures at childbearing age

5.3 Guidelines for patients known to be pregnant

• Benefit-risk evaluation for mother and fetus

• Optimized medical radiation application tailored fetus

dose

• Informed decisions for higher (>100 mGy) fetal dose

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• Embryo/fetus protection level = members of the public

• Personal dosimeter worn by diagnostic radiology workers

may overestimate fetal dose by factor of 10 (inside lead

apron) or 100 (outside)

• Discrimination should be avoided based on radiation risks

during pregnancy

5.4 Occupational exposure and pregnancy

conception Declaration of pregnancy

Fetal dose < 1 mSv

a. On a voluntary basis and understand radiation risks

b. Use specific dosimeter at level of abdomen monthly

c. Radiological protection program exists and supervised

d. Know practical methods to reduce occupational dose

e. Control workload in fluoroscopy during pregnancy

f. Know and reduce risk of potential exposures

pregnant woman wishes to continue her work in a fluoroscopy guided

procedures laboratory should be allowed with the following conditions:

• Additional sensitivity to radiation damage, potentially longer

lifetime, 3x – 5x cancer induction than adults

• Approaches to reduce children dose

• Justification (see ICRP report 105, 2007)

• Optimized and tailored radiological protection for child

• Appropriate procurement policy

• Good quality control (QA) program

5.5 Procedures in children

• Height and weight of children is very dependent on age

use absorbed dose (gray, Gy) instead of equivalent dose

(sievert, Sv)

• Age groups for children (UNSCEAR, 2010)

• 1-year-old, 5-year-old, 10-year-old, 15-year-old

• Cancer induction in diagnostic levels is main issue

• Supporting family dose during radiological exam ~ 4-7 μSv

5.5.1 Levels of radiation dose

• Dose reduction using specific technical factors:

a. No grids

b. Proper collimation

c. Extra beam filtration

d. Low pulsed fluoroscopy

e. High SOD (source-to-object distance)

f. Digital subtraction in angiography

5.5.2 Radiation dose management

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TRAINING

• Introduction – ICRP report 113, 2009

• Curriculum

• Who should be the trainer

• How much training

• Recommendations on training

• Training oriented towards the type of practice with which the target

audience is involved:

• Lectures: essential background knowledge and advice and skills

on practical situations

• Practice: in a similar environment, providing knowledge and skills

6.2 Curriculum

• Experts in radiological protection in the practice:

• Clinical practice, nature, measurement, interactions with tissues,

and related effects of radiation, principles and philosophies of

radiological protection, international and nation guidelines

• Topics of radiation units, interaction of radiation with matter, and

even structure of the atom and atomic radiations are not

appropriate

• Practicing clinicians’ lectures on radiological protection is highly

recommended

6.3 Who should be the trainer ?

• Linked with evaluation methodology – pre- and post-

training to access the knowledge and practical skills

• Self-assessment examination systems is encouraged

• Radiation level, exposure frequency determine training

• Radiation therapy: ~ tens Gy

• Interventional procedures: ~ Gy

• Computed Tomography: ~ mGy

• Radiography: ~ μGy

6.4 How much training ?

• Training for healthcare professionals in radiological

protection should be related to their specific jobs and roles

• Evaluation and appropriate recognition of training course

• Training at start of career for physicians

• Nurses should be familiar with radiation risks and

protection principles

• Medical physicists should be familiar with specific

procedures

• Program includes initial, regular and retraining

6.4 Recommendation on training

RECOMMENDATIONS

• Fluoroscopic procedures outside imaging department involves high radiation levels exceeding skin injury threshold

• Patients require regular and repeated radiation exposure for years, and justification and optimization of protection is needed

• Radiation dose quantities in fluoroscopy to represent patient dose should be familiar with

• Manufacturers should develop:

• shielding screens to protect workers

• patient dose indicating systems

• devices providing occupational dose information

• Scientific and professional societies should contribute to the development of training syllabuses, and to the promotion and support of education and training

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CLINICAL RADIATION DOSE INDEX

Exposure Indicator

Dose-Area Product

Dose Index

Average Glandular Dose

Computed Tomography Dose Index

EXPOSURE INDICATOR

• Modality: plain x-ray exams (CR or DR)

• Terms:

EI = 1000 + 1000 × 𝑙𝑜𝑔10(𝑒𝑥𝑝𝑜𝑠𝑢𝑟𝑒)

i.e. Carestream

exposure is measured in μGy

DOSE AREA PRODUCT

DAP is measured in Gycm2

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DOSE INDEX

𝐷𝑜𝑠𝑒 𝐼𝑛𝑑𝑒𝑥 = 10 × 𝑙𝑜𝑔10𝐾𝐼𝑁𝐷𝐾𝑇𝐺𝑇

AVERAGE (MEAN) GLANDULAR DOSE

𝐴𝐺𝐷 = 𝐸𝑥𝑝𝑜𝑠𝑢𝑟𝑒 × 𝐾

AGD < 300 mrad

CTDI

32 cm 16 cm

15

cm