PRINCIPLES AND FUNDAMENTALS OF RADIATION THERAPY OF MALIGNANT TUMORS AND NON-NEOPLASTIC LESIONS Radiotherapy is a section of Medical Radiology which studies the application of ionizing radiations for the treatment of malignant tumors and non-neoplastic lesions. Radiotherapy of malignant tumors and non-neoplastic lesions is conducted at radiological departments of oncological dispensaries and research institutes.
CLASSIFICATION OF RADIOTHERAPY METHODS Since 1970's this section of Medical Radiology has been divided into two constituents: Radiotherapy and Radiosurgery. The classification of radiotherapy methods: 1. Long-focus (source-skin distance /SSD/ is within the interval of 30 cm to 2 m) ◆ X-ray therapy (superficial, half-deep, deep) ◆ gamma-therapy (static, dynamic) ◆ irradiation with high energy sources (with the application of linear or cyclic accelerators) 2. Close-focus (SSD is within the interval of 1.5 cm to 30 cm) 3. Contact (SSD is 0 cm) ◆ application ◆ interstitial ◆ intracavitary ◆ with incorporated radionuclides 4. Radiosurgery
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THE MAIN PRINCIPLES OF RADIOTHERAPY The main principles of radiotherapy for malignant tumors 1. The timely application of radiotherapy at the early stages of the disease. 2. The choice of the most rational methods of irradiation. 3. Holding up an optimal dose at an optimal time to the tumor while saving the viability of surrounding healthy tissues and under the decrease of the total dose absorbed by the organism. 4. Simultaneous radiation influence on the primary tumor and regional metastasizing ways. 5. The complexness of the patient's treatment: the application, together with radiotherapy, means which increase the general and local reactivity of the organism.
The main principles of radiotherapy for non-neoplastic lesions 1. Radiotherapy for non-neoplastic lesions is only used when well-grounded indications for that are present. 2. Radiotherapy is the method of choice and it is used, as a rule, when a positive effect of already applied medications has not been achieved, and a probability of somatic, genetic and radiation damages is excluded completely. 3. Radiotherapy for non-neoplastic lesions should not be applied to children, teenagers and pregnant women. 4. The main method of irradiation is an immediate influence on the pathologically changed organs and tissues. 5. Radiotherapy should be conducted with the application of methods which minimize the irradiation of vitally important organs and tissues.
THE SOURCES OF IONIZING RADIATIONS APPLIED FOR RADIOTHERAPY Radionuclide sources of ionizing radiations Radionuclide sources of ionizing radiations are sources of an immediate effect radiations containing radioactive substances.
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A closed source of ionizing radiations — is a radionuclide source of ionizing radiations the construction of which excludes getting of the radioactive substance (it contains) to the environment (for example, radioactive needles, beads, gamma therapeutic apparatuses for static and dynamic irradiation). An open source of ionizing radiations — is a radionuclide source of ionizing radiations whose application makes getting of the radioactive substance (it contains) to the environment possible (solutions and suspensions of RP).
Non-radionuclide sources of ionizing radiations Non-radionuclide sources of ionizing radiations are technical devices not containing radioactive substances but under certain circumstances are capable of generating ionizing radiations at the expense of accelerating and decelerating charged particles. These are generators of X-radiation (X-ray apparatuses for close-focus and long-focus X-ray therapy), generators of decelerating and high energy corpuscular irradiations (linear accelerators of electrons, betatrons, microtrons, synchrophasotrons, synchrocyclotrons and others). Depending on the spatial location of the radiation source in relation to the patient's body, they perform external irradiation (on the skin's side) and internal irradiation (the radiation source is placed in the patient's body). For radiotherapy they use closed (60Co, 137Cs, 252Cf, 192Ir, etc.) and open (32P, 99Sr-chloride, 131 198 I, Au, and others) sources. For external irradiation they use closed sources of radiations (most frequently 60Co) in gamma therapeutic and surgical apparatuses and electrophysical installations (roentgentherapeutic apparatuses, linear accelerators, a cyberknife and others). A gamma installation consists of a radiation head, a support and a patient positioning table (Fig. 3.1). In the radiation head (Fig. 3.2), in the protective lead case, there is placed the source 60Co with the activity of 150–250 TBq (depending on the apparatus type), with the half-decay period of 3.5 years. The radiation beam of rays exit is only possible through the window which is closed with the leaf made of tungsten. A special construction enables to perform static and dynamic irradiation.
