Part 2

What can radiation do? Death Cancer Skin Burns Cataract Infertility Genetic effects 2

What can radiation do? Deterministic effects death, skin burns, cataract, infertility Stochastic effects cancer, genetic effects 3

Early Observations of the Effects of Ionizing Radiation Part No 3, Lesson No 1 Biology Early Observations of the Effects of Ionizing Radiation 1895 X Rays discovered by Roentgen 1896 First skin burns reported 1896 First use of X Rays in the treatment of cancer 1896 Becquerel: Discovery of radioactivity 1897 First cases of skin damage reported 1902 First report of X Ray induced cancer 1911 First report of leukaemia in humans and lung cancer from occupational exposure 1911 94 cases of tumour reported in Germany (50 being radiologists) IAEA Training Material: Radiation Protection in Radiotherapy

OBJECTIVES OF RADIATION PROTECTION PREVENTION of deterministic effect. LIMITING the probability of stochastic effect 5

Radiosensitivity [RS] RS = Probability of a cell, tissue or organ of suffering an effect per unit of dose.

Part 1. Biological effects of ionizing radiation Radiation Protection in Nuclear Medicine RADIOSENSITIVITY: High RS Medium RS Low RS Gonads Thyroid Eye lens Bone Marrow Spleen Lymphatic nodes Lymphocytes Skin Mesoderm organs (liver, heart, lungs…) Muscle Bones Nervous system

Why do we need protection? Part No...., Module No....Lesson No Part 3. Principles. International framework Radiation protection in nuclear medicine Module title Why do we need protection? It is generally assumed that even very small doses of ionizing radiation can potentially be harmful . Therefore, persons must be protected from ionizing radiation at all dose levels. This follows from the linear no-threshold hypothesis for stochastic effects 8 IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

Who should be protected in Hospital? Patients. Members of his/her family. Workers. General public. 9

Ionizing Radiation We live with 1-3 mSv/y Can kill 4000 mSv 10

Part No...., Module No....Lesson No Module title Patients Protection: Persons are medically exposed as part of their diagnostic or treatment According to IAEA, ICRP and BSS, two basic principles of radiation protection are to be complied with: justification and optimization Explanation or/and additional information Instructions for the lecturer/trainer IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

RP Principles vs. Actions Justification Optimization Dose Limitations Time (dose directly proportional to length of exposure). Shielding (b/w source and patient). Distance (Intensity and StP distance).

Justification No use of ionizing radiation is justified if there is no benefit. All applications must be justified. This implies: All, even the smallest exposures are potentially harmful and the risk must be offset by a benefit. 13

The justification of a practice The decision to adopt or continue any human activity involves a review of benefits and disadvantages of the possible options E.g.: choosing between the use of X Rays or ultrasound Most of the assessments needed for the justification of a practice are made on the basis of experience, professional judgement, and common sense.

Risk/Benefit analysis: Need to evaluate the benefits of radiation - an easy task in the case of nuclear medicine. Radiation is the diagnostic and therapeutic agent. Assessment of the risks requires the knowledge of the dose received by persons. 15

Part No...., Module No....Lesson No Part 3. Principles. International framework Radiation protection in nuclear medicine Module title Optimization When radiation is to be used then the exposure should be optimized to minimize any possibility of detriment. Optimization is “doing the best you can under the prevailing conditions”. Need to be familiar with techniques and options to optimize the application of ionizing radiation - this is really the main objective of the present course. This is a very important slide as it summarizes the aim of the material: If optimization is doing the best one can under prevailing conditions, it is essential to know the conditions very well. The knowledge of these conditions (and constraints) also helps to avoid controversy. 16 IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

Optimization: Reducing the patient dose may reduce the quantity as well as the quality of the information provided by the examination or may require important extra resources. Means that doses should be “As Low As Reasonably Achievable” ALARA, economic and social factors being taken into account” compatible with achieving the required objective.