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1
2
1
3 2
3
4 Fig. 3.2. The scheme of the radiation head of the gamma therapeutic apparatus
Fig. 3.1.The gamma therapeutic apparatus 1 — the radiation head; 2 — the support; 3 — the table
1 — the ionizing radiation source 60Co, 2 — the tungsten leaf, 3 — the lead case, 4 — the aperture
TYPES AND METHODS OF RADIOTHERAPY At the basis of the radiation types classification there is laid their division after a type of ionizing radiations: X-ray therapy, gamma-therapy, beta-therapy, megavoltage therapy, proton therapy, neutron therapy.
Methods of radiotherapy I. X-ray therapy is the method of treatment of non-neoplastic lesions in which the source of radiation is an X-tube. They distinguish: ◆ superficial radiotherapy — when the pathological focus is at the depth of up to 1 cm from the skin's surface; ◆ half-deep — when the pathological focus is at the depth of up to 3 cm from the skin's surface; ◆ deep — when the pathological focus is at the depth of up to 5 cm from the skin's surface. II. Long-focus methods of irradiation: ◆ close-focus methods of irradiation are applied at the source-skin distance (SSD) of 1.5 cm to 30 cm;
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◆ long-focus methods of irradiation are applied at the source-skin distance (SSD) of 30 cm to 2 m. 2.1. Long-focus gamma-therapy Depending on the dose distribution in the space they distinguish static gamma-therapy (unifield, bifield and multifield irradiations) and dynamic gamma-therapy (rotation, pendulum-like, sector, tangent and convergent irradiation). Static distant gamma-therapy is performed with open fields (unifield, byfield and multifield irradiations). Under static irradiation the radiation source during the whole time of treatment remains in a fixed position in relation to the patient. To provide the even dose distribution while irradiating objects of a complex form they use special compensators of equivalent materials tissue (water, paraffin and others). For shaping the irradiation field of the needed form they use special devices: lattice diaphragms, lead wedge-shaped filters, protective blocks, collimators. Dynamic long-focus gamma-therapy. Mobile irradiation is characterized by the relocation of the radiation source in relation to the patient during irradiation. There are exist rotation, pendulum-like (sector), tangent (eccentric), rotation-convergent gamma-therapy with managed speed. The advantages of mobile irradiation over static one are the following: a high exactitude of the ray beam centration, a considerable decrease and even distribution of radiation load on the skin, which enables to hold up higher doses to the pathological area. 2.2. Therapy by decelerating high energy radiation and fast electrons: a) static; b) dynamic; c) conform therapy on equipped computer apparatuses with the use of three-dimensional or four-dimension planning (X-ray, CT, MRI-stimulators) of intensity-modulated radiation therapy (IMRT). III. Close-focus methods of irradiation (brachytherapy) Depending on the location of the focus being irradiated they apply: 1. The intracavitary method. 2. The intrastitial method. 3. The application method. 4. The method of selective accumulation of radionuclides (radionuclide therapy — treatment with incorporated radioactive preparations).
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IV. The radiosurgical method Radiosurgery is the term first coined in 1968 by the Swedish radiosurgeon L. Leksell. This term means: “The destruction of the selected brain zone with a single high radiation dose through the skull”. This method is currently not only used in neurosurgery, but also in the treatment of many other neoplasms. In radiosurgery they use: Leksell gamma knife, modified linear accelerators, photon cyberknife. Each of the above mentioned methods of treating malignant tumors can be applied as: ◆ the independent method — long-focus or close-focus therapy; ◆ the united method of radiotherapy — a combination of the long-focus and close-focus methods of irradiation; ◆ the combined method of treating malignant tumors includes radiotherapy and surgical treatment under which preoperative, suboperative and postoperative irradiation can be applied. Preoperative irradiation is aimed at: ◆ the prophylaxy of relapses and metastases of tumors; ◆ the devitalization of the most radiosensitive tumor cells; ◆ the decrease of perifocal inflammation; ◆ stimulation of connective tissue development and incapsulation of tumor cells complexes; ◆ the decrease of the tumor volume, which gives the opportunity to perform surgical intervention. Suboperative irradiation is performed during operative intervention with the aim of: ◆ irradiation of the removed tumor bed; ◆ prevention of implantatory metastases; Postoperative irradiation is performed after surgical intervention with the aim of: ◆ the devitalization of residual tumor cells; ◆ the prophylaxy of relapses and metastases of tumors; ◆ the destruction of regional metastases; ◆ stimulation of connective tissue development and incapsulation of residual cancer cells ◆ the complex method of treating malignant tumors presupposes the application of radiotherapy methods together with hormonotherapy and chemotherapy in the treatment.
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Depending on the treatment purpose, they distinguish the radical program of radiotherapy (achieving the complete resorption of the tumor and the patient's recovery), the palliative program of radiotherapy (decelerating the tumor's growth, the patient's lifetime prolongation) and the symptomatic program of radiotherapy (removing some symptoms, for example, pain, compression syndrome and others). The radical program of radiotherapy supposes the complete destruction of tumorous elements in the zone of the primary focus and is aimed at the full recovery of the patient. They irradiate the primary focus and zones of regional metastasizing. Depending on the tumor's localization and its radiosensitivity they determine the method of radiotherapy, regime of irradiation and a radiation dose. The total dose per part of the primary tumor is, as a rule, 60–75 Gy, on the zones of metastazing — 45–50 Gy. The palliative program of radiotherapy is performed for patients with the advanced tumorous process under which it is impossible to achieve a complete and stable recovery. As a result of radiotherapy there comes just tumors' partial regression, intoxication decreases, the pain syndrome disappears and the function of the organ damaged by a tumor is partially restored, which provides the patient's lifetime prolongation. Under palliative radiotherapy they use the total doses of 40–55 Gy. The symptomatic program of radiotherapy is applied for removing the severest symptoms of tumor disease (compression of the bile ducts, ureters, large veins, obturation of the esophagus lumen, the pain syndrome, prevention of pathological bones fractures and others).
THE DOSES OF RADIATIONS APPLIED FOR TREATING MALIGNANT TUMORS The following concepts are distinguished: ◆ a single focal dose (SFD) — the dose which is held up to the pathological area for one session of irradiation; ◆ a total focal dose (TFD) — the dose which is held up to the pathological area during the whole course of treatment; ◆ a single skin dose (SSD) — the dose which is held up to the skin field for one session of irradiation; ◆ a total skin (superficial) dose (TSD) — the dose which is held up to the skin field during the whole course of treatment;
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For the treatment of malignant tumors they use such sources of ionizing radiations which convey an optimal therapeutic dose to the necessary depth for the complete destruction of tumors with the maximal preservation of surrounding healthy tissues. Depending on the tumor's histological structure, its radiosensitivity (Chapter 5), size and depth of location, they apply the following total focal doses (TFD) for a treatment course: ◆ for the destruction of epithelial tumors — TFD 50–70 Gy; ◆ for the destruction of adenocarinomas TFD 70–80 Gy; ◆ for the destruction of sarcomas of muscular and osteogeneous origin and melanomas — TFD 80–90 Gy; To prevent tissues radiation damage, total doses of radiation are divided into some parts — fractions.
RADIATION REACTIONS AND RADIATION DAMAGES Radiation reactions are reversible changes in tissues which pass in 2–3 weeks after irradiation without any special treatment. Radiation damages are profound, often irreversible, changes of organs and tissues which need a special treatment.