Optimization principle ALARA Part 3. Principles. International framework Part No...., Module No....Lesson No Radiation protection in nuclear medicine Module title Optimization principle ALARA The lecturer should point out that: a) Acronyms are always a shortening of the actual problem and may create confusion b) BSS deliberately avoids the use of the acronym ALARA - it is mentioned here because it is so widely used, but should be avoided c) It is essential to also include the second part of the statement: “keeping in mind …” 18 IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

OPTIMIZATION OF PATIENT EXAMINATION Part 6. Medical exposure Part No...., Module No....Lesson No Radiation protection in nuclear medicine Module title OPTIMIZATION OF PATIENT EXAMINATION Optimization of medical exposure means a proper balance between the diagnostic objective and radiation burden for the patient Diagnostic objective Medical exposure IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

Optimization of image quality Part 6. Medical exposure Part No...., Module No....Lesson No Radiation protection in nuclear medicine Module title Optimization of image quality Image quality depends on: Administered activity Technical factors - equipment used - acquisition protocol - image processing & evaluation - noise - spatial resolution - scatter Patient factors - size - age - disease - movement IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

Framework of RP for medical exposure Justification Optimization The use of doses limits is NOT APPLICABLE Dose constraints and guidance (or reference) levels ARE RECOMMENDED

Three types of exposure Medical Exposure (principally the exposure of persons as part of their diagnostic or treatment) Occupational Exposure (exposure incurred at work, and practically as a result of work) Public Exposure (including all other exposures)

Medical exposure Medical Exposure Exposure of persons as part of their diagnostic or treatment. Exposures incurred by volunteers as part of a program of biomedical research.

Responsibilities for Medical Exposure Part No...., Module No....Lesson No Part 3. Principles. International framework Radiation protection in nuclear medicine Module title Responsibilities for Medical Exposure (a) No patient to be administered a diagnostic or therapeutic medical exposure unless the exposure is prescribed by a medical practitioner; (d) For therapeutic uses of radiation, the calibration, dosimetry and quality assurance requirements of the Standards be conducted by or under the supervision of a qualified expert in radiotherapy physics. The insert shows one of the first diagnostic X-rays ever taken. Father Slattery exposed the hand of a boy who was accidentally shot by a shot gun in 1896 in Australia. This resulted in taking the gun shot out instead of amputating the hand as it would have been likely otherwise. The bright spots are the gun shot in the picture. 24 IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

PUBLIC: effective dose of 1 mSv/year equivalent dose to lens of the eye 15 mSv/yr equivalent dose to skin of 50 mSv/year.

Guidance levels for diagnostic radiography (typical adult patient) Examination Entrance surface dose per radiograph (mGy) Lumbar spine AP 10 Lumbar spine LAT 30 Lumbar spine LSJ 40 Abdomen, IVU and cholecystography AP

Guidance levels for diagnostic radiography (typical adult patient) Examination Entrance surface dose per radiograph (mGy) Pelvis AP 10 Hip joint AP Chest PA 0.4 Chest LAT 1.5

Typical effective doses from diagnostic medical exposures procedure Typical effective dose (mSv) Equiv. no. of chest x-rays Approx. equiv. period of natural background radiation Chest (single PA film) 0.02 1 3 days Skull 0.07 3.5 11 days Thoracic spine 0.7 35 4 months Lumbar spine 1.3 65 7 months From: Referral Criteria For Imaging. CE, 2000.

Typical effective doses from diagnostic medical exposures procedure Typical effective dose (mSv) Equiv. no. of chest x-rays Approx. equiv. period of natural background radiation CT head 2.3 115 1 year CT chest 8 400 3.6 years CT Abdomen or pelvis 10 500 4.5 years From: Referral Criteria For Imaging. CE, 2000.

OCCUPATIONAL - APPENDIX I Part No...., Module No....Lesson No Part 3. Principles. International framework Radiation protection in nuclear medicine Module title OCCUPATIONAL - APPENDIX I Dose Limits effective dose of 5mSv per year averaged over five consecutive years equivalent dose to lens of eye of 150mSv in a year equivalent dose to extremities or skin of 500mSv in a year. For apprentices (16-18 years of age) effective dose of 6mSv in a year These are the dose limits for workers. 30 IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

Part No...., Module No....Lesson No Part 3. Principles. International framework Part No...., Module No....Lesson No Radiation protection in nuclear medicine Module title OCCUPATIONAL Female workers should notify pregnancy. Working conditions shall be adapted to ensure that the embryo and fetus are afforded the same broad level of protection as for members of the public. 31 IAEA Post Graduate Educational Course in Radiation Protection and Safe Use of Radiation Sources

Class Activity 3 Mr. Sharp, I am given to understand that 2 bone scans and a cardiac study done on me have given me 22 mSv whereas 20 mSv is the safe dose. I want to file legal suit against the doctor. What do you feel??