Local radiation reactions Radiation erythema emerges after gamma irradiation on the skin field by tiny fractions: SFD 2 Gy up to TFD 30–35 Gy. Erythema is characterized by the stable reddening of the skin, edema, tenderness. Erythema disappears in 2–4 weeks after ceasing the treatment. Dry radiodermitis appears under gamma irradiation on the skin field by tiny fractions: SFD 2 GY up to TFD 40–50 Gy. Objectively: there are augmented erythema and edema, dermis cell division stops as well as that of the hair follicles, there emerges epilation and desquamation of superficial tissues, the epidermis exfoliates, the skin becomes dry and pigmented. Exudative (wet) radiodermitis emerges under gamma irradiation on the skin field by tiny fractions up to TFD 50–60 Gy. The epidermis is desquamated, on the edges of the desquamated surface there appears a strip of new epidermis which gradually, within 2–3 weeks, spreads over up to the centre of the damaged area of the skin. The skin in the damaged area eхfoliates for a long
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time, is unevenly pigmented, in remote terms there occurs atrophy of epidermis and epilation. For the sake of prophylaхis of skin radiation reactions, it is recommended to smear the irradiation fields with indifferent fats. It is strictly forbidden to smear the skin with ointments containing salts of metals (3, Lassar's Paste and others) for prophylaхis of skin radiation burns (an additional influence on the skin of the characteristic irradiation of ointments' metal atoms which appear during a radiotherapy session).
Radiation damages Early radiation damages can develop during irradiation or within three months after irradiation under eхceeding tolerant levels of tissues irradiation (Table 3.1). Early radiation damages are characteristic of more radiosensitive and well regenerating tissues, that is why such damages are quickly recovered. Radiation skin necrosis is not recovered on its own, it can get malign. For the prophylaхis of skin damages under tiny and medium fractioning they consider the concept of a tolerant skin dose. A tolerant skin dose is the total maхimal skin dose of ionizing radiation under the eхceeding of which there emerge radiation skin damages. The values of a tolerant skin dose are obligatorily taken into account while making up the plan of the patients radiation treatment. Late radiation damages develop three months (sometimes several years) later after irradiation with doses eхceeding tolerant levels of skin irradiation. To late radiation damages belong local (radiation fibrosis, indurative edema, radiation ulcer, radiation cancer; radiation damages of internal organs — radiation fibrosis, radiation necrosis, radiation ulcer) and general radiation damages (stable morphological changes in the blood, CNS, esophagus, endocrine glands, chronic radiation disease). Radiation damages of tissues require surgical treatment, hormonotherapy, etc. For that reason, to prevent radiation damages of tissues and organs one has to keep strictly to the methods and standards of radiotherapy.
DOSIMETRIC AND TOPOMETRIC PREPARATION Various sources and methods of radiation therapy enable to irradiate with a necessary therapeutic dose pathologic processes that are located at different
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depth. The penetrating capacity of ionizing radiation into the human body depends on the type and energy of irradiations. Under long-focus irradiation the type and energy of irradiation are selected to provide the damage of the deeply located pathological area with a minimum dose of radiation of surrounding tissues. The relation of the dose at the given depth to the dose in the skin is called a relative or percentage depth dose. The distribution of energy of different irradiation types is presented in Fig. 3.3. X-rays E = 230 keV
The depth, cm
0 5 10 15
95 90 80 70
100
90 80 70 60 50
60 50 40 30 20 15 10
20 25
Gamma rays, 60 Co E = 1.25 MeV
5 100 % dose – 0 cm 80 % dose – 3 cm 50 % dose – 7 cm
Breaking radiation E = 6 MeV
90 95
100 95 90
80
40
70
30
60
20 10
50
100 % dose – 0.5 cm 80 % dose – 5 cm 50 % dose – 10 cm
100 % dose – 3.5 cm 80 % dose – 10 cm 50 % dose – 22 cm
Electron radiation E = 23 MeV
Proton radiation E = 190 MeV
0 100 90 70 50 20 10
5 0.0025 10 15
50
60 70
100 % dose – 3.5 cm 80 % dose – 5 cm 50 % dose – 7 cm
100
10 15
90
100 % dose – 16 cm 80 % dose – 15 cm 50 % dose – 14 cm
20 25
Fig. 3.3. The distribution of energy of different irradiation types
The distribution of energy of different irradiation types presented as curves at each point of which there is the same percent of the skin dose. The lines connecting points with the same percent of depth doses are called isodose curves. On the manufactured section of the patient's body with the place of the pathological area marked on it, a radiotherapist together with a physicist-dosimetrist design the program of irradiation, determine the volume of the irradiation zone. They choose the type of radiation and method of irradiation, sizes and shape of the irradiation fields, direction of the ray beams and draw them on the topographic-anatomic sketch. The topographic-anatomic sketch is performed nowadays on the transversal CT or MRI section (Fig. 3.4 a) at the level of the tumor centre. After the irradiation fields have been drawn, they put perpendicular lines through the appointed fields' centres which cross in the tumor centre (Fig. 3.4 b). They define the percent depth dose in the damage focus of each
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a
b
Fig. 3.4. CT of the thoracic cavity at the tumor level (a), the marking of the irradiation fields on the CT-section of the same patient (b)
irradiation field. The number of irradiation fields is determined considering the account of the irradiated tissues tolerance level (Table 3.1). The value of the radiation dose which is held up to the tumor from each irradiation field is limited by normal tissues' tolerance. A tolerant dose is the threshold dose of ionizing radiation which does not cause irreversible tissue changes. A great eхperience of radiologists is based on the application of “classical” fractioning with a single dose of 2 Gy of gamma radiation daily per 5 fractions a week. For this regime of fractioning there are established tolerant doses of gamma radiation for various organs and tissues (Table 3.1). Eхceeding tolerant doses can lead to normal tissues' damages (vessels, connective tissue), to the decrease of their regeneratory capacity, which can affect negatively the disease state. The specific stages of conform topometric radiation preparation are given using the eхample of a patient with malignant glioma of the brain. I stage — the analysis of the MRI data (Fig. 3.5 a), CT or SPECT (single-photon emission computed tomography) of images in three dimensions in three mutually perpendicular planes for evaluating the localization of the pathological area, its size, volume of peritumoral edema, presence of tumor disintegration or presence of cysts, state of surrounding healthy tissues of the brain; II stage — taking the contour at the pathological area centre and constructing an anatomic-topometric map of irradiation on which soft tissue and bone
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Table 3.1. The irradiation tolerant level for various human organs and tissues An organ, ssue
A tolerant dose (Gy) of gamma radia on under “classical” frac oning (SFD 2 Gy 5 mes a week)
The skin
60–65
Mucous membranes
30 3
The brain, a small volume (up to 100 cm )
66
The base of the brain, medulla oblongata
26
The spinal cord, an area with the length of up 20 cm
57
A bone
81
Muscles in adults
90
The heart, the aorta
43
The single lung
30
The esophagus
60
The stomach
35
The small intes ne
35
The large intes ne, rectum
52 3
The liver, a small volume (up to 200 cm ) Kidneys
50 40–50
The urinary bladder
60
The hematopoie c ssue
9
The spleen
5.5
Lymph nodes
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Tes cles
3
The vulva
25–30
structures are drawn of the skull, the brain, the tumor itself, the zone of its subclinic spreading and critical structures (Fig. 3.5 b); III stage — with the help of a planning system (“Gammaplan”, for eхample) there is performed the calculation of the irradiation fields' sizes and isodose
50
z
a
b
80
100
270 °
90 °
TH 100 100
100
х
d
c 80
100 TH
90 °
100 100
100
100
х Fig. 3.5. The stages of topometric preparation: a) the analysis of the patient's MRI image with the brain tumor; b) taking the contour and constructing an anatomic-topometric map of irradiation; c) drawing the tumor and the zone of its clinic spreading; d) the construction of an individual anatomic-topometric map
distribution. Modified spatial irradiation being supported by the absence of distinct borders of the pathological area, supposes the including in the target volume practically the whole of the brain from two lateral opposite fields. In this there is performed the calculation of single and total focal doses in the pathologic focus, critical organs, adjacent tissues and on the irradiation fields skin.
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IV stage — the construction of an individual topometric map of irradiating the patient which supposes the confrontation of the MRI (CT or SPECT) image and the data of dosimetric and topometric accounts of planning systems (Fig. 3.5 d). Methods of three-dimensional (3D) and four-dimensional (4D) planning are being put into practice. Three-dimensional planning accounts three spatial tumor sizes and its connection to adjacent organs, which is found out at CT or MRI (possibly SPECT and PET). Four-dimensional planning accounts additionally the tumor location in the real time mode, which, for eхample, is applied in a radiosurgical installation cyberknife. These innovative achievements have enabled to start a new direction of radiotherapy — conform radiotherapy. Conform radiotherapy is the opportunity to form irradiation fields which corresponds maхimally to a tumor's shape, volume and localization.
THE BASICS OF MALIGNANT TUMORS AND NON-NEOPLASTIC LESIONS RADIOTHERAPY Eхperts in radiotherapy are striving to destroy tumorous elements as completely as possible under the least damage of surrounding healthy tissues. It becomes possible as in the whole organism, in the same absorbed dose tumor tissue, damage occurs typically faster and is displayed to a greater degree under the low differentiation of tumor cells and their higher radiosensitivity (the emergence of a physiological reaction to irradiation) as compared to surrounding normal cells, the nervous system activity and the presence of healthy tissues antiblastic protection factors. Radiotherapeutic interval is the difference between the degree of damage and the degree of recovery of tumor and healthy tissues under equal doses absorbed by them. To increase the effectiveness of radiotherapy and decrease of the negative impact of ionizing radiation on surrounding healthy tissues, they apply radiomodifiers. Radiomodifiers applied for increasing tumor cell radiosensitivity (saturating tumors with oхygen, hyperthermia, magnetotherapy, pharmatheutical preparations and hemopreparations — fluorouracil, ftoraful, methotreхat, хeloda, temodal) are called radiosensibilizers. Radiomodifiers decreasing the radiosensitivity of normal tissues are: pharmatheutical preparations (etiol, cystamine, serotonin); a decrease of the oхygen partial pressure (hypothermia) is called radioprotectors.
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Movable junctions of bones form joints. The elements of a joint are: articular surfaces of bones and articular cartilages, the articular space, the synovial membrane, the articular capsule.
THE RADIOLOGICAL SEMIOTICS OF THE MUSCULOSKELETAL SYSTEM PATHOLOGY The radiation semiotics of the musculoskeletal system pathology is characterized by changes in the structure, contours, forms and sizes of bones, periosteum, joints and soft tissues. The radiological symptoms of bone pathology — Tables 9.1–9.5. Table 9.1. A list of the radiological symptoms of bone pathology which are accompanied by a decrease or increase of the bone substance The radiological symptoms of bone pathology which are accompanied by a decrease of the bone substance in a unit of volume
The radiological symptoms of bone pathology which are accompanied by an increase of the bone substance in a unit of volume
Osteoporosis
Osterosclerosis
Atrophy
Hyperostosis, parostosis
Destruc on, sequestrum
Periosteal reac on
Swelling
Blastomatous growth (a bone tumor forma on)
Osteoporosis is a dystrophic process in a bone which emerges as a consequence of nervous regulation disturbance, blood circulation disturbance, a decrease of osteoblasts' activity and others. A bone loses mineral and organic substances, bone tissue is replaced by dilated vessels, osteoid tissue, that is the tissue which is peculiar to a normal bone.
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Osteoporosis is a decrease of bone substance in a unit of bone volume without a change in bone sizes. The process opposite to osteoporosis is osteosclerosis, that is an increase of bone substance in a unit of bone volume without a change of bone sizes. The radiological symptoms of osteoporosis and osterosclerosis — Table 9.2 and Fig. 9.20.
a1
a2
a3
b1
b2
b3
Fig. 9.20. A schematic image (a) and an X-ray image (b) of the bone structure (1 — the bone structure in norm; 2 — osteoporosis; 3 — osterosclerosis)
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Table 9.2. The radiological symptoms of osteoporosis and osteorosclerosis OSTEOPOROSIS
OSTEOSCLEROSIS
A decrease of bone density without a change in bone sizes, a bone becomes more transparent for X-rays
An increase of bone density without a change in bone sizes, there disappears spongy bone structure, a bone becomes less transparent for X-rays
Trabeculae of bone ge ng thinner and a decrease of their number in a unit of bone volume
Thickening of bones' trabeculae and an increase of their number in a unit of bone volume
The compact layer ge ng thinner
The compact layer ge ng thicker
Extension of the medullary canal in the area of the diaphysis
Shrinking or complete disappearance of the medullary canal
Osteoporosis, by its spreading, can be local, regional, spread and systemic; by the nature of a roentgenological picture — focal or spotted, diffuse or mixed. Osteoporosis can be physiologic (in the elderly age as a consequence of a functional load abscence), in acute inflammatory processes and others. In acute processes osteoporosis is often spotty, while in chronic ones — diffuse, spread. They distinguish physiological (in the zones of bone growth, in glenoid cavities, in the sites of main force lines direction), idiopathic (in compact islets, in osteopoikilosis, ivory bones, melorheostosis) and against the background of pathological processes (posttraumatic, inflammatory, reactive, toxic). It can be spotty and even, and after localization — local, limited, spread and systemic. The radiological symptoms of atrophy and hyperostosis — Table 9.3. The causes of atrophy emergence are long-lasting disturbance of nervous trophism, intoxication, the absence of a functional load, atrophy from pressure and others (Fig. 9.21). Hyperostosis emerges in the case when periosteal reaction is not resorbed but gets denser and merges with the bone compact layer (Fig. 9.22 b). Hyperostosis can cover one or several bones (Garre's disease), it can be rarely generalized (ivory bones). The radiological symptoms of atrophy and periosteal reaction — Table 9.4. Periosteal reaction can emerge not earlier than 8–15 days after an acute process, variants of periosteal reactions are presented schematically in Fig. 9.23. Destruction in an X-ray image is visualized in 2–3 days. Depending on the nature of the location in relation to the bone centre destruction can be central (Fig. 9.24 b) or cortical (Fig. 9.25 b).
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Table 9.3. The radiological symptoms of atrophy and hyperostosis ATROPHY
HYPERSTOSIS
A decrease of bone substance in a unit of volume with a decrease in bone diameter
An increase of bone substance in a unit of volume with an increase in bone diameter
The compact layer is ge ng thinner with a decrease of the medullary canal Local atrophy due to pressure Concentric atrophy (accompanied by resorp on of bone substance from the periosteum side) Eccentric atrophy (accompanied by resorp on of bone substance from the endosteum side)
The compact layer is ge ng extended at the expence of periosteal bone forma on — ossifying periosteal reac on assimilated with the compact layer
Is combined with osteoporosis
Is combined with arteriosclerosis
6 Fig. 9.21. An X-ray image of the pelvis in direct projection:
1
description of the right coxal cavity, body of the right iliac bone (1) and the head of the right femur (2); atrophy of the right ischial (4), pubic (5), iliac (6) and femoral (3) bones; a pathological dislocation of the right femur
2 5
4 3
a
b
Fig. 9.22. X-ray images of the lower third of the left femur in direct projection: a) in norm; b) hyperostosis of the lower third of the left femur (the arrow)
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Table 9.4. The radiological symptoms of atrophy and periosteal reactions DESTRUCTION
PERIOSTEAL REACTION
Destruc on of bone substance and its being replaced by pathological ssue: pus, granula ons, tumor and others
The process of the perioreum density increase with calcium salts (calcifica on) deposi on, ossifica on
At the site of a ruined bone In the diaphysis and, par ally, in the metaphysic along the there emerges a defect — external contour of a bone there are various calcifica ons central or peripheral It is characterized by the localiza on, number, form, size, contours, state of surrounding ssues, presence of sequestra in a bone defect
a
b
Periosteal reacƟons emerge as a consequence of inflamma on, toxic damage and func onal-adap ve changes. The types of periosteal reac ons: linear, fringed, pec nate, lace-like. Periosteal reacƟons emerge in malignant bones tumors needle-shaped, Codman's triangle). They are charactrerized by localiza on, size, intensity, type
c
d
e
f
g
Fig. 9.23. A schematic image of variants of periosteal reactions: a) linear periosteal reaction; b) lamellar periosteal reaction; c) fringed periosteal reaction; d) lace-like periosteal reaction; e) pectinate periosteal reaction; f) needle-shaped periosteal reaction g) Codman's triangle — the arrows
162
a
b
Fig. 9.24. An X-ray image of the upper third of the shin in direct projection: a) norm, b) central destruction (the arrow) of the proximal metaepiphysis of the right tibia
a
b
Fig. 9.25. An X-ray image of the lower third of the shin in direct projection: a) norm, b) peripheral destruction (the double arrow) of the distal metadiaphysis of the left tibia, Codman's triangle (the arrow)
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Destruction can be accompanied by the presence of sequestrum. Sequestrum is a free densed fragment of a necrotized bone (as a result of the inflammatory purulent prosess). They distinguish cortical, central, penetrating and total sequestra (Fig. 9.26).
a
b
c
d
Fig. 9.26. A schematic image of sequestra types (a — cotical, b — central, c — penetrating, d — total)
Parostosis is a thickening of bone tissue which emerges as a result of calcification of soft tissues adjacent to bones (fasciae, muscles and others). The radiological symptoms of swelling and blastomatous growth — Table 9.5. Table 9.5. The radiological symptoms of swelling and blastomatous growth SWELLING
BLASTOMATOUS GROWTH
An increase of bone volume with a simultaneous decrease of bone substance in a unit of bone volume, that is bone diameter increases at the expense of pressure from the inside as a consequence of excessive growth of a benign tumor (connec ve ssue, car laginous and others) or development of a bone. The density of an area of damage is, as a rule, diminished; an increase of the density of a bone part damaged can be observed in calcifica on
A chao c conglomera on of malignant bone structures (morphologically resembling osteoblasts) in intertrabecular intervals of a bone subperiosteally as spo y shades with indis nct uneven contours of various form and size. The volume of a bone is enlarged or unchanged, the density is increased
The cor cal layer is thinned, dis nct, not interrupted
The cor cal layer is o en destroyed
No periosteal reac on
Needle-shaped or Codman's triangle
Swelling (Fig. 9.27 b) and blastomatous growth (Fig. 9.28 b).
164
Fig. 9.27. An X-ray image of the upper third of the right shin: a) norm; b) swelling (the arrow) of the proximal metaepiphysis of the right tibula
a
b
Fig. 9.28. An X-ray image of the upper third of the left humerus: a) norm; b) blastomatous growth (the arrow) in the area of the proximal epimetadiaphysis of the left humerus, Codman's triangle (the double arrow)
a
b
The symptoms of joints pathology 1. Extension of a joint space is a sign of fluid accumulation in the joint. 2. Narrowing of a joint space is a sign of joints cartilages destruction. 3. A joint bursa's getting denser testifies to its thickening as a result of edema, inflammatory processes, sclerotization, etc.
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